β-diketone-Carbonyl Complexes of Rhenium(I)

Abstract

<p>The reaction between chloropentacarbonyl rhenium(I) and β-diketones is shown to give two types of poducts, Re₂(CO)₆(dik)₂. A unique structure could not be established for either type using infra-red, nmr, mass spectrometry and magnetic measurements. Thus, a crystal structure of one member from each series was undertaken to solve the problem.</p> <p>Re₂(CO)₆Cℓ₂(bamH)₂: the two halves of the molecule are related by a two fold axis and are held together by chlorine bridges. The neutral β-ketoenol groups are cis to-the chlorine bridges, are both on the same side of the molecule, and are each bonded to the rhenium atom via only one oxygen.</p> <p>Re₂(CO)₆(dbm)₂: the two halves of the molecule are related by an inversion centre and are held together by one bridging oxygen from each β-diketone group. The angle between the O-Re-O plane and the OCCCO S-diketone plane is 37°, the largest ever observed for a metal β-diketonate.</p> <p>The Re2(CO)6(dik)2 series was shown to undergo bridge breaking and further substitution to give products of the type Re(CO)₃dik)L and Re(CO)₂(dik)L₂ where L = Co, py, Ph₃P.</p> <p>Finally, the crystal structure of an impurity, Re₂Cℓ₄(CO)ᵪ, was partially solved.</p>