Versatile binding properties of di-pyridyl ligands with Cu(II) complexes: The syntheses, structural...

This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institution

and sharing with colleagues.

Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third party

websites are prohibited.

In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further information

regarding Elsevier’s archiving and manuscript policies areencouraged to visit:

http://www.elsevier.com/copyright

http://www.elsevier.com/copyright

Author's personal copy

Versatile binding properties of di-pyridyl ligands with Cu(II) complexes: Thesyntheses, structural characterization and thermal analysis of six new species

Salah S. Massoud a,*, Elodie Druel a, Marisa Dufort b, Roger Lalancette b, Jarrett Kitchen c, Janusz Grebowicz c,Ramon Vicente d, Uday Mukhopadhyay e, Ivan Bernal e, Franz A. Mautner f

a Department of Chemistry, University of Louisiana at Lafayette, P.O. Box 44370, Lafayette, LA 70504-4370, USAb Department of Chemistry, Rutgers University, Olson Laboratories, Newark, NJ 07102, USAc Department of Natural Sciences, University of Houston-Downtown, Houston, TX 77002, USAd Departament de Química Inorgànica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spaine Department of Chemistry, University of Houston, Houston, TX 77204, USAf Institut für Physikalische and Theoretische Chemie, Technische Universität Graz, A-8010 Graz, Austria

a r t i c l e i n f o

Article history:Received 29 July 2009Accepted 20 August 2009Available online 23 August 2009

Keywords:CopperDi-pyridyl bridgedCoordination polymerCrystal structureMagnetic behaviorThermal analysis

a b s t r a c t

A novel series of 4,40-bipyridine- and 1,2-bis(4-pyridyl)ethane-Cu(II) complexes were synthesized using avariety of amine ligands (DPA = di(2-pyridylmethyl)amine, Medpt = 3,30-diamino-N-methyldipropyl-amine, Hbpca = bis(2-pyridylcarbonyl)amine, TPA = tris(2-pyridylmethyl)amine) and cyclen = 1,4,7,10-tetraazacyclododecane). Different complexes were obtained including mononuclear [Cu(cyclen)(4,40-bipy)](ClO4)2 (1), dinuclear {[Cu(l2-bpca)(4,40-bipy)(H2O)]ClO4}2 (2), [Cu2(DPA)2(l2-4,40-bipy)(ClO4)4)]�H2O (3), [Cu2(cyclen)2(l2-bpe)](ClO4)4 (4) and [Cu2(TPA)2(l2-bpe)](ClO4)4 (5) and the 1-D poly-mer, {[Cu(Medpt)(l2-4,40-bipy)](ClO4)2}n (6). In the 1–6 samples, cooling up to 100 K produces only theexpected, minor, changes in cell constants given no space group changes. Therefore, data for the 100 Kstructures are reported only. Single-crystal X-ray crystallography reveals the monodentate coordinationof the 4,40-bipy in 1 and 2, and the bridged nature of the di-pyridyl ligands in the dinuclear complexes2–5 and in the polymeric complex 6. In this series, structures 3–6 consist of the 4,40-bipy or bpe bridgingthe two Cu(II) centers, the coordination by the tri- or the tetra-N donors of the amine, and the ClO4

�

groups as counter ions in 4–6 complexes. In the complexes 3–6, the Cu��Cu distances across the bridgeddi-pyridyl ligands were found to be greater than 11 Å. The magnetic properties of complex 3 reveal noevidence for magnetic coupling between the two Cu(II) centers (J = �0.58 cm�1).

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Molecular architecture through self assembly of discrete coordi-nation compounds is a growing attractive field for inorganic chem-ists and for material scientists [1]. Many novel coordinationcompounds of polymeric networks and with extended structureshave been synthesized and structurally characterized [2–11]. Thesynthesis of these supramolecular coordination compounds affordsa variety of assembled structures and cavities that make them use-ful for a reaction environment for guest molecules and as porousmaterials for gas adsorption and active body sensors [7–11], as

well as for molecular recognition [1–4,6,12,13]. Also, other uniqueinteresting properties have been emerged from studying thesescompounds including long range magnetic interactions [14], cata-lytic, conductivity, electronic and optical properties [15–17].

Ligands having two pyridyl donors such as 4,40-bipyridine(4,40-biby) [7–9,13,18–21], bis(4-pyridyl)disulfide (bpds) [7,22],1,2-bis(2-pyridyl)ethane (bpe) [2,4,7,21,23] and 1,3-bis(4-pyri-dyl)propane (bpp) [4,6,24–26] have been extensively used for con-struction of coordination polymers with different dimensionality[2,4,6,7–9,18–27]. These compounds were used to assemble theinorganic building layers to provide porous coordination polymerswith variable properties [28]. This class of ligands led also to theformation of a wide variety of new network topologies and struc-tural motifs [6–9,13,25–29]. Moreover, networks prepared fromthe flexible di-pyridyl ligands such as bpp are of great interestbecause of the possible occurrence of these compounds in differentconformations within the lattice [29]. The intramolecular separa-tion between the metal centers in the bridged di-pyridyl

0277-5387/$ - see front matter � 2009 Elsevier Ltd. All rights reserved.doi:10.1016/j.poly.2009.08.019

Abbreviations: DPA, di(2-pyridylmethyl)amine; TPA, tris(2-pyridylmethyl)amine; cyclen, 1,4,7,10-tetraazacyclododecane; Medpt, 3,30-diamino-N-methyldi-propylamine; Hbpca, bis(2-pyridylcarbonyl)amine; 4,40-bipy, 4,40-bipyridine; bpe,1,2-bis(4-pyridyl)ethane; bpp, 1,3-bis(4-pyridyl)propane.

* Corresponding author. Tel.: +1 337 482 5672; fax: +1 337 482 5676.E-mail address: [email protected] (S.S. Massoud).

Polyhedron 28 (2009) 3849–3857

Contents lists available at ScienceDirect

Polyhedron

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


complexes varies over a large range and could be as large as 14 ÅA0

depending on the nature of the di-pyridyl ligand and on its adoptedconformation [30].

In this study, a new series of Cu(II)–di-pyridyl complexes aresynthesized based on 4,40-bipy and bpe and derived from structur-ally different blocking amines (cyclen, Medpt, DPA, TPA). The studyreveals the flexibility of the di-pyridyl ligands to bind metal ionsleading to a wide variety of polymeric species.

