Synthesis, Structure and Magnetic Properties of Two Cobalt（Ⅱ） Dicyanamide （dca） Complexes with Heterocyclic Nitrogen Donors Tetra（2-pyridyl）pyrazine （tppz） and 2,4,6-Tri（2- pyridyl）-1,3,5-triazine （tptz）： Co2（tppz）（dca）4·CH3CN and Co（tptz）（dca...

摘要

Two new transition metal dicyanamide complexes [Co2（tppz）（dca）4]·CH3CN （1） [tppz=tetra（2-pyridyl）pyrazine, dca=dicyanamide] and [Co（tptz）（dca）（H20）]（dca） （2） [tptz=2,4,6-tri（2-pyridyl）-1,3,5-triazine] were synthesized and characterized by single crystal X-ray diffraction analysis. In 1 each cobalt（Ⅱ） atom is coordinated to three dca anions and one tppz molecule to form a distorted octahedral geometry, the neigbour two cobalt（Ⅱ） atoms are bridged by one tppz ligand to form a dimer, then the cobalt（Ⅱ） atoms in each dimer are joined together to form a ladder chain structure. In 2 the coordination geometry around the central metal is also distorted octahedral, each cobalt（Ⅱ） atom is coordinated by two dca anions, one tptz molecule and one water ligand to form a cationic part, and the cationic part is linked with the free dca anions via the electrostatic attraction to give an infinite chain structure. Magnetic susceptibility measurement in the range of 2-300 K indicates that there are antiferromagnetic couplings between adjacent metal ions in 1 （T〉29 K, θ=-9.78 K, C=4.92 cm^3·K·mo1-1） and ferromagnetic couplings in 2 （T〉 150 K, θ=7.97 K, C=2.59 cm^3·K·mol^-1） respectively.