1H-31P coupling constants across the central metal atom (2JP-M-H) were measured in a series of octahedral hydridometalphosphine complexes [MRH(PP3), PP3 = P(CH2CH2CH2P(CH3)2) 3; M = Ru, Fe; R = H, Cl, 1-pentenyl, cyclopentenyl, 2-methyl-1-butenyl, 3,3-dimethyl-1-butenyl] using a selective two-dimensional NMR experiment. The use of band-selective pulses focused on a narrow frequency range in the 1H NMR spectrum (encompassing the metal-bound hydride resonances) provided spectra with high resolution as well as removed the need for suppression of intense signals arising from protic organic solvents. The magnitude of 2JP-M-H was found to depend on the relative disposition of the coupled nuclei and about the central metal atom, as well as the nature of the metal. For FeRH(PP3) complexes, the magnitude of 2JP-M-H(cis) > 2JP-M-H(trans), while for analogous Ru complexes, 2JP-M-H(trans)>2JP-M-H(cis). Irrespective of whether the metal center is Fe or Ru, the sign of 2JP-M-H(trans) is opposite that of 2JP-M-P(cis), and 2JP-M-P(cis), but the same as 2JP-M-P(trans).
|Number of pages||7|
|Publication status||Published - 1993|