2. Experimental

2.1. Materials and methods

4,40-Bipyridine and 1,2-bis(4-pyridyl)ethane, 2-pyridylmethyl-amine, 2-picolylchloride hydrochloride and 2,4,6-tris(2-pyridyl)-s-triazine were purchased from Aldrich Chem. Comp., USA.Di(2-pyridylmethyl)amine (DPA) was purchased from TCI-Amer-ica, and 1,4,7,10-tetraazacyclododecane from Strem Chem. Comp.All other chemicals were reagent grade quality. Tris(2-pyridyl-methyl)amine (TPA) ligand was synthesized and characterizedfollowing the reported literature methods [31,32]. Infrared spectrawere recorded on JASCO FT/IR-480 plus spectrometer as KBr pel-lets. Electronic spectra were recorded using Agilent 8453 HP diodeUV–Vis spectrophotometer. Elemental analyses were carried outby the Atlantic Microlaboratory, Norcross, Georgia, USA. Magneticsusceptibility of compound 3 was measured on polycrystallinepowder at the Unitat de Mesures Magnètiques of the Universitatde Barcelona with a Quantum Design SQUID MPMS-XL susceptom-eter working in the range 2–30 K under magnetic field of 500 G andin the range 2–300 K under magnetic field of 1 T. Diamagnetic cor-rections were estimated from Pascal Tables.

Caution: Salts of perchlorate and their metal complexes arepotentially explosive and should be handled with great care andin small quantities.

2.2. Synthesis of the Cu(II) complexes

2.2.1. [Cu(cyclen)(4,40-bipy)](ClO4)2 (1)To a hot solution containing copper(II) perchlorate hexahydrate

(0.376 g, 1.0 mmol) and 1,4,7,10-tetraazacyclododecane (0.173 g,1.0 mmol) dissolved in 30 mL of CH3OH, an equimolar amount of4,40-bipyridyine (0.160 g, 1.0 mmol) dissolved in 10 ml of CH3OHwas added drop-wise. The mixture was heated on a steam bathfor 10 min, filtered while hot through celite and allowed to crystal-lize at room temperature. After two days, the large blue needleswhich separated out were collected by filtration, washed withether and then air dried (overall yield: 0.535 g, 91%). Characteriza-tion: Anal. Calc. for C18H28Cl2CuN6O8: C, 36.59; H, 4.77; N, 14.22.Found: C, 36.66; H, 4.83; N, 14.25%. Selected IR bands (cm�1):3171 (s), 1110 (vs, centered). UV–Vis spectrum in CH3OH {kmax,nm (emax, M�1 cm�1)}: 592 (278).

2.2.2. {[Cu(l2-bpca)(4,40-bipy)(H2O)](ClO4)}2 (2)To a hot solution containing copper(II) perchlorate hexahydrate

(0.190 g, 0.5 mmol) and 2,4,6-tris(2-pyridyl)-triazine (0.160 g,0.5 mmol) dissolved in 30 mL of H2O, 4,40-bipyridine (0.160 g,1.0 mmol) dissolved in 5 ml of CH3OH was added drop-wise. Themixture was heated on a steam bath for 15 min and filtered whilehot. The blue precipitate which separated after 1 h was collectedby filtration. Crystallization from aqueous solution afforded largeblue single crystals which were collected by filtration, washed with2-propanol and ether and then air dried (overall yield: 0.186 g,66%). Characterization: Anal. Calc. for C22H18ClCuN5O7 (563.41 g/mol): C, 46.90; H, 3.22; N, 12.43. Found: C, 46.53; H, 3.11; N,

12.18%. Selected IR bands (cm�1): 3363 (s,br), 1664 (s), 1089 (vs).UV–Vis spectrum in H2O {kmax, nm (emax, M�1 cm�1)}: 639 (109).

2.2.3. [Cu2(DPA)2(l2-4,40-bipy)(ClO4)4]�H2O (3)This complex was prepared using procedures similar to that de-

scribed for complex 1. Well-shaped bluish-mauve crystals of X-rayquality were obtained by re-crystallization from H2O (overall yield:71%). Characterization: Anal. Calc. for C34H36Cl4Cu2N8O17: C, 37.21;H, 3.31; N, 10.21. Found: C, 37.23; H, 3.25; N, 10.19%. Selected IRbands (cm�1): 3449 (w), 1119 (vs). UV–Vis spectrum in H2O {kmax,nm (emax, M�1 cm�1)}: 655 (225).

2.2.4. [Cu2(cyclen)2(l2-bpe)](ClO4)4 (4)The complex was prepared using the same procedures de-

scribed for 1 except, 1,2-bis(4,40-pyridyl)ethane was used insteadof 4,40-bipy (overall yield: 92%). Shiny blue crystals of X-ray qualitywere obtained by re-crystallization from H2O. Characterization:Anal. Calc. for C28H52Cl4Cu2N10O16: C, 31.82; H, 4.97; N, 13.29.Found: C, 31.96; H, 5.02; N, 13.34%. Selected IR bands (cm�1):1108 (vs). UV–Vis spectrum in CH3OH {kmax, nm (emax, M�1 cm�1)}:592 (552).

2.2.5. [Cu2(TPA)2(l2-bpe)](ClO4)4 (5)To a hot solution containing copper(II) perchlorate hexahydrate

(0.190 g, 0.5 mmol) and tris(2-pyridylmethyl)amine (0.145 g,0.5 mmol) dissolved in 20 mL of CH3OH, an equimolar amount of1,2-bis(4-pyridyl)ethane (0.090 g, 0.5 mmol) dissolved in 10 ml ofCH3OH was added drop-wise. The mixture was heated on a steambath for 10 min, filtered while hot through celite and then allowedto crystallize at room temperature. In the following day, the result-ing large blue crystals were collected by filtration, washed withether and then air dried (overall yield: 0.256 g, 79%). Crystals suit-able for X-ray analysis were obtained from dilute solutions whenthe filtrate was allowed to stand at room temperature. Character-ization: Anal. Calc. for C42H48Cl4Cu2 N10O16: C, 44.70; H, 3.75; N,10.86. Found: C, 44.50; H, 3.71; N, 10.81%. Selected IR bands(cm�1): 1089 (vs). UV–Vis spectrum in H2O {kmax, nm (emax,M�1 cm�1)}: 660 (sh), 860 (500).

2.2.6. {[Cu(Medpt)(l2-4,40-bipy)](ClO4)2}n (6)The complex was synthesized using a procedure similar to that

described above for 5 (overall yield; 85%). Re-crystallization fromH2O afforded blue single crystals suitable for X-ray measurement.Characterization: Anal. Calc. for C17H25Cl2CuN5O8: C, 36.21; H, 4.83;N, 12.42. Found: C, 36.38; H, 4.83; N, 12.45%. Selected IR bands(cm�1): 3292 (m), 3283 (m); 1090 (vs, centered). UV–Vis spectrumin H2O {kmax, nm (emax, M�1 cm�1)}: 640 (125), 734 (sh).

