SYNTHESIS OF METAL-CARBONYL MONO-ANIONS BY TRIALKYLBOROHYDRIDE CLEAVAGE OF METAL-CARBONYL DIMERS - CONVENIENT ONE-FLASK PREPARATION OF METAL ALKYLS, METAL ACYLS, AND MIXED-METAL COMPOUNDS

Commercially available trialkylborohydrides Li(C2H5)3BH, Li(sec-C4H9)3BH, and K(sec-C4H9)3BH effect the near-quantitative, homogeneous, room-temperature synthesis of transition-metal monoanions [Co(CO)4]-, [(C5H5)Mo(CO)3]-, [Mn(CO)5]-, and [(C5H5)Fe(CO)2]- from the corresponding metal carbonyl dimers. Reactions are nearly instantaneous except in the case of [(C5H5)Fe(CO)2]2, which is reduced over a 3-h period by K(sec-C4H9)3BH in THF or within 2 h by Li(C2H5)3BH in≥50% HMPA cosolvent. Metal carbonyl anions are also produced by the action of Li(C2H5)3BH on [Mn(CO)5]Br and [(C5H5)Mo(CO)3]Cl. These anions are subsequently subjected in situ to a variety of alkylation, acylation, and metalation reactions. This methodology offers considerable advantage over more conventional means for the synthesis of metal carbonyl anions and their derivatives; these aspects are discussed in detail. © 1979, American Chemical Society. All rights reserved.