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Journal of Organometallic Chemistry 696 (2012) 4298e4308

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Journal of Organometallic Chemistry

journal homepage: www.elsevier .com/locate/ jorganchem

Diorganotin(IV) complexes of N-mono-, di- and tri-chloroacetyl,N0,N00-bis(isopropyl) phosphoric triamide

Khodayar Gholivand*, Sedigheh Farshadian, Zahra HosseiniDepartment of Chemistry, Faculty of Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran

a r t i c l e i n f o

Article history:Received 31 July 2011Received in revised form24 September 2011Accepted 6 October 2011

Keywords:CarbacylamidophosphateDiorganotin compoundsNMR spectroscopyX-ray structuresHydrogen bond

* Corresponding author. Tel.: þ98 2182884422; faxE-mail address: gholi_kh@modares.ac.ir (K. Gholiv

0022-328X/$ e see front matter � 2011 Elsevier B.V.doi:10.1016/j.jorganchem.2011.10.013

a b s t r a c t

Three new carbacylamidophosphates with formula CHnCl3�nC(O)NHP(O)(NHCH(CH3)2)2 (n ¼ 2 (1); n ¼ 1(2); n ¼ 0 (3)) and their organotin compounds with formula (1)SnCl2Me2(m-1)SnCl2Me2 (4),SnCl2Me2(2)2$C6H5CH3 (5) and [SnCl2Me2(3)]n (6) were synthesized and characterized by elemental, IRand NMR spectra analyses. The spectroscopic properties of complexes were compared with those cor-responding ligands. The crystal structures of complexes were determined by X-ray crystallography,which reveals that complex 4 is binuclear structure with two non-equivalent Sn atoms. One adoptsa distorted trans(C,C) cis(OP,OP) cis(Cl,Cl) octahedral configuration, while the other adopts a distortedtrigonal bipyramidal geometry composed of two methyl groups, two chlorine atoms and carbonyl group.Molecule 5 is centrosymmetric with two OP, disordered chlorine and methyl groups in trans positions.Toluene molecules are located in the interlayer spaces of 5. In compound 6, bonding via both PO and COfunctionalities forms 1D infinite chain structures along b axis. The SneOP bond length in 6 is significantlylonger than the same distance in 4 and 5, while the O]P and SneCl bonds are shorter. The bond lengthsin these complexes were compared with those of N-benzoyl carbacylamidophosphates.

� 2011 Elsevier B.V. All rights reserved.

1. Introduction

In recent years, considerable effort has been devoted to theinvestigation of coordination behavior of P,N-substituted analogs ofb-diketones with general formula RC(O)NHP(O)(R0)2ecarbacylamidophosphates (CAPh). Their complexes with actinides,lanthanides and transition metals possess antivirus [1] and anti-cancer activity [2,3] and show nonlinear optical properties [4e6].They can be used as components of ion-selective electrodes [7], oras extragents and masking reagents in analytical chemistry [8].

It was shown that the ligands of this type (R ¼ tri chloroacetyland benzoyl derivatives) bind to the d- and f-metal cations gener-ally in a bidentate mode and form six-membered metalocycles inneutral [9] and deprotonated [10] forms. Moreover, it is found thatthe phosphoryl group is more reactive than the carbonyl counter-part due to the further increasing of negative charge on the phos-phoryl oxygen (OP) upon complexation [11].

In addition, an application as structural blocks for thesynthesis of supramolecular coordination compounds hasexcited a new wave of interest in the coordination chemistry ofcarbacylamidophosphates. Different di- and polymeric compl-

: þ98 2182883455.and).

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exes of deprotonated tri chloroacetyl derivative have beensynthesized either by h2-phosphorylic bridges, donor atoms ofthe substitute (R0) or employing an additional bridging ligand[12,13].

On the other hand, organotin compounds continue to attractsignificant attention, owing to their applications in agriculture,biology, catalysis, organic synthesis, etc [14e19]. Recently, wehave reported diorganotin(IV) compounds of the N-benzoylderivatives of carbacylamidophosphates (BeCAPh) [20e22], inwhich the coordination of the ligands were only through theoxygen atom of the phosphoryl group. The solid state resultsshowed the monomeric all-trans octahedral complexes due tothe fewer steric hindrance in the trans geometry. Two transecisisomers were also obtained with the presence of CH3CN mole-cules in the crystal packing [22]. However, to our knowledge noorganotin complexes of N-acetyl derivatives of carbacylamido-phosphates (AeCAPh) are known. Our previous investigationsestablished that N-acetyl derivatives have different C]O,CeNamide and P]O bond lengths relative to their N-benzoylanalogs [23]. Therefore, replacing the benzoyl moiety with anacetyl group can alter the electronic properties of phosphoryland carbonyl centers, thus influencing their coordinating abilitiestoward Sn(IV). In an attempt to investigate this matter, three newligands, N-mono (1), di (2) and tri (3) chloroacetyl, N0,N00-bis(i-sopropyl) phosphoric triamide and their complexes with

POSn

NH

NH

NH

CH

CH3H3C

CH

H3C CH3

O

Cl

ClCl

CH3

H3C

Cl

Cl

n

Sn

H3C

ClCl

CH3

OO P

HN

NH

NH

O

CH2

Cl

Sn

CH

H3CCH3

CHCH3

CH3

Cl

Cl

H3C

CH3

PHN

O

H2C

Cl

HNHN

CH

CH3

CH3

CHH3C CH3

Sn

Cl

Cl

OO

CH3

H3C

P

NH

CH

CH3

H3C

NHHN

CH

CH3

CH3

OCHCl

Cl

P

NH

HN

HN

O

CH Cl

Cl

CHH3C

CH3

CH

H3C CH3

CHnCl3-n

O

NHP

O

NHCH(CH3)2

NHCH(CH3)2

+

SnCl2(CH3)2

n=2

n=1

n=0

4

5

6

Scheme 1. Preparation pathway of diorganotin(IV) phosphoramidate 4e6.

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e4308 4299

SnCl2Me2 (4e6) have been synthesized (Scheme 1) and charac-terized. The structures of complexes have been determined by X-ray crystallography and compared with each other and those ofthe N-benzoyl derivatives. In contrast to the BeCAPh complexes,coordination of AeCAPhs to tin (IV) can occur through bothoxygen atoms of phosphoryl and carbonyl groups.

2. Experimental

2.1. Materials and methods

All the chemicals used are commercially available and wereused as received without further purification. 1H, 13C, 31P wererecorded on a Bruker Avance DRS 500 spectrometer at 500.13,125.77, 202.46 MHz, respectively. 1H and 13C chemical shifts weredetermined relative to Si(CH3)4 and 31P chemical shifts were

measured relative to 85% H3PO4 as external standard. Infrared (IR)spectra were recorded on a Shimadzu model IR-60 spectrometer.Elemental analysis was performed using a Heraeus CHN-O-RAPIDapparatus. Melting points were obtained with an electrothermalinstrument.

2.2. Synthesis of ligands

CHnCl3�nC(O)NHP(O)Cl2 (n ¼ 2, 1 and 0) were synthesized andpurified using reported method [24].

Compounds 1e3 were synthesized from the reaction ofCHnCl3�nC(O)NHP(O)Cl2 (n ¼ 2, 1 and 0, respectively) with iso-propylamine in 1:4 molar ratio. The amine was added drop wise toa CH3CN solution (30 ml) of CHnCl3�nC(O)NHP(O)Cl2 and stirredat �1 �C. After 5 h, the products were filtered off and then washedwith distilled water and dried.