2.3. X-ray data collection and processing

Clear, dark blue crystals of each of the compounds were used forthe X-ray crystallographic analyses. The X-ray single-crystal dataof the six compounds were collected on a Bruker-AXS SMART APEXII CCD diffractometer at 100(2) K. The crystallographic data, condi-tions retained for the intensity data collection and some features ofthe structure refinements are listed in Table 1. Intensities of com-pound 3 were collected with graphite-monochromated Mo Karadiation (k = 0.71073 Å), the other data sets with Cu Ka radiation(k = 1.54178 Å). Data processing, Lorentz-polarization and absorp-tion corrections were performed using SAINT, APEX and the SADABS

computer programs [33]. The structures were solved by directmethods and refined by full-matrix least-squares methods on F2,using the SHELXTL V 6.14 [34] program package. All non-hydrogenatoms were refined anisotropically. The hydrogen atoms wereassigned with isotropic displacement factors and included in thefinal refinement cycles by use of geometrical constraints

3850 S.S. Massoud et al. / Polyhedron 28 (2009) 3849–3857


(Car–H = 0.93 Å; CMe–H = 0.96 Å; N–H = 0.90 Å; O–H = 0.82 Å). Incase of 4, split occupancies were applied to six oxygen atoms ofthe disordered ClO4

� counter ions.

2.4. Thermoanalytical measurements

Thermal decomposition was evaluated by simultaneous differ-ential thermal analysis/thermogravimetry/mass spectrometry(DTA/TGA/MS), the NETZSCH STA 409 CD-Skimmer system [35].Powder samples (10–15 mg) were heated between room tempera-ture and 400 �C at the rate of 10 �C/min under helium atmosphere.The evolved gases were introduced into the quadrupole mass spec-trometer by the Skimmer coupling located directly above the sam-ple surface at a distance around 7 mm where the sampletemperature was almost the same as the evolved gases. The timedelay for analysis of evolved gas was less than 1 s.

3. Results and discussion

3.1. Synthesis and spectroscopic characterization of the complexes

The complexes under investigation, 1–6 were synthesized ingood yield (60–90%) by using a general straight forward methodwhere an aqueous solution of the preformed 1:1 complex Cu

(ClO4)2-amine is treated with a methanolic solution of the di-pyr-idyl ligand. Re-crystallization of the isolated di-pyridyl complexesfrom H2O afforded crystals suitable for X-ray analysis. It should beemphasized that in case of complex 2, {[Cu(bpca)(4,40-bipy)(H2O)]-ClO4}2, the ligand Hbpca, py–CO–NH–CO–py was obtained via thehydrolysis of 2,4,6-tris(2-pyridyl)-triazine promoted by Cu2+ ion.This hydrolysis does not seem to be uncommon, but it was ob-served in a number of reactions [36].

The IR spectra of the complexes 2 and 3 display broad bands inthe 3360–3450 cm�1 range assigned to m(O–H) stretching vibra-tions of water molecules. The fact that this band is strong in 2 isindicative for the presence of coordinated water molecule. The per-chlorate ions displayed very strong absorptions in the range 1120–1090 cm�1.

The visible spectral data for the Cu(II) complexes 1–6 and inMeOH or in H2O are similar and characterized by a rather broadd–d absorption band in the 600–900 nm region. In general, thisfeature is characteristic for five-coordinate Cu(II) complexes, thatoften may be associated with a low-, or high-energy shoulder. Inmany cases, the presence of the broad band in the 550–660 nmrange with a low-energy shoulder indicates a square pyramidal(SP) geometry whereas, a single d–d band at k > 800 nm with ahigh-energy shoulder is typical for trigonal bipyramidal (TBP) ste-reochemistry [37]. Thus, on the basis of this criterion, the elec-

Table 1Crystallographic data and processing parameters.

Compound 1 2 3 4 5 6

Empirical formula C18H28Cl2CuN6O8 C22H18ClCuN5O7 C34H36Cl4Cu2N8O17 C28H52Cl4Cu2N10O16 C48H48Cl4Cu2N10O16 C17H27Cl2CuN5O8

Formula mass 590.90 563.40 1097.61 1053.68 1289.86 563.89System monoclinic triclinic triclinic triclinic monoclinic monoclinicSpace group C2/c P�1 P�1 P�1 P21/c P21/na (Å) 14.9563(3) 7.4829(3) 8.5108(3) 9.3276(4) 22.3883(11) 9.6756(5)b (Å) 13.6077(3) 9.9637(4) 15.4328(5) 11.2042(4) 9.5978(5) 17.4411(9)c (Å) 12.0552(2) 16.2793(6) 16.9681(6) 12.0685(4) 25.4833(12) 13.3238(7)a (�) 90 102.8820(10) 71.4140(10) 63.551(1) 90 90b (�) 91.9210(10) 102.390(2) 82.8250(10) 74.446(2) 98.985(2) 90.353(1)c (�) 90 99.2690(10) 88.6590(10) 71.320(2) 90 90V (Å3) 2452.11(8) 1127.52(8) 2095.59(13) 1057.98(7) 5408.6(5) 2248.4(2)Z 4 2 2 1 4 4Wavelength (Å) 1.54178 1.54178 0.71073 1.54178 1.54178 1.54178l (mm�1) 3.761 2.961 1.355 4.258 3.464 4.055Dcalc (Mg m�3) 1.601 1.659 1.740 1.654 1.584 1.666Crystal size (mm) 0.31 � 0.23 � 0.21 0.29 � 0.25 � 0.18 0.50 � 0.44 � 0.14 0.36 � 0.25 � 0.16 0.34 � 0.23 � 0.11 0.25 � 0.20 � 0.16hmax (�) 68.02 66.94 27.48 67.85 67.97 66.97Unique reflection/Rint 2125/0.0430 3664/0.0229 9567/0.0523 3276/0.0154 9528/0.0235 3814/0.0232Parameters 161 326 586 327 721 300Goodness-of-fit (GOF) on F2 1.072 1.070 1.094 1.088 1.032 1.054R1/wR2 (all data) 0.0323/0.0891 0.0433/0.1091 0.0521/0.1260 0.0528/0.1384 0.0462/0.1183 0.0280/0.0741Residual extrema (e Å�3) 0.50/�0.30 1.62/�0.87 1.23/�0.73 0.90/�0.54 2.61/�1.55 0.38/�0.32

Fig. 1. Perspective view of [Cu(cyclen)(4,40-bipy)](ClO4)2 (1) with the atom labeling scheme. Symmetry code: (0): 1�x,y,1/2�z.

S.S. Massoud et al. / Polyhedron 28 (2009) 3849–3857 3851


tronic spectral data of the Cu(II)–di-pyridyl complexes 1, 2, 4 and 6can be described by SP geometry around the central Cu(II) ions. Onthe other hand, the aqueous solution spectrum of 5 {kmax = 660 (sh)and 860 nm} clearly demonstrates the TBP environment aroundthe Cu(II) center [32,37]. In most cases, the complexes may haveintermediate geometries that are slightly distorted from the ideal

SP or TBP. These findings in solution for the geometry about theCu(II) ion (SP in 1, 2, 4 and 6; TBP in 5) are in complete agreementwith the assigned geometries based on X-ray data (see next sec-tion). The aqueous visible spectrum of [Cu2(DPA)2(l2-4,40-bipy)(ClO4)4]�H2O (3) displays a very broad band around 655 nm witha small shoulder at �735 nm which is most likely attributable tostrong distorted octahedral environment around the central Cu+2

ion.

