Nitrogen derivatives of iron carbonyls. Part 5. New routes in the mechanism of reaction of dodecacarbonyl-triangulo-tri-iron with nitro-alkanes, and X-ray analysis of µ-[acetone oximato(1—)-NO]-µ-isopropyl-amido-bis(tricarbonyliron)(Fe–Fe)

Abstract

The reaction of [Fe₃(CO)₁₂] with RNO₂(R = Et or Pr^I) gives, among complexes of well known structures, many other iron–nitrogen–carbonyl complexes which are indicative of novel reaction paths, such as reduction of a nitro-to a nitroso-group, hydrogen abstraction, and N–C bond breakage. The complexes have been fully characterized by means of i.r., mass, and ¹H and ¹³C n.m.r. spectroscopy. The crystal structure of the title complex has been determined by X-ray diffractometry from 2 446 reflections (R 0.037). Crystals are triclinic, space group P, with Z= 2 in a unit cell of dimensions a= 12.008(5), b= 9.827(4), c= 8.580(4), Å, α= 120.53(4), β= 99.29(1), and γ= 96.80(1)°. The structure consists of two Fe(CO)₃ units linked by an Fe–Fe bond and doubly bridged by the nitrogen of the isopropylamido-ligand and the nitrogen and oxygen of the oximato-ligand. The n.m.r. study shows the presence of a substantial torsional barrier about the N–Fe and N–O bonds and localized carbonyl interchange.