79255-79-1Relevant academic research and scientific papers
Thermal and photochemical reactions of dinuclear metal carbonyl compounds with metal hydrides
Wegman, Richard W.,Brown, Theodore L.
, p. 47 - 52 (2008/10/08)
The thermal or photochemical reaction of bis(tri-n-butylphosphine)hexacarbonyldicobalt, Co2(CO)6[P(n-Bu)32, with tri- n-butyltin hydride, HSn(n-Bu)3, leads to H2 and (rc-Bu)3SnCo(CO)3P(ra-Bu)3 as products. The rate law for the photochemical reaction and product distribution are consistent with a pathway involving loss of CO from the Co(CO)3P(ra-Bu)3- radical following metal-metal bond rupture, oxidative addition of the H-Sn bond to the cobalt center, a hydrogen atom transfer from a second HSn(n-Bu)3 to cobalt, and then a reductive elimination of H2, as the pathway for reaction. A similar reaction pathway is indicated for reaction of (η-C5H5)2M2(CO)6 (M = Mo, W) with HSn(n-Bu)3 or (η5-C5H5)2Mo 2(CO)6 with HMo(CO)3(η5-C5H5). On the other hand reaction of (η-C5H5)2Mo2(CO)6 with HMn(CO)5 leads to HMo(CO)3(η5-C5H5) and Mn2(CO)10 as products, suggesting a simple hydrogen atom transfer reaction between the Mo(CO)3(η5-C5H5)- radical and HMn(CO)5. The choice between the oxidative addition and hydrogen atom transfer pathways is determined by the donor M-H bond energy; a low M-H bond energy favors hydrogen atom transfer. On the basis of studies to date, the oxidative addition pathway, as described above, is the more common. Reaction of HMo(CO)3(7/5-C5H5) with HSn(n-Bu)3 leads to (n-Bu)3SnMo(CO)3(η5-C5H 5) and H2. The rate law is of the form d(product)/dt = {κa[HSn(n-Bu)3]/(κa + κc[HSn(n-Bu)3])}[HMo(CO)3(η 5-C5H5]. The rate law suggests the existence of a preequilibrium involving either a formyl intermediate, formed via a hydride migration, or a change in hapticity of the cyclopentadienyl ring to form a -cyclopentadienyl intermediate.