3.2. Description of the structures

3.2.1. [Cu(cyclen)(4,4’-bipy)](ClO4)2 (1)A perspective view together with the atom labeling scheme is gi-

ven in Fig. 1, and selected bond parameters are given in Table 2. Thestructure consists of monomeric [Cu(cyclen)(4,4’-bipy)]2+ cationswith site symmetry 2, and perchlorate counter anions. Each coppercenter is penta-coordinated by the four N atoms of the cyclen [Cu1–Namine varies from 2.0236(19) to 2.0312(17) Å], in basal positions,and the N3 atom of the monodentate 4,4’-bipy ligand and is inthe apical position [Cu1–N3 = 2.141(2) Å]. The coordination poly-hedron may be described as axially elongated square pyramid withs = 0.005 [38]. The metal center is shifted by 0.441 Å from the basalCuN4 plane towards N3. The pyridyl ring of N3 has an interplanarangle of 32.3� with the uncoordinated pyridyl ring of N4, and of90� with the basal CuN4 plane, respectively. The shortest internu-clear Cu��Cu separation is 7.2040(4) Å. Hydrogen bonds of typeN–H��O from N donor atoms of cyclen ligand to oxygen atoms ofperchlorate counter ions [N1��O2 = 3.019(2) Å; N(2)��O(2)#1 (#1:1/2�x,1/2�y, �z) = 3.161(2) Å and N(2)��O(3)#1 = 3.030(2) Å] forma supramolecular 1-D system extended along the c-axis of themonoclinic unit cell (Table 3, Fig. S1).

3.2.2. {[Cu(bpca)(H2O)]ClO4}2 (2)An ORTEP plot together with the atom labeling scheme is given

in Fig. 2 and selected bond parameters are summarized in Table 2.Each penta-coordinated copper atom forms bonds to the three N

Table 2Selected bond lengths (Å) and angles (�) for compounds 1–6.

Compound 1a

Cu1–N1 2.0312(17) Cu1–N2 2.0236(19)Cu1–N3 2.141(2)N1–Cu1–N1’ 148.26(10) N2–Cu1–N2’ 148.57(10)N1–Cu1–N2 85.79(7) N2–Cu1–N1’ 85.71(7)N1–Cu1–N3 105.87(5) N2–Cu1–N3 105.72(5)

Compound 2b

Cu1–N1 2.017(2) Cu1–N3 2.028(2)Cu1–N2 1.943(2) Cu1–N4 1.998(2)Cu1–O5 2.302(2) Cu1–O7’ 2.838(3)N2–Cu1–N4 169.79(10) N1–Cu1–N2 81.93(10)N4–Cu1–N1 98.51(10) N2–Cu1–N3 81.90(10)N4–Cu1–N3 96.64(10) N1–Cu1–N3 163.27(10)N2–Cu1–O5 93.51(9) N4–Cu1–O5 96.67(9)N1–Cu1–O5 91.67(8) N3–Cu1–O5 93.59(9)

Compound 3Cu1–N1 1.993(3) Cu1–N4 2.006(3)Cu1–N2 2.006(3) Cu1–N3 1.990(3)Cu1–O6 2.482(3) Cu1–O15 2.616(3)Cu2–N6 2.008(3) Cu2–N5 1.986(3)Cu2–N7 2.004(3) Cu2–N8 1.987(3)Cu2–O2 2.490(3) Cu2–O12 2.543(3)N1–Cu1–N3 165.96(12) N5–Cu2–N8 98.48(12)N2–Cu1–N3 83.18(12) N5–Cu2–N7 177.73(13)N2–Cu1–N1 82.90(12) N8–Cu2–N7 83.70(13)N4–Cu1–N3 97.12(12) N5–Cu2–N6 95.15(12)N4–Cu1–N1 96.72(12) N8–Cu2–N6 166.04(12)N4–Cu1–N2 177.77(13) N7–Cu2–N6 82.71(13)O6–Cu1–O15 164.32(12) O2–Cu2–O12 164.65(10)

Compound 4Cu1–N1 2.034(3) Cu1–N3 2.019(3)Cu1–N2 2.012(4) Cu1–N4 2.046(3)Cu1–N5 2.153(3)N2–Cu1–N3 85.97(16) N1–Cu1–N2 86.68(17)N3–Cu1–N1 146.46(17) N2–Cu1–N4 147.33(17)N4–Cu1–N3 84.28(14) N1–Cu1–N4 84.48(15)N2–Cu1–N5 106.84(14) N3–Cu1–N5 106.88(14)N1–Cu1–N5 106.58(15) N4–Cu1–N5 105.83(14)

Compound 5Cu1–N1 2.082(3) Cu1–N3 2.115(2)Cu1–N2 2.021(2) Cu1–N4 2.039(3)Cu1–N5 1.972(2) Cu2–N1A 2.043(2)Cu2–N2A 2.024(2) Cu2–N3A 2.148(2)Cu2–N4A 2.051(2) Cu2–N5A 1.996(2)N2–Cu1–N5 173.86(10) N2A–Cu2–N5A 174.82(10)N4–Cu1–N5 92.85(10) N4A–Cu2–N5A 99.92(10)N4–Cu1–N2 81.49(10) N4A–Cu2–N2A 80.38(10)N1–Cu1–N5 99.78(10) N1A–Cu2–N5A 93.76(10)N1–Cu1–N2 82.38(10) N1A–Cu2–N2A 82.59(10)N1–Cu1–N4 131.54(10) N1A–Cu2–N4A 135.85(9)N3–Cu1–N5 104.44(10) N3A–Cu2–N5A 103.51(9)N2–Cu1–N3 80.66(10) N2A–Cu2–N3A 81.43(9)N3–Cu1–N4 120.85(10) N3A–Cu2–N4A 102.18(9)N1–Cu1–N3 100.95(10) N1A–Cu2–N3A 115.11(10)

Compound 6Cu1–N1 2.0163(17) Cu1–N3 2.0023(17)Cu1–N2 2.1034(17) Cu1–N4 2.1084(16)Cu1–N5 2.2537(16)N2–Cu1–N3 93.49(7) N1–Cu1–N2 92.08(7)N3–Cu1–N1 168.09(7) N2–Cu1–N4 150.73(6)N4–Cu1–N3 85.25(7) N1–Cu1–N4 84.75(6)N2–Cu1–N5 105.96(6) N3–Cu1–N5 95.58(7)N1–Cu1–N5 92.99(6) N4–Cu1–N5 103.26(6)

a Symmetry code for 1: (0): 1�x,y,1/2�z.b Symmetry code for 2: (0): 1�x,1�y,2�z.

