Studies of Rhenium β-diketone Complexes. IV. The Synthesis, Properties, and Crystal Structure of Bis(μ-chlorotricarbonyl(1-phenyl-1-hydroxobut-1-ene-3-one)rhenium(I)), a Compound Containing a Monodentate Neutral β-Ketoenol

Abstract

The title compound, [Re(CO)3Cl(C6H5•COH•CH•CO•CH3)]2, is one of a series of compounds obtained by the reaction of chloropentacarbonylrhenium(I) with β-diketones and has been characterized by n.m.r. and infrared spectroscopy and single crystal X-ray diffraction. The crystals are monoclinic with lattice parameters a = 14.77(2), b = 17.98(2), c = 13.48(2) Å, β = 124.34(9)°; C2/c, Z = 4. A total of 1293 independent reflections were measured on a single crystal X-ray diffractometer and the structure was refined by full matrix least squares analysis to a weighted R2 value of 0.0444. The dimeric halves of the molecules are held together by two chlorine atoms symmetrically bridging the rhenium atoms (Re—Cl = 2.511(5) Å The structure is thus very like that of [Re(CO)4Cl]2, except that two neutral β-ketoenol molecules replace two carbon monoxide molecules (one on each rhenium) and are bonded through the ketone group (Re—O = 2.16(1) Å). The arrangement of the keto and enol groups is such that hydrogen bonding can occur between them.