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e43084300

Physical and spectroscopic data of the compounds 1e3 arepresented below:

2.2.1. CH2ClC(O)NHP(O)(NHCH(CH3)2)2 (1)Yield: 58%. M.p. 162 �C. Anal. Calc. for C8H19ClN3PO2 (255.69): C,

37.58; H, 7.49; N, 16.43. Found: C, 37.68; H, 7.45; N, 16.35%. 1H NMR(CDCl3): d¼ 1.14 (d, 3JHH¼ 6.4 Hz, 6H, CH3),1.19 (d, 3JHH¼ 6.4 Hz, 6H,CH3), 2.88 (dd, 2JPH¼ 8.8 Hz, 2H, NHamine), 3.49 (dsept, 3JHH¼ 6.5 Hz,2H, CH), 4.06 (s, 2H, CH2), 8.67 (br, 1H, NHamide) ppm. 13C NMR(CDCl3): d¼ 24.69 (d, 3JPC¼ 4.7Hz, CH3), 25.02 (d, 3JPC¼ 6.8Hz, CH3),42.51 (d, 3JPC ¼ 8.1 Hz, CH2), 42.90(s, CH), 168.10 (s, C]O) ppm. 31PNMR (CDCl3): d ¼ 5.41(s) ppm. IR (KBr): n ¼ 3310 (s, NH), 3120 (m,NH), 2978 (s), 1703 (s, C]O), 1482 (s), 1436 (m), 1363 (w), 1312 (w),1204 (w),1161 (s, P]O),1138 (s),1070 (s),1026 (m), 909 (m), 892 (m),852 (m), 827 (w), 755 (w), 560 (w), 448(w) cm�1.

2.2.2. CHCl2C(O)NHP(O)(NHCH(CH3)2)2 (2)Yield: 80%. M.p. 185 �C. Anal. Calc. for C8H18Cl2N3PO2 (290.13): C,

33.12; H, 6.25; N, 14.48. Found: C, 33.15; H, 6.28; N, 14.40%. 1H NMR(CDCl3): d ¼ 1.14 (d, 3JHH ¼ 6.4 Hz, 6H, CH3), 1.19 (d, 3JHH ¼ 6.2 Hz,6H, CH3), 2.93 (br, 2H, NHamine), 3.49 (m, 2H, CH), 6.11 (s, 1H, CHCl2),9.56 (br, 1H, NHamide) ppm. 13C NMR (CDCl3): d ¼ 25.18 (d,3JPC ¼ 4.4 Hz, CH3), 25.56 (d, 3JPC ¼ 6.9 Hz, CH3), 43.56 (s, CH), 66.50(d, 3JPC ¼ 10.2 Hz, CHCl2), 165.84 (s, C]O) ppm. 31P NMR (CDCl3):d ¼ 5.50 (br) ppm. IR (KBr): n ¼ 3275 (s, NH), 2965 (m), 1690 (s, C]O), 1465 (s), 1418 (s), 1381 (w), 1301 (w), 1211 (s, P]O), 1171 (s),1132 (s), 1037 (s), 899 (w), 849 (m), 745 (w), 636 (w), 509 (m) cm�1.

2.2.3. CCl3C(O)NHP(O)(NHCH(CH3)2)2 (3)Yield: 75%. M.p.172 �C. Anal. Calc. for C8H17Cl3N3PO2 (324.58): C,

29.60; H, 5.28; N,12.95. Found: C, 29.55; H, 5.33; N, 12.98%. 1H NMR(CDCl3): d¼ 1.16 (d, 3JHH¼ 6.4 Hz, 6H, CH3),1.21 (d, 3JHH¼ 6.4 Hz, 6H,CH3), 2.90 (dd, 2JPH¼ 9.1 Hz, 2H, NHamine), 3.55 (m, 2H, 3JHH¼ 6.4 Hz,CH), 7.96 (br, 1H, NHamide) ppm. 13C NMR (CDCl3): d ¼ 25.23 (d,3JPC¼ 4.7 Hz, CH3), 25.62 (d, 3JPC¼ 6.8 Hz, CH3), 43.59 (s, CH),162.41(s, C]O)ppm. 31PNMR (CDCl3): d¼4.60 (m) ppm. IR (KBr,): n¼3390(s, NH), 3045 (m, NH), 2945 (s), 1693 (s, C]O), 1449 (s), 1401 (m),1364 (w),1301 (w),1249 (m),1227 (s, P]O),1165 (w),1127 (s), 1020(m), 893 (m), 862 (s), 826 (w), 788 (w), 678 (s), 511 (w) cm�1.

2.3. Synthesis of (CH2ClC(O)NHP(O)(NHCH(CH3)2)2)SnCl2(CH3)2 (m-CH2ClC(O)NHP(O)(NHCH(CH3)2)2) SnCl2(CH3)2 (4)

To a stirred solution of ligand 1 (52 mg, 0.203 mmol), a solution of(CH3)2SnCl2 (22 mg, 0.1 mmol) in toluene was added and heated(50e60 �C) for 2 h and the resultingmixture was then stirred at roomtemperature.After2days, themixturewasfilteredandcrystals suitablefor X-ray diffraction were obtained from evaporation of the resultingsolution. Yield: 75%. M.p. 143 �C. Anal. Calc. for C20H50Cl6N6O4P2Sn2(950.68): C, 25.27; H, 5.30; N, 8.84. Found: C, 25.32; H, 5.38; N, 8.74. 1HNMR (CDCl3): d¼ 1.16 (d, 3JHH¼ 6.4 Hz, 6H, CH3),1.19 (d, 3JHH¼ 6.4 Hz,6H, CH3), 1.22 (s, 2J(119Sn, 1H) ¼ 64.6 Hz, 6H, Sn(CH3)2), 2.91 (dd,2JPH¼ 9.2 Hz, 2H, NH), 3.48 (m, 3JHH¼ 6.5 Hz, 2H, CH), 4.05 (s, 2H, CH),8.18(br, 1H, NH) ppm. 13C NMR (CDCl3): d ¼ 9.33(s), 25.21 (d,3JPC¼ 4.7 Hz, CH3), 25.52 (d, 3JPC¼ 6.8 Hz, CH3), 42.93 (d, 3JPC¼ 7.7 Hz,CH2Cl), 43.68 (s, CH), 168.66 (s, C]O) ppm. 31P NMR (CDCl3):d ¼ 4.12(m) ppm. IR (KBr): n ¼ 3325 (s, NH), 3195 (m, NH), 2975 (m),1718 (s, C]O), 1667 (s), 1483 (s), 1457 (s), 1416 (s), 1383 (m), 1312 (w),1249 (w), 1199 (w), 1143 (s, P]O), 1062 (s), 1026 (s), 913 (w), 891 (m),852 (m), 780 (m), 615 (w), 564 (w, SneC), 521 (w), 474 (w, SneO) cm�1.