Table 3Hydrogen bonding system for compounds 1–4 and 6.

D–H��Aa Symmetry of A D��A (Å) D–H��A (�)

Compound 1N1–H1A��O2 [1/2 + x,1/2 + y,z] 3.019(2) 175.4N2–H2A��O2 [1/2�x,1/2�y,�z] 3.161(2) 141.3N2–H2A��O3 [1/2�x,1/2�y,�z] 3.030(3) 144.7

Compound 2O5–H5��O3 [�x,�y,1�z] 2.838(4) 175.4O5–H5A��N5 [�x,1�y,1�z] 2.795(4) 171.6

Compound 3N2–H2A��O7 3.038(4) 157.8N7–H7C��O7 [1 + x,y,�1 + z] 3.086(4) 146.5O17–H17A��O16 [1�x,2�y,2�z] 3.145(5) 175.9O17–H17B��O9 [1�x,1�y,2�z] 2.990(5) 180.0

Compound 4N1–H1C��O4 2.961(6) 154.6N2–H2C��O4 [1�x,1�y,2�z] 3.025(5) 140.0N3–H3C��O6b [1�x,2�y,1�z] 3.061(8) 120.7N3–H3C��O8b [1�x,2�y,1�z] 3.046(9) 171.5N4–H4C��O5b 3.189(11) 141.0N4–H4C��O8b 2.923(9) 143.6

Compound 6N1–H1A��O2 [1 + x,y,z] 3.128(3) 166.9N1–H1B��O4 [1�x,�y,�z] 3.197(2) 171.3N3�H3A��O5 [1�x,�y,1�z] 3.392(3) 147.3N3–H3A��O8 [1�x,�y,1�z] 3.186(2) 156.3N3–H3B��O5 [1 + x,y,z] 3.003(3) 153.2

a D = donor, A = acceptor.b Disordered atom.



atoms of the bpca anion and N4 of the terminal 4,4’-bipy ligand,[Cu–N bonds from 1.943(2) to 2.028(3) Å] in basal sites, and toO5 atom of the aqua ligand in apical site [Cu1–O5 = 2.302(2) Å].The CuN4O chromophore has as a distorted SP geometry(s = 0.108). Taking into account an additional semi-coordinatebond of 2.838(3) Å to O7’ [1�x,1�y,2�z] of an adjacent bpca anion,a centrosymmetric dimeric [Cu(bpca)(4,4’-bipy)(H2O)]2

2+ unit witha 4+1+1 geometry around the Cu1 center is formed. The intra-di-mer Cu1��Cu1’ distance is 5.2068(5) Å, and the shortest inter-dinu-clear Cu��Cu separation is 7.4829(7) Å. The terminal 4,4’-bipyligand has a C16–C15–C18–C22 torsion angle of �33.3�. O5 ofthe aqua ligand acts as donor for two hydrogen bonds: a hydrogenbond of type O–H��O to O3# [�x,�y,1�z] of a perchlorate counterion and a hydrogen bond of type O–H��N to non-coordinated N5”[�x,1�y,1�z] of the terminal bipy ligand (Table 3, Fig. S2).

3.2.3. [Cu2(DPA)2(l2-4,4’-bipy)(ClO4)4]�H2O (3)A perspective view together with the atom labeling scheme is

given in Fig. 3A and selected bond parameters are summarized inTable 2. Both copper centers in the acentric dinuclear complexform an axially elongated octahedral complex with three nitrogendonors of the DPA blocking ligand and one nitrogen atom of the4,4’-bipy bridge in equatorial sites [Cu–N bonds from 1.986(3) to2.008(3) Å], and two trans-coordinated oxygen atoms of ClO4

� ionsin axial sites [Cu–O from 2.482(3) to 2.616(3) Å]. The bridging 4,4’-bipy ligand has a C14–C15–C18–C19 torsion angle of 30.8�. O17 ofthe lattice water molecule, N2 and N7 atoms act as donors forhydrogen bonds of type O–H��O and N–H��O generating supramo-lecular chains along [1 0 �1] (Table 3, Fig. S3).

3.2.4. [Cu2(cyclen)2(l2-dpe)](ClO4)4 (4)The structure of complex 4 consists of centrosymmetric dimeric

[Cu2(cyclen)2(dpe)]4+ complex cations and disordered perchloratecounter ions. An ORTEP plot together with the atom labeling schemeis given in Fig. 3B and selected bond parameters are summarized inTable 2. The CuN5 chromophore with SP geometry (s = 0.015) isachieved by the 4N atoms of the cyclen ligand [Cu–N bonds varyfrom 2.012(4) to 2.046(3) Å] in basal sites, and the N5 atom of thebridging dpe in apical site [Cu1–N5 = 2.153(3) Å]. Cu1 deviates by0.461 Å from the CuN4 basal plane. The bridging dpe ligand is locatedat the inversion center, thus the torsion angle C5–C14–C14’–C5’ = �180� and the two pyridyl rings are parallel. The N atoms ofthe cyclen blocking ligands act as donor atoms for hydrogen bondsof type N–H��O to O atoms of the disordered perchlorate counter

ions, generating a supramolecular 2D network oriented along[1 �1 0] and [1 0 �1] (Table 3, Fig. S4).

3.2.5. [Cu2(TPA)2(l2-dpe)](ClO4) (5)The structure of complex 5 consists of acentric dimeric

[Cu2(TPA)2(dpe)]4+ complex cations and perchlorate counter ions.A perspective view together with the atom labeling scheme isdepicted in Fig. 3C and selected bond parameters are presented inTable 2. Each CuN5 chromophore with distorted TBP geometry(s = 0.705 for Cu1 and 0.650 for Cu2, respectively) is achieved bythree pyridyl-N atoms of a TPA blocking ligand [Cu–N bonds from2.039(3) to 2.148(2) Å] in equatorial sites, and a central amine-Natom of the TPA and one N-pyridyl atom from the bridging dpe ligandin axial positions [Cu–N from 1.966(2) to 2.024(2) Å]. The bridgingdpe ligand adopts an anti-periplanar conformation [C21–C24–C24A–C23A torsion angle of �171.8�]. The mean planes of the twopyridyl rings of the dpe bridge form an interplanar angle of 94.6�(the packing plot of 5 is shown in Fig. S5).

