www.elsevier.nl/locate/ica

Inorganica Chimica Acta 299 (2000) 65–79

Influence of sterically demanding groups on the structure andstability in the solid and solution state of

(acylpyrazolonate)bis(phosphine)copper(I) derivatives

Fabio Marchetti a,*1, Claudio Pettinari a, Riccardo Pettinari a Augusto Cingolani a,Mercedes Camalli b, Riccardo Spagna b,*2

a Dipartimento di Scienze Chimiche, Uni6ersita degli Studi, 6ia S. Agostino 1, 62032 Camerino, Macerata, Italyb Istituto di Strutturistica Chimica ‘G. Giacomello’, CNR, CP 10, 00016 Monterotondo Stazione, Rome, Italy

Received 24 June 1999; accepted 27 September 1999

Abstract

New neutral derivatives [Cu(L)(PR3)2] (LH=1-phenyl-3-methyl-4-R1(C�O)-pyrazol-5-one, in detail L1H, R1=C6H5; L2H,R1=CH3; L3H, R1=CF3; L4H, R1=C6H11; L5H, R1=C6H5CH2; L6H, R1= (C6H5)2CH; R=C6H5, p-CH3C6H4, C6H5CH2 orC6H11) and [Cu(L)2] (L=L4, L5 and L6) have been synthesised and characterised by analytical and spectroscopic techniques. TheX-ray crystal and molecular structures of [Cu(L1)(PCy3)2], [Cu(L5)(PPh3)2] and [Cu(L6)(PPh3)2] have been resolved, in which thecopper atom is found in a strongly distorted tetrahedral CuO2P2 environment. The interbond angles P�Cu�P, P�Cu�O andO�Cu�O are strongly influenced by the steric properties of PR3 and also to a lesser degree by the 4-acyl moiety of the L donor.[Cu(L)(PR3)2] derivatives undergo partial dissociation in chloroform solution through breaking of Cu�P and, when R=Cy, alsoof Cu�O bonds. [Cu(L4)(PPh3)2] reacts with 1-methylimidazolin-2-thione (Hmimt), with 1,10-phenanthroline (Phen), with2,9-dimethyl-1,10-phenanthroline (Cupr) and with bis(diphenylphosphino)propane (DPPP), yielding the mixed-ligand compounds[Cu(PPh3)(Hmimt)3](L4), [Cu(L4)(PPh3)(Phen)], [Cu(Cupr)2](L4) and [Cu(DPPP)2](L4), respectively. © 2000 Elsevier Science S.A.All rights reserved.

Keywords: Copper structures; Copper complexes; Acylpyrazolone complexes

1. Introduction

The chemistry of copper(I) derivatives has receivedincreased attention over the last decades, being themetal in this intermediate oxidation state involved in anumber of very important reactions which are relevantfor biological and industrial purposes [1]. Copper(I)-diphosphino derivatives have also shown cytotoxic anti-tumor activity [2]. However, to date one of the mostpromising applications of copper(I) derivatives is theiruse as precursors in CVD techniques [3]. Among them,copper(I)-b-diketonates of general formula [Cu(b-dike)Bn ], where B is a monodentate Lewis base like

triorganophosphine, diene or alkyne, have been widelystudied by Hampden-Smith and Kodas [4]. They haveshown that [Cu(b-dike)Bn ] are able to deposit goodquality copper films on both W and SiO2 surfaces inaccordance with the thermally-induced disproportiona-tion reaction (1):

2[Cu(I)(b-dike)B]�Cu(0)+ [Cu(II)(b-dike)2]+2B (1)

We have recently started an investigation on copper(I)[5] and copper(II) [6] complexes containing a new fam-ily of b-diketonate donors, the 4-acyl-5-pyrazolones(LH) (Fig. 1): these ligands possess a heterocyclic ringfused to the chelating moiety and represent an originalvariation to classic acetylacetonates, in which respectthey can be more easily functionalised in the R1, R2 andR3 positions so as to vary their steric and electronicfeatures. Moreover, their synthesis is at a lower costwith respect to other b-diketones. Acylpyrazolones are

1*Corresponding author. Tel.: +39-737-402 217; fax: +39-737-637 345; pettinar@camserv.unicam.it (F. Marchetti)

2*Corresponding author for X-ray structures; spagna@isc.mlib.cnr.it (R. Spagna)

0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.

PII: S 0 0 2 0 -1693 (99 )00463 -6

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–7966

Fig. 1. Acylpyrazolone proligands used.

VXR-300 Varian spectrometer operating at room tem-perature. Proton chemical shifts are reported in ppmversus Me4Si while phosphorus chemical shifts are inppm versus H3PO4 85%. Melting points were deter-mined on an IA 8100 electrothermal instrument. Themagnetic susceptibilities were measured at room tem-perature (20°C) by the Gouy method, with a SherwoodScientific magnetic balance MSB-Auto, using Hg-Co(NCS)4 as calibrant and correcting for diamagnetismwith the appropriate Pascal constants. The magneticmoments (in Bohr magnetons mB=eh/2mc=9.274×10−24 JT−1) were calculated from the equation meff=2.84 (XM

corr T)1/2. (XMcorr is the molar susceptibility

corrected for diamagnetism and T is the temperature inkelvin degrees).

2.1. Synthesis

The proligands L1H, L2H and L3H were synthesisedaccording to the procedure described by Jensen [16].The proligands L4H, L5H and L6H have been synthe-sised for the first time by us, following the same proce-dure as that employed for L1H, by using C6H11COCl,C6H5CH2COCl and (C6H5)2CHCOCl, respectively, asreactants.

2.1.1. 4-Benzoyl-3-methyl-1-phenyl-pyrazol-5-one(L1H)

Yield 72%. M.p.: 92–93°C. (Found: C, 73.5; H, 5.2;N, 10.1. Anal. Calc. for C17H14N2O2: C, 73.4; H, 5.1; N,10.1%). IR (Nujol) data: 2400–2800br, n(O�H···O);1596vs, n(C�O). 1H NMR (CDCl3): d 2.11s (3H,C3�CH3); 7.25–7.34m, 7.42–7.68m, 7.86–7.93m (10H,C6H5C�O and N�C6H5); 10.5br (1H, OH ···O).

2.1.2. 4-Acetyl-3-methyl-1-phenyl-pyrazol-5-one (L2H)Yield 56%. M.p.: 70–72°C. (Found: C, 66.7; H, 5.6;

N, 12.9. Anal. Calc. for C12H12N2O2: C, 66.6; H, 5.6; N,12.9%). IR (Nujol) data: 2700–3200br, n(O�H···O);1620vs, n(C�O). 1H NMR (CDCl3): d 2.46s, 2.48s (6H,C3�CH3 and CH3C�O); 7.30t, 7.45t, 7.83d (5H,N�C6H5); 12.2br (1H, OH ···O).

2.1.3. 4-Trifluoroacetyl-3-methyl-1-phenyl-pyrazol-5-one (L3H)

Yield 85%. M.p.: 151–152°C. (Found: C, 53.4; H,3.4; N, 10.1. Anal. Calc. for C12H9F3N2O2: C, 53.3; H,3.4; N, 10.4%). IR (Nujol) data: 2700–3200br,n(O�H···O); 1673vs, n(C�O). 1H NMR (CDCl3): d

2.46q (3H, C3�CH3); 7.35t, 7.48t, 7.78d (5H, N�C6H5);11.0br (1H, OH ···O). 19F NMR (CDCl3): d −75.2.

2.1.4. 4-Cyclohexanecarbonyl-3-methyl-1-phenyl-pyrazol-5-one (L4H)

Yield 82%. M.p.: 78–80°C. (Found: C, 71.9; H, 7.2;N, 10.0. Anal. Calc. for C17H20N2O2: C, 71.8; H, 7.1; N,

bulky molecules widely employed for several applica-tions, for example as pigments for dyes [7], as metalextractants from acidic solutions [8] and also as seques-tering agents toward polluting metal ions such as cad-mium and lead [9].

The structural flexibility of acylpyrazolonato ligand(L)− often results in a better adaptability to accommo-date M�O bond length elongation or shortening, as inskewed trapezoidal bipyramidal geometries of R2SnL2

derivatives [10], in contrast to regular octahedraldiorganotin-b-diketonates [11], or in PhHgL com-pounds [12,13].

In some cases the peripheral pyridinic nitrogen atomof pyrazole participates, through weak intermolecularinteractions, in coordination of a metal [9c] or in anintermolecular hydrogen-bonding network [14]. Wehave recently reported the X-ray characterisation ofbarium(II) [15], calcium(II) and copper(II) [6] acylpyra-zolonate derivatives, whose supramolecular latticestructures are strongly influenced by the presence ofintermolecular H-bonding involving protic moleculesdirectly bonded to the metal and the above-mentionednitrogen atoms of the donors.

To gain a better understanding of the factors thataffect the bonding of acylpyrazolonato ligands to themetal and influence the stability of the complexes, weextend our investigation to the synthesis of copper(I)acylpyrazolonate derivatives [5]. Here we report theresults of the interaction of new functionalisedacylpyrazolonates (Fig. 1) with copper(I) in the pres-ence not only of sterically demanding phosphines, butalso of mono- and bidentate S- and N-donor ligands.

