Pincer-ligand platinum complex

Pyridine complexes of Pd- and Pt-pincer ligands are also suitable substrates for olefin metathesis [116]. The first-generation catalyst 9 efficiently mediates the RCM of diallylphosphines and diallyl sulfide when the heteroatom is com-plexed by a cationic [C5H5(NO)(PPh3)Re] moiety [117]. This principle has been exploited in the same study for tungsten, rhodium, and platinum complexes. 

In recent years, a number of low-valent group 10 complexes with anionic pincer ligands have been isolated and characterized. Milstein investigated the chemical reduction of palladium [81] and platinum [82] complexes with PCP Hgands with sodium (Scheme 2.8). The Pd-pincer framework of complex 2 does not resist reduction and collapses, giving rise to the unusual binuclear complex 29. In this compound, both PCP ligands are covalently bound to one of the Pd atoms, which... 

Finally, an interesting reaction induced by carbon monoxide leading to the formation of a platinum fris-carbene pincer complex (37) is produced by the reaction at room temperature in pentane or hexanes of the Pt-olefln-carbene complex (36) with CO (1 atm) [16]. This compound contains a tridentate pincer ligand in which all three donors are carbenes (Scheme 2.19). The structure of complex (37) was fully determined by single-crystal X-ray diffraction analysis. 

For example, several pincer ligands with a central amido moiety, such as those of type 11, have been developed by several groups and their complexes with metal centers such as paUadium(II), platinum(II), and rhodium(I) have been characterized. The aim was on the one hand to synthesize robust, electron-rich organometaUic compounds which easily undergo oxidative addition at the metal center and, on the other hand, to develop bifiinctional catalysts in which the central amido moiety can cooperatively act with the metal center in a catalytic event, for example, by accepting/releasing protons... 

In a manner similar to platinum ones, rhodium—carbene complexes have been recently tested in the hydrosilylation of alkenes and alkynes (3). Especially, rhodium complexes with N-heterocyclic carbene (NHC) ligands have attracted considerable attention. Their performance is comparable with that of phosphine complexes. The following exemplary ligands were used 1,3-imidazoylidene chelate bis(imidazolinum-carbene) phosphine-functionalized NHC alkylammonium-imidazolium chloride salts NHC pincer complexes, pyridine-functionalized N-heterocyclic carbenes (also with iridium), and bis(dichloroimidazolylidene) (also with iridium). 

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