3.2.6. {[Cu(Medpt)(l2-4,4’-bipy)](ClO4)2}n (6)A labeled ORTEP plot for compound 6 is shown in Fig. 4A and

selected bond parameters are given in Table 2. The structure con-sists of positively charged polymeric [Cu(Medpt)(4,4’-bipy)]n

2n+

chains and ClO4� counter anions. Each copper center is penta-coor-

dinated by the three N donor atoms of the Medpt blocking ligand[Cu1–Namine varies from 2.0023(17) to 2.1034(17) Å], and N4 atomof the bridging 4,4’-bipy ligand in basal positions [Cu1–N4 =2.1084(16) Å], and N5 of a 4,4’-bipy ligand in apical position[Cu1–N5 = 2.2537(16) Å]. The CuN5 chromophore has a distortedSP geometry with s = 0.289. The metal center is shifted by0.274 Å from the basal CuN4 plane towards N5. The bridging 4,4’-bipy ligands connect the copper centers to form cis-1D polymericchains of polyhedra oriented along the b-axis of the unit cell. Thetwo pyridyl rings of have an interplanar angle of 52.7�. Hydrogenbonds of type N–H��O from N1 and N3 donor atoms of Medpt li-gand to oxygen atoms of the perchlorate counter ions generate asupramolecular 2-D system extended along [0 0 1] and [1 �1 0](Table 3 and Fig. 4B).

The di-pyridyl ligands have been used for long time to study theelectronic interaction in solution between metal ions and as abridging ligand in the solid state [4–27]. The bridging ability wasdemonstrated in complexes 3–6. The Cu��Cu distances across thebridged di-pyridyl ligands range from 11.012–11.426 Å for the4,40-bipy to 13.033–13.561 Å for the corresponding bpe, whereasthe shortest inter-dinuclear Cu��Cu separations vary from 6.528

Fig. 2. Perspective view of {[Cu(l2-bpca)(4,40-bipy)(H2O)](ClO4)2}2 (2) with the atom labeling scheme. Symmetry codes: (0): 1�x,1�y,2�z; (00): �x,1�y,1�z; (#): �x,�y,1�z.



to 7.882 Å. However, the formation of mononuclear complexes 1and 2 need to be addressed here. It has been reported, that the

di-pyridyl ligands can play three roles: monoprotonated cations,hydrogen-bonded neutral species, and bridges between metal ions

A

B

C

Fig. 3. ORTEP plot or perspective view and atom labeling scheme for the bridged di-pyridyl Cu(II) complexes: (A) [Cu2(DPA)2(l2-4,40-bipy)(ClO4)4]�H2O (3). (B)[Cu2(cyclen)2(l2-dpe)](ClO4)4 (4), only one orientation of disordered ClO4

� counter ions is given for clarity. Symmetry code: (0): �x,2�y,2�z. (C) [Cu2(TPA)2(l2-dpe)](ClO4)4

(5).



[39]. In this work, the involvement of the terminal 4,4’-bipy nitro-gen atom in hydrogen bonding would be responsible for the stabil-ity of the mononuclear complex 2 (see Fig. S2). This was alsoobserved in [Cu(dien)(4,4’-bipy)(H2O)](ClO4)2 [19]. The formationof the mononuclear species [Cu(cyclen)(4,4’-bipy)](ClO4)2 (1)seems to be unusual and it cannot be accounted based on any ofthe three reasons cited above; the uncoordinated nitrogen of the4,40-bipy ligand was not participating in hydrogen bonding(Fig. 1 and Fig. S1). The isolation of 1 may be attributed to the con-strain implied by the coordinated cyclen ligand that inhibits theterminal N- of the non-flexible 4,40-bipy ligand to bind a second[Cu(cyclen)]2+. Interestingly, this was not the case with the moreflexible dpe ligand which allows the formation of the bridged com-plex [Cu2(cyclen)2(l2-dpe)](ClO4)4 (4).

3.3. Thermal analysis

The complexes under investigation were heated between roomtemperature and 400 �C under helium atmosphere. The DTA andTGA data (Table S1) showed that all samples were exploded duringdecomposition with 60–80% mass loss, except complex 5 whichdecomposes in three steps without explosion. The explosive natureof the decomposition reactions were identified by sharp exother-mic processes as detected by DTA. These reactions were accompa-nied by huge sudden weight increase (�1500%) followed byequally sudden weight decrease to the fraction of the initial mass.The apparent weight increase was associated with jet propulsioneffect causing sample container to apply pressure on the microbal-ance which resulted in ‘mass increase’. The major species of the

A

B

Fig. 4. (A) Perspective view of {[Cu(Medpt)(l2-4,40-bipy)](ClO4)2}n (6) with the atom labeling scheme. Symmetry codes: (0): 5/2�x,1/2 + y,1/2�z; (#): 5/2�x,�1/2 + y,1/2�z.(B) Hydrogen bonding system of 6 and packing plot viewed along the a-axis of the unit cell.



sample mass loss correspond to H2O, O2, N2 and CO2 evolution.Also it has been observed that explosion, occurring at 304, 339,287, 313 and 273 �C for 1, 2, 3, 4 and 6, respectively, did not leadto full chemical decomposition. The thermogravimetric analysesof the six compounds are depicted in Fig. 5.

Probably, it should be mentioned that the di-pyridyl com-pounds are known to exhibit phase transition with stereochemicalchanges [2] or different conformations within the lattice [29] andthat is why we studied the thermal behavior of these complexes.Unfortunately, compounds 1–6 did not show any of these changesbetween 294 and 100 K.

3.4. Magnetic properties of [Cu2(DPA)2(4,40-bipy(ClO4)4)]�H2O (3)

The vMT product versus T in the 2–300 K range of 3 is plotted inFig. 6. The overall behavior of 3 corresponds to magnetically noncoupled systems: at room temperature vMT has values of0.88 cm3 K mol�1 (0.75 cm3 K mol�1 for two isolated copper atomswith g = 2) and is practically constant under the full range of tem-peratures: only at very low temperature decreases slightly on cool-ing reaching a value of 0.76 cm3 K mol�1 at 2 K. vM values for 3increase on cooling from the same value of 0.03 cm3 mol�1 at roomtemperature and have no maximum in the range of temperaturesstudied. The experimental magnetic data have been fitted usingthe expression derived through the Hamiltonian H = �JSA�SB withSA = SB = 1/2.

vM ¼ ð2N g2l2B=kTÞ ðexpðJ=kTÞÞ=ð1þ 3 expðJ=kTÞÞ½ � ð1Þ

The parameters N, lB and k in Eq (1) have their usual meanings.Least-squares fitting of all experimental data leads to the followingparameters J = �0.58 cm�1, g = 2.16. The low |J| value confirms thenon existence of magnetic coupling.

Since the magnetic properties of complex 3 were in the samerange as was expected for bridged di-pyridyl Cu(II) complexes withintramolecular Cu��Cu bond distances larger than 11 ÅA

0

, showingweak antiferromagnetic coupling [18,19,22,30], no further mag-netic measurements were needed for the remaining complexes.

