Transition Metal Carbonyl Derivatives of Magnesium

Transition metal carbonyl derivatives of magnesium can be prepared readily by the reductive cleavage of the metal-metal bond in numerous dimeric transition metal carbonyl complexes or by the removal of halogen from transition metal carbonyl halide complexes with an excess of 1 % magnesium amalgam in the presence of a Lewis base. These preparations may be represented by the general equations 

Their excellent hydrocarbon solubility makes these complexes useful as unique metallating agents, especially in the preparation of mixed metal-metal bonded complexes which, in the presence of polar solvents, undergo solvent-aided disproportionations. Although only three reactions are described in detail here, many additional magnesium-transition metal complexes can be prepared by following similar reduction procedures. 

Inorganic Syntheses, Volume XVI Edited by Fred Basolo Copyright 1976 by McGraw-Hill, Inc. 

All reactions and sample preparations are carried out in an inert-atmosphere enclosure under dry nitrogen. Solvents and reagents are dried in the following manner. Benzene, tetrahydrofuran, and n-pentane are freshly distilled from lithium aluminum hydride pyridine is distilled over barium oxide and tetramethylethylenediamine is distilled over calcium hydride. Solvents used in preparing nmr and infrared samples are degassed by a freeze-thaw technique. Nmr spectra are obtained with torch-sealed nmr tubes. The commercial transition metal carbonyl complexes are recrystallized and vacuum-dried before use. Glassware is routinely flame-dried. 

BIS[DICARBONYL-j7-CYCLOPENTADIENYL(TRIBUTYL-PH0SPHINE)M0LYBDENUM]TETRAKIS(TETRAHYDR0-FURAN)MAGNESIUM 

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This, like other transition metal carbonyl derivatives of magnesium, is pyrophoric. 

Caution. Transition metal carbonyl derivatives of magnesium are pyrophoric and must be handled with extreme care (see Properties). The toxicity of the magnesium derivatives is not known but is probably of the same magnitude as the parent carbonyls. The magnesium-transition metal-carbonyl complexes exhibit low vapor pressures and therefore do not present a vapor-transport toxicity problem when an inert-atmosphere enclosure is employed. 

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