Addition to Unsaturated Ligands

Department of Applied Chemistry, Osaka University, Suita, Osaka 565-0871, Japan 

Current Methods in Inorganic Chemistry, Volume 3 Editors H. Kurosawa and A. Yamamoto 2003 Elsevier Science B.V. AH rights reserved 

The metal-bound carbonyl ligand is readily subjected to the attack of not only carbanions but heteroatom nucleophiles such as alcohols and amines to form ligands useful for formation of compounds containing ester and amide functionalities. The ease with which the nucleophilic attack takes place at metal-coordinated alkenes and alkynes provides a basis for oxidation of these molecules in the presence of a transition metal complex catalyst [3,4a], as exemplified by the Wacker type alkene oxidation by the use of a Pd catalyst. Metal catalyzed addition of alcohols or amines to alkenes and alkynes also involve the analogous nucleophilic attack [4b-e]. The attack of carbanions and heteroatom nucleophiles 

2-alkoxyalkylpalladium species, followed by incorporation of only one carbon monoxide to give 2-alkoxy esters. To explain these results, it was postulated that the nucleophilic attack at the carbonyl ligand is accelerated by the addition of a base to a greater extent than that at the alkene ligand. Mechanistic aspects of the related stoichiometric nucleophilic attack of alcohols will be described in sections 

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Nucleophilic addition to unsaturated ligands, such as olefins, acetylenes, and arenes, coordinated to various metal centers is a useful strategy in organic synthesis (98). The ion-pair interaction of organometallic cations and anions is facile and can successfully lead to the nucleophilic activation of ethylene, acetylene, and benzene (99), for example,... 

Compounds.- A third part of a review of P-H addition to unsaturated systems has appeared, covering addition to unsaturated ligands in the coordination sphere of a metal.Addition of diphenylphosphine to the free vinyl group of the [4+2]cycloadduct of 3,4-dimethyl-l-phenylphosphole and phenyldivinylphosphine (both in the form of metal complexes) has led to the unsymmetrical triphosphine (40), isolated as the related metal complex.A similar u.v.-induced addition to methyl(vinyl)cyclotetrasiloxane has given a tetraphosphine which, on treatment with acid, forms an... 

H. Kurosawa, Additions to Unsaturated Ligands, In Fundamentals of Molecular Catalysis, H. Kurosawa and A. Yamamoto, Eds., Elsevier Amsterdam, 2003, Chap. 8. 

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