Magnetic susceptibility of a series of dinuclear Ⅴ(Ⅳ) . Co(Ⅱ) and Mn(Ⅲ) complexes has been measured in the temperature range of 1. 5 ～300K. The isotropic Heisenberg theory has been applied to study the temperatur...Magnetic susceptibility of a series of dinuclear Ⅴ(Ⅳ) . Co(Ⅱ) and Mn(Ⅲ) complexes has been measured in the temperature range of 1. 5 ～300K. The isotropic Heisenberg theory has been applied to study the temperature-dependent behaviour of the magnetic susceptibility of these complexes and a corresponding program for fitting the experimental results has been set up on a VAX 11/785 computer. Conclusions can be drawn that the three complexes studied are all anti-ferromagnetically coupled with coupling constants -4. 4 , -115. 2 , and - 8. 4 cm￣(-1) for Ⅴ(Ⅳ) . Co(Ⅱ) ,and Mn(Ⅲ) complexes, respectively.展开更多
Two helical one-dimensional complexes [MnII(MeOH)4][MnIV(L·)2]·2MeOH (1) and [MnⅢ(salen)][MnⅢ(L)2] (2) (H2L = HON=C(Ph)N=NC_(6)H_(4)CO_(2)H) contain the noninnocent ligand [Mn(L·)2]2- and innocent low...Two helical one-dimensional complexes [MnII(MeOH)4][MnIV(L·)2]·2MeOH (1) and [MnⅢ(salen)][MnⅢ(L)2] (2) (H2L = HON=C(Ph)N=NC_(6)H_(4)CO_(2)H) contain the noninnocent ligand [Mn(L·)2]2- and innocent low-spin [Mn(L)2]-. Intrachain antiferromagnetic interaction between adjacent manganese ions via the syn-anti carboxylate bridges in complex 1. Alternate syn-anti and anti-anti carboxylate bridges have been found to transmit ferro-and antiferromagnetic coupling between high-spin and low-spin Mn(Ⅲ) ions in complex 2.展开更多
A tetranuclear Li2Cr2 acetylide precursor complex, [Li(Tp)CrIII(C≡CSiMe3)2(μ_3-pz)]2·(n-pentane)2 (Tp=hydridotris(pyrazolyl)borate, pz = pyrazolate) (1) has been synthesized and characterized. The X-ray structu...A tetranuclear Li2Cr2 acetylide precursor complex, [Li(Tp)CrIII(C≡CSiMe3)2(μ_3-pz)]2·(n-pentane)2 (Tp=hydridotris(pyrazolyl)borate, pz = pyrazolate) (1) has been synthesized and characterized. The X-ray structure analysis shows that the complex contains a Li2Cr2 core bridged by two μ_3-pyrazolates. The magnetic data exhibit the existence of weak antiferromagnetic interaction in the cluster.展开更多
文摘结合对称性破损(BS)方法,采用不同的密度泛函理论(DFT)对反铁磁性μ-1,3-N3-Ni(II)叠氮配合物[LNi2(N3)](Cl O4)2(L=pyrazolate)的磁特性进行了研究.结果显示,杂化密度泛函理论(HDFT)的计算结果与实验数据非常吻合,能够准确描述配合物的磁特性.磁轨道研究结果表明,配合物表现出较大的单占据轨道能量劈裂(0.93-0.99 e V),显示配合物的单占据轨道去简并化程度较大,且配合物中的2个磁通道(叠氮基、配体pyrazolate)中都分别存在有氮原子之间的p轨道重叠,这些都使得体系表现为反铁磁耦合作用.另外,配合物的磁性与叠氮桥和两金属离子间形成的二面角(τ,Ni-N-N-N-Ni)密切相关,τ从-55.38°逐渐变化到-1.5°的过程中,其反铁磁性逐渐增强,交换耦合常数(Jab)的绝对值逐渐增大,并在-11.95°处达到最大值(Jab=-151.02 cm-1).在此过程中,配合物中叠氮桥及其所连接的2个Ni离子与pyrazolate基配体L-中的2个桥原子N(4)、N(5)形成的七元环共平面性不断增强,即共平面性会诱导增强体系的反铁磁相互作用.
文摘Magnetic susceptibility of a series of dinuclear Ⅴ(Ⅳ) . Co(Ⅱ) and Mn(Ⅲ) complexes has been measured in the temperature range of 1. 5 ～300K. The isotropic Heisenberg theory has been applied to study the temperature-dependent behaviour of the magnetic susceptibility of these complexes and a corresponding program for fitting the experimental results has been set up on a VAX 11/785 computer. Conclusions can be drawn that the three complexes studied are all anti-ferromagnetically coupled with coupling constants -4. 4 , -115. 2 , and - 8. 4 cm￣(-1) for Ⅴ(Ⅳ) . Co(Ⅱ) ,and Mn(Ⅲ) complexes, respectively.
文摘Two helical one-dimensional complexes [MnII(MeOH)4][MnIV(L·)2]·2MeOH (1) and [MnⅢ(salen)][MnⅢ(L)2] (2) (H2L = HON=C(Ph)N=NC_(6)H_(4)CO_(2)H) contain the noninnocent ligand [Mn(L·)2]2- and innocent low-spin [Mn(L)2]-. Intrachain antiferromagnetic interaction between adjacent manganese ions via the syn-anti carboxylate bridges in complex 1. Alternate syn-anti and anti-anti carboxylate bridges have been found to transmit ferro-and antiferromagnetic coupling between high-spin and low-spin Mn(Ⅲ) ions in complex 2.
文摘A tetranuclear Li2Cr2 acetylide precursor complex, [Li(Tp)CrIII(C≡CSiMe3)2(μ_3-pz)]2·(n-pentane)2 (Tp=hydridotris(pyrazolyl)borate, pz = pyrazolate) (1) has been synthesized and characterized. The X-ray structure analysis shows that the complex contains a Li2Cr2 core bridged by two μ_3-pyrazolates. The magnetic data exhibit the existence of weak antiferromagnetic interaction in the cluster.
