Synthesis and Structural Characterization of [Te{(SePPh)₂N}₂] and [4-MeO[PhTe{(SPPh₂)₂N}]₂

Reaction of K[(SePPh2)(2)N] with [Te(tu)4]Cl-2 (tu = thiourea) in methanol gave [Te{(SePPh2)(2)N}(2)] (1), while reaction of K[(SPPh2)(2)N] with 4-MeOPhTeCl3 in methanol gave [4-MeOPhTe-{(SPPh2)(2)N}](2), (2). The crystals of 1 are triclinic and contain centrosymmetric molecules. The ligands are bidentate and form a true square planar Te(ll) complex: with TeSe4 coordination. For 2, the crystals ave also triclinic, and the dimeric molecules are centrosymmetric. Each dithiolate ligand bridges the two Te(ll) atoms; the result is a T-shaped coordination around each tellurium atom. A tendency to weak Te-Te bonding across the ring-formed dimer roughly in the direction of the missing fourth ligand in a potential square planar tellurium coordination sphere is also found [Te-Te = 3.761 (1) Angstrom]. In 1, the Te-Se bonds have an average length of 2.797 Angstrom. The Te-S bonds in 2 ave quite asymmetric with Te(1)-S(1) = 2.551 (3) Angstrom and Te(1)-S(2a) = 2.873 (3) Angstrom, while Te(1)-C(1) = 2.10 (1) Angstrom. (C) 1998 John Wiley & Sons, Inc.