2. Experimental

Solvents were used as supplied or distilled usingstandard methods. The reagents were obtained fromAldrich or Fluka. Chemical analyses of the samplesdried in vacuo to constant weight (20°C, ca. 0.01 Torr)were performed using a Fisons Instruments’ 1108CHNS-O elemental analyser. IR spectra in the range4000–100 cm−1 were recorded on a Perkin–ElmerSystem 2000 FT IR spectrometer. 1H (300 MHz ) and31P NMR (121.4 MHz) spectra were measured using a

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–79 67

9.9%). IR (Nujol) data: 2300–2700br, n(O�H···O);1600vs, n(C�O). 1H NMR (CDCl3): d 2.48s (3H,C3�CH3); 1.20–1.55m, 1.60–2.00m, 2.85t (11H, C6H11-C�O); 7.28t, 7.50t, 7.85d (5H, N�C6H5); 12.2br (1H,OH ···O).

2.1.5. 4-Phenylacetyl-3-methyl-1-phenyl-pyrazol-5-one(L5H)

Yield 82%. M.p.: 104–106°C. (Found: C, 73.9; H, 5.6;N, 9.6. Anal. Calc. for C18H16N2O2: C, 74.0; H, 5.5; N,9.6%). IR (Nujol) data: 2400–2800br, n(O�H···O);1619vs, n(C�O). 1H NMR (CDCl3): d 2.53s (3H, C3�CH3); 4.09s (2H, C6H5CH2C�O); 7.12–7.48m, 7.82d(10H, C6H5CH2C�O and N�C6H5); 10.6br (1H,OH ···O).

2.1.6. 4-Diphenylacetyl-3-methyl-1-phenyl-pyrazol-5-one (L6H)

Yield 56%. M.p.: 113–115°C. (Found: C, 73.6; H, 5.2;N, 10.1. Anal. Calc. for C24H20N2O2: C, 73.4; H, 5.2; N,10.1%). IR (Nujol) data: 2700–3200br, n(O�H···O);1620vs, n(C�O). 1H NMR (CDCl3): d 2.42s (3H, C3�CH3); 5.64s (1H (C6H5)2CHC�O); 7.15–7.59m, 7.82d(15H (C6H5)2CHC�O and N�C6H5); 11.3br (1H, OH ···O).

2.1.7. (4-Benzoyl-3-methyl-1-phenylpyrazolon-5-ato)bis(tricyclohexyl-phosphine)copper(I),[Cu(L1)(PCy3)2] (1)

A benzene solution (30 ml) of the proligand L1H(0.278 g, 0.001 mol) was added to a methanolic solution(10 ml) of NaOCH3 (0.054 g, 0.001 mol) and refluxedfor 1 h. Then a benzene solution (30 ml) of [CuNO3-(PCy3)2] [17] (0.680 g, 0.001 mol) was added dropwise tothe above solution and the reaction mixture was stirredat room temperature for about 12 h. Sodium nitrate wasfiltered off and the solvent was removed under reducedpressure on a rotary evaporator. After addition ofmethanol (20 ml) a yellow powder was slowly afforded,which was filtered off and re-crystallised with CHCl3–Et2O and was shown by analysis to be compound 1.Yield 85%. M.p.: 179–181°C. (Found: C, 70.8; H, 9.0;N, 3.0. Anal. Calc. for C53H79CuN2O2P2: C, 70.6; H,8.8; N, 3.1%). IR (Nujol): 1622vs, n(C�O); 402vs,n(Cu�O). 1H NMR (CDCl3): d 1.95sbr (3H, C3�CH3);7.12t, 7.38t, 7.45m, 8.11d (10H, C6H5C�O andN�C6H5); 1.05–1.50m, 1.58–2.00m (66H, P(C6H11)3).31P NMR (CDCl3): 34.2s, 13.6s, 11.8br (20°C); 34.2s,34.1s, 29.8s, 28.5br, 13.0s, 11.8s (−50°C). Derivatives2–14 were obtained similarly, by using [CuNO3(PBz3)2],[CuNO3(P-p-tol3)2] or [CuNO3(PPh3)2] [17].

2.1.8. (4-Benzoyl-3-methyl-1-phenylpyrazolon-5-ato)-bis(tribenzylphosphine) copper(I), [Cu(L1)(PBz3)2] (2)

Yield 70%. M.p.: 121–123°C. (Found: C, 74.4; H, 5.9;N, 3.0. Anal. Calc. for C59H55CuN2O2P2: C, 74.6; H,

5.8; N, 2.9%). IR (Nujol): 1618vs, n(C�O); 408m,n(Cu�O). 1H NMR (CDCl3): d 1.98sbr (3H, C3�CH3);7.00–7.20m, 7.25t, 7.39–7.60m, 7.95d (40H, C6H5C�O,N�C6H5 and P(CH2C6H5)3); 2.78sbr (6H, P(CH2-C6H5)3). 31P NMR (CDCl3): −7.4br (20°C); −3.1s,−9.4s, −11.8s (−50°C).

2.1.9. (4-Benzoyl-3-methyl-1-phenylpyrazolon-5-ato)-bis(tri-p-tolyl-phosphine)copper(I), [Cu(L1)(P(p-tol)3)2](3)

Yield 82%. M.p.: 238–240°C. (Found: C, 74.5; H, 6.0;N, 2.9. Anal. Calc. for C59H55CuN2O2P2: C, 74.6; H,5.8; N, 2.9%). IR (Nujol): 1621vs, n(C�O); 435vs,n(Cu�O). 1H NMR (CDCl3): d 2.42sbr (3H, C3�CH3);6.92d, 7.12m, 7.30m, 7.52m, 7.78m (34H, C6H5C�O,N�C6H5 and P(4-CH3�C6H4)3); 2.30sbr (9H, P(4-CH3�C6H4)3). 31P NMR (CDCl3): −4.8br (20°C);−4.7s, −5.6s, −7.5s (−50°C).

2.1.10. (4-Acetyl-3-methyl-1-phenylpyrazolon-5-ato)-bis(tricyclohexylphosphine)copper(I), [Cu(L2)(PCy3)2](4)

Yield 78%. M.p.: 187–189°C. (Found: C, 68.5; H, 9.3;N, 3.4. Anal. Calc. for C48H77CuN2O2P2: C, 68.7; H,9.2; N, 3.3%). IR (Nujol) data: 1628vs, n(C�O); 398vs,n(Cu�O). 1H NMR (CDCl3): d 2.44sbr (6H, C3�CH3

and CH3C�O); 7.12t, 7.35t, 7.49m (5H, N�C6H5); 1.12–1.56m, 1.62–1.98m (66H, P(C6H11)3). 31P NMR(CDCl3): 33.9s, 29.4br, 11.8br (20°C); 34.0s, 29.5br, 11.9(−50°C).

2.1.11. (4-Acetyl-3-methyl-1-phenylpyrazolon-5-ato)-bis(tribenzylphosphine)copper(I), [Cu(L2)(PBz3)2] (5)

Yield 58%. M.p.: 131–134°C. (Found: C, 72.9; H, 6.1;N, 3.4. Anal. Calc. for C54H53CuN2O2P2: C, 73.1; H,6.0; N, 3.6%). IR (Nujol) data: 1622vs, n(C�O); 407m,n(Cu�O). 1H NMR (CDCl3): d 2.35sbr, 2.45sbr (6H,C3�CH3 and CH3C�O); 7.05–7.20m, 7.25t, 7.55m, 8.08d(35H, N�C6H5 and P(CH2C6H5)3); 2.75sbr (6H, P(CH2-C6H5)3

31P NMR (CDCl3): −11.9br (20°C); −2.6s,−10.3s, −11.9s (−50°C).

2.1.12. (4-Acetyl-3-methyl-1-phenylpyrazolon-5-ato)bis(tri-p-tolylphosphine)copper(I), [Cu(L2)(P(p-tol)3)2] (6)

Yield 84%. M.p.: 155–160°C. (Found: C, 72.8; H, 6.2;N, 3.7. Anal. Calc. for C54H53CuN2O2P2: C, 73.1; H,6.0; N, 3.6%). IR (Nujol) data: 1624vs, n(C�O); 433s,n(Cu�O). 1H NMR (CDCl3): d 2.20sbr, 2.45sbr (6H,C3�CH3 and CH3C�O); 6.98d, 7.12m, 7.25m, 7.54m,7.90m (29H, N�C6H5 and P(4-CH3�C6H4)3); 2.33sbr(9H, P(4-CH3�C6H4)3). 31P NMR (CDCl3): −4.3br(20°C); −4.8s, −6.0s, −7.6s (−50°C).

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–7968

2.1.13. (4-Trifluoroacetyl-3-methyl-1-phenylpyrazolon-5-ato)bis(tricyclohexyl-phosphine)copper(I),[Cu(L3)(PCy3)2] (7)

Yield 74%. M.p.: 185–186°C. (Found: C, 64.5; H, 8.4;N, 3.2. Anal. Calc. for C48H74F3CuN2O2P2: C, 64.5; H,8.3; N, 3.1%). IR (Nujol) data: 1645vs, n(C�O); 408m,n(Cu�O). 1H NMR (CDCl3): d 2.40qbr (3H, C3�CH3);7.15m, 7.36m, 7.98m (5H, N�C6H5); 1.10–1.55m, 1.60–1.95m (66H, P(C6H11)3). 31P NMR (CDCl3): 33.8s,10.8br (20°C); 33.6s, 30.0br, 11.7s, 9.2s. 7.1s (−50°C).19F NMR (CDCl3): −73.9s, −75.3s (20°C); −73.7s,−75.0s, −75.6s (−50°C).

