183674-93-3Relevant academic research and scientific papers
Cationic hydrogen complexes of rhenium. 2. Synthesis, reactivity, and competition studies
Heinekey,Radzewich, Catherine E.,Voges, Mark H.,Schomber, Beth M.
, p. 4172 - 4181 (2007/10/03)
Cationic rhenium dihydrogen complexes, [Re(H2)(PR3)2(CO)3]B(Ar')4 (PR3 = PCy3, PiPr3, PiPrPh2, PPh3; Ar' = 3,5-(CF3)2C6H3), have been prepared by the protonation of ReX(PR3)2(CO)3 (X = H, CH3) with [H(Et2O)2]B(Ar')4 under a hydrogen atmosphere. Deuterium is incorporated into the H2 ligand when placed under a D2 atmosphere and large JHD values (30-33 Hz) are consistent with a dihydrogen formulation. Relaxation data indicate very short T(1 min) for these complexes. These complexes are susceptible to heterolytic cleavage of dihydrogen, and the reactivity with several bases has been investigated. Under vacuum or argon atmosphere the complexes readily lose hydrogen to form 16-electron complexes. In the solid state, [Re(PCy3)2(CO)3]B(Ar')4 exhibits an agostic interaction to a β C- H bond of the phosphine ligand. Variable-temperature 31P{1H} NMR spectra of [Re(PCy3)2(CO)3]B(Ar')4 indicate a dynamic process involving hindered rotation about the Re-P bond. Competition studies have been conducted, and the hydrogen binding affinity is higher for [Re(H2)(PCy3)2(CNtBu)3]B(Ar')4 (5) than for [Re(H2)(PCy3)2(CO)3]B(At')4 (2a). Similar experiments also find that 5 also binds hydrogen preferentially over W(H2)(PCy3)2(CO)3.
