Synthesis and Characterization of a Terminal Iron(II)-PH2 Complex and a Series of Iron(II)-PH3 Complexes.

Reported is the reaction of a series of iron(II) bisphosphine complexes with PH3 in the presence of NaBArF4 [where BArF4 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate]. The iron(II) bisphosphine reagents bear two chlorides or a hydride and a chloride motif. We have isolated six different cationic terminal-bound PH3 complexes and undertaken rigorous characterization by NMR spectroscopy, single crystal X-ray diffraction, and mass spectrometry, where the PH3 often remains intact during the ionization process. Unusual bis- and tris-PH3 complexes are among the compounds isolated. Changing the monophosphine from PH3 to PMe3 results in the formation of an unusual Fe7 cluster, but with no PMe3 being ligated. Finally, by using an iron(0) source, we have provided a rare example of a terminally bound iron-PH2 complex.