Preparation, spectroscopy and reaction with oxygen of [Co(en)2]2+ on the surface of hectorite
Abstract
Planar low-spin [Co(en)2]2+ is prepared by vacuum decomposition of [Co(en)3]2+ on the surface of hectorite in the temperature range 423–500 K. The e.p.r. parameters of [Co(en)2]2+ are: g⊥= 2.579 ± 0.002, A⊥= 0.0174 cm–1, g∥= 1.964 ± 0.002 and A∥= 0.0149 cm–1. The unpaired electron spin density is distributed as follows: 68% in Co(3dz2), 13% in Co(4s) and 19% on ligand orbitals. The d–d reflectance spectrum is analysed in the strong ligand-field limit and in the angular-overlap model approximation with D4h symmetry. The most probable parameters are: B= 455 cm–1, 10Dq= 16709 cm–1, E(dx2–y2)–E(dz2)= 17 800 cm–1 and E(dx2–y2)–E(dxz, dyz)= 22 909 cm–1, lσ= 8900 cm–1, lπx= 1896 cm–1 and lπy= 2498 cm–1. The reaction of [Co(en)2]2+ with O2 is diffusion controlled on the surface of hectorite.