Telluranes:: potential synthons for charge-transfer complexes (involving hypervalent Te-I bonds) and serendipitous synthesis of the first triphenyl methyl phosphonium salts containing [C4H8TeI4]2- and [TeI6]2-anions

Hypervalent Te-I bonds of telluranes (C4H8TeI2, C5H10TeI2 and alpha-Me2TeI2) have been utilised to form the charge transfer (CT) complexes (1-3). The reaction of cyclic tellurane (1,1-diiodotetrahydro tellurophene, C4H8TeI2) with I-2/ICl yields C8H16Te2I6 [IC4H8TeI-I-I-ITeC4H8I] (1); an unusual dinuclear species while the reaction of another cyclic tellurane (1,1-diiodo telluracyclo-hexane, C5H10TeI2) with I-2 yields C5H10TeI4 (2) possessing different structural motif than 1. In 2 the iodine molecules are on both sides bonded to iodine atom of hypervalent Te-I bond of C5H10TeI2 which is analogous to the structural type present in Me2TeI4 (3) obtained by the reaction of alpha-Me2TeI2 with ICI. The reaction of C4H8TeI2 with PPh3, serendipitously, yields the first triphenyl methyl phosphonium salts [PPh3Me](2)(2+) [C4H8TeI4](2-) (4) and [PPh3Me](2)(2+) [TeI6](2-) (5), indicating the oxidation of PPh3 whereas C4H8TeI2 itself, is converted into [C4H8TeI4](2-) and [TeI6](2-) anions. All the complexes 1-5 have been characterised through single crystal X-ray diffraction studies. (C) 2003 Elsevier B.V. All rights reserved.