Vanadium complexes carbonyl anion

Several anionic metal carbonyl hydrides stoichiometrically convert acyl chlorides to aldehydes. The anionic vanadium complex [Cp(CO)3VH] reacts quickly with acyl chlorides, converting them to aldehydes [44]. Although no further reduction of the aldehyde to alcohol was observed, the aldehydes reacted further under the reaction conditions in some cases, so a general procedure for isolation of the aldehydes was not developed. 

For example, in Ni(CO) nickel metal having 28 electrons coordinates four CO molecules to achieve a total of 36 electrons, the configuration of the inert gas krypton. Nearly every metal forming a carbonyl obeys the 18-electron rule. An exception is vanadium, forming a hexacarbonyl in which the number of electrons is 35. This carbonyl, which has a paramagnetism equivalent to one unpaired electron, however, readily adds one electron to form a closed valence shell complex containing the V(CO)(, anion. 

A similar reaction (see equation 27) has been reported for hexacarbonylvanadium(O). By these reactions, the tetracarbonylcobaltate(-I) and the hexacarbonylvanadate(-I) anions are generated. The crystal and molecular structure of the product of the disproportionation reaction of V(CO)6 with tetrahydrofuran of formula [V(THF)4][V(CO)6]2 has been shown to consist of vanadium(II) octahedrally surrounded by four thf s in the equatorial positions and by two axial carbonyl oxygens from two hexacarbonylvanadate anions resulting in a linear V-O-C-V sequence see Isocarbonyl Complexes). 

V(CO)6] , as well as the related [V(CO)sPPh3] and [V(CO)4L2] anions [L2 = bis(diphenylphosphino)ethane (dppe), bis(dimethylphosphino)ethane (dmpe), and 1,2-dimethylarsenobenzene (diars)], generally produce seven-coordinate, neutral vanadium carbonyl complexes when treated with group IVB halides ... 

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