2.4. SnCl2(CH3)2[CCl2HC(O)NHP(O)(NHCH(CH3)2)2]2$C6H5CH3 (5)

To a stirred solution of 2 (87 mg, 0.3 mmol), a solution of(CH3)2SnCl2 (33 mg, 0.15 mmol) in 10 ml of toluene was added and

heated (50e60 �C) for 2 h. The resulting mixturewas then stirred atroom temperature overnight. Crystals suitable for X-ray diffractionwere obtained from evaporation of this solution. Yield: 60%. M.p.160 �C. Anal. Calc. for C25H50Cl6N6O4P2Sn (892.04): C, 33.66; H,5.65; N, 9.42. Found: C, 33.60; H, 5.69; N, 9.35%. 1H NMR (CDCl3),d¼ 1.16 (d, 3JHH¼ 6.4 Hz,12H, CH3), 1.20 (d, 3JHH¼ 6.5 Hz,12H, CH3),1.23 (s, 2J(119Sn, 1H)¼ 78.0 Hz, 2J(119Sn, 1H)¼ 74.2 Hz, 6H, Sn(CH3)2),2.36 (s, 3H, CH3ePh), 2.89 (br, 4H, NHamine), 3.49 (m, 4H,3JHH ¼ 6.4 Hz, CH), 6.03 (d, 3JPH ¼ 6.8 Hz, 2H), 7.15 (d, 3JHH ¼ 7.6 Hz,1H, toluene), 7.17 (d, 3JHH ¼ 6.7 Hz, 2H, toluene), 7.25 (d,3JHH ¼ 7.6 Hz, 2H, toluene), 9.14 (br, 1H, NHamide) ppm. 13C NMR(CDCl3): d¼ 21.42 (s, CH3ePh), 25.18 (d, 3JPC¼ 4.4 Hz, CH3), 25.53 (d,3JPC ¼ 6.4 Hz, CH3), 43.68 (s, CH), 66.45 (d, 3JPC ¼ 10.3 Hz, CHCl2),125.30 (s, toluene), 128.22 (s, toluene), 129.03 (s, toluene), 137.78 (s,toluene), 165.81 (s, C]O) ppm. 31P NMR (CDCl3): d¼ 4.75 (br) ppm.IR (KBr): n ¼ 3375 (s, NH), 3105 (m, NH), 2970 (s), 1718 (s, C]O),1693 (m), 1461 (s), 1419 (s), 1380 (m), 1387 (w), 1213 (m), 1165 (s),1142 (s, P]O), 1054 (s), 1023 (m), 898 (s), 858 (s), 804 (s), 760 (w),715 (w), 616 (w), 534 (w, SneC), 513 (m), 463 (w, SneO) cm�1.

2.5. [(CH3)2SnCl2((CH3)2CHNH)2P(O)NHC(O)CCl3]n (6)

To a stirred solution of ligand 3 (70mg, 0.21 mmol), a solution of(CH3)2SnCl2 (47 mg, 0.21 mmol) in toluene was added and heated(50e60 �C) for 2 h and the resulting mixture was then stirred atroom temperature. After 2 days, the mixture was filtered andcrystals suitable for X-ray diffraction were obtained from evapo-ration of the resulting solution. This reactionwas also carried out in2:1 molar ratio of ligand/SnCl2Me2 and the same product was ob-tained. Yield: 71%. M.p. 127 �C. Anal. Calc. for C10H23Cl5N3O2PSn(544.22): C, 22.07; H, 4.26; N, 7.72. Found: C, 22.18; H, 4.31; N,7.62%. 1H NMR (CDCl3), d ¼ 1.17 (d, 3JHH ¼ 6.4 Hz, 6H, CH3), 1.20 (d,3JHH ¼ 6.5 Hz, 6H, CH3), 1.22 (s, 2J(119Sn, 1H) ¼ 79.2 Hz, 2J(117Sn,1H) ¼ 76.3 Hz, 6H, Sn(CH3)2), 2.96 (dd, 2JPH ¼ 10.2 Hz, 2H, NHamine),3.50 (m, 2H, CH), 8.23 (br, 1H, NHamide) ppm. 13C NMR (CDCl3),d ¼ 10.50(1JSnC ¼ 573.03, Sn(CH3)2), 25.16 (d, 3JPC ¼ 4.5 Hz, CH3),25.51(d, 3JPC ¼ 6.9 Hz, CH3), 43.89 (s), 162.61 (s) ppm. 31P NMR(CDCl3), d¼ 3.37 (m) ppm. IR (KBr): n¼ 3350 (s, NH), 2980 (m),1706(s, C]O), 1462 (m), 1434 (s), 1365 (w), 1313 (w), 1227 (s), 1180 (s,P]O), 1120 (s), 1042 (s), 892 (m), 861 (s), 822 (s), 792 (s), 644 (m),577 (w, SneC), 500 (w, SneO) cm�1.

2.6. Crystal structure determination

X-ray data of compounds 4, 5 and 6 were collected on a BrukerSMART APEX2 CCD area detector [25] with graphite-monochromated Mo Ka radiation (l ¼ 0.71073 Å). The structureswere refined with SHELXL-97 [26] by full-matrix least-squares onF2. The positions of hydrogen atoms were obtained from thedifference Fourier map. Table 1 presents the crystallographic datafor the compounds 4e6.

3. Results and discussion

3.1. Spectral characterization

The spectroscopic data of compounds 1e6 are summarized inTable 2. The NMR spectra of the ligands and complexes wererecorded in non-coordinating solvent, CDCl3 at room temperature.The chemical shifts and splitting of the CH(CH3)2 protons andcarbons of ligands are quite similar to those observed for BeCAPhs[22] and are almost insensitive to complexation. However theNHamine chemical shifts in the spectra of 1e3 and 4e6 show anupfield shift relative to those of ligands and complexes with N-benzoyl derivatives. The (2JPNH)amine values of 4 and 6 (9.2 and

Table 1Crystallographic data for compounds 4e6.

Compound 4 5 6

Empirical formula C20H50Cl6N6O4P2Sn2 C25H50Cl6N6O4P2Sn C10H23Cl5N3O2PSnFormula weight 950.68 892.04 544.22Temperature 100(2) K 100(2) K 100(2) KWavelength 0.71073 Å 0.71073 Å 0.71073 ÅCrystal system Triclinic Triclinic OrthorhombicSpace group P1 P1 Pbcaa (Å) 9.9812(17) 9.3027(4) 14.1171(9)b (Å) 13.466(2) 10.1430(4) 16.2833(10)c (Å) 15.147(3) 11.3958(5) 18.4384(12)a (�) 84.256(3) 105.5700(10) 90b (�) 91.589(2) 96.8800(10) 90g (�) 88.916(3) 106.1050(10) 90V (Å3) 1959.9(6) 973.00(7) 4238.5(5)Z 2 1 8Density (Mg/m3) 1.611 1.522 1.709Absorption coefficient (mm�1) 1.798 0.189 1.918F(000) 952 456 2160Crystal size (mm) 0.35 � 0.20 � 0.15 0.28 � 0.14 � 0.12 0.25 � 0.25 � 0.15Theta range for data collection (�) 1.96e26.00 1.90e29.00 2.21e29.00Index ranges �11 � h � 12 �12 � h � 12 �19 � h � 19

�16 � k � 16 �13 � k � 13 �22 � k � 220 � l � 18 �15 � l � 1 �25 � l � 25

Reflections collected/unique (Rint) 7649/7649(0.000) 11702/5157(0.0182) 47485/5546(0.0726)Completeness to q (%) 99.1 99.6 98.4Absorption correction Semi-empirical from equivalents Semi-empirical from equivalents Semi-empirical from equivalentsMaximum and minimum transmission 0.761 and 0.656 0.87 and 0.775 0.75 and 0.602Refinement method Full-matrix least-squares on F2 Full-matrix least-squares on F2 Full-matrix least-squares on F2

