Halocarbonyl Complexes

Baker, Paul K., The Organometallic Chemistry of Halocarbonyl Complexes of... 

The [M2(CO)8Cl3] anions are the first halocarbonyl complexes (without other ligands in the coordination sphere) of group VA metals to be reported. They probably originate from the unstable HM(CO)6 carbonyls. 

D. Other Aspects of 7r-AIlyl Halocarbonyl Complexes of Molyb-... 

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 III of the review is concerned with alkylidene and alkylidyne halocarbonyl complexes, and a review on recent advances in the chemistry of metal-carbon triple bonds by Mayr and Hoffmeister in 1991 contains material of interest.6 Section IV is concerned with halocarbonyl alkyne and alkene complexes described from 1987 to mid-1995, because an exten-... 

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)... 

This is the most common method of preparing halocarbonyl complexes, and the section is divided into a number of different parts depending on the other donor ligands attached to the metal. 

X-Ray Crystal Structure Determinations of Six- and Seven-Coordinate Halocarbonyl Complexes Reported after 1984... 

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