A tetranuclear carbonyl fluoro rhenium(I) cluster, [Re(CO)₃F]₄,4H₂O

Abstract

The title compound has been prepared from Re(CO)₅Br by a bromide-abstraction reaction with silver fluoride. It completes the series of known halide clusters of the type [Re(CO)₃X]₄ (where X = halide). The crystals are tetragonal, space group 14, with a 11.716(5), c 8.988(3) Å, and Z 2. The structure was refined by full-matrix least-squares to an R value of 0.027 for 1380 observed reflections. The molecules are cubane-type clusters of Re(CO)₃ groups at one set of corners interpenetrated with fluorine atoms at the other set. The clusters exhibit the molecular symmetry 43m. Each of the fluorine atoms is involved in μ₃ type bridging with the rhenium atoms at an average bonding distance of 2.200(5) Å. The clusters are held together by hydrogen bonding of fluoride to water molecules.