Data/restraints/parameters 7649/0/373 5157/0/269 5546/0/205Goodness-of-fit on F2 1.009 1.013 1.023Final R indices [for 6019 refl. with I > 2sigma(I)] R1 ¼ 0.0424 R1 ¼ 0.0209 R1 ¼ 0.0285

wR2 ¼ 0.0703 wR2 ¼ 0.0503 wR2 ¼ 0.0564R indices (all data) R1 ¼ 0.0769 R1 ¼ 0.0235 R1 ¼ 0.0543

wR2 ¼ 0.0768 wR2 ¼ 0.0514 wR2 ¼ 0.0662Largest diff. peak and hole (e Å�3) 0.962 and �0.711 0.937 and �0.666 1.189 and �0.412

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e4308 4301

10.2 Hz, respectively) are increased as compared to those of the freeligands (8.8 and 9.1 Hz for 1 and 3, respectively) probably due toa transfer of charge toward the phosphoryl group, which bonds tothe more electropositive Sn and different possible H-bonding. Thespectra of 2 and 5 exhibit a broad signal for NHamine protons at 2.93and 2.89 ppm, respectively.

The carbonyl chemical shifts in the 13C NMR spectra of 1e3 showan upfield shift: 3 (d ¼ 162.41 ppm) < 2 (d ¼ 165.84 ppm) < 1(d ¼ 168.10 ppm) due to increasing of the electronegativity bysubstitution of hydrogen atoms with chlorine atoms in 1e3. Theseresults are confirmed by crystallographic data by comparing theCeN bond lengths, which will be discussed in the X-ray structuralinvestigation (Section 3.2.3). No coupling between the carbonylcarbon atom and the phosphorus atom can be observed incompounds 1e6.

Table 2Spectroscopic NMR and IR data of the compounds 1e6.

Compound d31P (ppm) 2(JPNH)amine (Hz) 2J(119Sn, H) (Hz) 3J(P,Caliphatic) (Hz) 3J(P

1 5.41 8.8 e 4.7 8.6.8

2 5.50 br e 4.4 10.6.9

3 4.60 9.1 e 4.7 e

6.84 4.12 9.2 64.6 4.7 7.

6.85 4.75 br 78.0 4.4 10.

6.46 3.37 10.2 79.2 4.5 e

6.9

As shown in Table 2, chemical shift of 31P for compounds 1e3 are5.41, 5.50 and 4.60 ppm, respectively and are shifted upfield uponcomplexation as observed before for the carbacylamidophosphateorganotins. These signals are also upfield shifted relative to those inN-benzoyl derivatives [22].

The integrated proton NMR spectrum of 5 is in agreement withtwo ligands, one toluene molecule, and six dimethyltin protons inthe crystal structure. The 13C NMR spectrum also shows the cor-responding signals for the carbon atoms of toluene molecule atd ¼ 21.42, 125.30, 128.22, 129.03 and 137.78 ppm. Although twodifferent types of phosphoramidates are present in the crystalstructure of 4, only one set of signals are observed in the NMRspectra (1H, 13C and 31P).

The infrared spectra of ligands 1e3 show strong bands at, 1161,1211 and 1227 cm�1, respectively attributed to n(P]O) and as

,Cacetyl) (Hz) d(C]O) (ppm) n(NeH) (cm�1) n(C]O) (cm�1) n(P]O) (cm�1)

1 168.10 3310 1703 1161

2 165.84 3275 1690 1211

162.41 3390 1693 1227

7 168.66 3325 1718 11431667

3 165.81 3375 1718 1142

162.61 3350 1706 1180

Table 3Selected bond lengths and angles for compound 4.

Bond length (Å)Sn(1)eC(1) 2.105(4) P(1)eO(1) 1.498(3)Sn(1)eC(2) 2.108(4) P(1)eN(2) 1.603(4)Sn(1)eO(3) 2.215(3) P(1)eN(3) 1.611(4)Sn(1)eO(1) 2.238(3) P(1)eN(1) 1.669(4)Sn(1)eCl(2) 2.5393(11) P(2)eO(3) 1.487(3)Sn(1)eCl(1) 2.6125(12) P(2)eN(6) 1.608(4)Sn(2)eC(19) 2.096(5) P(2)eN(5) 1.609(4)Sn(2)eC(20) 2.105(4) P(2)eN(4) 1.703(4)Sn(2)eCl(6) 2.3854(12) O(2)eC(3) 1.210(5)Sn(2)eCl(5) 2.4136(12) O(4)eC(11) 1.216(5)Sn(2)eO(4) 2.599(3)

Bond angles (�)C(1)eSn(1)eC(2) 178.36(18) Cl(6)eSn(2)eC(15) 94.67(4)C(1)eSn(1)eO(3) 89.55(15) C(19)eSn(2)eO4) 79.97(16)C(2)eSn(1)eO(3) 89.67(15) C(20)eSn(2)eO(4) 82.74(16)C(1)eSn(1)eO(1) 90.13(15) Cl(6)eSn(2)eO(4) 77.47(7)C(2)eSn(1)eO(1) 88.37(14) Cl(5)eSn(2)eO(4) 171.99(7)O(3)eSn(1)eO(1) 85.85(11) O(1)eP(1)eN(2) 110.15 (18)C(1)eSn(1)eCl(2) 91.56(13) O(1)eP(1)eN(3) 119.10(19)C(2)eSn(1)eCl(2) 89.89(12) N(2)eP(1)eN(3) 105.72(19)O(3)eSn(1)eCl(2) 90.06(8) O(1)eP(1)eN(1) 105.12(18)O(1)Sn(1)eCl(2) 175.56(8) N(2)eP(1)eN(1) 113.58(19)C(1)eSn(1)eCl(1) 90.59(14) N(2)eP(1)eN(1) 103.25(19)C(2)eSn(1)eCl(1) 90.15(13) O(3)eP(2)eN(6) 110.64(19)O(3)eSn(1)eCl(1) 178.33(8) O(3)eP(2)eN(5) 119.56(19)O(1)eSn(1)eCl(1) 92.49(8) N(6)eP(2)eN(5) 105.3(2)Cl(2)eSn(1)eCl(1) 91.59(4) O(3)eP(2)eN(4) 105.11(17)C(19)eSn(2)eC(20) 139.7(2) N(6)eP(2)eN(4) 112.14(19)C(19)eSn(2)eCl(6) 105.94(14) N(5)eP(2)eN(4) 104.03(18)C(20)eSn(2)eCl(6) 105.39(14) P(1)eO(1)eSn(1) 143.72(18)

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e43084302

expected, these bands are shifted toward lower frequencies uponcomplexation.

The n(C]O) vibrational frequency of the free ligands 1e3appears in the range of 1690e1703 cm�1 and is shifted 28 and13 cm�1 to higher frequencies in complexes 5 and 6, respectively.The presence of two unequal carbonyl bonds in 4 has clear reflec-tance in IR spectrum revealing two bands n(C]O). One absorptionmaximum is slightly shifted to a higher frequency (15 cm�1), whilethe other is shifted to a lower frequency region (36 cm�1), indi-cating the formation of a (C])OeSn bond. The C]O vibrationalfrequencies of R-C6H4C(O)NHP(O)(NH(CH(CH3)2)2) ligands andtheir organotin complexes were observed at lower frequencies thanfor 1e3 and 4e6, 1634e1649 cm�1 and 1651e1669 cm�1, respec-tively, due to the greater electronegativity of CHnCln�3 comparedwith R-C6H4-groups. These results are confirmed by crystallo-graphic data by comparing the C]O bond lengths (Section 3.2.3).

