CHARACTERIZATION OF THE 17-ELECTRON RADICAL-CATION [CPCO(1,5-COD)](+)BY ESR SPECTROSCOPY

The 17e cation, [CpCo(1,5-COD)](+), generated by chemical or electroch emical oxidation of the neutral 18e complex in CH2Cl2/C2H4Cl2, exhibit s an intense, reasonably well resolved ESR spectrum at 77 K. The spect rum can be interpreted to yield the spin Hamiltonian matrices, g = (2. 120, 2.329, 2.003), A(Co) = (55.7, 20, 0.5) x 10(-4) cm(-1) where the x- and z-principal axes of the hyperfine matrix are rotated, relative to the g-matrix axes, by beta = 65 degrees. With the inclusion of spin -orbit coupling corrections, the ESR parameters lead to a singly occup ied molecular orbital with 57% 3d(xz), 6% 3d(x)(2)-(2)(y), and 3% 4s c obalt character.