Paramagnetic Organometallic Molecules. 13. Electron-Transfer-Catalyzed Reactions of Polynuclear Metal Carbonyls: Reactions of R2C2Co2(CO)6

Article abstract of DOI:10.1021/ja00345a037

Polynuclear metal carbonyls are shown to be suitable substrates for rapid electron-transfer-catalyzed (ETC) reactions that offer a new convinient method for the synthesis of many carbonyl derivatives.The factors that influence the applicability and yields of these reactions are discussed and examples with a variety of nucleophiles and substrates given.The distinction between electron-induced nucleophilic substitution (EINS) and ETC reactions is emphasized.ETC reactions of R'RC2Co2(CO)6 with MeCN and other Lewis bases using both electrolytic and chemical reductants are described in detail, in particular those where R' = R = CF3.The yields of the new products (CF3)2C2Co2(CO)5L , (CF3)2C2Co2(CO)4L2 , and (CF3)2C2Co2(CO)3L3 are virtually quantitative, with reaction times no longer than 5 min.In most cases reaction is over in 1 min at 293 K.Yields from ETC reactions with other R'RC2Co2(CO)6 compounds are variable but can be correlated with the lifetime of the radicals anions.Spectroscopic data characterized the phosphite or phosphine ligand as having an axial conformation in R2C2Co2(CO)5L complexes, but the X-ray structure of (CF3)2C2Co2(CO)5(MeCN) shows that the MeCN is equatorial.Steric factors are believed to account for this.However, the MeCN ligand is very labile in solution, and the electrochemistry of the MeCN adduct is characterized by abnormal limiting currents at 293 K that are absent at lower temperatures.The compound (CF3)2C2Co2(CO)5(MeCN) crystallizes in the space group Pna2₁; a = 15.794 (5) Angstroem, b = 9.803 (3) Angstroem, c = 10.936 (4) Angstroem, Z = 4, V = 1693.4 Angstroem³.