In the organotin(IV) complexes 4 and 5, the NeH stretchingvibrations shift to higher energy suggesting the presence ofdifferent hydrogen bonding of NeH moiety in ligands andcomplexes. The position of this band shifted to smaller frequency incomplex 6, is probably due to the hydrogen bond inwhich the NeHgroup is involved being stronger than in free ligand. This isconsistent with 1H NMR result. The spectrum of 6 shows a down-field shift of the NHamide resonance (8.23 ppm) compared with thefree ligand (7.96 ppm).

The absorption bands at 534e577 cm�1 and 474e500 cm�1 in4e6 are assigned to stretching vibrations of the SneC and SneOgroups, respectively, in agreement with literature results.

C(19)eSn(2)eCl(5) 101.02(15) P(2)eO(3)eSn(1) 152.91(18)C(20)eSn(2)eCl(5) 101.05(14) C(11)eO(4)eSn(2) 150.2(3)

3.2. X-ray crystallography investigation

3.2.1. Crystal structure of (CH2ClC(O)NHP(O)(NHCH(CH3)2)2)SnCl2(CH3)2 (m-CH2ClC(O)NHP(O)(NHCH(CH3)2)2) SnCl2(CH3)2 (4)

The molecular structure of complex 4 is shown in Fig. 1 andselected bond lengths and angles are given in Table 3. The asym-metric unit of 4 consists two different types of tin atoms (Sn(1) andSn(2)) and two ligands 1. One of the ligands coordinates Sn(1) justby the O(1) of the phosphoryl group, whereas the other one acts asa bridge between the two metal atoms: as an phosphoryl donor

Fig. 1. Molecular structure and atom-labeling sche

ligand with respect to Sn(1) and carbonyl donor ligand with respectto Sn(2).

The Sn(1) atom is hexacoordinated by two carbon atoms, twooxygen atoms from phosphoryl groups and two chlorine atoms andshows distorted transecis octahedral configuration in agreementwith SnCl2(CH3)2[4-RC6H4C(O)NHP(O)(NHCH(CH3)2)2]2$CH3CN(R ¼ H and OCH3) [24] and in contrast to other diorganotin phos-phoramidates [20e22]. The trans bond angles around Sn(1) are

me for complex 4 (50% probability ellipsoids).

Fig. 2. View of two adjacent molecules in the crystal structure of 4, showing Sn(2)/O(2) interaction.

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e4308 4303

178.36(18) [C(1)eSn(1)eC(2)], 175.56(8) [O(1)eSn(1)eCl(2)] and178.33(8)� [O(3)eSn(1)eCl(1)], being smaller than the ideal valueof 180�. The deviation of CeSneC angle in SnCl2 (CH3)2[4-RC6H4C(O)NHP(O)(NHCH(CH3)2)2]2$CH3CN (R ¼ H: 6.03� andR ¼ OCH3: 8.56�) were larger than the corresponding one found for4 (1.64�).

There are two different Sn(1)eO distances (2.215(3) and2.238(3) Å) and also two different PeOeSn(1) angles (143.72(18)and 152.91(18) �), in 4. The shorter Sn(1)eO distance correspondsto the larger PeOeSn(1) angle (and reverse), as observed forSnCl2(CH3)2[C6H5C(O)NHP(O)(NHCH(CH3)2)2]2. Although both ofthe SneO bond lengths are longer than the sum of the covalentradii of the tin and oxygen 2.13 Å [27], they are similar to thosereported in the literature [28]. The Sn(1)eC bond lengths are2.105(4) and 2.108(4) Å, in good agreement with the publishedvalues [29]. These values also correspond well with the sum of thecovalent radii (2.15 Å) of tin and carbon [27].

In trans position of the two oxygen atoms are chlorines anddistances are correlated: the shorter is SneO, the longer is SneCl(perhaps ‘trans effect’), in agreement with other organotin phos-phoramidates [22].

The smallest bond angle for the couples of cis atoms is thatrelevant to the O(3)eSn(1)eO(1) angle (85.85(11)�); whereas thelargest value is that for O(1)eSn(1)eCl(1) (92.49(8)�). So, The cisbond angles deviates slightly from the idealized value, 90�, andthe deviation is smaller than the corresponding one foundfor SnCl2(CH3)2[C6H5C(O)NHP(O)(NHCH(CH3)2)2]2$CH3CN andSnCl2(CH3)2[p-CH3OC6H4C(O)NHP(O)(NHCH(CH3)2)2]2$CH3CN (85.57(10)e99.76(4) and 84.43(6)�93.87(5)�, respectively). In thesecompounds the OeSneO angles 86.17(10) and 90.97(4)�, respectivelywere closer with 90�.

The tin atom is almost eclipsed with N(1) and N(4) (corre-sponding torsional angles Sn1eO1eP(1)eN(1) �5.8(3) and Sn(1)eO(3)eP(2)eN(4) 4.2(5)�).

Table 4Hydrogen bonds for compounds 4�6 [Å, �].

Compound DeHeA d(

4 N(1)eH(1N1)/Cl(1) [x, y, z] 0.8N(2)eH(1N2)/Cl(5) [xþ1, y, z�1] 0.8N(3)eH(1N3)/Cl(1) [�xþ2, �y, �z] 0.8N(4)eH(1N4)/Cl(2) [x, y, z] 0.8N(4)eH(1N4)/Cl(4) [x, y, z] 0.8N(5)eH(1N5)/Cl(2) [�xþ2, �y, �zþ1] 0.8N(6)eH(1N6)/Cl(6) [x, y, z] 0.8

5 N(1)eH(1)/Cl(1) [�x, �y, �z] 0.7N(1)eH(1)/Cl(10) [�x, �y, �z] 0.7N(2)eH(2)/O(2) [�x, �y, �zþ1] 0.8

6 N(1)eH(1)/Cl(1) [�xþ1/2, yþ1/2, z] 0.9N(2)eH(2)/Cl(1) [xþ1/2, �yþ1/2, �zþ1] 0.9N(3)eH(3)/Cl(2) [x, y, z] 0.9

The Sn(2) atom is merely penta-coordinated and has a distortedtrigonal bipyramidal geometry with the oxygen of the carbonylgroup and a chlorine atom in axial sites (Cl(5)eSn(2)eO(4),171.99(7)�) and another chlorine and two methyl groups occupyingthe equatorial plane which is in accordance with previously pub-lished results [30]. The low donor strength of carbonyl group givesrise to a considerable distortion of the trigonal-bipyramide aroundthe tin atom toward a monocapped tetrahedron. This is indicatedby the long SneO distance of 2.559(3) Å with the correspondinglow values of the Pauling-type bond order (BO ¼ 0.31) [31] andparticularly by the relatively small value of 54.29� for the differencebetween the sum of the three equatorial and the three axial angles(to the chlorine atom) in the trigonal-bipyramidal coordinationsphere around the tin atom (

P£Sneq �

P£Snax: TBP ¼ 90�,

tetrahedron ¼ 0� [32,33]). In addition, the metal appears 0.359 Åout of the trigonal plane (defined by Cl(6), C(19) and C(20)) towardCl(5) (TBP: 0 Å, tetrahedron: 0.71 Å [33]).

