Three Novel End-to-End Single Azido-Bridged Ferromagnetic Copper(II) Chains: Synthesis, Crystal Structure, and Magnetic Behavior

摘要

Three new single end-to-end azido-bridged copper(II) chains [Cu(L1)N_3)_n(ClO_4)_n (1) [Cu(L2)N_3)_n(ClO_4)_n (2), and [Cu(L3)N_3)_n(ClO_4)_n (3) using three different tridentate Schiff bases L1, L2, and L3, obtaiend from condensation of pyridine-2-carbaldehyde with N,N-dimethylethane-1,2-diamine, N,N-diethylethane-1,2-diamine, and 4-(2-aminoethyl)morpholine, respectively, have been synthesized, and their crystal structures have been determined by X-ray diffraction methods. Compelx 1, C_(10)H_(15)CuN_6ClO_4, crystallizes in an orthorhombic system, space group P2_12_12_1, with a=7.434(3), b=12.047(4), c=17.404(6) A, and Z=4; complex 2, C_(12)H_(19)CuN_6ClO_4, crystallizes in an orthorhombic system, 2, C_(12)H_(19)CuN_6ClO_4, crystallizes in an orthorhombic system, space group Pna2_1, with a=14.723(5), b=13.829(5), c=8.002(5), A, and Z=4 and compelx 3, C_(12)H_(17)CuN_6ClO_5, crystallizes in an orthorhombic system, space group Pna2_1, with a=13.837(15), b=14.804(2), c=8.050(4) A, and Z=4. Each structue consists of a single end-to-end azido-bridged copper(II) 1D chain where each copper(II) center possesses a square pyramidal geometry. Magnetic susceptibility data, measured from 4 to 300 K, show weak ferromagnetic interaction through the end-to-end bridging azido pathway in all the complexes. The magnetic datawere fitted to a high temperature series-expansion for a one-dimensional system with S=1/2 locla spin based on the Hamiltonian H=-J#SIGMA#s_i centre dotS_(i+1) for all the compelxes, giving the parameters J=+2.15 cm~(-1), g=2.23 for 1, J=+3.61 cm~(-1), g=2.16 for 2, and J=+2.06 cm~(-1), g=2.17 for 3. This unusal magnetic behavior through the end-to-end bridging azido pathway has been correlated to the structural parameters.