MULTINUCLEAR SOLID-STATE NUCLEAR-MAGNETIC-RESONANCE STUDIES ON TRANSITION-METAL CLUSTERS CONTAINING HYDRIDES

Solid-state H-1 and D NMR measurements have been made for all transiti on-metal carbonyl clusters containing interstitial hydrides/deuterides previously characterised by neutron diffraction. There is a close agr eement between the values of delta(H-1/D) in solution and the solid st ate except for [Co6H(CO)(15)](-). The values of delta(H-1) for interst itial hydrides are in the range delta + 18.5 to -26.8; the shift to hi gh field is shown to be due to an increasing displacement of H from th e centre of the metal octahedral cavity, consistent with surface tenso r harmonic theory. Whereas migration of H readily occurs in both [Rh13 Hx(CO)(24)]((5-x)-) (x = 2 or 3) and [Ru2Rh2H2(CO)(12)] in solution, s olid-state H-1 NMR measurements on [Rh13Hx(CO)(24)]((5-x)-) (x = 2 or 3) showed that there is no evidence for such migration in the solid st ate and for [Ru2Rh2H2(CO)(12)] oscillation of H about the metal-metal edge(s) occurs rather than migration to different edges as found in so lution.