650 zyxwvutsrqpo J. CHEM. zyxwv SOC., CHEM. COMMUN., 1984 z Structure and Mechanism of Formation of [Fe(C0)2(PME3)2{C(=CH2)-Nc6Hl 1-C- (=N+HC6H1 1)}]BPh4-. A New Type of Intramolecular Oxidative Addition to lsocyanide Co-ordinated to Iron Giuseppe Cardaci,a* Gianfranco Bellachioma,a and PierFrancesco Zanazzib a zyxwvutsrqponmlkjihgf Dipartimento di Chimica, University of Perugia, Via €Ice di Sotto, 8, 06100 Perugia, Italy b Dipartimento di Scienze della Terra, Sez. Cristallografia, University of Perugia, Piazza Universita, 06 100 Perugia, ltal zyxwvutsrqp y zyxwvutsrqponm The structure of the title complex (lb) was resolved by X-ray diffraction methods and is supported by i.r. and zy 1H n.m.r. spectral evidence; its formation proceeds via insertion of isocyanide into an iron-methyl bond, intramolecular oxidative addition to another co-ordinated isocyanide ligand, and finally iminium-enammonium rearrangement. The insertion of isocyanide into a metal-alkyl bond to give 71-iminoalkyl derivatives has been studied extensively; according to theoretical predictions2 it proceeds via a dihapto- iminoalkyl intermediate, which in a few cases has been isolated and characterized. 3 In some cases polyinsertion of isocyanide ligands has also been observed, in particular with Ni, Pd, and Fe derivatives.4The nitrogen of the ql-iminoalkyl derivatives also reacts with electrophiles to give carbene structures.3.5 In this communication we describe a new type of intramolecular reaction, which gives ferraheterocyclic butane derivatives. The reaction of [Fe(CO)2(PMe3)2(Me)I] (2) and C6HlINC in benzene gave the complex [Fe(CO)(PMe3)2(COMe)- 2160 cm-l). Complex (3) reacted further with C6H11NC to give the ionic precipitate [Fe(C0)2(PMe3)2{ C(=CH2)- NC6H11-C(=NHC6H11)}]+I- (la),? which was transformed into the tetraphenylborate salt (lb). ? Good crystals of (lb) were obtained by adding LiI in MeOH in order to control the formation rate. (CNChHll)I] (3), (YCO 1940, YCOMe 1585, and VCN Analysis was carried out by X-ray diffraction methods.$ Complex (lb) crystallized in the monoclinic system with a = 20.175(4), b = 14.833(3), c = 16.052(2) A, 6 = 106.97(2)", zy D, = 1.179 g cm-3,Z = 4, space group P21/a. Intensity data were measured with a Philips PW 1100 single-crystal diffrac- tometer, using Mo-K, radiation, p = 4.02 cm-1. The structure was resolved by direct methods and refined by full-matrix least squares with SHELX-76.6 The refinement converged at R 0.077 and R, 0.083 for 231 parameters and 2172 observed reflections. Anisotropic thermal parameters were refined for Fe, P, 0, and N atoms and for the carbon atoms linked to iron. The molecular structure of the cation [Fe(CO),- (PMe3)2{C(=CH2)-NC6Hll-~(=NH~6~~l)}]+ is shown in Figure 1 and selected bond lengths and angles are given in the caption. Complex (lb) has an octahedral arrangement with two cis carbonyl ligands and two trans phosphine ligands. The organic moiety occupies the remaining two cis co-ordination sites; it bonds to iron by two a-carbon bonds, forming a cyclic structure of four atoms with the iron. The atoms N(2)-C(17)- t Elemental analyses of complexes (la) and (lb) are in agreement with the formulae proposed. $ The atomic co-ordinates for this work are available on request from the Director of the Cambridge Crystallographic Data Centre, University Chemical Laboratory. Lensfield Road, Cambridge CB2 1EW. Any request should be accompanied by the full literature citation for this communication. Published on 01 January 1984. Downloaded by University of Illinois at Chicago on 25/10/2014 17:50:22. View Article Online / Journal Homepage / Table of Contents for this issue