New dinuclear diphenylphosphido-bridged palladium(I) derivatives and the X-ray crystal and molecular structures of the mononuclear homoleptic diphenylphosphine complexes Pd(PPh2H)(4) and [Pd(PPh2H)(4)](BF4)(2)

By reacting CpPd(eta(3)-C3H5) with PPh2H we isolated the doubly bridged din uclear complex [Pd-2(mu-PPh2)(2)(PPh2H)(3)] (1). This reacts with HBF4 yiel ding the mono-phosphido-bridged cationic derivative [Pd-2(mu-PPh2)(PPh2H)(4 )]BF4 (2)BF4, arising from the protonation of one of the bridging phosphide s. Contrary to our previous data on the parent t-butyl systems, a mononucle ar homoleptic phosphine complex is not an intermediate in the formation of 1. Pd(PPh2H)(4) (3), was in fact prepared by an independent route and was s hown to decompose thermally to another (uncharacterized) polynuclear deriva tive; fluoboric acid reacts with 3 yielding its palladium(II) analogue [Pd( PPh2H)(4)](BF4)(2) (3)(BF4)(2), with dihydrogen evolution. We also report t he crystal and molecular structures of 3 and (3)(BF4)(2), the first homolep tic transition metal complexes of diphenylphosphine to be structurally char acterized. (C) 2000 Elsevier Science S.A. All rights reserved.