Polynuclear complexes tetrahedral

Monomeric complexes have been formed with the bis(benzimidazolylmethyl) sulfide ligands to give tetrahedral N2S2 coordinated zinc in combination with thiolates.125 The benzimidazole ligand (9) shown has also been used to form polynuclear complexes with zinc and benzylthiolates.126... 

Classical or Werner complexes have a metal in a positive oxidation state coordinated by donor ligands. The coordination number and geometry are determined by size and bonding factors, octahedral and tetrahedral being common for 3d ions, and square-planar coordination for some (ft ions. Polynuclear complexes can have bridging ligands and/or metal-metal bonding. 

Unlike Pb(IV) compounds, which tend fairly universally to be four-coordinate and tetrahedral, Pb(II) componnds exist as both discrete and polynuclear complexes and exhibit a broad range of coordination numbers, from 2 to 12... 

Polynuclear Complexes. caJCTa-/x-Bis-(l,2-diphenylphosphinyl)ethane-dichlorocopper(ii), [CuClaCPhsPO-CHaCHaPO-Pha)], is polymeric (84). The copper atoms lie on crystallographic Cj axes and exhibit flattened tetrahedral co-ordination. The angle between the CuOj and CuCla planes is 57.7 , and the Cu-Cl and Cu-O distances are respectively 2.195 and 1.960 A. 

A plethora of polynuclear copper(I) complexes with bi-, tri-, and tetracon-necting dithiophosphato ligands have been discovered. These include cyclic dimers, [CuS2P(OEt)2 PPh3]2,43 tetrahedral Cu4[S2P(OPr )2]4,44 prismatic Cu6 S2P(OR)2 6, cubane Cu8(p8-E )[S2P(OEt)2]6 (E = S, Se),45 (also known for silver)46 and [Cu8 S2P(OPr )6(p8-X)][PF6] (X = Cl, Br).47 A supramolecular chain-like array of cubane units interconnected through iodine bridges was found in Cu8(S)[S2P(OEt)2]6(p-I) x.48... 

Numerous d cobalt(III) complexes are known and have been studied extensively. Most of these complexes are octahedral in shape. Tetrahedral, planar and square antiprismatic complexes of cobalt(lII) are also known, but there are very few. The most common ligands are ammonia, ethylenediamine and water. Halide ions, nitro (NO2) groups, hydroxide (OH ), cyanide (CN ), and isothiocyanate (NCS ) ions also form Co(lII) complexes readily. Numerous complexes have been synthesized with several other ions and neutral molecular hgands, including carbonate, oxalate, trifluoroacetate and neutral ligands, such as pyridine, acetylacetone, ethylenediaminetetraacetic acid (EDTA), dimethylformamide, tetrahydrofuran, and trialkyl or arylphosphines. Also, several polynuclear bridging complexes of amido (NHO, imido (NH ), hydroxo (OH ), and peroxo (02 ) functional groups are known. Some typical Co(lll) complexes are tabulated below ... 

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