Hydride complexes manganese

Relaxation studies have also been used to estimate metal-hydrogen bond distances in rhenium and manganese hydride complexes (Gusev et al., 1993). 

The mechanism of the reaction of the alcohol (or water) with the acyl complex to produce ester (or acid) and regenerate the cobalt hydride complex is not known. Because the reaction of the analogous manganese complex with alcohols is known to proceed through a hemiacetal-like complex, this mechanism has been written for the carboxylation reaction (equation 42). 

An unusual reaction, with loss of a phenyl group from HSnPh3, occurs with some din-uclear manganese-hydride carbonyl complexes (equation 84)240. The chemistry outlined in the previous equations, involving elimination of H2, occurs in many regions of the periodic table and produces good yields of the metal-tin bonded complex. 

Carbonyl Complexes of the Transition Metals Electronic Sfructme of Organometalhc Compounds Hydride Complexes of the Transition Metals Ligand Field Theory Spectra Manganese Organometalhc Chemistry Photochemistry of Transition Metal Complexes Rhenium Organometalhc Chemistry Rutheiuum Organometalhc Chemistry. 

The reaction of metal carbonyl dimers with silicon hydrides also probably involves an initial oxidative addition step. Chiral silyl-cobalt and silyl-manganese carbonyl complexes have been obtained through the reaction of optically active organosilicon hydrides with metal carbonyls65 68 (equation 15 and 16). Phosphine-substituted cobalt complexes were similarly obtained by reaction of a chiral hydrosilane with Co2(CO)6L2 [L = PPh3, P(OPh)3, P(c-C6Hn)3]69. 

In a new and significant development, it was found that chlorocyclohexadienyl manganese tricarbonyl complexes undergo palladium-catalyzed coupling reactions with a variety of carbon nucleophiles to afford products from which hydride may be abstracted with trityl cation, thus generating new [( -arene)Mn(CO)3]+ complexes containing substituents that cannot be introduced in any other manner. This is particularly true of electron-withdrawing substituents. Scheme 16 illustrates the chemistry involved. 

Many parameters have been shown to effect the value of T,. Halpem conducted an extensive study of the factors that can effect the value of Tj in transition metal hydride complexes. He noted, among other conclusions, that relaxation can be affected by metals having a high gyromagnetic ratio, such as cobalt, rhenium, and manganese. Despite these issues, and later studies that express reservations about Halpem s conclusions, the Tj criterion is commonly used and can be powerful if used for metals other than Co, Re, and Mn (or with corrections for the relaxation provided by these metals) and with an imderstanding of potential pitfalls. 

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