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本文报道簇合物(Et_4N)(MoFe_3S_4(Et_2dtc)_5)CH_3CN(1)和(MoFe_3S_4(C_5H_10NCSS)_5)CH_2Cl_2(2)在室温和液氮温度(77K)测试的ESR谱。在77K簇合物(1)和(2)的ESR谱分别解释为来自具有双量子跃迁(△W=2hv_0)的S=1和菱形对称的S=1/2的自旋体系,基态自旋S值与根据反铁磁性自旋耦合模型和9N—L规则计算结果一致。 簇合物(1)出现gx=gy=gz=(15/7)g_0≈4.3(E》g_0βH,D≈0)的ESR谱可以确认为Fe~(2+)碎片信号,而具有~(95,97)Mo特征超精细结构(a_0(1)≈38G)的g_0(1)=1.9735±0.0002信号来自Mo~(5+)碎片。簇合物(2)亦出现Mo~(5+)碎片信号(g_(2)=1.9748±0.0002,a_0(2)≈38G)。上述事实说明在分子内发生Fe~(2+)→Mo~(6+)净电子密度转移自氧化还原作用,选种电子非定域化有利于簇骼的形成与稳定。
The ESR spectra of (Et_4N) (Mo_Fe_3S_4 (Et_2dtc) _5) CH_3CN (1) and (Mo_Fe_3S_4 (C_5H_10NCSS) _5) CH_2Cl_2 (2) were measured at room temperature and liquid nitrogen temperature (77K) The ESR spectra of the 77K clusters (1) and (2) are respectively interpreted as coming from a spin system with S = 1 with double quantum transition (ΔW = 2hv_0) and S = 1/2 with diamond symmetry, The S-value is consistent with the calculated results based on the anti-ferromagnetic spin-coupled model and the 9N-L rule. The ESR spectra of cluster (1) with gx = gy = gz = (15/7) g_0≈4.3 (E "g_0βH, D≈0) were confirmed to be Fe 2+ fragments with ~95 , 97) The g_0 (1) = 1.9735 ± 0.0002 signal of Mo feature hyperfine structure (a_0 (1) ≈38G) is from Mo ~ (5+) fragments. Cluster (2) also appeared Mo ~ (5+) fragment signal (g_ (2) = 1.9748 ± 0.0002, a_0 (2) ≈38G). The above fact indicates that the electron density shift of Fe ~ (2+) → Mo ~ (6 +) occurs in the molecule, and the de-localization of the selected species is favorable for the formation and stabilization of the cluster.