Comparative Crystallography. 5. Crystal Structures, Electronic Properties, and Structural Pathways of Five [Cu(phen)2Br][Y] Complexes, Y = [Br]-·H2O, [ClO4]-, [NO3]-·H2O, [PF6]-, and [BPh4]-

Abstract

The crystal structures of [Cu(phen)2Br][Br]·H2O (1, phen = 1,10-phenanthroline), [Cu(phen)2Br][ClO4] (2), [Cu(phen)2Br][NO3]·H2O (3), [Cu(phen)2Br][PF6] (4), and [Cu(phen)2Br][BPh4] (5) have been determined by X-ray diffraction. Four of the complexes, 1−4, have a CuN4Br chromophore with a square based pyramidal distorted trigonal bipyramidal (SBPDTB) stereochemistry, while 5 involves an extreme trigonal bipyramidal distorted square based pyramidal (TBDSBP) stereochemistry. The geometries of the CuN4Br chromophores in 1−5 are compared by scatter plot analysis with a single [Cu(phen)2Br][ClO4] complex, 6, of known crystal structure involving a crystallographic 2-fold axis of symmetry. The distortion isomers of 2 and 6 are significantly different. The scatter plots of the six cation distortion isomers of the [Cu(phen)2Br][Y] series of complexes suggest that all six complexes lie on a common structural pathway, involving a mixture of the symmetric, νsym, C2 mode and the asymmetric, νasym, non-C2 mode of vibra...