Synthesis, Structure and Reactivity of a Cationic Bis(N-Heterocyclic Carbene) Complex of Thallium

Abstract

The cationic bis N-heterocyclic carbene (NHC) thallium species [Tl(IPr)2][Al{OC(CF3)3}4] (1) and [Tl(IMes)2][Al{OC(CF3)3}4] (2) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; IMes = 1,3bis(2,4,6-trimethylphenyl)imidazol-2-ylidene) have been prepared. The solid-state structures of these species display considerable distortion of the NHC binding to thallium as a result of donation of electron-density from the metal s-type lone-pair orbital into the empty p-orbital of the carbenes. Attempts to utilise 1 and 2 as dualpurpose NHC transfer and halide abstractor compounds with Rh proved to be unsuccessful with the thallium being retained in Rh-Tl-Rh bridging products. 2