ELECTRON-SPIN RESONANCE OF SOME PARAMAGNETIC COMPOUNDS OF IRIDIUM(II)

This paper deals with some electronic problems suggested by Malatesta. Electron spin resonance with [IrBr3(NO)(PPh3)2] shows that the electronic configuration of the paramagnetic compound is described by that of the Ir-NO moiety. Specifically the three values of g tensor components demonstrate that the unpaired electron is located in a largely comprised π* (NO) orbital, so that the electronic state of NO is similar to that of gaseous trapped NO. The overlap between Ir and NO orbitals is through the dπ (dxz or dyz) metal orbitals, with consequent bent coordination of NO ligand. In conclusion the stability of d7 configuration of Ir in this monomeric compound is due to the easy electron transfer between metal and ligand, in agreement with that described in other monomeric Ir(II) compounds. © 1982.