Phosphine/phosphite ligands, transition metal

The vast majority of phosphine/phosphite-substituted products involve F-ligand ligation at late transition metals. In contrast, phosphite ligands displaced rhenium-coordinated CO or acetylene in [RePt3(/i-dppm)3(CO)3(L)l", - which are the... 

Most of the major developments in homogeneous transition metal-catalyzed hydrocyanation since the early 1980s have been reviewed 62 67 considerable effort in this area has focused on enantioselective reactions.68 In this regard, the emphasis has been on complexes of the group 10 metals (particularly Ni and Pd) incorporating new classes of phosphine, phosphite, and phos-phinite ligands. 

Among transition metal complexes used as catalysts for reactions of the above-mentioned types b and c, the most versatile are nickel complexes. The characteristic reactions of butadiene catalyzed by nickel complexes are cyclizations. Formations of 1,5-cyclooctadiene (COD) (1) and 1,5,9-cyclododecatriene (CDT) (2) are typical reactions (2-9). In addition, other cyclic compounds (3-6) shown below are formed by nickel catalysts. Considerable selectivity to form one of these cyclic oligomers as a main product by modification of the catalytic species with different phosphine or phosphite as ligands has been observed (3, 4). 

A general inspection of the Tables of published phosphorus chemical-shift data on co-ordination complexes (in Section VII) indicates the difficulties in any quantitative understanding. In general it appears that the majority of transition metal— phosphine complexes (particularly those containing the metal in its zerovalent state) have resonances at lower field than the corresponding unco-ordinated phosphine. On the other hand the chemical shifts of all phosphorus trichloride complexes occur at higher field than the free ligand, while the behaviour of phosphite complexes is rather more variable. Phosphine... 

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