Synthesis and reactivity of iron(II) hydride complexes containing diphenylphosphine ligands

A series of iron(II) hydride complexes containing diphenylphosphine ligands is reported. In the presence of five equivalents of Ph2PH, the ionic complex trans-[(Ph2PH)4Fe(H)(NCMe)](Ph2P{BH3}2) (1) with the rather unusual Ph2P{BH3}2-anion is formed, whereas with four equivalents of Ph2PH, the fluxional cis-[(Ph2PH)4Fe(H)2] (2) can be isolated under otherwise identical conditions. Furthermore, our attempts to synthesize a mixed phosphine iron(II) hydride complex resulted in the isolation of [(dppe)(Ph2PH)Fe(H)(BH4)] (3, dppe = 1,2-bis(diphenylphosphino)ethane). The behavior of complexes 1-3 in solution was investigated by 1H NOESY NMR spectroscopy and compared with those of the corresponding ruthenium complex cis-[(Ph2PH)4Ru(H)2], revealing that no chemical exchange between the hydride ligands and the P–H-proton of the coordinated Ph2PH can be observed.

A series of iron(II) hydride complexes containing diphenylphosphine ligands is reported. NMR spectroscopic investigations of the solution behavior of these complexes and of a corresponding ruthenium complex revealed that no chemical exchange between the hydride ligands and the P–H-proton and therewith no reversible heterolytic cleavage of dihydrogen can be observed.Figure optionsDownload as PowerPoint slide