Monoxide Insertion. General Considerations and Background

CARBON MONOXIDE INSERTION. GENERAL CONSIDERATIONS AND BACKGROUND 

Carbon monoxide insertion reactions may be represented by the equation  

Some transition metal systems M(CO)R react with a wide range of L, including phosphites, phosphines, arsines, stibines, organic amines, iodide, and CO, to mention a few, yielding the corresponding acyls. Other systems, e.g., CpFe(CO)2R (2S), display a marked selectivity toward various L. Certain unsaturated molecules L [SOj (239), CF2=Cp2 (238), inter alia] insert themselves into the M—R bond instead of effecting the reaction shown in Eq. (8). 

Carbon monoxide insertions are intramolecular. It therefore follows that an important requirement for occurrence of these processes is presence of the CO and R in the reacting complex in a suitable position to combine. Accordingly, compound (I) does not react with CO under ambient conditions (105). The dinuclear [MeCo(DH)2]2 (DH = dimethylglyoximate) reacts with CO, but not by insertion, to give (II) in solution (125). Forma- 

Carbon monoxide insertion is not restricted to transition metal-carbon bonds, although M—C is by far the most common substrate involved. Reactions have also been reported which lead to insertion of CO into M—O (114) and M—N (199) bonds. 1,1-Additions of M—H (27, 114) and M—M (104) linkages to CO have been postulated, too. However, direct replacement of CO, without rupture of the W—H bond, is indicated for the reaction between CpW(CO)3H (or -D) and PPhj (5)  

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II. Carbon Monoxide Insertion. General Considerations and Background... 

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