Some mononuclear seven-co-ordinate rhenium(III) carbonyl complexes; the crystal and molecular structure of (2,2′-bipyridyl)tribromodicarbonylrhenium(III)

Abstract

Treatment of fac-[ReX(CO)₃(diamine)] with halogens has afforded the seven-co-ordinate rhenium(III) complexes [ReX₃(CO)₂(diamine)][diamine = 2,2′-bipyridyl (bipy), X = Cl or Br; diamine = 2,9-dimethyl-1,10-phenanthroline, X = Br]. Infrared evidence suggests that [ReBr₃(CO)₂(diamine)](diamine = 1,10-phenanthroline or 2,2′-biquinolyl) and [ReBr₃(CO)₂(amine)₂](amine = pyridine or 2-methylpyridine) may be formed in an analogous manner, but the desired products could not be separated from rhenium(IV) bromo-complexes also formed in the bromination reactions. Crystals of [ReBr₃(CO)₂(bipy)] are monoclinic, with a= 7.062(8), b= 14.914(8), c= 14.186(12)Å, β= 100.8(1)°, Z= 4, and space group P2₁/c. 1 120 Independent reflections above background have been collected on a diffractometer and refined to R 0.079. The metal atom has a distorted capped-octahedral environment in which a carbonyl group occupies the capping position [1.96(5)Å], a carbonyl group [1.96(3)Å], a nitrogen atom of the bidenate ligand [2.22(3)Å], and a bromine atom [2.635(5)Å] make up the capped face, and two bromine atoms [2.551(5) and 2.576(4)Å] and the other nitrogen atom [2.15(2)Å] complete the uncapped face.