2H MAS NMR of strongly dipolar coupled deuterium pairs in transition metal dihydrides:: extracting dipolar coupling and quadrupolar tensor orientations from the lineshape of spinning sidebands

A selectively D-2 labeled transition metal dihydride, Os(D-2)(Cl)(2)(CO)((PPr3)-Pr-i)(2), was synthesized and studied by H-2 magic angle spinning (MAS) NMR spectroscopy. It was found that the interference between the quadrupolar and homonuclear dipolar interaction results in a characteristic lineshape of the MAS sidebands. The basic properties of the interference of homonuclear dipolar and quadrupolar coupling on the H-2 NMR lineshape were elucidated, using average Hamiltonian theory, and exact simulations of the experiments were achieved by stepwise integration of the equation of motion of the density matrix. These simulations show that it is possible to determine the size of the dipolar interaction and thus the D-D distance from the lineshape of the sidebands.