Transition-Metal Complexes Containing Parent Phosphine or Phosphinyl Ligands and Their Use as Precursors for Phosphide Nanoparticles

P–H functional
transition-metal complexes were synthesized without using hazardous
PH3 gas in good yields by photolysis of the transition-metal
carbonyl complexes M­(CO)6‑x (M
= Cr, W, Fe; x = 0, 1) in tetrahydrofuran followed
by reaction with P2(SiMe3)4 and subsequent
methanolysis to give the bridging complexes [(CO)xM­(μ-PH2)]2 (M = Fe, x = 3 (1), M = Cr, x = 4 (2a), M = W, x = 4 (2b)). The photolysis
of [(CO)4M­(μ-PH2)]2 (M = Cr
(2a), M = W (2b)) with P­(SiMe3)3 was applied followed by methanolysis to synthesize
the PH2 bridging transition-metal binuclear complexes with
terminal PH3 groups. The products [(CO)4M­(μ-PH2)2­M­(CO)3(PH3)] (M =
Cr (3a), M = W (3b)) and [(CO)4W­(μ-PH2)2W­(CO)2(PH3)2] (4b) were isolated in moderate
yield. Another synthetic approach to this type of compounds is the
direct photolysis of the complexes [(CO)3M­(PH3)3] (M = Cr (5a), M = W (5b)).
The products were comprehensively characterized by 31P
NMR and IR spectroscopy as well as by X-ray structural analysis. Additionally,
the relevancy of 2a as single source precursor for the
synthesis of stoichiometry-controlled CrP nanoparticles has been demonstrated.