不对称四核环状CO_3~ⅡM~Ⅲ簇合物的磁化学

Magnetic Chemistry of Tetranuclear Co_3^(II)M^(III) Complexes

本文用一种新的方法对三个四核环状化合物Co_3Fe(mp)_4(Hmp)(PBu_3~n)_3(1)Co_4(mp)_4·(Hmp)(PMe_2Ph)_3(2)(H_2mp=2-巯基苯酚)和Co_4(mp)_4(PBu_3~n)_3Cl(MeOH)(3)进行了1.5～300K温度范围的磁性质研究,即在各向同性海森堡模型的基础上,用全矩阵对角化方法求自旋态能量本征值,从而得到化合物的磁化率,然后用阻尼最小二乘法拟合变温磁化率,得到磁交换常数.因避免了使用Kambe理论,无需对化合物进行模型简化处理,所以得到更多、更准确的磁交换信息.拟合结果显示三个化合物都呈较弱的磁偶合作用.对化合物1得到J_1=-3.14cm^(-1),J_2=-3.04cm^(-1),J_3=2.92cm^(-1)和J_4.08cm^(-1),对2得到J_1=-3.07cm^(-1),J_2=-3.19cm^(-1),J_3=-0.33cm^(-1)和J_4=-1.91cm^(-1);对3得到J_1=-4.818cm^(-1),J_2=-4.244cm^(-1),J_3=-1.164cm^(-1)和J_4=-2.634cm^(-1),其中J_1和J_2代表通过双重μ_2-S桥,J_3和J_4分别代表通过单重和双重μ2-O桥进行的磁交换作用常数.

Magnetic properties of three tetranuclear complexes Co3Fe(mp)4(Hmp) (PBu3n)3(1) Co4(mp)4(Hmp)(PMe2Ph)3(2) and Co4(mp)4(PBu3n)3Cl(MeOH) (3) have been studied in the temperature range of 1.5-300K. On the basis of isotropic Heisenberg model ,the eigenvalues for the possible spin states were obtained with the full - matrix diagonalisation method and variable -temperature magnetic susceptibilities were fitted by the least - squares calculation. The fitting results show J1 = -3.14cm-1,J2=-3.04cm-1, J3 = 2.92cm-1 and J4 = 4.08cm-1 for 1;J1 = -3.07cm-1 ,J2= - 3. 19cm-1 , J3 = -0.33cm-1 and J4=-1.91 cm-1 for2 ; J1 = -4.818cm-1,J2= -4.244cm-1,J3= -1.164cm-1 and J4= -2.634cm-1 for3,where J1 and J2 are the exchange coupling constants transmitted by two u2 - S bridges, J3 and J4 by one u2 - O and two u2-O bridges,respectively.