Such a trend away from TBP geometry can also be observed byexamining the bond angles subtended by O(4) on the equatorialplane. The angles O(4)eSn(2)eC(19), O(4)eSn(2)eC(20) and O(4)eSn(2)eCl(6) are 79.97(16), 82.74(16) and 77.47(7) �, respectively, areall much lower than the expected 90� for a regular TBP geometry.However, at the other apex of the bipyramid, Cl(5) subtends muchlarger angles; the angles Cl(5)eSn(2)eC(19), Cl(5)eSn(2)eC(20)and Cl(5)eSn(2)eCl(6) are 101.02(15), 101.05(14) and 94.67(4)�,respectively.

The two Sn(2)eCl bond lengths lie in the range of the normalcovalent radii [34,29] but are not equivalent, that trans to O atombeing longer than the other (Sn(2)eCl(6), 2.3854(12) Å, equatorialbond and Sn(2)eCl(5), 2.4136(12) Å, axial bond), as observed forother organotin compounds with the same geometry [30]. Thedifference between two axial and equatorial SneCl bonds in 4 issmaller than the corresponding one found forSnCl2(CH3)2[C6H5P(O)(NHC(CH3)3)2] (2.3510(11) and 2.5037(10) Å)

DeH) d(H/A) d(D/A) <DHA

00 2.417 3.183(4) 16100 2.602 3.397(5) 17300 2.686 3.476(4) 17000 2.514 3.272(4) 15900 2.574 3.008(3) 11600 2.621 3.363(4) 15500 2.765 3.559(4) 172

9(2) 2.38(2) 3.1475(15) 164(2)9(2) 2.42(2) 3.1954(15) 169(2)0(2) 2.21(2) 3.0078(16) 173.1(18)

0 2.64 3.483(2) 1570 2.63 3. 452(2) 1520 2.45 3.329(2) 167

Fig. 3. A two dimensional supramolecular structure obtained from intermolecular hydrogen bonds in the crystalline network of 4. The dashed lines represent the hydrogen bonds.Hydrogen atoms are omitted for clarity.

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e43084304

due to the shorter axial SneO(P) band in the later (2.258(2) Å) [30].As expected, the Sn(1)eCl bonds are longer than S(2)eCl bonds.

There is also a very weak intermolecular Sn/O interaction incomplex 4 between Sn(2) and the uncoordinated oxygen atom ofcarbonyl group of a neighboring molecule and link the discretemolecular into a 1D chain with the Sn/Sn separation of 8.629 Å(Fig. 2). Although the SneO distance [Sn(1)eO(2) ¼ 2.975 Å,(BO ¼ 0.1)] is considerably longer than the normal SneO covalentbond, it lies in the range of Sn/O distances of 2.61e3.02 Å thathave been reported to suggest SneO bonding [35,36]. However,such an elongation of SneO bond from the normal covalent bonddistance point to a considerable ionic character associated withSneO bond.

If this short contact of tineoxygen is considered, the shape ofthe Sn(2) is best described as the so-called “bicapped” tetrahedronand this compound is an example of [4 þ 1þ1]-coordination. Theangle Cl(6)eSn(2)eO(2) 177.41� is close to a linear arrangementand the value of O(4)eSn(2)�O(2) bonding angle (104.82�) showthe cis coordination of oxygen donor atoms of the ligands. Along

Fig. 4. Independent part of unit cell of 5. In the crystal, complex occupies a specialposition at inversion center (Sn(1)). Toluene solvate molecule is disordered aboutinversion center. Methyl and chlorine ligands are also disordered with equaloccupancies.

with this relatively weak coordination to the central metal atom,there are also N(2)eH/Cl(5) hydrogen bonds between each twoneighbor molecules in the 1D chain (Table 4, Fig. 2).

Furthermore, the Cl(1) and Cl(2) chlorine atoms function asbifurcated acceptors and are involved in intramolecular hydrogenbonds with NHamidic groups forming six-membered[SneCl/HeNePeOe] rings similar to our previous reportedorganotin phosphoramidates [22]. On the other hand, each of themis linked to the NHamine group in a neighboring complex thus twohydrogen bonds of the DA ¼ AD type (A ¼ H bond acceptor andD ¼ H bond donor) are formed. The intermolecular NH/Clhydrogen bonds produce two dimensional supramolecular struc-tures in the lattice (Fig. 3).

Another intramolecular NH/Cl interaction is also observedbetween Cl(6) and one NH group of isopropylamine. As a result ofthis interaction, an eight membered ring is formed in this complex.

Furthermore, it is noteworthy that chlorine atoms of acetylmoieties and Cl(2) participate in weak intermolecular CH/Clinteractions with C/Cl distances in the range 3.66e3.71 Å, whichare in the expected region reported for this type of week hydrogenbonds [37,38]. It is reported that the CH/X (halogen) hydrogenbond is more effective than the CH/p bond [39]. So, these weakinteractions stabilize the structure, effectively.

The N(6)/O4¼C distance is 3.008 Å, which is shorter than thesum of the van derWaals radii and this type of interaction is mainlyattributed to electrostatic interactions [40].

Fig. 5. ORTEP view of 5 (50% probability ellipsoids). H atoms excluding NH groups areomitted for clarity.

Table 5Selected bond lengths and angles for compound 5.

Bond length (Å)Sn(1)eC(10) 2.104(4) P(1)eO(1) 1.4942(10)Sn(1)eC(1) 2.105(4) P(1)eN(2) 1.6124(12)Sn(1)eO(1) 2.2195(9) P(1)eN(3) 1.6151(12)Sn(1)eCl(1) 2.5852(7) P(1)eN(1) 1.6882(12)Sn(1)eCl(10) 2.6061(7) O(2)eC(2) 1.2074(17)

Bond angles (�)C(10)#1eSn(1)eC(10) 180.0(3) C(10)eSn(1)eCl(10) 89.65(12)C(10)#1eSn(1)eC(1)#1 18.29(11) C(1)#1eSn(1)eCl(10) 108.42(12)C(10)eSn(1)eC(1)#1 161.71(11) C(1)eSn(1)eCl(10) 71.58(12)C(10)#1eSn(1)eO(1)#1 86.48(10) O(1)#1eSn(1)eCl(10) 91.68(3)C(10)eSn(1)eO(1)#1 93.52(10) O(1)eSn(1)eCl(10) 88.32(3)O(1)#1eSn(1)eO(1)#1 88.88(11) Cl(1)#1eSn(1)eCl(10) 161.19(2)C(1)eSn(1)eO(1)#1 91.12(11) Cl(1)eSn(1)eCl(10) 18.81(2)O(1)#1eSn(1)eO(1) 180.0 Cl(10)eSn(1)eCl(10)#1 180.00(3)C(10)eSn(1)eCl(1) 108.46(12) O(1)eP(1)eN(2) 109.49(6)C(10)eSn(1)eCl(1)#1 71.54(12) O(1)eP(1)eN(3) 119.77(6)C(1)eSn(1)eCl(1) 90.39(12) N(2)eP(1)eN(3) 105.39(6)C(1)eSn(1)eCl(1)#1 89.61(12) O(1)eP(1)eN(1) 105.08(6)O(1)eSn(1)eCl(1) 89.24(3) N(2)eP(1)eN(1) 113.74(6)O(1)eSn(1)eCl(1)#1 90.76(3) N(3)eP(1)eN(1) 105.54(6)Cl(1)#1eSn(1)eCl(1) 180.0 P(1)eO(1)eSn(1) 149.28(6)C(10)#1eSn(1)eCl(10) 90.35(12)

#1 �x, �y, �z.

