Nuclear dynamics 3 isotopomers

A combined electronic structure DFT/QND (density functional theory/quan-tum nuclear dynamics) study has been carried out by Gelabert et al. on the compressed dihydride complex [Cp lr(dmpm)H2], where dmpm denotes bis(dimethylphosphino)methane, with a goal to determine from the first-principles the unusual temperature dependence of the spin-spin coupling, Vhd, observed in its isotopomer [Cp Ir(dmpm)HD]. ... 

Tritium NMR of partially tritiated complexes has been carried out, and dynamically averaged 7HT occur at 51-65 Hz for [TpIrH(H2)(PR3)]+55 The true JHT should be about three times this value. Tritium (3H) has a nuclear spin of i, the same as H but unlike deuterium with spin equal to 1. Distinct resonances for the T3) T2H, and TH2 isotopomers occur at -10 to -11 ppm, and the 3H chemical shift for the T3 isotopomer is the same as that for the H3 isotopomer in the NMR (Figure 5.8). These relatively large shifts are a manifestation of isotopic perturbation of resonance (IPR),56 which also occurs for deuterium versus protio isotopomers here and in other rapidly exchanging polyhydride complexes, including classical systems with inequivalent hydrides.57 50 In the fast exchange of H NMR spectra of isotopomers of nonclassical polyhydrides, each isotopomer shows a separate... 

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