Pait Moumita, Bauzá Antonio, Frontera Antonio, Colacio Enrique, Ray Debashis
†Department of Chemistry, Indian Institute of Technology (IIT), Kharagpur 721 302, India.
‡Departament de Química, Universitat de les Illes Balears (UIB), Carretera de Valldemossa, km 7,5, 07122 Palma, Balearic Islands, Spain.
Inorg Chem. 2015 May 18;54(10):4709-23. doi: 10.1021/acs.inorgchem.5b00039. Epub 2015 May 1.
Carboxylato (R = (t)Bu and Et) and carbonato bridges have been utilized for nickel(II)-based aggregates Ni4(μ-H2L)2(μ3-OH)2(μ1,3-O2CBu(t))22·H2O·2DMF (1·H2O·2DMF), Ni4(μ-(hy)HL)2(μ3-OMe)2(μ1,1-N3)2(μ1,3-O2CEt)2]·4H2O (2·4H2O), and Ni6(μ4-L)(μ3-L)2(μ6-CO3)(H2O)8](ClO4)·9H2O (3·9H2O). Building blocks Ni2(μ-H2L), Ni2(μ-(hy)HL), and Ni2(μ-L) originating from Ni2(μ-H2L) have been trapped in these complexes. The complexes have been characterized by X-ray crystallography, magnetic measurements, and density functional theory (DFT) analysis. In 1, the magnetic interactions are transmitted through the μ3-phenoxido/μ3-hydroxido/syn-syn-(t)BuCO2(-), μ3-phenoxido/μ3- hydroxido, and double μ3-phenoxido/double μ3-hydroxido bridges with J = +11.4 cm(-1), J1 = -2.1 cm(-1), and J2 = -2.8 cm(-1), respectively. In 2, the interactions are ferromagnetic, with J1 = +27.5 cm(-1), J2 = +20.62 cm(-1), and J3 = +1.52 cm(-1) describing the magnetic couplings through the μ-phenoxidoo/μ3-methoxido, μ-azido/μ3-methoxido, and μ3-methoxido/μ3-methoxido exchange pathways, respectively. Complex 3 gives J1 = -3.30 cm(-1), J2 = +1.7 cm(-1), and J3 = -12.8 cm(-1) for exchange pathways mediated by μ-phenoxido/μ-carbonato, μ-alkoxido/μ-alkooxido/μ-syn-syn-carbonato, and the μ-phenoxido/μ-carbonato, respectively. Interestingly, 1 and 3 below 20 K and 35 K, respectively, show an abrupt increase of the χMT product to reach a magnetic-field-dependent maximum, which is associated with a slightly frequency-dependent out-of-phase alternating-current peak. DFT calculations have also been performed on 1-3 to explain the exchange interaction mechanisms and to support the magnitude and sign of the magnetic coupling constants between the Ni(II) ions.
羧基（R =叔丁基和乙基）和碳酸酯桥已用于基于镍（II）的聚集体Ni4(μ-H2L)2(μ3-OH)2(μ1,3-O2CBu(t))22·H2O·2DMF (1·H2O·2DMF)、Ni4(μ-(hy)HL)2(μ3-OMe)2(μ1,1-N3)2(μ1,3-O2CEt)2]·4H2O (2·4H2O)和Ni6(μ4-L)(μ3-L)2(μ6-CO3)(H2O)8](ClO4)·9H2O (3·9H2O)。源自Ni2(μ-H2L)的结构单元Ni2(μ-H2L)、Ni2(μ-(hy)HL)和Ni2(μ-L)已被困在这些配合物中。这些配合物已通过X射线晶体学、磁性测量和密度泛函理论（DFT）分析进行了表征。在1中，磁相互作用通过μ3-苯氧基/μ3-羟基/顺式-顺式-叔丁基碳酸根（-）、μ3-苯氧基/μ3-羟基以及双μ3-苯氧基/双μ3-羟基桥传递，J分别为+11.4 cm(-1)、J1 = -2.1 cm(-1)和J2 = -2.8 cm(-1)。在2中，相互作用是铁磁性的，J1 = +27.5 cm(-1)、J2 = +20.62 cm(-1)和J3 = +1.52 cm(-1)分别描述了通过μ-苯氧基/μ3-甲氧基、μ-叠氮基/μ3-甲氧基以及μ3-甲氧基/μ3-甲氧基交换途径的磁耦合。配合物3对于由μ-苯氧基/μ-碳酸根、μ-烷氧基/μ-烷氧基/μ-顺式-顺式-碳酸根以及μ-苯氧基/μ-碳酸根介导的交换途径，给出J1 = -3.30 cm(-1)、J2 = +1.7 cm(-1)和J3 = -12.8 cm(-1)。有趣的是，1和3分别在20 K和35 K以下显示χMT产物突然增加，达到与磁场相关的最大值，这与略微频率依赖的异相交流峰值相关。还对1 - 3进行了DFT计算，以解释交换相互作用机制并支持Ni(II)离子之间磁耦合常数的大小和符号。
