Nuclear Spin Relaxation and Double Resonance in HD Gas

Abstract

Nuclear magnetic double-resonance experiments were performed on a gaseous sample containing a mixture of HD and CO2 at high pressure by observing the spin-spin multiplet in the proton-resonance spectrum and irradiating either the deuteron transitions or some of the proton transitions. The spectra show features arising from spin relaxation in HD. These features are analyzed by using the density-matrix theory of double resonance, assuming "strong"-and "weak"-collision models for the system. The equation of motion of the spin density matrix is exactly of the same form for both collision models, the only distinction coming from the dependence of the correlation times on the transformation properties of the lattice operators and on the quantum numbers characterizing the lattice states. The results of the analysis of HD double-resonance spectra indicate that the collisions in this case are "strong." The cross products between lattice terms which transform identically but belong to two different relaxation mechanisms make significant contributions to some of the correlation functions involved and thereby affect the final results.

A dinuclear silver hydride and an umpolung reaction of CO2

“…The addition of a drop of D 2 O to these solutions did not greatly affect the decomposition: the same products were formed, the rate was similar (33% aer 24 h), and the only form of dihydrogen observed by 1 H NMR spectroscopy was 1 H 2 . The 1 : 1 : 1 triplet resonance of H-D, 31 which would arise from direct deuterolysis of the hydride, was not observed.…”

The Activation of Dihydrogen

“…The observed J HD coupling constant for HD gas is 43.2 Hz [68]. The coordination of HD to a transition metal center leads to weakening of the H-D bond, an increase in the H-D distance and a decrease in the J HD coupling constant.…”

Bonding and Reactivity of a μ‐Hydrido Dicopper Cation

“…For comparison, in a dicopper(I) complex with a s-bridging acetonitrile ligand, three-center bonding does give rise to a bond critical point between the copper centers. [36] Addition of CD 3 OD to a solution of 1 in [D 8 ]THF results in a rapid reaction to form HD, [37] as judged by 1 Figure S5). Generally, the reactivity of metal hydrides toward CO 2 depends on the degree of anionic character at hydrogen.…”