Organometallics 1993, 14, 4989-4991
4989
Synthesis and Crystal Structure of a New Binuclear Organoiron Nonbridged Complex: Bis(tert-butoxycarbonyl)octacarbonyldiiron, [Fe(C02tBu)(C0)412 Denis Luart,? Murielle Sellin,?Pascale Laurent,? Jean-Yves Salaun,? Roger Pichon,* Lo'ic Toupet,§and Hew6 des Abbayes"?? Laboratoire de Chimie, Electrochimie Molbculaires et Chimie Analytique, URA CNRS 322, and Laboratoire de Rtsonance Magdtique Nuclbaire, Universitt de Bretagne Occidentale, UFR Sciences et Techniques, BP 809, 29285 Brest cedex, France, and Groupe Matiare Condenste et Mattriaux, URA CNRS 804, Universitt de Rennes 1, Campus de Beaulieu, 35042 Rennes cedex, France Received July 19,1995@ Summary: The reaction of NaLFe(COztBu)(CO)alwith 0.5 equiv of ClCOCOCl in tetrahydrofuran affords the new complex [Fe(C02tBu)(CO)a12,which is characterized by single-crystal X-ray difraction analysis. Structural and spectroscopic observations show that it does not present any bridging ligands. Binuclear complexes appear to afford an obvious link between the chemistry of mononuclear complexes, used extensively as homogeneous catalysts,l and those of polynuclear clusters, which may act as models for complex systems such as heterogeneous catalysts.2 The nature of the chemical bonding in metal dimer compounds is of considerable interest, and among the numerous complexes with a direct metal-metal bond,3 those that are stable without bridging ligands are more ~carce.~ Homodinuclear complexes with a metal-metal single bond and an unsupported linkage are known in particular for metals in lower (-1, 0, 1)oxidation states. For example, compounds such as Mz(C0)lo (M = Mn, Tc, ReI5 and cyclopentadienylmetal complexes MzCpZ(c0)S (M = Cr, Mo, WY are worthy of mention. Among the transition metals of the group 8, the nonbridged binuclear complexes 0s~Hz(CO)a,~ OS&z(CO)8 (X= C1, 1),7,80szMe~(CO)s,~ and Ruz(EMe&(CO)8 (E = + Laboratoire de Chimie, Electrochimie Moleculaires et Chimie Analytique, Universite de Bretagne Occidentale. Laboratoire de Resonance Magnetique Nucleaire, Universite de Bretagne Occidentale. 5 Universite de Rennes 1. Abstract published in Advance ACS Abstracts, November 1,1995. (1)(a) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles and Applications of Organotransition Metal Chemistry, 2nd ed.; University Science Books: Mill Valley, CA, 1987.(b) Parshall, G. W. Homogeneous Catalysis; Wiley: New York, 1980.( c ) Masters, C. Homogeneous Transition Catalysts; Chapman and Hall: London, 1981. (2)(a) Muetterties, E. L.; Rhodin, P. N.; Brucker, C. F.; Pretzer, W. R. Chem. Reu. 1979,79,91.(b) Transition Metal Clusters; Johnson, B. F. G., Ed.; Wiley: New York, 1985.( c ) Metal Clusters; Muskovits, M., Ed.; Wiley: New York, 1986. (3)(a) Cotton, F. A.; Walton, R. A. Multiple Bonds Between Metal Atoms, 2nd ed., Oxford University Press: London, 1993.(b) Chisholm, M. H. ACC.Chem. Res. 1990,23,419. (4)Herberhold, M.; Jin, G.-X. Angew. Chem., Int. Ed. Engl. 1994, 33,964. (5) (a) M = Mn: Almeningen, A.; Jacobsen, G.G.;Seip, H. M. Acta Chem. Scand. 1969,23, 685. (b) M = Tc: Bailey, M. F.; Dahl, L. F. Inorg. Chem. 1965,4,1140.( c ) M = Mn, Re: Churchill, M. R.; Amoh, K. N.; Wasserman, H. J . Inorg. Chem. 1981,20,1609. (6) (a) M = Cr: Adams, R. D.; Collins, D. M.; Cotton, F. A. J. Am. Chem. SOC.1974,96, 749.(b) M = Mo, W: Adams, R. D.; Collins, D. M.; Cotton, F. A. Inorg. Chem. 1974,13,1086. (7)Moss, J. R.; Graham, W. A. G.Inorg. Chem. 1977,16, 75.
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@
Si, Ge, Sn)lohave been characterized. Their homologue FezIz(C0)8 has been spectroscopically described,ll but compounds such as FeZ(R)(R')(C0)8with R, R = alkyl, acyl, alkoxycarbonyl, ..., are, to our knowledge, un-
known. We report herein the synthesis and the spectroscopic and the structural characterizations of the first nonbridged binuclear iron complex bearing alkoxycarbonyl and carbonyl ligands. We recently described the synthesis of cis-bis(alkoxycarbony1)tetracarbonyliron complexes, Fe(COZR)z(C0)4, with R = Me, Et, 'Pr by reaction of (alkoxycarbony1)tetracarbonylferrates, [Fe(C0~R)(C0)41-, with ' / z equiv of oxalyl chloride (eq 1).12 IFe(CqR)(CO)41' +
1/2 ClCOCOCl
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