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e4308 4305

The two coordination types for ligands in 4, are also reflected inthe disparity in the respective bond lengths within the OPNCOskeleton: the C(11)eO(4) bond length (1.216(5) Å) is slightly longerthan the C(3)eO(2) (1.210(5) Å) bond, however, there are moredifferences between CeN, PeNamide and PeO bonds of the twoligands. Although, it is expected that the shorter SneO bond should

Fig. 6. H-bonded chain in the crystal of 5 along the [111] direc

be related to the longer PeO bond, however, the P(1)eO(1) distanceis longer than P(2)eO(3) bond, 1.498(3) versus 1.487(3) Å. TheC(11)eN(4), C(3)eN(1), P(2)eN(4) and P(1)eN(1) bond lengths are1.353(5), 1.366(5), 1.703(4) and 1.669(4) Å respectively.

3.2.2. SnCl2(CH3)2[CCl2HC(O)NHP(O)(NHCH(CH3)2)2]2$C6H5CH3 (5)The independent part and the ORTEP view of 5 are shown in

Figs. 4 and 5, respectively; selected bond lengths and angles aregiven in Table 5. The compound 5 is crystallized with a solventmolecule of C7H8 which is disordered over two orientations withsite occupancy ratio of 0.5:0.5.

The phosphoramidate 2 acts as a monodentate ligand towardthe tin atom, which is six-coordinate with a slightly distortedoctahedral geometry. The tin atom is situated on a crystallographiccenter of inversion and coordinates to two oxygen atoms of phos-phoryl groups, two carbons as well as two chlorine atoms in an all-trans configuration, by contrast to that observed in 4 and similar tothose reported for some of the N-benzoyl carbacylamidophos-phates adducts of dimethyltin dichloride.

In the molecule of 5, the methyl and chlorine atoms defined byC(1) and Cl(1) are disordered over two sites of equal occupancy. Theatoms disordered in this way are present in the structural model inpairs as, C(1)/C(10) and Cl(1)/Cl(10) (Figs. 4 and 5). For this reasonthose distances and angles involving these atoms are of littlesignificance and are not discussed here. The all-trans octahedral tinatom exhibits remarkably short SneO bond, 2.195(9) Å, and idealOeSneO trans angle, 180�. Since the complex is centrosymmetric,the two phosphoramidates have identical conformation.

Each molecule is associated with two adjacent moleculesthrough centrosymmetric pairs of N(2)eH(2)/O(2) hydrogenbonds of the AD¼DA type giving one-dimensional chains along the

tion. Hydrogen atoms and toluene molecules are omitted.

Fig. 7. Fragment of the crystal packing of 5. Hydrogen atoms are omitted for clarity.

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e43084306

[111] direction (Fig. 6). Two neighboring chains are linked byCeH/Cl interaction between CH group of acetyl moiety anddisordered chlorine atoms leading to the formation of 2D layerswhich are directed along the [011] plane of the unit cell (Fig. 7). Thesolvent toluene molecules occupy interlayer spaces and formweakCeH/CleSn and (NeH)amine/p interactions withmolecules of thelayers.

3.2.3. [Me2SnCl2((CH3)2CHNH)2P(O)NHC(O)CCl3]n (6)Complex 6 crystallizes in the orthorhombic system with space

group Pbca. Selected structural parameters are summarized inTable 6. The five primary bonds to tin in 6 are to the two methylgroups [SneC(10) ¼ 2.090(3) Å; SneC(9) ¼ 2.094(3) Å], and to O ofthe phosphoryl group [SneO(1) ¼ 2.3479(18) Å] and the twochlorine atoms [SneCl(1) ¼ 2.4951(7) Å; SneCl(2) ¼ 2.4102(7) Å],thus generating a distorted trigonal bipyramidal geometry at tin. In

Table 6Selected bond lengths and angles for compound 6.

Bond length (Å)Sn(1)eC(10) 2.090(3) P(1)eO(1) 1.4865(19)Sn(1)eC(9) 2.094(3) P(1)eN(2) 1.610(2)Sn(1)eO(1) 2.3479(18) P(1)eN(1) 1.617(2)Sn(1)eCl(2) 2.4102(7) P(1)eN(3) 1.718(2)Sn(1)eCl(1) 2.4951(7) O(2)eC(7) 1.215(3)

Bond angles (�)C(10)eSn(1)eC(9) 151.48(12) O(1)eP(1)eN(2) 119.38(12)C(10)eSn(1)eO(1) 85.39(9) O(1)eP(1)eN(1) 113.35(11)C(9)eSn(1)eO(1) 84.31(9) N(2)eP(1)eN(1) 104.84(12)C(10)eSn(1)eCl(2) 103.06(9) O(1)eP(1)eN(3) 102.67(10)C(9)eSn(1)eCl(2) 102.86(8) N(2)eP(1)eN(3) 104.28(11)O(1)eSn(1)eCl(2) 86.93(5) N(1)eP(1)eN(3) 112.07(11)C(10)eSn(1)eCl(1) 95.96(8) P(1)eO(1)eSn(1) 156.27(11)C(9)eSn(1)eCl(1) 94.53(8) C(1)eN(1)eP(1) 123.45(18)O(1)eSn(1)eCl(1) 178.65(5) C(1)eN(1)eH(1) 112.8Cl(2)eSn(1)eCl(1) 92.66(2) P(1)eN(1)eH(1) 111.6

addition, there is a very weak intermolecular SneO interaction[SneO(2) ¼ 2.7420(10) Å, (BO¼ 0.19)], the geometry at Sn becomesa highly distorted 6-coordinate octahedral with the two methylgroups in trans orientation, C(10)eSn(1)eC(9) ¼ 151.48(12)� whichdeviates markedly from standard 180�. The SneO(1) (2.3479(18) Å)and SneO(2)#1 (2.7420(10) Å) bond distances in 6 are longer thanthe sum of the covalent bond radii of Sn and O, but are considerablyshorter than the sum of their van derWaals radii of 3.71 Å [25]. TheSneO(2) distance in 6 is longer than Sn(2)eO(4) bond and shorterthan Sn(2)eO(2) distance in 4.

The values of O(1)eSn(1)eO(2) and Cl(1)eSn(1)eCl(2) bondingangles (98.42 and 92.66(2)�) show the cis coordination of bothoxygen atoms of the ligands and the two chlorine atoms. The transbond angles O(1)eSn(1)eCl(1) and O(2)eSn(1)eCl(2) are 178.65(5)and 174.37�, respectively. The expected differences in SneCl bondlengths (2.4951(7) and 2.4102(7) Å) were observed. The shorterdistance belonging to the chlorine atom in trans position to O(2).

The intermolecular C]O/Sn coordination in complex 6 link thediscrete molecular into a 1D chain, extending in the crystallo-graphic b direction and have Sn/Sn separation of 8.863 Å. Therepeating unit and 1D infinite zigzag chain of complex 6 are illus-trated in Figs. 8 and 9, respectively. Besides, the Cl(1) atom formsa strong hydrogen bond with the N(1)eH(1) group of neighbormolecule in the chain and further stabilize the structure. In thedirection of a axis intermolecular N(2)eH/Cl(1) hydrogen bondsconnect these 1D chain together and 2D layer was formed in the bcplane (Fig. 10).

