Crystal structure of bis(2,2′-bipyridyl)monochlorocopper(II) tetrafluoroborate. A relook at the structural pathway of the bis(2,2′-bipyridyl)monochlorocopper(II) cation

Abstract

The crystal structure of [Cu(bipy)₂Cl]BF₄(I)(bipy = 2,2′-bipyridyl) has been determined using diffractometer data collection. It was solved by the heavy-atom method and successive Fourier difference syntheses. Compound (I) crystallises in the monoclinic space group P2₁/n with a= 16.187(4), b= 12.177(3), c= 10.793(3)Å, β= 104.49(3)°, Z= 4, and R= 0.058 for 1 451 unique reflections. The CuN₄Cl chromophore involves a square-based-pyramidal distorted trigonalbipyramidal stereochemistry. The extent of the square-pyramidal distortion is mirrored in the twin-peaked electronic reflectance spectrum, with absorption maxima at 10 100 and 13 900 cm^–1. The structure of complex (I) is compared with those of a series of eight cation distortion isomers of [Cu(bipy)₂Cl]Y which are related by a structural pathway. The nine complexes have been subjected to scatter-plot and factor-group analysis and the feasibility of extending the structural pathway to include two [Cu(bipy)₂Br]⁺ and two [Cu(bipy)₂I]⁺ complexes is examined.