Straightforward synthesis of phosphametallocenium cations of Rh and Ir

Reaction of 3,4-dimethylphospholylthallium (Tl-1) with [Cp∗MCl2]2 (M = Rh, Ir) leads to the formation of the dimeric species [(Cp∗M)2(Me2C4H2P)3]+2 and 3 with bridging μ-η1:η1-phospholyl ligands. The phosphametallocenium sandwich complexes [Cp∗M(Me2C4(SiMe3)2P)]+7 (M = Rh) and 8 (M = Ir) could be obtained from the reaction of [Cp∗MCl2]2 and the 2,5-bis(trimethylsilyl)-1-trimethylstannylphosphole 6, with the bulky trimethylsilyl groups preventing the phosphole from η1- and enforcing a η5-coordination. The structures of phospharhodocenium cation 7 and a byproduct 9 containing a phosphairidocenium moiety could be determined by X-ray diffraction.

Graphical abstractThe phospharhodocenium and iridocenium cations 7 and 8 were prepared in good yield. The Me3Si groups of the phosphole prevent the heterocycle from η1-P coordination and enforce the formation of the metallocene type structure. The byproduct 9 was also isolated. It features phosphairidocenium and Ir half-sandwich units, which are linked by a bridging phosphole ligand.Figure optionsDownload full-size imageDownload as PowerPoint slide