REACTION OF ELECTROPHILES WITH MANGANESE(I) AND RHENIUM(I) ALKOXIDE COMPLEXES - REVERSIBLE ABSORPTION OF ATMOSPHERIC CARBON-DIOXIDE

The transition metal alkoxides fac-(CO)3(P-P)MOR [where M is Mn or Re, P-P is either 1,2-bis(diphenylphosphino)ethane (dppe) or 1,3-bis(diphenylphosphino)propane (dppp), and R is either CH3, C2H5, or CF3CH2] react readily at room temperature with CO2, CS2, and PhNCO by insertion of these electrophiles into the metal-oxygen bond. The reactions with C02 leading to the corresponding carbonato complexes fac-(CO)3(P-P)MOC(O)OR are of special interest; benzene solutions of the alkoxides can even absorb CO2 from the atmosphere. All the carbonato complexes release C02 When argon is bubbled through solutions of them, regenerating the alkoxides. These equilibrium reactions make it possible to exchange the C02 of the carbonato complexes by treatment of them with CS2 or PhNCO. Only the C02 reaction is reversible under mild conditions. When a solution of fac-(CO)3(dppe)MnOC(O)OCH3 is treated with CH3NH2 followed by CO2 the metallourethane complex (CO)3(dppe)MnOC(O)NHCH3 is formed. The X-ray crystal structure of fac-(CO)3(dppe)MnOC(O)OCH3 is presented.