Telluranes: potential synthons for charge-transfer complexes (involving hypervalent Te–I bonds) and serendipitous synthesis of the first triphenyl methyl phosphonium salts containing [C 4H 8TeI 4] 2− and [TeI 6] 2−anions

Abstract

Hypervalent Te–I bonds of telluranes (C 4H 8TeI 2, C 5H 10TeI 2 and α-Me 2TeI 2) have been utilised to form the charge transfer (CT) complexes ( 1– 3). The reaction of cyclic tellurane (1,1-diiodotetrahydro tellurophene, C 4H 8TeI 2) with I 2/ICl yields C 8H 16Te 2I 6 [IC 4H 8TeI–I–I–ITeC 4H 8I] ( 1); an unusual dinuclear species while the reaction of another cyclic tellurane (1,1-diiodo telluracyclohexane, C 5H 10TeI 2) with I 2 yields C 5H 10TeI 4 ( 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 C 5H 10TeI 2 which is analogous to the structural type present in Me 2TeI 4 ( 3) obtained by the reaction of α-Me 2TeI 2 with ICl. The reaction of C 4H 8TeI 2 with PPh 3, serendipitously, yields the first triphenyl methyl phosphonium salts [PPh 3Me] 2 2+ [C 4H 8TeI 4] 2− ( 4) and [PPh 3Me] 2 2+ [TeI 6] 2− ( 5), indicating the oxidation of PPh 3 whereas C 4H 8TeI 2 itself, is converted into [C 4H 8TeI 4] 2− and [TeI 6] 2− anions. All the complexes 1– 5 have been characterised through single crystal X-ray diffraction studies.