Electronic and steric control of the formation of C-H-M from M-H-M interactions in carbon-atom-capped transition metal carbonyl clusters. Effect of the metal fragment

Synthesis of B2H5FeCo(CO)6, Fe2Co(CO)9(μ-CO)BH2, FeCo2(CO)9(μ-CO)BH, FeCo2(CO)9(BH)2, and HFe3Co(CO)12BH. Co(CO)3Fragment Addition and Fragment Exchange in Ferraborane Clusters

“…However, it does perturb both directly (change in metal atom properties) and indirectly (change in number of skeletal hydrogen atoms) the electronic structure to a significant extent as demonstrated by differences in spectroscopic, dynamic, and chemical reaction properties. These results complement our previous comparison of the organometallic clusters Co 3 (CO) 9 CCH 3 and HFeCo 2 (CO) 9 CCH 3 …”

“…The same type of interchange in terms of isolobal metal fragments is the replacement of a HFe(CO) 3 or [Fe(CO) 3 ] - fragment with a Co(CO) 3 fragment. Indeed we, and others, have explored the subtle changes induced by such an interchange in organometallic clusters. − An examination of the effects of metal variation on the structure and properties of a borane fragment in a metallaborane would complete the carbon−boron analogy. As there are numerous metallaboranes containing the η 5 -C 5 H 5 Co fragment, − which is isolobal with the Fe(CO) 3 fragment, one might argue that this has already been accomplished.…”

Kinetics and Mechanism of Reductive Elimination of C−H Bonds from (μ-H)3Ru3(μ3-CX)(CO)9 Revisited: CO Associative, CO Independent, or CO Dissociative?

“…Shapley also established a rapid equilibrium for eq 6 . Fehlner and co-workers established rapid equilibria for tautomerizations in eqs 7−9. , …”

“…The equilibrium constant for the tautomerization has been shown to be affected by the identity of the metal atoms and the substituents on carbon. The effect of the alkylidyne substituent appears to be primarily steric in origin, as the equilibrium constant for eq 9 decreases in the sequence R = H > Me > Ph . The equilibrium constant is also affected by the difference in electronegativities between carbon (or other capping atom) and the metals …”

“…20 Fehlner and co-workers established rapid equilibria for tautomerizations in eqs 7-9. 21,22 H 2 Os 3 (µ-CH 2 )(CO) 10 a HOs 3 (µ-η 2 -HCCH 2 )(CO) 10 (6) H 2 Fe 3 (µ 3 -η 2 -HCH)(CO) 9 a HFe 3 (µ 3 -η 3 -H 2 CH)(CO) 9 (7)…”