Reaction of large-bite ligands with various tellurium compounds: Synthesis and structural characterization of [Te₂(μ-Cl)₂{(SPPh₂)₂N}₂], [(4-MeOC₆H₄TeCl₃)₂{μ-Ph₂P(S)CH₂CH₂P(S)Ph₂}] and [Te₂(μ-Ph₂PS₂)₂] representing novel types of tellurium complexes

The three title compounds have been synthesized and their structures determined by X-ray crystallography. [Te-2(mu-Cl)(2){(SPPh2)(2)N}(2)], 1, is a dinuclear square planar Te(II) complex where each Te atom is coordinated to the two sulfur atoms of the bidentate dithiolate ligand and to the two bridging chloride ligands. The Te-S bond lengths are 2.4980(8) and 2.5054(8) Angstrom, while the Te-Cl bond lengths are 2.9065(9) and 2.9230(9) Angstrom. In [(4-MeOC6H4TeCl3)(2){mu-Ph2P(S)CH2CH2P(S)Ph-2}], 2, the dithio ligand is neutral and adds a molecule of [4-MeOC6H4TeCl3] at each sulfur atom, thus bridging the two Te(IV) atoms. The coordination of both tellurium atoms is psi-octahedral with the anisyl group and a lone pair of electrons in axial positions. The Te-S bonds, 2.7747(6) and 2.8198(5) Angstrom, are surprisingly weak while the Te-Cl bonds lie in the range 2.4247(5) to 2.5343(6) Angstrom, those trans to Te-S being shortest. [Te-2(mu-Ph2PS2)(2)], 3, is a binuclear Te(I) complex, mainly held together by a Te-Te bond of 2.7298(5) Angstrom. Both anisobidentate diphenyldithiophosphinate ligands bridge the two tellurium atoms. The resulting coordination around each tellurium is best described as T-shaped with the Te-Te bond along the stem. In the asymmetric near linear S-Te-S system, the short Te-S bonds are 2.487(2) and 2.495(2) Angstrom while the long bonds are 2.947(2) and 3.033(2) Angstrom, respectively. The strongly different trans influences of the dithio ligands of 1 and 2 are discussed and it is suggested that they are dependent upon the basicity of the sulfur atoms. (C) 1999 Elsevier Science Ltd. All rights reserved.