Tungsten , halocarbonyl complexes

Baker, Paul K., The Organometallic Chemistry of Halocarbonyl Complexes of Molybdenum (II) and Tungsten (II). 

VIII. Arene Halocarbonyl Complexes of Molybdenum(II) and Tungsten(II) 103... 

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. 

This article is concerned with six- and seven-coordinate halocarbonyl complexes of molybdenum(II) and tungsten(II) (Section II), of which earlier reviews by Colton et al.2 on substituted halocarbonyls of group 6 transition metals and on steric effects in substituted halocarbonyls of molybdenum and tungsten3 have been published. Also, reviews on the structures of seven-coordinate compounds by Drew in 19774 and by Melnik and Sharrock in 1985s contain relevant material. 

Section V describes the chemistry of 7r-allyl halocarbonyl complexes, mainly of the type [MX(CO)2(NCMe)2(i73-allyl)] and their derivatives. In 1995, Brisdon and Walton8 reviewed transition-metal complexes containing butadienyl ligands their review contains relevant material. Section VI is concerned with the relatively unexplored area of 7j4-diene halocarbonyl complexes of molybdenum(ll) and tungsten(II). 

Section VII describes Cp and related V-ligand halocarbonyl complexes, and Section VIII is concerned with the little-studied Tj6-arene halocarbonyl complexes. Finally, Section IX briefly discusses the halocarbonyl complexes of molybdenum(II) and tungsten(II) containing V-cycloheptatrienyl as a ligand. As Green and Ng9 have reviewed cycloheptatrienyl and -enyl complexes of the early transition metals, only one reference in this area is given. 

SIX- AND SEVEN-COORDINATE HALOCARBONYL COMPLEXES OF MOLYBDENUM(II) AND TUNGSTEN(II)... 

F. Synthesis of Halocarbonyl Complexes of Molybdenum(ll) and Tungsten(ll) by Other Methods... 

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. 

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