Synthesis and Structure of the Polycyclohexaphosphines P6(C5Me5)4 and P6(C5Me5)2

The cyclotriphosphine (PC5Me5)3 (1) decomposes in boiling benzene to give the bicyclo[3.1.0]hexaphosphine P6(C5Me5)4 (2) which yields the tricyclo[3.1.0.0(2.6)]hexaphosphine P6(C5Me5)2 (3) in boiling xylene. The structures of 2 and 3 have been determined by P-31-, C-13-, and H-1-NMR spectroscopy and by X-ray crystallography. 3 represents the first member of a new class of polyphosphines. The specific thermolysis of 1 and 2 under comparatively mild conditions is based on the easy homolytic cleavage of P-C5Me5 bonds in these compounds.