Spectroscopic studies of Ni(I) complexes with CO, O 2 and no ligands in a NiCa-Y zeolite

Abstract

Ni(I) ions formed in situ by reducing NiCa-Y zeolite by hydrogen at 200°C were allowed to react at room temperature with CO, O 2 or NO adducts and were studied by means of ESR spectroscopy with complementary aid of UV and IR spectroscopies. In the case of CO adduct, a weak interaction occurred between a Ni(I) ion and two coordinated CO molecules with a small unpaired spin delocalization towards CO ligands, the starting ions being restored by outgassing at 100°C. The ESR parameters of the Ni(CO) + 2 complex are as follows: g 1 = 2.225, g 2 = 2.075 anf g 3 = 2.062, a 1 ≈ 34 and a 2 ≈ a 3 = 31 Oc for 13C hyperfine splitting. In the case of oxygen, dispersed Ni(O) atoms were shown to be slowly oxidized into Ni(I) ions coordinated to O 2 molecules and further to Ni(II) and O − 2. In the case of NO, oxidation of Ni(O) and Ni(I) occurred very rapidly into Ni(II) coordinated with NO forming a Ni +NO + complex.