Studies on organometallic compounds with hetero multiple bridges : V. Crystal and molecular structure of the parent rhenium complex Re 2Br 2(CO) 6(THF) 2 and substituted products of tricarbonylrhenium(I) derived from it

Abstract

Reactions of the tetrahydrofuran adduct Re 2Br 2(CO) 6(THF) 2 with some phosphorous- and nitrogen-containing donors under mild conditions are reported, which led to the formation of substituted products of tricarbonylrhenium(I). Bromide abstraction from the THF adduct by secondary amines and CS 2 produced the dithiocarbamato derivatives Re(S 2CNR 2)(CO) 3(HNR 2) whose behaviour in solution with CO was also investigated. Mass spectral data for some of the substituted products have been measured. The title compound crystallizes in the space group P2 1/ n with cell constants a = 8.661(2), b = 11.251(3), c = 11.424(3) Å and β = 110.36(2)°, U = 1043.67 Å 3 and D calc = 2.686 g cm −3, Z = 2. The molecule consists of a planar Re 2Br 2 moiety, as demanded by symmetry. The two THF groups are on opposite sides of this plane and the three CO groups around each rhenium atom are arranged in a fac arrangement. The unique ReBr distances are 2.642(5) and 2.644(4)Å, while the ReO distance is 2.129(31) Å. The ReBrRe and BrReBr angles are 97.3(2) and 82.7(1)°, respectively. The Re⋯Re nonbonding distance is 3.967(3) Å. The THF ligands consist of a nearly planar C 4 fragment (maximum deviation from planarity 0.06 Å), while the oxygen is 0.348 Å out of that plane, the angle defined by the C 4 plane and the COC fragment of the THF ligand being 24.99°. Final values of the discrepancy indices are R( F) = 0.074 and R w ( F) = 0.095.