ELECTROCHEMISTRY OF COORDINATION-COMPOUNDS .16. NEW MIXED 1,2-BIS(DIPHENYLPHOSPHINO)ETHANE-ACETONITRILE OR 1,2-BIS(DIPHENYLPHOSPHINO)ETHANE-CARBON MONOXIDE IRON(II), IRON(I) AND IRON(0) COMPLEXES

The new iron compound, trans-[Fe(DPE)2(MeCN)2] (ClO4)2 (DPE=PPh2CH2CH2PPh2), has been prepared and investigated electrochemically. In acetonitrile the complex shows two reduction steps, consistent with the formation of the stable iron(I) species, [Fe(DPE)2(MeCN)]+ and the rather labile π-bonded acetonitrile adduct, Fe(DPE)2(π-MeCN), respectively. Acetonitrile substitution by carbon monoxide leads to formation of the carbonylated species, which have been characterized, and examined by electrochemical techniques. A significant feature is that trans-[Fe(CO)2(DPE)2]2+, unlike trans-[Fe(DPE)2(MeCN)2]2+, takes up two electrons in a single process, the unstable d7 intermediate undergoing a fast disproportionation. A tentative interpretation of this behaviour is suggested. © 1979.