Phosphorus transition metal-carbon bonds

Organometallic compounds are those in which there is a metal-carbon bond. According to this definition, in the case of transition metals, this group of compounds includes not only metal carbonyls, olefin complexes, cyclopentadienyl, and other 7r-complexes, but also cyanide and fulminate compounds. Certain difficulties arise in defining the metal of the main group elements. Usually, organometallic compounds are comprised not only of compounds of typical metals, but also of metalloids such as boron, silicon, phosphorus, arsenic, selenium, etc. In compounds of metals as well as in those of metalloids, the bond is generally polarized as follows C. Consequently, the... 

Coverage.—The literature appearing in 1980 has been scanned and compounds containing at least one metal-carbon bond have been included in Section 2. The definition of a metal in this context is taken to be any transition or inner transition element, or any member of Groups lA— VIA, with the exception of hydrogen, carbon, nitrogen, oxygen, phosphorus, and sulphur. 

Transition metal-mediated phosphorus-carbon bond cleavage and its relevance to homogeneous catalyst deactivation. P. E. Gorrou, Chem. Rev., 1985,85,171 (109). 

Pauling, L. (1977) "The nature of bonds formed by the transition metals with hydrogen, carbon, and phosphorus," Acta Crystal-logr., in press. 

Pauling, L. Nature of the Bonds Formed by the Transition Metals with Hydrogen, Carbon, and Phosphorus Acta Crystallogr. 1978, B34, 746-754. 

In this section we will survey the use of transition metal-catalyzed additions, at times accompanied by rearrangement processes, that lead to the generation of new carbon-phosphorus bonds. 

The breaking of carbon-to-phosphorus bonds is by itself not a useful reaction in homogeneous catalysis. It is an undesirable side-reaction that occurs in systems containing transition metals and phosphine ligands and that leads to deactivation of the catalysts. Two reaction pathways can be distinguished, oxidative addition and nucleophilic attack at the co-ordinated phosphorus atom (Figure 2.35). 

As a second step in the reaction, following co-ordination, most authors propose an oxidative addition of the C-S fragments to the transition metal, similar to the reaction found for carbon-to-phosphorus bond breaking. Since the C-S bond is rather weak it is easy to break and indeed several model reactions can be found in the literature. 

Various phosphaethenes prepared by the reactions of 11a and lib with aldehydes are shown in Chart 1 m-Bromophenyl-substituted phosphaethene was prepared by the phos-pha-Peterson reaction". 2-Pyridyl- or 2-fury 1-substituted (E)- and (Z)-phosphaethenes were prepared by the use of lib100. Compounds bearing several phosphorus-carbon double bonds have been prepared and their transition metal complexes were studied101-106. Azulenylphosphaethenes were also prepared107,108. 

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