Organotellurium(IV) derivatives of tetraphenyldichalcogenoimidodiphosphinates - The crystal and molecular structure of [C4H8TeI{Ph-2(Se)PNP(Se)Ph-2}], [C4H8TeI{ Ph-2(S)PNP(S)Ph-2}], [C4H8Te{Ph-2(S)PNP(S)Ph-2}(2)], [C8H8TeI{Ph-2(S)PNP(S)Ph-2}], and [O(TeC4H8)(2){Ph-2(O)PNP(O)Ph-2}](2)[I, I-3] representing a novel type of ring systems

The synthesis of the following organotellurium(IV) compounds [C4H8TeI(Ph-2( Se)PNP(Se)Ph-2)] (2), [C4H8TeI(Ph-2(S)PNP(S)Ph-2)] (3), [C8H8TeI(Ph-2(S)PNP (S)Ph-2)] (4), [C4H8-Te{Ph-2(S)PNP(S)Ph-2}(2)] (5), and [O(TeC4H8)(2){Ph-2( O)-PNP(O)Ph-2}](2)[I, I-3] (6) was achieved. These compounds have been char acterized by microanalysis, multielement NMR and IR spectroscopy, positive ion FAB mass spectrometry and single-crystal X-ray diffraction analysis. Th e solid-state structures show that the coordination geometry at the telluri um center in every derivative can be described as a distorted pseudo-trigon al bipyramid, in which the lone-pair of electrons is supposed to occupy an equatorial position. The selenium and sulfur ligands exhibit an aniso-biden tate chelating coordination mode on interaction with the tellurium center. When the aniso-bonded donor atoms are included in the coordination sphere, the environment about Te becomes distorted square-pyramidal for the monoche late derivatives 2-4 and distorted octahedral for the bis(chelate) compound 5. In compound 6, two oxygen ligands act as bridges between two C4H8Te-O-T eC4H8 units, forming a 16-membered cationic ring. The anions, I- and I-3(-) , are located above and below the twisted rind with Te . . .I interactions ranging from 3.532(2) to 3.902(3) Angstrom.