SOLUTION STUDIES OF TRIORGANOTELLURONIUM SALTS

Article abstract of DOI:10.1016/S0022-328X(00)82450-X

Evidence for telluronium ylid formation via the salt method is obtained for Ph2Te(CH2COPh)Br, but generally telluronium salts (aryl)2Te(CH2R)X rapidly dissociate in chloroform solution to (aryl)2Te and RCH2X.The relative rates of dissociation of Ph2(CH3)TeX in CHCl3 are: X=I > Br ca.NCS > Cl > PhCOO.Conductivity and 1H NMR data suggest the salts Ph2(CH3)TeX to be covalent and at least dimeric in CHCl3, but more ionic in DMSO and, to a lesser extent, DMF.IR data indicate association in solid Ph2(CH3)TeI.Kinetic data show that the reaction of CH3I with excess Ph2Te (solvent) affords an equilibrium mixture of ionic and covalent forms of Ph2(CH3)TeI, the ionic species being formed via the covalent one.Spin trapping experiments with phenyl(t-butyl)nitrone indicate that oxidative addition of alkyl halides to Ph2Te and reductive elimination of CH3SCN from Ph2(CH3)Te(NCS) proceed via radical pathways.A mechanism is proposed for oxidative addition which involves the preformation of a charge transfer complex of RX (alkyl halide) and diphenyltelluride.