Novel triphospholyl and diphosphastibolyl lead(II) complexes

Abstract

PbCl₂ reacted with the triphospholyl ring anion [P₃C₂Bu^t₂]^– to afford the hexaphospha-plumbocene [Pb(η⁵-P₃C₂Bu^t₂)₂] 3 which has been characterised by multinuclear NMR spectroscopy. In contrast the reaction between PbCl₂ and the diphosphastibolyl ring anion [P₂SbC₂Bu^t₂]^– led to the organo-antimony cage compound [P₄Sb₂C₄Bu^t₄] 4via an oxidative coupling route. Both the heteroleptic plumbocenes [Pb(η⁵-EP₂C₂Bu^t₂)(η⁵-C₅Me₅)] (E = P 5, E = Sb 6) could be prepared by treatment of the corresponding hetero-ring anion with a mixture of PbCl₂ and Li(C₅Me₅) (for 5) or the half sandwich complex [Pb(η⁵-C₅Me₅)Cl] (for 6). Both complexes were characterised by multinuclear NMR spectroscopy and single crystal X-ray diffraction studies. The novel, structurally characterised, hetero-bimetallic complex [Pb(η⁵-P₃C₂Bu^t₂)(µ-Cl)₂Li(tmen)₂] 7 could be synthesised by carrying out the reaction of PbCl₂ with [Li(dme)₃][P₃C₂Bu^t₂] in tmen rather than dme. This compound was found to be highly fluxional in solution even at low temperature.