Osmium dihydrogen complexes

Dihydrogen complexes, osmium, 37 3(X)-301 Dihydroxo-bridged complexes acid-base equilibria, 32 108-110 quantitative considerations, 32 115-118 binuclear, 32 66-67 crystallographic data, 32 61, 63 stability complexes, 32 103-104... 

Cofacial ruthenium and osmium bisporphyrins proved to be moderate catalysts (6-9 turnover h 1) for the reduction of proton at mercury pool in THF.17,18 Two mechanisms of H2 evolution have been proposed involving a dihydride or a dihydrogen complex. A wide range of reduction potentials (from —0.63 V to —1.24 V vs. SCE) has been obtained by varying the central metal and the carbon-based axial ligand. However, those catalysts with less negative reduction potentials needed the use of strong acids to carry out the catalysis. These catalysts appeared handicapped by slow reaction kinetics. 

Preparation and reactivity with azo-species of hydride and dihydrogen complexes of osmium stabilised by tris(pyrazolyl)borate and phosphite ligands... 

This hydride-dihydrogen complex allows the access of methyl propiolate and 1,1-diphenyl-2-propyn-l-ol into the osmium atom, and the carbon-carbon coupling between the resulting carbon-donor ligands [75] (Scheme 50). 

In contrast to the reaction with phenylacetylene, the treatment of 190 with 2 equiv of methyl propiolate leads to the alkenyl-alkynyl compound 200 (Scheme 55). The use of a 1 1 molar ratio of alkyne to osmium complex gives the same product along with unreacted dihydride-dihydrogen complex [79]. The addition of a toluene solution of HCl to a toluene solution of 200 produces the carbon-carbon coupling of the alkynyl and alkenyl fragments to give selectively the... 

Two significant surveys are published in the sane edition of Coordination Chemistry Reviews. Oxygen donor-ligand derivatives of tri-osmium dodecacarbonyl are covered by Frauenhoff and the reactions of transition metal dihydrogen complexes (of which many are carbonyl-containing) are outlined by Jessop and Morris. The crucial role of matrix Isolation studies is well covered in this article. A shorter review of interest here has been published on the role of the phosphorus d-orbitals in M-P bonding. ... 

Bajo S, Esteruelas MA, Lop AM, Onate E. Reactions of an osmium bis(dihydrogen) complex under ethylene phosphine addition to a C—C double bond and C—H bond activation of fluoroarenes. Organometallics. 2011 30 5710-5715. 

---