Carbonyl halides hydrides

Since these important findings near the end of the last century, metal carbonyls of a majority of the transition metals have been isolated and characterized. Many of these compounds are pure metal carbonyls, containing only the metal and CO. Many other types are also known, including metal carbonyl-halides, -hydrides, -anions, -7r-cyclopentadienyls, etc. A number of earlier reviews dealing primarily with metal carbonyls has been published 169, 197). Fortunately, there are also two recent reviews on the subject by Abel ) and Hileman ISO). A useful, recent... 

Carbonyl Halides and Hydrides. Fe2(CO) reacts with HBr or HI and Fe(CO)j with HBr under u.v. light to yield the halogeno-complexes [Fe(CO)3.X]2. Structure (16) is postulated, on the basis of the close similarity in i.r. spectra with those of [Fe(CO)3SR]2 complexes. 

Metal derivatives of cobalt carbonyl hydride such as Tl[Co(CO)4], Zn[Co(CO)4]2, or Cd[Co(CO)4]2 are formed upon reaction of cobalt octacarbonyl with these metals in the presence of carbon monoxide under pressure. Reaction with halogens (X) produces cobalt carbonyl halides, Co(CO)X2. 

Molybdenum hexacarbonyl also forms carbonylate anions, Mo(CO)5 , carbonyl halide anions, Mo(CO)5 " and carbonyl hydride anions, Mo(CO)5H in solution under controlled conditions. These species are unstable and have not been isolated. 

G. Mass Spectra of Metal Carbonyl Halides and Metal Carbonyl Hydrides. . 107... 

Elimination of hydrogen halides, particularly in the presence of base, is also a common reachon (equation 54). The actual mechanism of these reactions could involve nucleophihc displacement of halide by the metal carbonyl halide that is formed in situ from the hydride (equations 55 and 56). 

Deviating from the route via nucleophilic attack of the carbanion at the carbon atom of a CO ligand and then reaction of the acylmetallate with an electrophile are those methods which involve (a) addition of the carbanion to the carbon atom of a carbyne ligand, (b) displacement of halides from transition-metal carbonyl halides by cyclohepta-trienyllithium, or derivatives thereof, followed by hydride abstraction or (c) substitution of a coordinated solvent from a metal-carbonyl complex (see also reaction of LiR with carbene complexes). 

A3. P. J. Durrant and B. Durrant, Introduction to Advanced Inorganic Chemistry, 2nd ed. Longmans, London, 1970. Chapter 27, pp. 1125-1196 The carbonyls, carbonyl hydrides, carbonyl halides, nitrosyls, and Tt-complexes of the transition metals. Cursory survey of title topics. 

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