Tricarbonyliron complexes derived from dimethyl 1,3-butadiene-2,3-dicarboxylate: Formation of [Fe(CO)<inf>3</inf>]<inf>2</inf>-dimethyl 1,3-butadiene-2,3-dicarboxylate

Abstract

Treatment of dimethyl 1,3-butadiene-2,3-dicarboxylate with Fe2(CO)9provided the corresponding tricarbonyl(η4-dimethyl 1,3-butadiene-2,3-dicarboxylatoO)iron, [Fe(C8H10O4)(CO)3], (II), as the main product and the novel μ-[(1,2-η,κO3:3,4-η,κO2)-dimethyl 1,3-butadiene-2,3-dicarboxylato]bis(tricarbonyliron), [Fe2-(C8H10O4)(CO)6], (III). In the crystal structure of (II), the electron-deficient butadiene complexes with one Fe(CO)3group, whereas in (III), the butadiene adopts an unusual conformation and forms a complex with two Fe(CO)3groups. In (III), each Fe atom possesses a trigonal bipyramidal geometry, with one olefinic bond and two carbonyl ligands occupying the basal positions, and the keto oxygen of the ester and the other carbonyl ligand occupying apical positions.