4. Conclusion

The crystal structures of the six di-pyridyl Cu(II) complexes de-scribed here in this study clearly reveal the versatility of the di-pyr-idyl ligands in binding metal ions. In general, dinuclear andpolymeric bridged di-pyridyl complexes are formed (3–6) wherethe Cu(II) centers are separated by more than 11 ÅA

0

and the inter-molecular distances are even shorter (6�8 ÅA

0

). The magnetic analy-sis of complex 3 which was taken as a representative for the studiedbridged di-pyridyl complexes reveal the expected weak antiferro-magnetic coupling between the Cu(II) centers. This could be attrib-uted to the intra- and inter-molecular exchange pathways. On theother hand, separation of the mononuclear species 1 and 2 isinteresting. This can be accounted for the involvement of the termi-nal N- of the 4,40-bipy in hydrogen bonding in 1 whereas, in 2 thegeometrical stain imposed by the cyclen coligand and the less flex-ible 4,40-bipy may account for its monomeric nature. Nevertheless,none of these parameters would grantee the formation of mononu-clear di-pyridyl species in all cases. The use of excess amounts of thedi-pyridyl ligands may break down the H-bonding and leads tobridged species [19]. Also, flexible di-pyridyl ligands (bpe or bpp)may be able to bridge metal ion that is coordinated to geometricallystrained coligands as in case of cyclen compound, 4.

Acknowledgments

This research was financially supported by the University ofLouisiana at Lafayette, and SSM thanks Dean B. Clark (UL-Lafay-ette). The Robert A. Welch Foundation supported this investigationthrough grant E-592 to IB. The authors acknowledge support byNSF-CRIF grant no. 0443538 for part of the X-ray diffractometer.

Appendix A. Supplementary data

CCDC 740483, 740484, 740485, 740486, 740487 and 740489contain the supplementary crystallographic data for the complexes

Fig. 5. Thermogravimetric analysis for the six di-pyridyl compounds (heating rate = 10 �C/min).

0 50 100 150 200 250 300

0.4

0.6

0.8

1.0

χ MT(cm3 mol

-1K)

T (K)

Fig. 6. Magnetic properties of [Cu2(DPA)2(l2-4,40-bipy)(ClO4)4]�H2O (3).



1, 2, 3, 4, 5 and 6, respectively. These data can be obtained free ofcharge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, orfrom the Cambridge Crystallographic Data Centre, 12 Union Road,Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: [email protected]. Supplementary data associated with thisarticle can be found, in the online version, at doi:10.1016/j.poly.2009.08.019.

References

[1] (a) A.N. Khlobystov, A.J. Blake, N.-R. Champness, D.A. Lemenovskii, A.G.Majouga, N.V. Zyk, M. Schröder, Coord. Chem. Rev. 222 (2001) 155;(b) A. Erxleben, Coord. Chem. Rev. 246 (2003) 203;(c) B. Moulton, M.J. Zaworotko, Chem. Rev. 101 (2001) 1629;(d) J.-M. Lehn, Science 295 (2002) 2400.

[2] S.S. Massoud, J. Grebowicz, R. Vicente, R. Lalancette, U. Mukhopadhyay, I.Bernal, submitted for publication.

[3] (a) S. Leininger, B. Olenyuk, J. Stang, Chem. Rev. 100 (2000) 853;(b) M. Fujita, Chem. Soc. Rev. 27 (1998) 417.

[4] (a) M.J. Plater, M.R.St.J. Foreman, T. Gelbrich, M.B. Hursthouse, J. Chem. Soc.,Dalton Trans. (2000) 1995;(b) M.J. Plater, M.R.St.J. Foreman, T. Gelbrich, S.J. Coles, M.B. Hursthouse, J.Chem. Soc., Dalton Trans. (2000) 3065.

[5] R. Horikoshi, T. Mochida, N. Maki, S. Yamada, H. Motiyama, J. Chem. Soc.,Dalton Trans. (2002) 28.

[6] J. Zhang, Y.-B. Chen, S.-M. Chen, Z.-J. Li, J.-K. Cheng, Y.-G. Tao, Inorg. Chem. 45(2006) 3161.

[7] R. Kitaura, K. Seki, G. Akiyama, S. Kitagawa, Angew. Chem., Int. Ed. 42 (2003)428.

[8] S. Noro, S. Kitagawa, M. Kondo, K. Seki, Angew. Chem., Int. Ed. 39 (2000) 2082.[9] P. Losier, M.J. Zaworotko, Angew. Chem., Int. Ed. 35 (1996) 2779.

[10] (a) L. Pan, H. Liu, X. Lei, X. Huang, D.H. Olson, N.J. Turro, J. Li, Angew. Chem.,Int. Ed. 42 (2003) 542;(b) M. Oh, G.B. Carpenter, D.A. Sweigart, Angew. Chem., Int. Ed. 42 (2003)2026;(c) M.V. Bennett, M.P. Shores, L.G. Beauvais, J.R. Long, J. Am. Chem. Soc. 122(2000) 6664.

[11] (a) M. Ruben, J.-M. Lehn, G. Vaughan, Chem. Commun. (2003) 1338;(b) K. Maruoka, N. Murase, H. Yamamoto, J. Org. Chem. 58 (1993) 2938.

[12] A.K. Ghosh, A.D. Jana, D. Ghoshal, G. Mostafa, N.R. Chaudhuri, Cryst. GrowthDes. 6 (2006) 701.

[13] M. Kondo, T. Yoshitomi, K. Seki, H. Matsuzaka, S. Kitagawa, Angew. Chem., Int.Ed. 36 (1997) 1725.

[14] (a) L.G. Beauvais, J.R. Long, J. Am. Chem. Soc. 126 (2002) 12096;(b) O. Kahn, Acc. Chem. Res. 33 (2000) 647.

[15] (a) M. Ruben, J.-M. Lehn, G. Vaughan, Chem. Commun. (2003) 1338;(b) O.R. Evans, W. Lin, Acc. Chem. Res. 35 (2002) 511.

[16] C. Chen, K.S. Suslick, Coord. Chem. Rev. 128 (1993) 293.[17] L. Ouahab, T. Enoki, Eur. J. Inorg. Chem. (2004) 933.[18] S.V. Kolotilov, O. Cador, S. Golhen, O. Shvets, V.G. Ilyin, V.V. Pavlishchuk, L.

