is distorted, but notably less so than in bis(sulfide) 4-S. All compounds were fully characterized and except for bis(phosphine) 5 crystal structures were determined.

A comprehensive investigation of reactions of alkali-metal derivatives of the ditelluro dianion [TeP V (N t Bu)(-N t Bu)]2 2− (L 2− , E = Te) with p-block element halides produced a series of novel heterocycles incorporating P V 2N2 rings, tellurium and group 13-16 elements. The dianion engages in Te,Te′-chelation to the metal center in Ph2Ge and R2Sn (R = t Bu, n Bu, Ph) derivatives; similar behavior was noted for group 14 derivatives of L 2− (E = S, Se). In the case of group 13 trihalides MCl3 (M = Ga, In), neutral spirocyclic complexes (L)M[N t Bu(Te)P V (-N t Bu)2P III N(H) t Bu)] (M = Ga, In) comprised of a Te,Te′-chelated ligand L 2− and a N,Te-bonded ligand resulting from loss of Te and monoprotonation were obtained. In reactions with RPCl2 (R = t Bu, Ad, i Pr2N) a significant difference was observed between Se-and S-containing systems. In the former case, Se,Se′-chelated derivatives were formed in high yields, whereas the N,S-chelated isomers predominated for sulfur. All complexes were characterized by multinuclear (1 H, 31 P, 77 Se, 119 Sn and 125 Te) NMR spectroscopy; this technique was especially 2 useful in the analysis of the mixture of (L)(Se) and (L)(SeSe) obtained from the reaction of Se2Cl2 with L 2− (E = Te). Single crystal X-ray structures were obtained for the spirocyclic In complex (9), (L)GePh2