84108-59-8Relevant academic research and scientific papers
Acid-catalyzed hydrogenolysis of osmium-alkyl bonds
Desrosiers, Peter J.,Shinomoto, Ronald S.,Deming, Mark A.,Flood, Thomas C.
, p. 2861 - 2865 (1989)
Hydrogenolysis of the osmium-carbon bond in fac-L3Os(H) (η2-CH2PMe2) (1, L = PMe3) and cis-L4Os(H)Me (8) to form cis-L4OsH2 (2) has been found to proceed at 80°C in benzene or THF under less than 1 atm of H2 upon catalysis by [L4OsH3](OTf) (2-H+). The catalytic cycle, e.g. for 1, involves transfer of a proton from 2-H+ to 1; 1-H+ becomes [L4OsH]+ (4); 4 takes up H2 to form 2-H+; and 2-H+ again donates one of its protons to 1 liberating 2. The hydrogenolysis is retarded by excess L, which reversibly traps 4 to form [L5OsH]+ (5). Steps in this cycle have been corroborated by carrying out model reactions. The kinetic basicity of 1 and 8 (L4Os(H)R) is demonstrated by the following reactions. Treatment of L4Os(H)R with [L4OsH3]Cl yields 2 and L4Os(H)Cl; L4Os(H)R and [HPMe3]OTf form [L5OsH]OTf (5); and treatment of L4Os(H)R with HOTf generates cis-L4Os(H)OTf (7). Complex 7 rapidly reacts with H2 to form 2-H+ and with L to form 5. An equilibrium between 2-H+ + L and 5 + H2 has been demonstrated. A linear dependence of the rate constant (zero order in 1 or 8) on the concentration of 2-H+ has been shown.