2.1.14. (4-Trifluoroacetyl-3-methyl-1-phenylpyrazolon-5-ato)bis(tribenzyl-phosphine)copper(I), [Cu(L3)(PBz3)2](8)

Yield 66%. M.p.: 129–131°C. (Found: C, 69.0; H, 5.4;N, 3.2. Anal. Calc. for C54H50F3CuN2O2P2: C, 68.9; H,5.3; N, 3.0%). IR (Nujol) data: 1641vs, n(C�O); 364m,n(Cu�O). 1H NMR (CDCl3): d 2.42mbr (3H, C3�CH3);6.98–7.18m, 7.42m, 7.36m, 7.92m (35H, N�C6H5 andP(CH2C6H5)3); 2.78sbr (6H, P(CH2C6H5)3. 31P NMR(CDCl3): −5.8br (20°C); −2.8s, −11.7s (−50°C). 19FNMR (CDCl3): −75.2s (20°C); −74.9s, −75.0s(−50°C).

2.1.15. (4-Trifluoroacetyl-3-methyl-1-phenylpyrazolon-5-ato)bis(tri-p-tolyl-phosphine)copper(I),[Cu(L3)(P(p-tol)3)2] (9)

Yield 77%. M.p.: 202–204°C. (Found: C, 68.9; H, 5.4;N, 3.0. Anal. Calc. for C54H50F3CuN2O2P2: C, 68.9; H,5.3; N, 3.0%). IR (Nujol) data: 1642vs, n(C�O); 430m,n(Cu�O). 1H NMR (CDCl3): d 2.42mbr (3H, C3�CH3);7.02d, 7.10m, 7.25d, 7.50m, 7.84m (29H, N�C6H5 andP(4-CH3�C6H4)3); 2.35sbr (9H, P(4-CH3�C6H4)3). 31PNMR (CDCl3): −3.5br, −4.5br (20°C); −3.9s, −5.5s,−7.4s (−50°C). 19F NMR (CDCl3): −71.8s, −75.7s(20°C); −71.6s, −74.9s, −75.8s, −76.9s (−50°C).

2.1.16. (4-Cyclohexanecarbonyl-3-methyl-1-phenyl-pyrazolon-5-ato)bis(triphenyl-phosphine)copper(I),[Cu(L4)(PPh3)2] (10)

Yield 94%. M.p.: 190–191°C. (Found: C, 72.6; H, 5.9;N, 3.2. Anal. Calc. for C53H49CuN2O2P2: C, 73.1; H, 5.7;N, 3.2%). IR (Nujol): 1620vs, n(C�O); 441s, n(Cu�O).1H NMR (CDCl3): d 2.44sbr (3H, C3�CH3); 1.20–1.40m, 1.55–1.90m, 2.65mbr (11H, C6H11C�O); 7.02t,7.12–7.38m, 7.80d, 7.90d (35H, N�C6H5 and P(C6H5)3).31P NMR (CDCl3): −3.7br (20°C); −2.7s, −3.5s,−4.5s (−50°C).

2.1.17. (4-Cyclohexanecarbonyl-3-methyl-1-phenyl-pyrazolon-5-ato)bis(tricyclo-hexylphosphine)copper(I),[Cu(L4)(PCy3)2] (11)

Yield 86%. M.p.: 197–200°C. (Found: C, 70.0; H, 9.6;N, 3.3. Anal. Calc. for C53H85CuN2O2P2: C, 70.1; H, 9.4;

N, 3.1%). IR (Nujol): 1626vs, n(C�O); 449s, n(Cu�O).1H NMR (CDCl3): d 2.44sbr (3H, C3�CH3); 1.10–1.50m, 1.65–2.00m, 2.85mbr (77H, C6H11C�O andP(C6H11)3); 7.30t, 7.42t, 7.82d (5H, N�C6H5). 31P NMR(CDCl3): 33.7s, 33.5s, 11.5br (20°C); 33.9s, 33.7s, 27.7br,11.6s (−50°C).

2.1.18. (4-Benzoylacetyl-3-methyl-1-phenylpyrazolon-5-ato)bis(triphenyl-phosphine)copper(I), [Cu(L5)(PPh3)2](12)

Yield 86%. M.p.: 157–159°C. (Found: C, 73.5; H, 5.4;N, 3.3. Anal. Calc. for C54H45CuN2O2P2: C, 73.7; H, 5.2;N, 3.3%). IR (Nujol): 1621vs, n(C�O); 424s, n(Cu�O).1H NMR (CDCl3): d 2.35sbr (3H, C3�CH3); 3.68sbr(2H, C6H5CH2C�O); 6.92d, 7.05t, 7.15m, 7.25m, 7.90d(40H, N�C6H5, C6H5CH2C�O and P(C6H5)3). 31PNMR (CDCl3): −3.6br (20°C); −2.6s, −4.0s, −4.7s(−50°C).

2.1.19. (4-Benzoylacetyl-3-methyl-1-phenylpyrazolon-5-ato)bis(tricyclohexyl-phosphine)copper(I),[Cu(L5)(PCy3)2] (13)

Yield 74%. M.p.: 138–140°C. (Found: C, 70.6; H, 9.1;N, 3.2. Anal. Calc. for C55H81CuN2O2P2: C, 70.8; H, 8.9;N, 3.1%). IR (Nujol): 1632vs, n(C�O); 413m, n(Cu�O).1H NMR (CDCl3): d 2.53sbr (3H, C3�CH3); 4.03sbr(2H, C6H5CH2C�O); 1.15–1.55m, 1.60–2.04m (66H,P(C6H11)3); 7.30m, 7.37t, 7.42t, 7.80d (10H, N�C6H5 andC6H5CH2C�O). 31P NMR (CDCl3): 33.67s, 33.5s,28.2br, 11.6br (20°C); 33.79s, 33.57s, 29.2s, 11.5s, 5.8s(−50°C).

2.1.20. (4-Diphenylacetyl-3-methyl-1-phenylpyrazolon-5-ato)bis(triphenyl-phosphine)copper(I), [Cu(L6)(PPh3)2](14)

Yield 88%. M.p.: 149–152°C. (Found: C, 75.1; H, 5.3;N, 2.9. Anal. Calc. for C60H49CuN2O2P2: C, 75.4; H, 5.2;N, 2.9%). IR (Nujol): 1621vs, n(C�O); 428m, n(Cu�O).1H NMR (CDCl3): d 2.39sbr (3H, C3�CH3); 5.56sbr(1H (C6H5)2CHC�O); 7.04m, 7.10–7.56m, 7.92d(45H, N�C6H5 (C6H5)2CHC�O and P(C6H5)3). 31PNMR (CDCl3): −3.8br (20°C); −2.4s, −3.8s, −4.6s(−50°C).

Compounds 1–9, 11 and 13 can also be obtainedfrom the reaction of [Cu(L)(PPh3)2] with the appropri-ate phosphine PR3 (R=Cy, Bz or p-tol); as an examplewe report the following procedure for 1.

[Cu(L1)(PPh3)2] (0.865 g, 0.001 mol) was added to adiethyl ether solution (30 ml) of PCy3 (0.560 g, 0.002mol). The mixture was stirred overnight and a yellowprecipitate was afforded after evaporation of half of thesolvent. The precipitate was then filtered off, washedwith n-hexane (10 ml), dried to constant weight underreduced pressure and shown to be compound 1 byanalysis.

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–79 69

A further procedure for the synthesis of derivatives1–14, which involves the use of [Cu(L)2] compounds [5]is the following.

2.1.21. (4-Cyclohexanecarbonyl-3-methyl-1-phenyl-pyrazolon-5-ato)bis(triphenyl-phosphine)copper(I),[Cu(L4)(PPh3)2] (10)

[Cu(L4)2] (0.630 g, 0.001 mol) was added to anethanolic solution (60 ml) of PPh3 (0.786 g, 0.003 mol).The reaction mixture was heated to reflux for 12 h andslowly changed from the green suspension to a clearyellow solution. Then the volume was reduced on therotary evaporator until formation of a yellow powder,which was filtered off, washed with diethyl ether (10 ml)and shown to be compound 10.

2.1.22. Bis(4-cyclohexanecarbonyl-3-methyl-1-phenyl-pyrazolon-5-ato)copper(II), [Cu(L4)2] (17)

An ethanolic solution (40 ml) of L4H (0.568 g, 0.002mol) was added to a methanolic solution (10 ml) ofcopper(II) acetate monohydrate (0.200 g, 0.001 mol). Agreen precipitate was formed immediately. The reactionmixture was stirred overnight and the precipitate wasfiltered off, washed with methanol (10 ml) and shownto be compound 17. Yield 96%. M.p.: 267–269°C.(Found: C, 64.7; H, 6.2; N, 8.9. Anal. Calc. forC34H38CuN4O4: C, 64.8; H, 6.1; N, 8.9%). meff=1.92mB. IR (Nujol): 1603vs, n(C�O); 498vs, 269s, 238vs,n(Cu�O). Derivatives 15 and 16 were similarlyobtained.

