Novel triphospholyl and diphosphastibolyl lead(II) complexes

PbCl2 reacted with the triphospholyl ring anion [P3C2But2]– to afford the hexaphospha-plumbocene [Pb(η5-P3C2But2)2] 3 which has been characterised by multinuclear NMR spectroscopy. In contrast the reaction between PbCl2 and the diphosphastibolyl ring anion [P2SbC2But2]– led to the organo-antimony cage compound [P4Sb2C4But4] 4via an oxidative coupling route. Both the heteroleptic plumbocenes [Pb(η5-EP2C2But2)(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-P3C2But2)(µ-Cl)2Li(tmen)2] 7 could be synthesised by carrying out the reaction of PbCl2 with [Li(dme)3][P3C2But2] in tmen rather than dme. This compound was found to be highly fluxional in solution even at low temperature.