KINETIC STUDIES OF THERMAL-DECOMPOSITION AND SUBSTITUTION-REACTIONS OF CIS-MO(CO)4[P(C6H5)3](AMINE) COMPOUNDS - COMPETITIVE STUDY OF LEWIS BASES FOR INTERMEDIATE [MO(CO)4P(C6H5)3]
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Kinetic and mechanistic studies of thermal decomposition and substitution reactions of cis-Mo(CO)4[P(C6H5)3](amine) (where amine = NHC5 Hl0 or NC5 H5) are reported. Substitution reactions have been carried out for a.variety of entering ligands (L) to form ccis-Mo(CO)4[P(C6H5)3]L compounds. These substitution reactions proceed via the rate expression: rate = k[Mo(CO)4[P(C6H5)3](amine)], at low concentrations of L. When L is a strongly nucleophilic ligand and is employed at high concentrations, a second-order term must be added to give a rate expression of the form: rate= [k + k'[L]][Mo-(CO)4[P(C6H5)3](amine)]. Competitive reactions for the intermediate [Mo(CO)4P(C6H5)3] have been investigated for a number of ligands (L) including carbon monoxide, phosphines, and amines. There are only slight differences in the rate constants for the reactions of the [Mo(CO)4P(C6H5)3] intermediate with various ligands L. Substitution equilibria are however dependent on the nature of L. Steric factors have been shown to be important in these substitution reactions; e.g., for the sterically bulky ligand L = (o-tolyl)3P no substitution product is observed. 1973, American Chemical Society. All rights reserved.