2.1.23. Bis(4-diphenylacetyl-3-methyl-1-phenyl-pyrazolon-5-ato)copper(II), [Cu(L6)2] (15)

Yield 90%. M.p.: 253–255°C. (Found: C, 72.0; H,4.9; N, 7.1. Anal. Calc. for C48H38CuN4O4: C, 72.2; H,4.8; N, 7.0%). meff=1.80 mB. IR (Nujol): 1610vs,n(C�O); 476s, 465m, 263s, 237s, n(Cu�O). Derivative 15has been also obtained from interaction between[CuNO3(PCy3)2] and L6H in hot ethanol.

2.1.24. Bis(4-phenylacetyl-3-methyl-1-phenyl-pyrazolon-5-ato)copper(II), [Cu(L5)2] (16)

Yield 95%. M.p.: 264–266°C. (Found: C, 67.0; H,4.7; N, 8.6. Anal. Calc. for C36H30CuN4O4: C, 66.9; H,4.7; N, 8.8%). meff=1.79 mB. IR (Nujol): 1594vs,n(C�O); 490vs, 276vs, 259vs, n(Cu�O).

2.1.25. Tris(1-methylimidazolin-2-thione)(triphenyl-phosphine)copper(I)(4-cyclohexane-carbonyl-3-methyl-1-phenylpyrazolon-5-ato) [Cu(PPh3)(Hmimt)3](L4) (18)

To a solution of 1-methylimidazolin-2-thione(Hmimt) (0.456 g, 4 mmol) in diethyl ether (50 ml)[Cu(L4)(PPh3)2] (10) (0.870 g, 1 mmol) was added. Themixture was stirred overnight at room temperature,then filtered off, to give a yellow powder, which was

washed with Et2O (10 ml), dried to constant weightunder reduced pressure and shown to be derivative 18.Yield 85%. M.p.: 98–100°C. (Found: C, 59.2; H, 5.6;N, 11.5; S, 10.1. Anal. Calc. for C47H52CuN8O2PS3: C,59.3; H, 5.5; N, 11.8; S, 10.1%). LM (in acetone)=15.0V−1 cm2 mol−1. LM (in CH2Cl2)=0.4 V−1 cm2

mol−1. IR (Nujol): 1618vs, n(C�O). 1H NMR (CDCl3):d 2.47s (3H, C3�CH3); 1.20–1.35m, 1.75–1.94m,2.35mbr (11H, C6H11C�O); 7.25–7.58m, 7.65–7.90m(20H, N�C6H5 and P(C6H5)3); 3.49s, 3.59s, 3.75s (9H,CH3�N2C3H2SH); 6.66d, 6.75d (6H, CH3�N2C3H2SH);11.7br (6H, CH3�N2C3H2SH). 31P NMR (CDCl3):−4.9s (20°C); −4.7s, −6.6s (−50°C).

2.1.26. (4-Cyclohexanecarbonyl-3-methyl-1-phenyl-pyrazolon-5-ato)(1,10-phenanthroline)(triphenyl-phosphine)copper(I) [Cu(L4)(Phen)(PPh3)] (19)

To a solution of 1,10-phenanthroline (Phen) (0.360 g,2 mmol) in benzene (50 ml) [Cu(L4)(PPh3)2] (10) (0.870g, 1 mmol) was added. The suspension was stirredovernight at room temperature, then the light-brownprecipitate was filtered off, washed with benzene (10ml), dried to constant weight under reduced pressureand shown to be derivative 19. Yield 64%. M.p.: 140–142°C. (Found: C, 71.3; H, 5.5; N, 7.0. Anal. Calc. forC47H42CuN4O2P: C, 71.5; H, 5.4; N, 7.1%). LM (inacetone)=46.0 V−1 cm2 mol−1. LM (in CH2Cl2)=12.2V−1 cm2 mol−1. IR (Nujol): 1614vs, n(C�O); 448m,414m, n(Cu�O). 1H NMR (CDCl3): d 2.26s (3H,C3�CH3); 1.20–1.50m, 1.60–1.90m, 2.35mbr (11H,C6H11C�O); 7.10–7.80m (20H, N�C6H5 and P(C6H5)3);7.90mbr, 8.20–8.60mbr (8H, C12H8N2). 31P NMR(CDCl3): −3.4br (20°C); −3.4br (−50°C).

2.1.27. Bis(2,9-dimethyl-1,10-phenanthroline)copper(I)(4-cyclohexanecarbonyl-3-methyl-1-phenylpyrazolon-5-ato) [Cu(Cupr)2)](L4) (20)

To a solution of 2,9-dimethyl-1,10-phenanthroline(Cupr) (0.416 g, 2 mmol) in benzene (50 ml)[Cu(L4)(PPh3)2] (10) (0.870 g, 1 mmol) was added. Thesuspension was stirred overnight at room temperature,then the red precipitate was filtered off, washed withbenzene (10 ml), dried to constant weight under re-duced pressure and shown to be derivative 20. Yield70%. M.p.: 182–184°C. (Found: C, 70.9; H, 5.8; N,10.1. Anal. Calc. for C45H43CuN6O2: C, 70.8; H, 5.6; N,10.1). LM (in acetone)=78.2 V−1 cm2 mol−1. LM (inCH2Cl2)=14.3 V−1 cm2 mol−1. IR (Nujol): 1614vs,n(C�O). 1H NMR (CDCl3): d 2.47s (3H, C3�CH3);1.20–1.40m, 1.50–1.90m, 2.45mbr (11H, C6H11C�O);7.10–7.50m, 7.60–7.80m (5H, N�C6H5); 2.40s (6H, 2,9-(CH3)2�C12H6N2); 7.50d, 7.99s, 8.44d (6H, 2,9-(CH3)2�C12H6N2).

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–7970

Table 1Crystal data and structure refinement parameters for [Cu(L1)(PCy3)2] (1), [Cu(L5)(PPh3)2] (12) and [Cu(L6)(PPh3)2] (14)

[Cu(L6)(PPh3)2][Cu(L5)(PPh3)2][Cu(L1)(PCy3)2].CHCl3

C54H80Cl3CuN2O2P2 C54H45CuN2O2P2 C60H49CuN2O2P2Empirical formula1021.09Formula weight 879.45 955.55

Crystal size (mm) (0.45×0.25×0.25) (0.80×0.20×0.25) (0.35×0.20×0.15)293Temperature (K) 2932930.71069Wavelength (A, ) 0.71069 0.71069triclinicCrystal system Triclinic TriclinicP1(Space group P1( P1(

Unit cell dimensions10.588(6)A (A, ) 12.545(3) 9.754(2)

b (A, ) 12.085(6) 12.673(5) 12.772(2)16.117(7)c (A, ) 21.405(3)22.957(13)

102.88(4)a (°) 77.27(3) 81.32(1)b (°) 97.37(5) 68.19(3) 86.71(1)g (°) 82.91(1)74.27(2)104.68(4)

2269.2(1.5) 2613.8(7)2716.4(2.6)V (A, 3)2Z 2 21.249Dcalc (Mg m−3) 1.288 1.215

0.617Absorption coefficient (mm−1) 0.665 0.5411088F(000) 916 996

1.62°BuB27.56°1.68°BuB27.56°Data collection range 1.80°BuB27.57°05h513; −155k515;Index ranges 05h59; −165k515; 05h512; −165k516;−295l529 −205l519 −275l527

140978245Reflections collected 1364412544 (Rint=0.062) 7504 (Rint=0.042) 12051 (Rint=0.053)Independent reflections (Rint)2795 2316 4945Observed reflections [I\3s(I)]577Parameters refined 550 649

a, b, c in the weighting scheme 0.00436, 0.12862, 0.002110.04375, 0.15756, 0.00721 0.02040, 0.00689, 0.00001w=1.0/(a+bFo+cFo

2)R=0.073; wR=0.092Final R a indices R=0.039; wR=0.048 R=0.062; wR=0.081

Goodness of fit (S) b 0.9920.938 0.7390.004 0.03(D/s)max 0.020.31 0.93Drmax (e A, −3) 1.11

Drmin (e A, −3) −0.76−0.20−0.57

a R=���Fo�−�Fc��/�Fo; wR={�w(�Fo�−�Fc�)2/�w �Fo�2}1/2.b s={�w(�Fo�−�Fc�)2/(Nrefl−Nparam)}1/2.

