Synthesis and structural characterisation of lanthanide and actinide phosphaorganometallic complexes derived from the 3,5-di-tert-butyl-1,2,4-triphospholyl ring anion, P3C2But-2: Crystal and molecular structures of [M(?5-P3C2But2)2(?2-P3C2But2)] (M = Sc, Y, Tm, and U)

Treatment of MI3 ( M = Sc, Y, Tm, and U) with three equivalents of KP3C2Bu2t in refluxing toluene led to the corresponding monomeric, formally eight coordinate, complexes [M(eta(5)-P3C2Bu2t)(2)(eta(2)-P3C2Bu2t)] in moderate yields. In the solid state the complexes, which are all iso-structural, display an interesting assembly of ligands comprising of one eta(2)-(bent) and two eta(5)-ligated triphospholyl rings. NMR studies indicate that the complexes are fluxional in solution.