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The mechanisms of the hydrosilylation reactions of unsaturated compounds with the tungsten complexes are examined by using the density functional theory method. The results have shown that the hydrosilylation of acetone has proceeded through a metal hydride migration, while the hydrosilylation of nitrile has occurred through a silyl migration mechanism.

Density functional theory (DFT) calculations are performed to examine the reaction mechanism of hydrosilylation of carbonyl compounds catalyzed by high-valent rhenium(V)-di-oxo complexes ReO2I-(PR3)2 (R = Me, Ph). The results have indicated that the most favorable mechanisms involved the rate-determining dissociative [2+2] addition of the Si-H bond across a Re=O bond to form a Re(V) hydrido siloxy intermediate and the additional oxo ligand in the ReO2I(PR3)2 complexes has promoted the [2+2] addition across the rhenium-oxo bond both kinetically and thermodynamically.

Palladium-catalyzed terminal alkyne dimerization through oxidative homocoupling is a useful approach to the synthesis of symmetrical 1,4-diynes. Recent investigation suggested that this reaction might be accomplished in the absence of intentionally added stoichiometric oxidants to reoxidise Pd(0) to Pd(II).

DFT calculations have been carried out to study the Rh-catalyzed site selective ring-opening reactions of phenylcyclobutabenzenol (1a). calculations supported that the mechanism involves β-carbon elimination in a rhodium(I) phenylcyclobutabenzenolato complex followed by alcoholysis. The favorable β-carbon elimination involves the cleavage of the C(sp²)-C(sp³)(OH)(Ph) bond in 1a, which determines the site selectivity. The mechanism and regioseiectivity of the related Rh-catalyzed insertion reaction of the asymmetric alkyne MeC=CPh with phenylcyclobutabenzenol (1a) was also investigated. The key step involves the alkyne insertion into the Rh-C σ bond of a species resulting from the favorable β-carbon elimination in the rhodium(l) phenylcyclobutabenzenolato complex. The favorable insertion couples the metal-bonded carbon with the methyl-substituted carbon of MeC=CPh. [ABSTRACT FROM AUTHOR]