Limburg J, Vrettos J S, Crabtree R H, Brudvig G W, de Paula J C, Hassan A, Barra A L, Duboc-Toia C, Collomb M N
Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, USA.
Inorg Chem. 2001 Mar 26;40(7):1698-703. doi: 10.1021/ic001118j.
The isolation and structural characterization of [(terpy)Mn(III)(N3)3], complex 1, is reported (terpy = 2,2':6',2' '-terpyridine). Complex 1, a product of the reaction between the mixed-valence dimer (terpy)(H2O)Mn(III)(O)2Mn(IV)(OH2)(terpy)3 and NaN3, crystallizes in a triclinic system, space group P1, a = 8.480(1) A, b = 8.9007(2) A, c = 12.109(2) A, alpha = 93.79(1) degrees, beta = 103.17(1) degrees, gamma = 103.11(1) degrees, and Z = 2. Complex 1 exhibits a Jahn-Teller distortion of the octahedron characteristic of a six-coordinated high-spin Mn(III). A vibrational spectroscopic study was performed. The nu(asym)(N3) mode of complex 1 appears in the IR as a strong band at 2035 cm(-1) with a less intense feature at 2072 cm(-1), and in the FT-Raman as a strong band at 2071 cm(-1) with a weaker broad band at 2046 cm(-1). The electronic properties of complex 1 were investigated using a high-field and high-frequency EPR study (190-475 GHz). The different spin Hamiltonian parameters have been determined (D = -3.29 (+/-0.01) cm(-1), E = 0.48 (+/-0.01) cm(-1), E '= 0.53 (+/-0.01) cm(-1), g(x) = 2.00 (+/-0.005), g(y) = 1.98 (+/-0.005), g(z) = 2.01 (+/-0.005)). These parameters are in agreement with the geometry of complex 1 observed in the crystal structure, a D < 0 related to the elongated distortion, and a value of E/D close to 0.2 as expected from the highly distorted octahedron. The two values of the E-parameter are explained by the presence of two slightly different structural forms of complex 1 in the crystal lattice. A second hypothesis was explored to explain the experimental data. The calculation for the simulation was done taking into account that the g and D tensors are not collinear due to the low symmetry of complex 1. In that case, the spin Hamiltonian parameters found are D = -3.29 (+/-0.01) cm(-1), E = 0.51 (+/-0.01) cm(-1), g(x) = 2.00 (+/-0.005), g(y) = 1.98 (+/-0.005), and g(z) = 2.01 (+/-0.005).
报道了[(三联吡啶)锰(III)(叠氮化物)3]（配合物1）的分离及其结构表征（三联吡啶 = 2,2':6',2''-三联吡啶）。配合物1是混合价二聚体(三联吡啶)(水)锰(III)(氧)2锰(IV)(水)(三联吡啶)3与叠氮化钠反应的产物，结晶于三斜晶系，空间群P1，a = 8.480(1) Å，b = 8.9007(2) Å，c = 12.109(2) Å，α = 93.79(1)°，β = 103.17(1)°，γ = 103.11(1)°，Z = 2。配合物1呈现出六配位高自旋锰(III)八面体典型的 Jahn-Teller 畸变。进行了振动光谱研究。配合物1的ν(asym)(N3)模式在红外光谱中表现为位于2035 cm(-1)的强吸收带以及位于2072 cm(-1)的较弱吸收特征峰，在傅里叶变换拉曼光谱中表现为位于2071 cm(-1)的强吸收带以及位于2046 cm(-1)的较弱宽带。利用高场和高频电子顺磁共振研究（190 - 475 GHz）对配合物1的电子性质进行了研究。已确定了不同的自旋哈密顿参数（D = -3.29(±0.01) cm(-1)，E = 0.48(±0.01) cm(-1)，E' = 0.53(±0.01) cm(-1)，g(x) = 2.00(±0.005)，g(y) = 1.98(±0.005)，g(z) = 2.01(±0.005)）。这些参数与在晶体结构中观察到的配合物1的几何结构一致，D < 0与拉长畸变相关，且E/D值接近0.2，这是高度畸变八面体所预期的。E参数的两个值可通过晶格中配合物1存在两种略有不同的结构形式来解释。探索了另一种假设来解释实验数据。考虑到由于配合物1的低对称性，g和D张量不共线，进行了模拟计算。在这种情况下，得到的自旋哈密顿参数为D = -3.29(±0.01) cm(-1)，E = 0.51(±0.01) cm(-1)，g(x) = 2.00(±0.005)，g(y) = 1.98(±0.005)，g(z) = 2.01(±0.005)。