2.1.28. Bis[bis(diphenylphosphine)propane]copper(I)(4-cyclohexanecarbonyl-3-methyl-1-phenylpyrazolon-5-ato) [Cu(DPPP)2)](L4) (21)

To a solution of bis(diphenylphosphino)propane(DPPP) (0.824 g, 3 mmol) in acetonitrile (50 ml)[Cu(L4)(PPh3)2] (10) (0.870 g, 1 mmol) was added. Themixture was stirred overnight at room temperature. Acolourless precipitate was obtained, which was filteredoff, washed with acetonitrile (10 ml), dried to constantweight under reduced pressure and shown to be deriva-tive 21. Yield 84%. M.p.: 120–121°C. (Found: C, 72.5;H, 6.2; N, 2.2. Anal. Calc. for C71H71CuN2O2P4: C,72.8; H, 6.1; N, 2.4%). LM (in acetone)=64.7 V−1 cm2

mol−1. LM (in CH2Cl2)=14.1 V−1 cm2 mol−1. IR(Nujol): 1622vs, n(C�O). 1H NMR (CDCl3): d 2.47s(3H, C3�CH3); 1.20�1.40m, 1.50–1.85m, 2.40mbr (11H,C6H11C�O); 7.10–7.40m, 7.60–7.80m (45H, N�C6H5

and 1,3-[P(C6H5)2]2C3H6)2); 2.25s, 2.30br (6H, 1,3-[P(C6H5)2]2C3H6)2). 31P NMR (CDCl3): −8.9br.−13.3br (20°C); 2.8br, −9.9br, −11.8s, −12.3s,

13.2br (−50°C). The compounds (4-benzoyl-3-methyl-1-phenylpyrazolon - 5 - ato)bis(triphenylphosphine)-copper(I) [Cu(L1)(PPh3)2] and (4-acetyl-3-methyl-1-phenylpyrazolon - 5 - ato)bis(triphenylphosphine)copper-(I) [Cu(L2)(PPh3)2], were prepared according to theliterature [5]. 31P NMR (CDCl3) of [Cu(L1)(PPh3)2]:−4.6 (20°C); −3.9 (−50°C). 31P NMR (CDCl3)of [Cu(L2)(PPh3)2]: −3.6 (20°C); −2.7, −3.9, −4.6(−50°C).

2.2. Structure determination

Crystal and experimental data are summarised inTable 1. Crystals of the compounds, obtained from achloroform solution of 1, 12 and 14, were mounted ona Siemens P3 automatic four-circle diffractometer usinggraphite monochromatic Mo Ka radiation (l=0.71069A, ). The cell parameters were refined by least-squaresfrom the angular positions of 35 reflections in the range9.28B2uB23.19° for 1, of 21 reflections in the range

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–79 71

5.19B2uB23.22° for 12 and of 37 reflections in therange 4.70B2uB22.99° for 14, respectively. The datawere measured at room temperature for 3.0B2uB56.0° using a u/2u scan technique. The scan ratewas automatically chosen according to the peakintensity in the range 3.0–15.0° min−1 and thebackground counts were taken with stationary crystalsat each end of the scan and a total background time toscan time ratio of 0.5.

The data were processed to yield values of I and s(I).The intensity of three standard reflections, measuredevery 97 reflections throughout the data collection,shows no decay. The values of I and s(I) werecorrected for Lorentz, polarisation and shape aniso-tropy [18] effects. The observed reflections wereprocessed by the direct methods program SIR97 [19],which provided the complete structure. All non-hydrogen atoms were refined by full-matrix least-squares methods with anisotropic thermal parameters.The hydrogen atoms were idealised (C�H=0.96 A, )[20]. Each H atom was assigned the equivalent isotropictemperature factor of the parent atom and allowed toride on it. The final difference Fourier map, with aroot-mean-square deviation of electron density of 0.10and 0.04 e A, −3 for 1 and 12, respectively, showed nosignificant features. For compound 14, the differenceFourier map showed five peaks, but attempts tointerpret them as a disordered molecule of solvent wereunsuccessful. Nevertheless, introducing these peaks ascarbon lowered the R by a factor of more than twounits. The root-mean-square deviation of electrondensity of the final difference Fourier map was 0.08 eA, −3. Atomic scattering factors were taken from Ref.[21]. Calculations were performed on the DEC 3500AXP of Istituto di Strutturistica Chimica CNR, usingthe SIR CAOS [22] and SIR97 [19] structure determinationpackage.

3. Results and discussion

3.1. Synthesis of the copper compounds

The triorganophosphine-copper(I) derivatives[Cu(L)(PR3)2] 1–14 have been synthesised in goodyields from the reaction between the sodium salt of theacyl-pyrazolone ligand and [CuNO3(PR3)2] in benzeneat room temperature.

NaL+ [CuNO3(PR3)2]����Benzene

[Cu(L)(PR3)2]+NaNO3

1–14 (2)

(L=L1, L2, L3, L4, L5 or L6; R=Ph, Cy, Bz or p-tol).It was not possible to synthesise [Cu(L6)(PCy3)2] in

the same reaction conditions, the green paramagneticcupric complex [Cu(L6)2] (15) being recovered from themixture reaction.

Derivatives 1–9 can also be prepared from the tri-organophosphine displacement reaction (3).

[Cu(L)(PPh3)2]+2PR3�EtO2

[Cu(L)(PR3)2]+2PPh3 (3)1–9

(L=L1, L2 or L3; R=Cy, Bz or p-tol).Derivatives 1–14 are pale yellow or colourless solids,

very soluble in most organic solvents, insoluble inalcohols and aliphatic hydrocarbons. Chlorinated solu-tions of 1–14 slowly changed colour from yellow toblue–green after several days, indicating oxidation ofcopper(I) to copper(II). The interaction between LHand Cu(O2CCH3)2

. H2O in ethanol produced the cupricderivatives 15–17:

2LH+Cu(O2CCH3)2·H2O ��EtOH

[Cu(L)2]+2H2O

+CH3COOH (4)

(L=L6, L5 or L4).Compounds 15–17 are green, paramagnetic, high-

melting solids and are very stable to air. They slowlyabsorb molecules of water from the atmosphere yield-ing monohydrate [Cu(L)2(H2O)] complexes, for whichaccording to literature [5], a distorted square-pyramidalcopper environment has been proposed.

The water molecule can be easily removed by heatingabove 100°C, the anhydrous derivatives 15–17 beingrecovered. As previously found [5] compounds 1–14can be obtained by reaction of [Cu(L)2] species with anexcess of PR3.

Conductivity measurements in dichloromethane andacetonitrile indicate that derivatives 1–17 are not elec-trolytes in these solvents.

3.2. Spectroscopy

3.2.1. IRSelected relevant infrared absorptions are given in

Section 2. In the Cu(I) derivatives 1–14 the n(C�O) andn(Cu�O) bands [5,6,23] fall, respectively at higher andlower frequencies, with respect to Cu(II) derivatives15–17. In derivatives 7–9 the presence of a strongelectron-withdrawing group such as CF3 in the 4-acylmoiety of the ligand (L3)−, produces a shift of then(C�O) to higher frequencies with respect to all theother Cu(I) compounds.

3.2.2. NMRThe 1H NMR spectra of free neutral proligands and

those of the corresponding copper(I) derivatives arealso given in Section 2. The disappearance of the broad(O�H) absorption at approximately 10–12 ppm, due tothe enolic proton O�H in the free proligands, confirmsthat acyl-pyrazolonates act in the monoanionic form incomplexes 1–14. All the 1H NMR spectra generallyexhibit broad resonances at room temperature for bothacylpyrazolonato and phosphine protons, suggesting

15–17

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–7972

Fig. 2. 31P NMR at variable temperature of derivative 7.

the occurrence of a fast equilibrium in CDCl3 solutioninvolving breaking and formation of Cu�P and/orCu�O bonds. Variable temperature 31P NMR investiga-tions are in accordance with the same equilibrium (Fig.2): in fact the broad signals at room temperature wereresolved in several sharp absorptions at lowtemperature.

It has been found that the behaviour of[Cu(L)(PR3)2] in solution is strongly influenced by the

nature of the PR3 phosphine bonded to the copper.All the derivatives containing PCy3 as ligand, whichis more basic but also more hindered then PPh3,PBz3 or P-p-tol3 [24], are extensively dissociated insolution. In fact at low temperature in the 31P NMRspectra of 1, 4, 7, 11 and 13, five different signalshave been detected, most likely due to CuO2P2, CuO2P,CuOpP2 and CuOsP2 species and to free PCy3

(Fig. 2).

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–79 73

The triaryl phosphine-copper derivatives 2, 3, 5, 6, 9,10, 12 and 14, undergo partial dissociation; the 31PNMR spectra exhibit three signals in accordance withequilibrium (5):

[Cu(L)(PR3)2] X [Cu(L)(PR3)]+PR3 (5)

(R=Ph, Bz or p-tol).Only in the 31P NMR spectrum of compound

[Cu(L3)(PPh3)2] (8) two resonances are found, none ofthem corresponding to free PR3; for this compound thebreaking of only one Cu�O bond has been hypothesised[6].

The 19F spectra of derivatives 7–9 containing thefluorinated (L3)− donor, carried out at room tempera-ture and at −50°C, are in accordance with the signalmultiplicity found in the 1H and 31P NMR spectra (Fig.3).

It can be observed that steric and electronic featuresof the O2-donors also determine the stability in solutionof [Cu(L)(PR3)2] species. For example, by comparisonof the PPh3-copper(I) derivatives, breaking of the Cu�Obond was found only when the O2-donor possesses CF3

or CH2C(CH3)3 groups on the acyl-moiety. Breaking ofthe Cu�P bond has been observed in all other com-pounds, with the exception of [Cu(L1)(PPh3)2] [5],which is not dissociated in chloroform solution, only aresonance in the 31P NMR spectrum being found alsoat low temperature.

