Electronic spectrum and d-orbital energies of the planar CuCl42– ion in bis(creatininium) tetrachlorocuprate
Abstract
The low temperature, polarized electronic spectrum of the (100) crystal face of (creatininium)2CuCl4 is reported and interpreted in terms of a d-orbital energy sequence dx2–y2 > > dxy > dxz > dyz > dz2 for the planar CuCl42– ion present in this compound; the marked temperature dependence of the spectrum and its comparison with that of the similar compound (PhCH2CH2NH2Me)2CuCl4 suggests that coupling both with lattice modes and an out-of-plane bonding mode of very low energy is important in the mechanism by which the electronic transition gain intensity in compounds of this kind.