Spectroscopic characterization of primary and secondary phosphine ligation on ruthenium(II) complexes

Ruthenium(II) complexes of the primary phosphines PH(2)Fc and PH(2)CH(2)Fc and the secondary phosphine PH-(CH(2)Fc)(2), including [(p-cymene) RuCl(L)(2)](PF6) (p-cymene = p-(PrC6H4Me)-Pr-i, L = PH(2)CH(2)Fc and PH(CH(2)Fc)(2), 2b and 2c, respectively) and trans- [RuCl2(L)(4)] (L = PH(2)Fc, PH(2)CH(2)Fc, and PH(CH(2)Fc)(2), 3a-c, respectively) were prepared and characterized by IR, H-1 NMR, and P-31 NMR spectroscopy. 3b was additionally characterized by X-ray crystallography. The spectroscopic effects of phosphine ligation were determined. Characteristic downfield shifts of the P-31 NMR resonances and increases in energy of the v(P-H) modes were observed in all cases. Iterative fitting of coupling constants to second- order NMR spectra also resulted in a complete elucidation of P-31 H-1 and P-31-P-31 couplings. This analysis provides a basis for considering the influence of coordinate bonding on the observed (1)J(PH) and (2)J(PP) constants.