We also investigated the reactivity of the derivative[Cu(L4)(PPh3)2] (10) towards several mono- or biden-tate N-, P- and S-donor ligands (Scheme 1). The reac-tion of 10 in Et2O with an excess of an S-donor like1-methyl-imidazolin-2-thione (Hmimt) yielded the ionic

Scheme 1.

derivative [Cu(PPh3)(Hmimt)3](L4) (18), in which theacylpyrazolonate plays the role of the counterion. Thisderivative is analogous to [Cu(PPh3)(Hmimt)3]X com-pounds (where X=ClO4 or BF4) previously reported[25]. In solution the equilibrium (6) can be hypothesisedon the basis of conductivity data in dichloromethaneand also on variable temperature 31P NMR investiga-tion in chloroform-d3:

[Cu(PPh3)(Hmimt)3]+ (L4)− X [Cu(L4)(Hmimt)2]

+PPh3+Hmimt (6)

The 31P NMR spectrum of compound 18 exhibits atroom temperature a broad signal at −4.5 ppm, whichis split at −50°C into two sharp resonances at −4.7and −6.6 ppm. That at −4.7 ppm is due to free PPh3

ligand.Bidentate N2-donor ligands such as 1,10-phenanthro-

line (Phen) or 2,9-dimethyl-1,10-phenanthroline (Cupr)reacted in acetonitrile with derivative 10 yielding thecompounds [Cu(L4)(PPh3)(Phen)] (19) and [Cu(-Cupr)2](L4) (20), respectively (Fig. 4). Compound 19 ispartially dissociated in solution: broad signals for eachequivalent proton group of Phen in the 1H NMR and abroad resonance for the phosphorus nucleus of thecoordinated PPh3 (−3.4 ppm) in the 31P NMR spec-trum, also at low temperature, are observed.

From the reaction of derivative 10 with the P2-donors bis(diphenylphosphino)ethane (DPPE) and bis(-diphenylphosphino)ferrocene (DPPF) in acetonitrile,chloroform or benzene, no adducts were obtained. Inall cases the starting reactants were recovered from thereaction mixture. However, in the case of the reactionof bis(diphenylphosphino)propane (DPPP) with 10 the1:1 ionic compound [Cu(DPPP)2](L4) (21) (Fig. 4) isformed. The 31P NMR of 21 at −50°C shows severalbroad signals, also suggesting that this complex par-tially dissociates in solution through the breaking ofCu�P bonds.Fig. 3. 19F NMR at −50°C of derivative 8.

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–7974

Table 2Selected bond distances (A, ) and angles (°) for compounds 1, 12 and14.

[Cu(L5)(PPh3)2][Cu(L1)(PCy3)2] [Cu(L6)(PPh3)2]

Bond distances2.248(2)Cu�P(1) 2.243(4) 2.240(2)

2.255(4) 2.280(3) 2.245(2)Cu�P(2)2.16(1)Cu�O(1) 2.074(6) 2.075(5)

Cu�O(2) 2.16(1) 2.105(7) 2.110(4)

Bond angles137.5(2) 120.0(1)P(1)�Cu�P(2) 126.76(7)

O(1)�Cu�O(2) 87.4(4) 88.1(3) 89.1(2)O(1)�Cu�P(1) 98.4(3) 115.6(1) 102.2(1)

111.5(2)O(1)�Cu�P(2) 117.0(2) 119.0(1)111.2(2)O(2)�Cu�P(1) 114.6(1)109.9(2)

99.2(1)101.1(2)O(2)�Cu�P(2) 97.2(2)

of 87.4°. The degree of distortion decreases on goingfrom 1 to [Cu(L6)(PPh3)2] (14), the [Cu(L5)(PPh3)2] (12)being in an intermediate position. The P�Cu�P anglesare 126.76° in 14 and 120.0° in 12, whereas theO�Cu�O angles are similar, 89.1° in 14 and 88.1° in 12.The Cu�P distances fall in the range typical for othercopper(I)-phosphine derivatives [5,26], with those in 1slightly shorter than those in 2 and 3, according to thehigher s-donating ability of PCy3 with respect to PPh3.

The Cu�O distances are equal for 1, within theexperimental error of the data, but slightly different for12 and 14, where the acyl-pyrazolonates are moreasymmetric. By comparing the O(2)�Cu�P(1) angles ofderivatives 1, 12 and 14, the repulsion exerted by thebulky acyl-moiety of the ligand (L6)− can be seen, thevalue of this angle being 114.6°, whereas those in 1 andin 12 are lower (109.9 and 111.2°). Another difference isfound for the angle O(1)�Cu�P(1): in derivative 12 it ismore than 12° higher with respect to the other ones.These features may be due to the different steric hin-drance of b-diketonate donors and also to reticularpacking forces.

A significant difference was found in the dihedralangles between the pyrazole ring and its phenyl inposition 1: in 1 the two rings are almost coplanar, thisangle being 9.9°, whereas in 12 and 14 a greater devia-tion was observed, the dihedral angles being 20.9 and27.3°, respectively.

The distances and angles in the acyl-pyrazolonatesare similar to those previously found in other com-plexes containing similar O2-donors. From a compara-

3.3. Crystal structures

For derivatives [Cu(L1)(PCy3)2] (1), [Cu(L5)(PPh3)2](12) and [Cu(L6)(PPh3)2] (14), we have carried out anX-ray study (relevant crystal data and interatomic dis-tances and angles are reported in Tables 1 and 2,respectively). Their perspective drawings are shown inFigs. 5–7.

All three derivatives, 1, 12 and 14, are monomericwith a four-coordinate copper by two P atoms oftriorganophosphine ligands and two O atoms of theanionic b-diketonate. Compound [Cu(L1)(PCy3)2] is themost distorted from tetrahedral geometry, with aP�Cu�P angle of 137.5° and the acyl-pyrazolonate ‘bite’

Fig. 4. Structures hypothesised for derivatives 18–21.

F.

Marchetti

etal./

InorganicaC

himica

Acta

299(2000)

65–

7975

Table 3Selected structural data of several metal-acylpyrazolonato derivatives

C2�C3 C3�O2 O1�M�O2 M�O1�C1 M�O2�C3 O1�C1�C2Compound a C1�C2�C3Ref. C2�C3�O2M�O1 M�O2 O1�C1 C1�C2

1.45(2) 1.24(2) 87.4(4) 120.9(7) 128.2(8) 133(1)1.22(2) 123(1)1.45(2) 124(1)2.16(1)2.16(1)b[Cu(L1)(PCy3)2]1.28(1) 1.44(1) 1.41(2) 1.27(1) 88.1(3) 119.7(6) 126.0(8) 132.2(9) 122.8(7) 123.1(9)2.074(6)[Cu(L5)(PPh3)2] 2.105(7)b

1.412(9) 1.243(7) 89.1(2) 122.3(4) 127.9(4) 131.8(6)1.441(8) 123.0(5)b 124.7(5)[Cu(L6)(PPh3)2] 1.256(7)2.110(4)2.075(5)1.41(1)[5] 1.40(1) 1.26(1) 87.8(3) 122.9(6) 127.9(7) 131.4(9) 122.0(8) 127.0(9)2.109(7) 2.075(7) 1.26(1)[Cu(L3)(PPh3)2]

1.279(5) 1.414(6) 1.394(7) 1.266(6) 92.95(13) 122.0(3) 129.9(3) 130.5(4) 122.5(4) 121.7(4)1.911(3)[Cu(L7)2(H2O)] 1.938(3)[6]1.414(6) 1.262(5) 92.50(13) 121.2(3) 129.8(3) 131.1(4)1.414(6) 133.0(4)1.956(3) 120.9(4)1.281(5)1.923(3)

1.432(3)[6] 1.429(3) 1.244(3) 75.97(6) 129.47(14) 140.2(2) 131.3(2) 122.6(2) 120.2(2)2.291(2) 2.290(2) 1.262(2)[Ca(L7)2(EtOH)2]1.426(3) 1.245(3) 76.33(6) 129.78(14) 138.34(14) 131.2(2) 122.4(2) 121.2(2)2.293(2) 2.310(2) 1.254(3) 1.441(3)1.402(5) 1.269(4) 90.82(9) 120.6(2) 127.8(1) 131.2(3)1.421(4) 124.7(3)[27] 123.5(3)[Rh(L2)(COD)] 1.274(3)2.061(2)2.054(2)

1.428(7)[28] 1.399(7) 1.267(6) 88.6(1) 123.4(3) 131.3(3) 130.3(5) 122.6(5) 121.4(4)2.013(4) 2.030(4) 1.274(6)[Fe(L2)3][28] 1.406(10) 1.400(10) 1.275(8) 87.9(2) 122.6(4) 130.2(5) 129.6(6) 123.1(6) 120.9(6)1.983(5) 2.016(5)[Fe(L8)3] 1.285(8)

1.449(12) 1.237(10) 78.3(3) 119.4(6) 121.7(7) 130.3(7)1.420(13) 124.6(9)[12] 122.2(9)[PhHg(L1)] 1.289(10)2.585(9)2.087(7)1.40(1)[29] 1.43(1) 1.265(9) 80.5(2) 122.2(5) 129.6(5) 131.8(7) 123.0(7) 121.4(8)2.141(5) 2.296(6) 1.293(9)[Sn(L2)2]

