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- i PrC 6 H 4 Me, L = PH 2 CH 2 Fc and PH(CH 2 Fc) 2 , 2b and 2c, respectively) and trans-[RuCl 2 (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, 1 H NMR, and 31 P NMR spectroscopy. 3b was additionally characterized by X-ray crystallography. The spectroscopic effects of phosphine ligation were determined. Characteristic downfield shifts of the 31 P 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 31 P- 1 H and 31 P- 31 P couplings. This analysis provides a basis for considering the influence of coordinate bonding on the observed l J PH and 2 J PP constants.