Unstable intermediates. Part 169. Electron-gain and -loss centres in irradiated potassium dicyanoargentate(I)
Abstract
Exposure of K[Ag(CN)2] to 60Co γ-rays at 77 K gives two paramagnetic species, A and B. Species A, having g∥ 2.001, g⊥ 2.006. A∥(109Ag) 60 G, and A⊥(109Ag) 30 G, is identified as an electron-gain centre, [Ag(CN)2]2–, with the extra electron in a σ* orbital with 4dz2+ 5s character on silver and considerable density on the ligands. Species B, having gx 2.091, gy 2.051, gz 2.008. Ax(109Ag) 42 G, Ay 34 G, and Az⩽ 65 G, is thought to be the electron-loss centre, Ag[CN]2 with the hole largely localised in silver (again, 4dz2± 5s); on annealing above 77 K, centre B, acquired axial symmetry (g⊥ 2.078, A⊥ 29 G). Solutions in methanol give a poorly defined centre similar to A at 77 K. On annealing, a new species having Aiso.(109Ag) 155 G and A(14N)(one) 17.3 G with gav. 2.002 is obtained. This is tentatively identified as [Ag(CN)]– and reasons for the large hyperfine coupling to 14N are discussed.