Electron spin resonance of copper(II) in Hofmann-type benzene and aniline clathrates

EPR results of Cu(II) in Zn(NH3)2NI(CN)4·2X (X = benzene and aniline) are reported. The thermal behavior of the clathrated aromatic molecules and the declathrated host lattice is studied by using an electron as the microprobe. The spin-Hamiltonian parameters correspond to a dz2 ground state in the clathrates and a dxy ground state in the declathrated compounds. The g tensors and the hyperfine tensors are g∥ = 2.0191, g⊥ = 2.2269; 63Cu A∥ = 89.6±0.1; A⊥ = -65.4±0.1; N(NH3) A∥ = 20±1, H(NH3) A∥ = 5±0.5×10-4 cm-1 for the benzene clathrate and g∥ = 2.03474, g⊥ = 2.2090; 63Cu A∥ = 87.2±0.1, A⊥ = -58.9±0.1×10-4 cm-1 for the aniline clathrate. Upon thermal decomposition of the benzene clathrate two entirely different Cu(II) species are produced. In the are of the aniline clathrate a solid-state ligand displacement reaction has been inferred. Complete derivation of bonding parameters for the dz2 ground state has been carried out. The bonding parameters reveal that in the clathrated complexes both σ and π bonding are equally strong. In the declathrated benzene complex π bonding is found to be stronger than σ bonding. All work was done on polycrystalline materials except for benzene clathrate where only single-crystal measurements could be done. © 1979.