Seleniranium and Telluriranium Salts.

Seleniranium salts [Ad2 SeR]+ X- (2-8), which are moderately stable at room temperature, were synthesized by addition of RSe+ X- equivalents to the bulky olefin bis(adamantylidene) Ad=Ad (1), where R is aryl or alkyl and X- is Tf2 N- , B(C6 F5 )4 - , or SbCl6 - . Unstable telluriranium salts [Ad2 TeR]+ X- (9-12) were obtained by addition of RTe+ X- equivalents to 1 (R=Ph, Et; X- =Tf2 N- , BF4 - ). The compounds were characterized by NMR spectroscopy and quantum chemical calculations, and the Se compounds also by ESI mass spectrometry. Crystal structures were determined for seleniranium salts 2 and 7 and telluriranium salt 9.