Polarization transfer from the NMR silent p-H-2 to o-H-2 is possible through the intermediacy of a triruthenium his-hydride cluster. In fact, a strong emission signal for the molecular Wt resonance is observed when p-H-2 is allowed to react with Ru-3(CO)(11)(NCCH3) in the NMR tube at RT. The break of symmetry in p-H-2 is achieved at the intermediate. H(mu-H)Ru-3(mu-CO)(CO)(10) compound where the two hydrides form an AX spin system; the build-up of the longitudinal magnetization leaves a "memory" of this intermediate in the signal of the H-2 molecule formed by reductive elimination from the bis-hydride species. The observed behavior is fully accounted for in terms of the established relaxation theory.
A novel application of para H-2: the reversible addition/elimination of H-2 at a Ru-3 cluster revealed by the enhanced NMR emission resonance from molecular hydrogen
AIME, Silvio;DASTRU', Walter;GOBETTO, Roberto;VIALE, Alessandra;
1999-01-01
Abstract
Polarization transfer from the NMR silent p-H-2 to o-H-2 is possible through the intermediacy of a triruthenium his-hydride cluster. In fact, a strong emission signal for the molecular Wt resonance is observed when p-H-2 is allowed to react with Ru-3(CO)(11)(NCCH3) in the NMR tube at RT. The break of symmetry in p-H-2 is achieved at the intermediate. H(mu-H)Ru-3(mu-CO)(CO)(10) compound where the two hydrides form an AX spin system; the build-up of the longitudinal magnetization leaves a "memory" of this intermediate in the signal of the H-2 molecule formed by reductive elimination from the bis-hydride species. The observed behavior is fully accounted for in terms of the established relaxation theory.
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