1.42(1) 1.28(1) 79.6(2) 122.7(5) 128.1(5) 130.8(7) 123.8(7) 120.5(8)2.133(5) 2.313(6) 1.277(9) 1.43(1)1.37(2) 1.28(2) 84.5(4) 124.0(9) 129.6(9) 130(1)1.43(2) 132(1)[10d] 123(1)[Ph2Sn(L9)2] 1.30(1)2.223(8)2.12(1)

1.42(2) 1.39(2) 1.28(1) 85.1(3) 119.7(9) 127.1(8) 131(1) 125(1) 115(1)2.143(7) 2.26(1) 1.29(2)1.41(1) 1.26(1) 79.8(2) 129.1(5) 132.0(6) 131.7(7) 123.6(7)[But

2Sn(L1)2] 121.1(8)[10a] 2.145(5) 2.381(7) 1.292(9) 1.42(1)1.41(1) 1.27(1) 79.3(2) 130.5(5) 128.7(6) 130.2(8)1.42(1) 124.6(8)2.461(6) 123.0(8)1.286(9)2.135(6)

1.410(7)[10b] 1.401(6) 1.266(6) 80.9(1) 124.5(3) 130.8(3) 132.2(4) 123.2(4) 122.1(4)2.104(3) 2.337(4) 1.306(5)[Me2Sn(L1)2]1.401(6) 1.259(7) 80.7(1) 128.9(3) 128.5(3) 132.3(4) 123.9(4) 122.0(4)2.103(4) 2.412(4) 1.284(6) 1.422(5)1.37(3) 1.31(3) 72.0(7) 133(2) 141(2) 128(2)1.44(3) 126(2)2.39(2) 118(2)[UO2(L2)(H2O)] [30] 2.33(2) 1.26(3)1.30(4) 1.34(3) 73.2(7) 129(2) 135(2) 131(2) 123(2) 125(2)2.31(2) 2.41(2) 1.34(3) 1.39(4)

(continued)

F.

Marchetti

etal./

InorganicaC

himica

Acta

299(2000)

65–

7976

Table 3 (Continued)

C1�C2Ref. C2�C3 C3�O2 O1�M�O2 M�O1�C1 M�O2�C3 O1�C1�C2 C1�C2�C3 C2�C3�O2M�O1 M�O2 O1�C1Compound a

1.47(7) 1.20(6) 73.0(9) 122(2) 134(3)[UO2(L1)(PrOH)] 136(5)[30] 113(4) 128(5)2.36(2) 2.34(3) 1.22(6) 1.42(7)1.42(7) 1.23(6) 72(1) 136(3) 137(3) 123(4)1.46(6) 124(4) 121(5)1.28(5)2.40(3)2.26(3)

1.41(1)[31] 1.39(1) 1.26(1) 72.0(2) 131.4(6) 138.9(6) 130(1) 121.8(9) 121.8(9)2.325(7) 2.403(6) 1.28(1)[UO2(L1)(DMSO)]1.40(1) 1.27(1) 71.8(2) 131.9(7) 134.5(7) 128(1) 123(1) 121(1)2.350(7) 2.388(7) 1.27(1) 1.42(1)1.42(2) 1.26(2) 75.6(4) 123(1) 130(1) 132(1)1.41(2) 124(1)2.422(11) 122(1)1.28(2)[Pb(L2)2] c [9b] 2.367(11)

1.421(5)[9b] 1.426(5) 1.248(5) 76.8(5) 122.8(2) 130.1(2) 132.2(3) 124.2(3) 122.5(3)2.305(3) 2.446(3) 1.275(5)[Pb(L8)2] c

1.442(24) 1.241(22) 76.4(4)[Tb(L10)3(H2O)2] [32] 2.304(12) 2.345(11) 1.271(20) 1.385(21)1.411(26) 1.233(24) 75.4(4)1.381(24)1.273(22)2.362(14)2.313(12)

1.389(24) 1.463(27) 1.216(22) 74.5(4)2.332(14) 2.372(2) 1.284(21)1.314(8) 1.247(9) 82.0(2){[Ph3Sb(L1)]2O} [33] 2.205(5) 2.208(5)

1.256(9) 78.7(2)1.275(9)2.392(5)2.208(5)1.433(6)[15] 1.412(7) 1.246(6) 66.79(11) 129.6(3) 139.3(3) 130.7(4) 123.1(4) 121.5(4)2.575(3) 2.625(3) 1.267(5)[Ba2(L7)4(H2O)4]

1.426(6) 1.269(6) 59.00(9) d 115.1(3) d 120.2(3) d 130.3(4) 122.1(4) 120.2(4)2.822(3) d 2.819(4) d 1.266(6) 1.429(7)56.90(9) d 116.8(3) d 121.8(3) d2.948(3) d2.881(3) d

1.439(5)[15] 1.438(4) 1.248(4) 64.81(7) 132.5(2) 139.8(2) 132.9(3) 122.4(3) 121.7(3)2.644(2) 2.753(2) 1.253(4)[Ba(L7)2(phen)2]1.255(4) 1.430(6) 1.426(7) 1.241(5) 64.42(9) 133.8(3) 138.5(3) 131.2(4) 123.4(4) 122.5(4)[15][Ba(L7)2(tetraglyme)] 2.665(3) 2.751(3)

1.441(6) 1.245(5) 65.60(8) 132.4(2) 142.4(2) 132.4(4)1.425(6) 123.1(4)2.682(3) 121.8(4)1.262(5)2.718(3)1.434(9)[34] 1.462(9) 1.245(7) 133.1(6) 123.4(5) 120.4(5)1.233(8)L1H

1.319(5) 1.386(6) 1.433(6) 1.256(6) 106(3) 104(2) 127.8(4) 120.1(4) 118.1(4)[28]L8H 0.89(5) 1.81(5)

a The donors L1–L6 have been explained in Fig. 1, whereas L7=3-methyl-1-phenyl-4-tertbutylacetyl-pyrazolon-5-ato; L8=3-methyl-1-phenyl-4-butanoyl-pyrazolon-5-ato; L9=3-methyl-1-phenyl-4-(4-bromobenzoyl)-pyrazolon-5-ato; L10=3-methyl-1-phenyl-4-propionyl-pyrazolon-5-ato.

b This work.c Average values (there are three distinct asymmetric units in [Pb(L2)2]).d Bridging acylpyrazolonate.

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–79 77

Fig. 5. Molecular structure of derivative [Cu(L1)(PCy3)2] (1).

Fig. 6. Molecular structure of derivative [Cu(L5)(PPh3)2] (12).

Fig. 7. Molecular structure of derivative [Cu(L6)(PPh3)2] (14).

Scheme 2.

than those found in the neutral enolic 4-acylpyrazoloneligands and are of the same order of magnitude as thosefound in the ketonic form of 1-phenyl-3-methyl-4-ben-zoyl-pyrazol-5-one. We also noted that the Cu�O dis-tances are higher in Cu(I) than in Cu(II) derivatives andthat they are dependent on the basicity and sterichindrance of the supporting ligand. The M�O2�C3 andO2�C3�C2 angles in Cu(I) derivatives are, respectivelylower and higher with respect to all the other metalacylpyrazolonates, whereas the C1�C2�C3 angles donot vary significantly. Finally the C1�C2 and C2�C3bond distances in the Cu(I) derivatives are significantlylonger than those in derivatives containing hard accep-tors such as organotin(IV) and iron(III) centres, andare of the same order of magnitude as those found inthe neutral ketonic free ligand. This seems to indicate

tive investigation (Table 3) on the structural data ofmetal derivatives containing the acylpyrazolonato lig-ands [5,6,9b,10a,b,d,12,15,26–34] (Scheme 2), severalempirical trends emerge: the lowest C�O bond lengths,which suggest a weaker interaction between the O andthe metal, are found in the Cu(I) derivatives[Cu(L)(PR3)2]. The C�O bond lengths are also shorter

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–7978

that the coordination of the O2-donor 4-acylpyra-zolonate to a hard acceptor such as tin(IV) producesgreater changes in the molecular parameters with re-spect to those produced from a soft acceptor such asCu(I).

4. Conclusions

New copper acylpyrazolonato derivatives of generalformula [Cu(L)(PR3)2] have been synthesised, contain-ing b-diketonato and phosphine donors with differentsteric and electronic features. The bulkiness of theO2-donors and of the phosphines is important in theformation and stability of these derivatives. For exam-ple, the hindered PCy3 and the donor (L6)− did notallow the synthesis of the compound [Cu(L6)(PCy3)2].These complexes undergo partial dissociation in chloro-form solution through the breaking of Cu�P and/orCu�O bonds. The degree of dissociation is influencednot only by the steric hindrance of the phosphine,but also by the steric and electronic features of acyl-pyrazolonate donors. The X-ray determinations of[Cu(L1)(PCy3)2], [Cu(L5)(PPh3)2] and [Cu(L6)(PPh3)2]show the copper four-coordinate in a skewed tetrahe-dral environment. The distortion is mainly due to thesteric demand of phosphine donor ligands. S-, P2- andN2-donor ligands such as Hmimt, Phen, Cupr andDPPP, are able to partially or completely displace PR3

donors from the copper coordination sphere, affordingnew neutral or ionic mixed ligand complexes.

