Radiation induced electron loss-electron capture processes in irradiated coordination compounds: Polyazamacrocyclic complexes of Ni(II) in tetrahydrofurane and halocarbon matrices

Abstract

The low temperature γ irradiation of Ni(II) complexes with N -cetyltetraazamacrocyclic ligands in CH 2Cl 2 and tetrahydrofurane matrices lead to the selective production of electron loss and electron capture centres which were identified by ESR as Ni(III) and Ni(I). The analysis of the g tensors is consistent with tetragonally distorted D 4 h d 7 and d 9 configurations with the unpaired electron in d z2 and d x2− y2 orbitals respectively. The irradiation of the neat compounds selectively yields alkyl type radicals from the cetyl chains; a mechanism based on the migration of the Ni(III) and Ni(I) states in the crystalline matrix and the reduction of Ni(III) centres by carbon centred radicals is invoked to explain these results.