Synthesis and Characterization of a Terminal Iron(II)-PH 2 Complex and a Series of Iron(II)-PH 3 Complexes.

Reported is the reaction of a series of iron(II) bisphosphine complexes with PH 3 in the presence of NaBAr F 4 [where BAr F 4 = 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 PH 3 complexes and undertaken rigorous characterization by NMR spectroscopy, single crystal X-ray diffraction, and mass spectrometry, where the PH 3 often remains intact during the ionization process. Unusual bis- and tris-PH 3 complexes are among the compounds isolated. Changing the monophosphine from PH 3 to PMe 3 results in the formation of an unusual Fe 7 cluster, but with no PMe 3 being ligated. Finally, by using an iron(0) source, we have provided a rare example of a terminally bound iron-PH 2 complex.