MANGANESE(I) AND CHROMIUM(0) COMPLEXES OF PHENYL ISOCYANIDE

The syntheses of [Mn(CO)6-n,(CNC6H5)n]PF6 complexes (n = 2-6) are accomplished from reactions of Mn(CO)5-n(CNC6H5)n Br, either CO or CNC6H5, and a halide acceptor. Stereospecific replacement of Br by CO or CNC6H5 occurs in these syntheses; this specificity permits the syntheses of the isomers fac-and mer-[Mn(CO)3(CNC6H5)3]PF6 and cis and trans-[Mn(CO)2(CNC6H5)4)PF6. Cyclic voltammetry defines E1/2 values for one-electron oxidations of each member of this series. The values of E1/2 decrease in a linear fashion with each additional CNC6H5 substitution. The syntheses of cis-Cr(CO)2(CNC6H5)4 and tr(CO)(CNC6H5)5 from Cr(CO)6 and Cr(CNC6H5)n, are described. Electrochemical data on these compounds are obtained, but this investigation is complicated by rapid ligand redistribution of the products derived on one-electron oxidation. From a reevaluation of the redox data for the series of compounds Cr(CO)6-n(CNC6H5)n (n= 0-6), we conclude that the previously suggested 1-oxidation state complexes [Cr(CNR)6) are incorrectly formulated.The electrochemical data on this system seem best in accord with the three sequential one-electron oxidation processes Cr(CNR)6 ⇋ [Cr(CNR)6]+ ⇋ [Cr(CNR)6]2+ ⇋ [Cr(CNR)6]3+. © 1979, American Chemical Society. All rights reserved.