5. Supplementary material

Tables of atomic coordinates, isotropic equivalentthermal parameters, structure factors, bond lengths,angles and anisotropic displacement parameters areavailable on request from one of the authors. Crystallo-graphic data for the structural analysis have been de-posited with the Cambridge Crystallographic DataCentre. Copies of this information may be obtainedfree of charge from: The Director, CCDC, 12 UnionRoad, Cambridge, CB2 1EZ, UK (fax: +44-1223-336033; email: deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).

Acknowledgements

Financial support by Carima Foundation for a grantto Dr R. Pettinari, Universita degli Studi di Camerino,Consiglio Nazionale delle Ricerche CNR, Rome.

References

[1] (a) H.B. Gray, E.I. Solomon, in: T.G. Spiro (Ed.), CopperProteins, Wiley-Interscience, New York, 1981 (Chapter I). (b) H.Sigel (Ed.), Metal ions in biological systems, Copper Proteins,vol. 13, Marcel Dekker, New York, 1981. (c) G. La Monica,M.A. Angaroni, G.A. Ardizzoia, J. Organomet. Chem. 1988,348, 279 and references therein.

[2] S.J. Berners-Price, R.K. Johnson, C.K. Mirabelli, L.F. Faucette,F.L. McCabe, P.J. Sadler, Inorg. Chem. 1987, 26, 3383 andreferences therein.

[3] A. Maverick, G.L. Griffin, in: T.T. Kodas, M.J. Hampden-Smith (Eds.), The Chemistry of Metal CVD, VCH, Weinheim,1994 (Chapter 4) and references therein.

[4] M.J. Hampden-Smith, T.T. Kodas, Polyhedron 14 (1995) 699and references therein.

[5] F. Marchetti, C. Pettinari, A. Cingolani, D. leonesi, M. Camalli,A. Pifferi, Polyhedron 15 (1996) 3835.

[6] F. Marchetti, C. Pettinari, A. Cingolani, D. Leonesi, A. Droz-dov, S.I. Troyanov, J. Chem. Soc., Dalton Trans. (1998) 3325.

[7] K. Venkataraman, The Chemistry of Dyes, vol. 1, AcademicPress, New York, 1952.

[8] (a) Y.A. Zolotov, N.M. Kuzmin, in: Metal Extraction withAcylpyrazolones, Izdat Nauka, Moscow, 1977. (b) E.C. Okafor,Z. Naturforsch., Teil B, 36 (1981) 213. (c) S. Umetani, H.Freiser, Inorg. Chem. 26 (1987) 3179. (d) E.C. Okafor, B.A.Uzoukwu, Radiochim. Acta 51 (1990) 167.

[9] (a) S. Umetani, S. Kihara, M. Matsui, Anal. Chim. Acta 232(1990) 293. (b) B.A. Uzoukwu, P.U. Adiukwu, S.S. Al-Juaid,P.B. Hitchcock, J.D. Smith, Inorg. Chim. Acta 250 (1996) 173.(c) B.A. Uzoukwu, P.U. Adiukwu, Synth. React. Inorg. Met.-Org. Chem. 27 (1997) 187.

[10] (a) C. Pettinari, G. Rafaiani, G. Gioia Lobbia, A. Lorenzotti, F.Bonati, B. Bovio, J. Organomet. Chem. 405 (1991) 75. (b) B.Bovio, A. Cingolani, F. Marchetti, C. Pettinari, J. Organomet.Chem. 458 (1993) 39. (c) C. Pettinari, F. Marchetti, D. Leonesi,M. Rossi, F. Caruso, J. Organomet. Chem. 483 (1994) 123. (d)F. Caruso, D. Leonesi, F. Marchetti, E. Rivarola, M. Rossi, V.Tomov, C. Pettinari, J. Organomet. Chem. 519 (1996) 29. (e) C.Pettinari, F. Marchetti, A. Gregori, A. Cingolani, J. Tanski, M.Rossi, F. Caruso, Inorg. Chim. Acta 257 (1997) 37. (f) C.Pettinari, F. Marchetti, A. Cingolani, A. Lorenzotti, E. Mun-dorff, M. Rossi, F. Caruso, Inorg. Chim. Acta 262 (1997) 33. (g)C. Pettinari, F. Marchetti, A. Cingolani, D. Leonesi, E. Mun-dorff, M. Rossi, F. Caruso, J. Organomet. Chem. 557 (1998)187.

[11] (a) G.A. Miller, E.O. Schlemper, Inorg. Chem. 12 (1977) 677. (b)G. Poli, C.J. Cheerand, W.H. Nelson, J. Organomet. Chem. 306(1986) 347.

[12] M.F. Mahon, K.C. Molloy, B.A. Omotowa, M.A. Mesubi, J.Organomet. Chem. 525 (1996) 239.

[13] (a) R. Allman, K. Flatau, H. Musso, Chem. Ber. 105 (1972)3067. (b) K. Dietrich, H. Musso, R. Allman, J. Organomet.Chem. 93 (1975) 15. (c) R. Allman, H. Musso, Chem. Ver. 106(1973) 3001. (d) L.E. McCandlish, J.W. Macklin, J. Organomet.Chem. 99 (1975) 31.

[14] (a) F. Marchetti, C. Pettinari, A. Cingolani, G. Gioia Lobbia, A.Cassetta, L. Barba, J. Organomet. Chem. 517 (1996) 141. (b)M.F. Mahon, K.C. Molloy, B.A. Omotowa, M.A. Mesubi, J.Organomet. Chem. 511 (1996) 227.

[15] C. Pettinari, F. Marchetti, A. Cingolani, D. Leonesi, S.I. Troy-anov, A. Drozdov, J. Chem. Soc., Dalton Trans. (1999) 1555.

[16] B.S. Jensen, Acta Chem. Scand. 13 (1959) 1347.[17] R.J. Restivo, A. Costin, G. Ferguson, A.J. Carty, Can. J. Chem.

53 (1975) 1949.[18] A.C.T. North, D.C. Phillips, F.S. Matthews, Acta Crystallogr.,

Sect. A 24 (1968) 351.

F. Marchetti et al. / Inorganica Chimica Acta 299 (2000) 65–79 79

[19] A. Altomare, M.C. Burla, M. Camalli, G.L. Cascarano, C.Giacovazzo, A. Guagliardi, A.G.G. Moliterni, G. Polidori, R.Spagna, J. Appl. Crystallogr. 32 (1999) 115.

[20] H.F. Allen, O. Kennard, D.G. Watson, L. Brammer, A.G.Orpen, J. Chem. Soc., Perkin Trans. 2 (1987) S1.

[21] International Tables for X-ray Crystallography, vol. IV, 99,Kynoch Press, Birmingham, 1974.

[22] M. Camalli, D. Capitani, G. Cascarano, S. Cerrini, C. Giacov-azzo, R. Spagna, Italian Patents No. 35403c/86. SIR CAOS userguide, Istituto di Strutturistica Chimica CNR.

[23] (a) J. Bradbury, K.P. Forest, R.H. Nuttall, S.W.A. Sharp,Spectrochim. Acta 23 (1967) 2701. (b) K. Shobatake, C.Postmus, J.R. Ferraro, K. Nakamoto, Appl. Spectrosc. 23 (1969)12.

[24] C.A. Tolman, Chem. Rev. 77 (1977) 313.[25] C. Pettinari, R. Pettinari, M. Pellei, G. Gioia Lobbia, Polyhe-

dron 18 (1999) 1941.[26] (a) H.K. Shin, M.J. Hampden-Smith, T.T. Kodas, E.N. Duesler,

Can. J. Chem. 70 (1992) 2954. (b) S.J. Lippard, G.J. Palenik,Inorg. Chem. 10 (1971) 1322 and references therein.

[27] C. Pettinari, F. Accorroni, A. Cingolani, F. Marchetti, A. Cas-setta, L. Barba, J. Organomet. Chem. 566 (1998) 187.

[28] A.B. Uzoukwu, S.S. Al-Juaid, P.B. Hitchcock, J.D. Smith, Poly-hedron 12 (1993) 2719.

[29] C. Pettinari, F. Marchetti, A. Cingolani, C. Marciante, R.Spagna, M. Colapietro, Polyhedron 13 (1994) 939.

[30] E.C. Okafor, A.B. Uzoukwu, P.B. Hitchcock, J.D. Smith, Inorg.Chim. Acta 172 (1990) 97.

[31] R.R. Ryan, G.D. Jarvinen, Acta Crystallogr., Sect. C 43 (1987)1295.

[32] D. Zhou, Q. Li, C. Huang, G. Yao, S. Umetani, M. Matsui, L.Ying, A. Yu, X. Zhao, Polyhedron 16 (1997) 1381.

[33] M.F. McMahon, K.C. Molloy, B.A. Omotowa, M.A. Mesubi, J.Organomet. Chem. 560 (1998) 95.

[34] M.J. O’Connel, C.G. Ramsay, P.J. Steel, Aust. J. Chem. 38(1985) 401.

.