Probing Highly Selective H/D Exchange Processes with a Ruthenium Complex through Neutron Diffraction and Multinuclear NMR Studies.

Deuterium labeling is a powerful way to gain mechanistic
information in biology and chemistry. However, selectivity is hard
to control experimentally, and labeled sites can be difficult to assign
both in solution and in the solid state. Here we show that very selective
high-deuterium contents can be achieved for the polyhydride ruthenium
phosphine complex [RuH2(H2)2(PCyp3)2] (1) (PCyp3 = P­(C5H9)3). The selectivity of the H/D exchange
process is demonstrated by multinuclear NMR and neutron diffraction
analyses. It has also been investigated through density functional
theory (DFT) calculations. The reactions are performed under mild
conditions at room temperature, and the extent of deuterium incorporation,
involving selective C–H bond activation within the cyclopentyl
rings of the phosphine ligands, can easily be tuned (solvent effects,
D2 pressure). It is shown that D2 gas can inhibit
the C–H/C–D exchange process.