Phosphorus transition metal complex

Keywords. White phosphorus, Transition metal complexes, 31P NMR spectroscopy, Polyphosphorus ligands, Mechanistic studies... 

C. A. McAuliffe and W. Levason, Phosphine, Arsine and Stibine Complexes of the Transition Elements, Elsevier, Amsterdam, 1979, 546 pp. A review with over 2700 references. See also C. A. McAuliffe (ed,), Transition-Metal Complexes of Phosphorus, Arsenic and Antimony Donor Ligands, Macmillan, London, 1972,... 

C. A. McAuliffe (ed.), Transition Metal Complexes of Phosphorus, Arsenic and Antimony Ligands, Macmillan, London, 1973, 428 pp. 

As well as phosphorus ligands, heterocyclic carbenes ligands 10 have proven to be interesting donor ligands for stabilization of transition metal complexes (especially palladium) in ionic liquids. The imidazolium cation is usually presumed to be a simple inert component of the solvent system. However, the proton on the carbon atom at position 2 in the imidazolium is acidic and this carbon atom can be depro-tonated by, for example, basic ligands of the metal complex, to form carbenes (Scheme 5.3-2). 

Table 3. Bond lengths (A), bond dissociation energies (kcal/mol), a- and n-bond strengths (kcal/mol), charges on phosphorus (e), and orbital energies (eV) for first row transition metal complexes ML =PH ...

The methods available for synthesis have advanced dramatically in the past half-century. Improvements have been made in selectivity of conditions, versatility of transformations, stereochemical control, and the efficiency of synthetic processes. The range of available reagents has expanded. Many reactions involve compounds of boron, silicon, sulfur, selenium, phosphorus, and tin. Catalysis, particularly by transition metal complexes, has also become a key part of organic synthesis. The mechanisms of catalytic reactions are characterized by catalytic cycles and require an understanding not only of the ultimate bond-forming and bond-breaking steps, but also of the mechanism for regeneration of the active catalytic species and the effect of products, by-products, and other reaction components in the catalytic cycle. 

In this chapter, synthesis, structure, and reactions of various classes of diazaphospholes have been reviewed. Recently used synthetic methods and variations for obtaining diversely substituted diazaphospholes have been discussed. On account of the cycloadditions on P=C bond of [1,4,2]- and [l,2,3]diazaphospholes, a number of organophos-phorus compounds incorporating a bridgehead phosphorus atom have become accessible. Recently reported complexation reactions of diazaphospholes, illustrate their capability to form transition metal complexes via different coordination modes. 

Non-heteroatom-substituted carbene complexes can also be generated by treatment of electrophilic transition metal complexes with ylides (e.g. diazoalkanes, phosphorus ylides, nucleophilic carbene complexes, etc. Section 3.1.3). Alkyl complexes with a leaving group in the a-position are formed as intermediates. These alkyl complexes can undergo spontaneous release of the leaving group to yield a carbene complex (Figure 3.2). 

In 1995 a breakthrough occurred in this field in February we were able to show the synthesis and the spectroscopic properties of the first complexes of type B [7], and in August the first isolated and structurally characterized complexes containing terminal metal-phosphorus triple bonds (type A) were independently obtained and published in back-to-back articles by the groups of Cummins [8] and Schrock [9]. Since then, a rapid development has occurred in the synthesis and particularly in the study of the reactivity pattern of complexes with phosphorus-transition metal triple bonds. This review chapter will highlight the development in this field by giving an overview from 1995 until the current stage of research. 

The diazaphospholyl iminophosphine (see above) uses alternatively N-1, P-3, or the side group phosphorus atom for transition metal complexation <93BSF726>. 

Me Auliffe, C A. (ed.) Transition metal complexes of phosphorus, arsenic and antimony ligands. London Me Millan 1973... 

The reliable prediction of redox potentials as a function of composition is useful in the synthetic design and application of technetium and other transition metal complexes. A parametric procedure for doing so on the basis of ligand additivity principles has been developed by Lever [28]. Lu etal. [29] used this scheme to correlateTc / ",Tc "/ , andTc hi potentials with the composition of octahedral technetium complexes containing halide, nitrogen, and phosphorus donor ligands. The results are illustrated in Fig. 2 [29], where the observed potentials are plotted according to... 

Ni phosphorus-ylide complexes were reported by Ittel and co-workers to be active for the co-polymerization of ethylene and non-vinyl-functionalized monomers, yielding functionalized polyethylenes (PEs). These results demonstrate the high potential of late transition metal complexes for the production of co-polymers from hydrocarbon and polar monomers. 

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