Tungsten , halocarbonyl complexes reactions

The organometallic chemistry of halocarbonyl complexes of molybde-num(II) and tungsten(II) has been extensively studied since the early report in 1956 by Piper and Wilkinson1 of the cyclopentadienyl halocarbonyl complexes [MoX(CO)3Cp] (X = Cl, Br, I). More than 700 references of relevance to the review were collected up to June 1995, and hence some selection had to be made. The review is concerned with molybde-num(II) and tungsten(II) complexes containing both carbon monoxide and at least one halide ligand. The review is mainly restricted to the formation of complexes with those ligands as the final products of reactions, and not reactions of this type of complex. 

As stated in the Introduction, Templeton7 published a comprehensive review entitled Four Electron Alkyne Ligands in Molybdenum(II) and Tungsten(II) Complexes, including halocarbonyl complexes, which dealt with the literature up to 1987. Hence, this section of the review deals with the literature on halocarbonyl alkyne and alkene complexes published from 1987 to mid-1995. The vast majority of papers that have appeared during this period are concerned with the reactions of [MI2(CO)3(NCMe)2] (M = Mo, W) and their derivatives with alkynes, which begin this section of the review. 

Thus far, the reactions of the diiodo-complexes [MI2(CO)3(NCMe)2] with alkynes have been described. In this section the reactions of other seven-coordinate molybdenum(II) and tungsten(II) halocarbonyls with alkynes are described. 

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