Quahab, Inorg. Chim. Acta 360 (2007) 1883.[19] M. Julve, M. Verdaguer, J. Faus, F. Tinti, J. Moratal, A. Monge, E. Gutiérrez-

Puebla, Inorg. Chem. 26 (1987) 3520.[20] (a) J. Greve, I. Jeb, C. Näther, J. Solid State Chem. 175 (2003) 328;

(b) C. Näther, J. Greve, I. Jeb, Chem. Mater. 14 (2002) 4536.[21] M. Lu-Fang, L.-Y. Wang, Y.-Y. Wang, S.R. Batten, J.-G. Wang, Inorg. Chem. 48

(2009) 915.[22] (a) S.C. Manna, A.K. Ghosh, E. Zangarando, N.R. Chaudhuri, Polyhedron 27

(2007) 1105;(b) S.C. Manna, S. Konar, E. Zangarando, K. Okamoto, J. Ribas, N.R. Chaudhuri,Eur. J. Inorg. Chem. (2005) 4646;(c) S.C. Manna, J. Ribas, E. Zangarando, N.R. Chaudhuri, Polyhedron 26 (2007)4923;

(d) A.J. Blake, N.R. Brooks, N.R. Chaudhuri, M. Crew, D.H. Gregory, P.Hubberstey, M. Schröder, A. Deveson, D. Fenske, L.R. Hanton, Chem.Commun. (2001) 1432;(e) M. Hong, W. Su, R. Cao, M. Fujita, J. Lu, Chem. Eur. J. 3 (2000) 427.

[23] J. Atineza, A. Gutiérrez, M.F. Perpiñán, A.E. Sánchez, Eur. J. Inorg. Chem. (2008)5524.

[24] C.C. Corrêa, R. Diniz, L.H. Chagas, B.L. Rodrigues, M.I. Yoshida, W.M. Teles, F.C.Machdo, L.F.C. de Oliveira, Polyhedron 26 (2007) 989.

[25] M.V. Marinho, M.I. Yoshida, K.J. Guedes, K. Krambrock, A.J. Bortoluzzi, M.Hörner, F.C. Machado, W.M. Teles, Inorg. Chem. 43 (2004) 1539.

[26] M.J. Plater, M.R.S. Foreman, T. Gelbrich, M.B. Hursthouse, Inorg. Chim. Acta 318(2001) 171.

[27] (a) R. Wang, L. Han, Y. Sun, Y. Gong, D. Yuan, M. Hong, J. Mol. Struct. 694(2004) 79;(b) X.-J. Luan, Y.-Y. Wang, D.-S. Li, P. Liu, H.-M. Hu, Q.-Z. Shi, S.-M. Peng,Angew. Chem., Int. Ed. 44 (2005) 3864.

[28] (a) D.N. Dybtsev, M.P. Yutkin, E.V. Peresypkina, A.V. Virovets, C. Serre, G. Férey,V.P. Fedin, Inorg. Chem. 46 (2007) 6843;(b) G. Férey, C. Mellot-Draznicks, C. Serre, F. Millange, J. Dutour, S. Surblé, I.Margiolaki, Science 295 (2005) 238;(c) A.G. Wong-Foy, A.J. Matzger, O.M. Yaghi, J. Am. Chem. Soc. 128 (2006)3494;(d) H. Chun, D.N. Dybtsev, H. Kim, K. Kim, Chem. Eur. J. 11 (2005) 3521.

[29] (a) L. Carlucci, G. Ciani, D.M. Proserpio, S. Rizzato, Cryst. Eng. Commun. 4(2002) 121;(b) F.M. Tabellion, S.R. Seidel, A.M. Arif, P.J. Stang, J. Am. Chem. Soc. 123 (2001)11982;(c) E.-Q. Gao, Z.-M. Wang, C.-S. Liao, C.-H. Yan, New J. Chem. 26 (2002) 1096.

[30] E.-Q. Gao, Y.-X. Xu, A.-L. Cheng, M.-Y. He, C.-H. Yan, Inorg. Chem. Commun. 9(2006) 212.

[31] Z. Tyeklár, R.R. Jacobson, N. Wei, N.N. Murthy, J. Zubieta, K.D. Karlin, J. Am.Chem. Soc. 115 (1993) 2677.

[32] (a) S.S. Massoud, F.A. Mautner, R. Vicente, F.R. Louka, Eur. J. Inorg. Chem.(2008) 3709;(b) F.A. Mautner, J.B. Soileau, K.P. Bankole, A. Gallo, S.S. Massoud, J. Mol. Struct.(2008);(c) S.S. Massoud, F.A. Mautner, R. Vicente, B.M. Rodrigue, Inorg. Chim. Acta 359(2006) 3321;(d) U. Mukhopadhyay, I. Bernal, S.S. Massoud, F.A. Mautner, Inorg. Chim. Acta357 (2004) 3673.

[33] (a) Bruker, SAINT v. 7.23, Bruker AXS Inc., Madison, Wisconsin, USA, 2005.;(b) Bruker, APEX 2, v. 2.0-2, Bruker AXS Inc., Madison, Wisconsin, USA, 2006.;(c) G.M. Sheldrick, SADABS v. 2, University of Goettingen, Germany, 2001.

[34] G.M. Sheldrick, SHELXTL v. 6.14, University of Goettingen, Germany, 2004.[35] E. Keiserberger, E. Post, Thermochim. Acta 295 (1997) 73.[36] (a) H. Casellas, F. Costantino, A. Mandonnet, A. Caneschi, D. Gatteschi, Inorg.

Chim. Acta 358 (2005) 177;(b) P. Paul, B. Tyagi, A.K. Bilakhiya, M.M. Bhadbhade, E.J. Suresh, J. Chem. Soc.,Dalton Trans. (1999) 2009;(c) P. Paul, B. Tyagi, A.K. Bilakhiya, M.M. Bhadbhade, E.J. Suresh, G.Ramachandraiah, J. Inorg. Chem. 37 (1999) 5733;(d) P. Paul, B. Tyagi, A.K. Bilakhiya, M.M. Bhadbhade, E.J. Suresh, J. Chem. Soc.,Dalton Trans. (1997) 2273;(e) S. Wocadlo, W. Massa, J.-V. Folgado, Inorg. Chim. Acta 207 (1993) 199;(f) I. Castro, J. Faus, M. Julve, Y. Journaux, J. Sletten, J. Chem. Soc., Dalton Trans.(1991) 2533;(g) D. Marcos, J.-V. Folgado, D. Beltrán-Porter, M.T. de Prado-Gambardella, S.H.Pulcinelli, R.H. de Almeida-Santos, Polyhedron 9 (1990) 2699;(h) A. Cantarero, J.M. Amigo, J. Faus, M. Julve, T. Dabaerdemaekar, J. Chem.Soc., Dalton Trans. (1988) 2033.

[37] B.J. Hathaway, in: G. Wilkinson, R.D. Gillard, J.A. McCleverty (Eds.),Comprehensive Coordination Chemistry, vol. 5, Pergamon Press, Oxford,England, 1987, p. 533.

[38] A.W. Addison, T.N. Rao, J. Reedijk, J.V. Rijin, G.C. Verschoor, J. Chem. Soc.,Dalton Trans. (1984) 1349.

[39] T.J.R. Weakley, Inorg. Chim. Acta 96 (1985) 151.


Versatile binding properties of di-pyridyl ligands with Cu(II) complexes: The syntheses, structural...

Documents

Transcript of Versatile binding properties of di-pyridyl ligands with Cu(II) complexes: The syntheses, structural...