The intramolecular distance between the carbonyl oxygen andphosphorus atoms (2.996 Å) is considerably shorter than the sum ofVan der Waals radii (3.3 Å). This may be rationalized in terms ofa strong attractive interaction between PdþeOd�. Similar contactswere also found in some of the carbacylamidophosphate ligands[41]. There is also an intramolecular electrostatic interactionbetween O(2) of C]O group and N(1) atomwith the O/N distanceof 3.048 Å.

Fig. 8. ORTEP view of 6; thermal displacement ellipsoids drawn at 50% probabilitylevel. Sn1 atom adopts distorted octahedral coordination with one elongated Sn(1)eO(2A) bond shown by open line. O(2A) is generated from O(2) by 0.5�x, �0.5 þ y, zsymmetry operation.

Fig. 9. 1D chain structure of complex 6. Hydrogen atoms are omitted for clarity.

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e4308 4307

3.2.4. Comparison of the structures for complexes 4e6 anddiorganotin complexes of N-benzoyl carbacylamidophosphates

Mono, di and three chloroacetyl derivatives of carbacylamido-phosphates coordinate to tin(IV) atom in different ways. In monoand tri chloroacetyl derivatives in addition to phosphoryl group,the carbonyl group is also coordinated to the tin atom, though thephosphoryl oxygen atom exhibits stronger donating ability thanthe carbonyl oxygen. In 4 two different type tin atoms are present.One of them is coordinated by two phosphoryl oxygens and has thetransecis configuration; another tin is coordinated by carbonyloxygen. The tin atom in 6 also shows transecis octahedral config-uration and bonding via both PO and CO groups forms polymericchains in the structure of 6. However, dichloroacetyl derivative isbounded by the monodentate bond fashion and the tin atom hasall-trans octanhedral geometry, similar to those of BeCAPhs. Asmentioned in the introduction, BeCAPhs act as monodentateligands, bound to the tin atom solely through phosphoryl oxygenatom. Most of them showed the monomeric all-trans octahedralcomplexes due to the fewer steric hindrance in the trans geometry.

The SneO(¼P) bond length in 6 is significantly longer than thesame distance in 4 and 5, while the O]P and SneCl bonds areshorter, suggesting aweaker coordination of ligand 3 compared to 1and 2 with SnCl2Me2. Also, the SneO(¼C) bond in 6 is longer thanthat of 4. These bond length changes presumably reflect the effect ofsubstitution of the hydrogen atoms in N-acetyl derivatives bychlorine atoms. Since, formation of complex is acidebase reactionbetween tin metal atom and oxygen atoms of phosphoryl andcarbonyl groups, decreases of the Lewis basicity of oxygen atoms byaddition of more electronegative chlorine atom can increase theSneObond length. As a consequence, the PeNamide bond in complex6 is the longest (1.718(2) in 6 versus 1.6882(12) in 5, 1.669(4) and1.703(4) Å in 4) and the CeNamide bond is the shortest due toincreased delocalization of the nitrogen lone pairs to the carbonyl

Fig. 10. Crystal packing fragment of 6. Layer formed by NeH/Cl H-bonds.

group. Generally, the interaction between nitrogen lone pair andC(O) moiety in carbacylamidophosphates causes increasing in thePeNamide bond length compared to the PeNamine ones and theelectron withdrawing effect of CCl3 group support this interaction.

Compounds 4 and 6 have longer C]O bond lengths than 5 dueto the weakening caused by the competition of the metal.Comparing the SneO, P]O, PeNamide and CeNamide bond lengthsfor 4 and 5 shows that these bond lengths in 5 are midway betweenthose in 4.

In the molecular core unit, C(O)NHP(O), the C(O) and P(O)oxygen atoms are in anti-positions to each other, hence, the OeCand OeP dipoles can avoid each other [13]. The OePeNeCcarbonyltorsion angles in 4e6 are in the range �162.8(4) to 168.1(2)�.

It is interesting to compare 4e6 with the previously character-ized diorganotin complexes, SnCl2(CH3)2[4-RC6H4C(O)NHP(O)(NHCH(CH3)2)2]2 (R ¼ H, OCH3, CH3 and Cl). Recently,comparison of the crystal structures of the N-benzoyl, N-di and trichloroacetyl derivatives of carbacylamidophosphates have shownthat the C]O and CeNamide bond lengths are shorter in the N-acetyl derivatives and the PeNamide bond length is longer. It prob-ably leads to vanishing the coupling between phosphorus atom andamidic hydrogen atom as 2JPNH ¼ 0 Hz in N-acetyl derivatives. Thesame results are also observed between their corresponding orga-notin complexes, and N-di and tri chloroacetyl derivatives haveshorter C]O and CeNamide bond lengths and longer PeNamide

bonds. In 6 the SneO distance is longer than those observed in theBeCAPhs, the SneCl and P]O bonds are shorter. On the contrary, in5 the SneO distance is shorter than BeCAPhs and the SneCl andP]O distances remain approximately unchanged. In 4 there aretwo ligands with significantly different tineoxygen distances thatone SneO bond is slightly longer and another one is shorter thanthose of BeCAPhs. There are also two different P]O, PeNamide andCeNamide bonds in 4 that one of the two P]O and PeNamide bondsare significantly shorter while the other ones are larger than thoseof BeCAPhs. Both of the CeNamide bonds in 4 are smaller.

The P]O distance in 6 is comparable to that found for o-C6H4(SnClMe2)2$(Me2N)3PO (1.489(3) A) [42] with three PeNaminebonds, while the SneO bond is longer than o-C6H4(SnClMe2)2$(Me2N)3PO and (Ph2ClSnCH2)2$(Me2N)3PO [42,43].

The binding of the tin atom to the phosphoramide is not linear;the SneOeP angle of 156.27(11)� in 6 is typical for polymericstructures (150e160�) and is larger than those observed in 4, 5 andBeCAPhs. The SneOeC angles are 150.2(3) and 161.16� in 4 and 6respectively. This nonlinear binding has important consequencesfor the position of tin relative to the phosphoramides.

The SneC bonds in 4�6 (2.090(3)e2.108(4) Å) are characteristicof covalent bonds and in agreement with the values found forBeCAPhs.

As expected, the phosphorus atoms have distorted tetrahedralconfigurations. It is of interest to note the low values of the OPNa-

mide compared to OPNamine angles which are 105.11(18)� for 4 and105.08(6)� for 5, falling in the range for BeCAPhs. This angle is thelowest in 6, 102.67(10)�. The low values observed for OPNamideangles can be explained by the influence of the hydrogen bonds.

Appendix A. Supplementary data

CCDC Nos. 785715 (C20H50Cl6N6O4P2Sn2) (4); 785713(C25H50Cl6N6O4P2Sn) (5) and 785714 (C10H23Cl5N3O2PSn) (6)contain the supplementary crystallographic data for this paper.Crystallographic data have been deposited with Cambridge Crys-tallographic Data Center. Copies of the datamay be obtained, free ofcharge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ,UK (fax: þ44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk orhttp://www.ccdc.cam.ac.uk).

K. Gholivand et al. / Journal of Organometallic Chemistry 696 (2012) 4298e43084308

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