Hydrogen/deuterium reaction with cobalt

The reversibility of orthometallation was shown in reactions of HCo(N2)(PPh3)3 with deuterium in which 19 hydrogens per mole of cobalt were exchanged . It was shown that the incorporation into the aryl groups occurred exclusively in the ortho position . 

Co2(CO)8 and HCo(CO)4 using HP-IR. A cobalt carbonyl-butadiene complex and an allylcobalt carbonyl species were formed from the reaction of butadiene with Co2(CO)8. Reaction with HCo(CO)4 gradually afforded an alkenyl complex which reacted to form further byproducts. The reaction of cobalt carbonyls with hydrogen or deuterium, and the stoichiometric interaction of the resultant hydride with alkenes has also been studied with HP-IR. Ojima reported HP-IR studies into Co-Rh bimetallic carbonyl catalysts, and observed a CoRh(CO)7 species which was active for hydroformylation-amidocarbonylation. 

Small ey(Ib) that cobalt and niobium clusters react in a very selective fashion with deuterium was rapidly followed by similar studies on a variety of other metal systems. Three groups simultaneously reported similar dramatic behavior for iron c usters( 2b, 3b). Di hydrogen or di deuteri urn addition reactions have been reported for vanadium( 3e), i ron(lc,2a-d,3b), cobalt(lb),... 

The first step of the reduction by cobalt(II) chloride and NaBH4 involves the production of cobalt hydride species which is capable of exchanging hydrogen ligands with the medium. The second step is a hydrometallation reaction followed by a reductive cleavage of the carbon-cobalt bond. The hydrocobaltation seems to be reversible, as indicated by deuterium label incorporation93. 

The participation of a cysteine thiol in the abstraction of hydrogen from ribose C-3 coenzyme B12, which is not a feature of any other of the reactions of Table 1, leads to exchange of H between this thiol group, the 5 -methylene group of coenzyme Bi2 and water (22). It was also shown that ribonucleotide reductase catalyzes the conversion of adenosylcobalamin labeled with one deuterium atom at C-5 (initial R/S ratio = 3 1) to monodeuterated coenzyme with R/S ratio = 1. This result shows that the cobalt-carbon 0-bond is reversibly cleaved to a 5 -deoxyadenosyl radical, which permits rotation about the C-47C-5 0-bond. 

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