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

Article abstract of DOI:10.1016/S0022-328X(99)00276-4

By reacting CpPd(η³-C₃H₅) with PPh₂H we isolated the doubly bridged dinuclear complex [Pd₂(μ-PPh₂)₂(PPh₂H)₃] (1). This reacts with HBF₄ yielding the mono-phosphido-bridged cationic derivative [Pd₂(μ-PPh₂)(PPh₂H)₄]BF₄ (2)BF₄, arising from the protonation of one of the bridging phosphides. Contrary to our previous data on the parent t-butyl systems, a mononuclear 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 shown to decompose thermally to another (uncharacterized) polynuclear derivative; fluoboric acid reacts with 3 yielding its palladium(II) analogue [Pd(PPh₂H)₄](BF₄)₂ (3)(BF₄)₂, with dihydrogen evolution. We also report the crystal and molecular structures of 3 and (3)(BF₄)₂, the first homoleptic transition metal complexes of diphenylphosphine to be structurally characterized.