Exchange reactions metal carbonyl derivatives

It should be noted that cyclobutadiene always replaces carbon monoxide in reactions with metal carbonyl derivatives. Yields of product parallel the known rate of exchange of CO in the starting carbonyl 184). Highest yields of ligand transfer products are attained with nickel and cobalt carbonyls which are known to very rapidly exchange their CO groups by a D-type mechanism 185-188). Lowest yields have been reported with Mo and W complexes, the carbonyls of which exchange with CO very slowly 188). 

The relationship between metal carbonyl hydrides and dihydrogen complexes of metal carbonyl derivatives has been further explored.The interactions of d ML5 fragments with H2 have been studied by EHMO methods,and the structures and some reactions of n -H2 complexes of Cr, Mo, W, Fe and Co carbonyl derivatives examined.Intramolecular ligand rearrangements in [M(C0)5H] anions (M = Cr or Mo) have been investigated using variable temperature n.m.r. A twist mechanism that provides a pathway for intramolecular axial-equatorial CO exchange is favoured.The catalytic role of these... 

A number of studies have been carried out on the ligand reactivities of the metal complexes of Schiff bases derived from amino acid esters and carbonyl compounds. Ester exchange reactions were first reported by Pfeiffer et a/.492 and extended by other investigators.493 496... 

Allylation of carbonyl and imino groups is one of the most convenient methods for the introduction of allylic functions.107-110 Allylic tin compounds have high interaction between C=C and C-Sn bonds which makes them more reactive than the corresponding silicon derivatives.111,112 In spite of their high reactivity, tin compounds are stable enough to be isolated and to react at ambient temperature under aerobic conditions. These factors allow them to be applicable to various types of reactions, for example, thermal,113 high-pressure,116 transition metal-catalyzed,117,118 radical,119,120 photochemical,121,122 tin-lithium exchange reactions,108,113 and so on. A broad... 

Organocerium derivatives posses low basicity. 5-Pyrimidinylcerium dichlorides (302) are available by low-temperature metal-metal exchange using cerium trichloride and 5-lithiated pyrimidines (Scheme 50). The 5-pyrimidinylcerium dichloride was superior to its 5-lithio analogue in reactions with aldehydes and ketones, especially in reactions with enolizable aldehydes and ketones (304), and in the 1,2-addition to a] -unsaturated carbonyl derivatives (303) <89ACS816>. 

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