ESR for Single Crystal of Trans-bis(α-Picoline), Bis(4,4,4-Trifluoro-1-(2-Thenoyl)Butanedione-1,3) Copper(II)

The single crystal of the title complex was prepared by doping into the isomorphous diamagnetic complex and studied by ESR at X-band, room temperature. The Spin Hamiltonian parameters were calculated using the least-square-litting program for the non-coincident system of \overrightarrow\mathbfg and \overrightarrow\mathbfA tensors. The results show the principal values of \overrightarrow\mathbfg and \overrightarrow\mathbfA tensors:g_z=2.346, g_x=2.079, g_y=2.075, A_z=-154 × 10^-4cm^-1, A_x=A_y=-26 × 10^-4cm^-1. It is proved that α-picoline is an axial ligand coordinated to cengtre Cu (Ⅱ). Based on Swallen's process, the orbital coefficients of Kramers doublet have been calculated, with results:a=0.954, b=0.226 c=0.177, d=e=0.064 corresponding to atomic orbitals d_x²-y², d_z², d_xy, d_xz, d_yz respectively, electron spin density population is mainly in d_x²-y² orbital. The bonding parameters of Cu (Ⅱ) with four coplanar oxygens were estimated, the results show that the ground state molecular orbital B_1g has more covalency than the other orbitals and the coplanar orbital d_xy has more delocalization than d_xz and d_yz orbitals which are out of the chelate plane.