Structures and properties of weakly associated polyoxometalate-transition metal complexes

本研究项目旨在合成多金属氧酸盐与过渡金属离子的配合物，分析其晶体结构，并研究其结构特有的物理化学性质。首先，研究了作者首次合成并表征的[Cu_2(OH)_2(OH_2)_6][Cu_2(OH_2)_8][V_&lt；10&gt；O_&lt；28&gt；]-4(CH_3)_2CO，的磁性。该化合物的[V_&lt；10&gt；O_&lt；28&gt；]^&lt；6-&gt；核两侧有两对Cu2+&gt；阳离子，其间距分别为2.89Å和3.37Å。这些电子对中未成对的电子没有耦合，每个铜原子都作为一个独立的自旋中心工作。其次，合成了[V_&lt；10&gt；O_&lt；28&gt；]^&lt；6-&gt；与Cu~(2+)、NH_4~(2+)、K~(++)或Rb~(2+)复盐，并测定了它们的晶体结构。在这些晶体中，与阳离子配位的水分子通过氢键支持[V_&lt；10&gt；O_&lt；28&gt；]^&lt；6-&gt；核心上的氢原子，并稳定单质子化物种[HV…更多_&lt；10；_O&lt；28&gt；]^&lt；5-&gt；。在这些晶体中，首次明确地确定了质子在单质子化的十钒酸根离子上的精确位置。化合物[Siw_&lt；11&gt；O_&lt；39&gt；]^&lt；8-&gt；的结构测定表明，尽管过渡金属没有被Na~+离子连接，但化合物呈现出新的螺旋结构[Siw_&lt；11&gt；O_&lt；39&gt；]^&lt；8-&gt；它的结构表明，它可能会表现出非线性光学性质，从而照射波长为800 nm的脉冲激光，从而观察到二次谐波的产生。在这些研究的同时，研究人员在两个同步加速器设施安装和升级了衍射仪：高能加速器研究组织的Spring-8和光子工厂。这些工作有助于对上述NLO活性硅钨酸盐晶体的精确结构分析，以及对具有纳米环状的混合价钼巨型团簇的分子生长和分子间凝聚的结构解释。较少

This research project aims at synthesizing complexes of polyoxometalates with transition metal ions, analyzing their crystal structures, and then examining the physicochemical properties that are specific to their structures. First, the magnetic properties of [Cu_2(OH)_2(OH_2)_6][Cu_2(OH_2)_8][V_<10>O_<28>]-4(CH_3)_2CO, which was first synthesized and characterized by the investigator, were investigated. The compound has two pairs of Cu^<2+> cations on the two sides of the [V_<10>O_<28>]^<6-> core, which are separated by 2.89 Å and 3.37 Å, respectively. The unpaired electrons of these pairs were not coupled and each Cu^<2+> atom works as an independent spin center. Second, double salts of [V_<10>O_<28>]^<6-> with Cu^<2+> and NH_4^+, K^+ or Rb^+ were synthesized and their crystal structures were determined. In these crystals, a water molecule coordinating to the cation supports a hydrogen atom on the [V_<10>O_<28>]^<6-> core via hydrogen bond and stabilizes a monoprotonated species, [HV … More _<10>_O<28>]^<5->. In these crystals, the precise location of the protons on the monoprotonated decavanadate anion was first determined unambiguously. Also, the structure determination of [SiW_<11>O_<39>]^<8-> crystallized with Na^+ and guanidinium cations revealed that the compound exhibits a novel screw structure of [SiW_<11>O_<39>]^<8-> linked by Na^+ cation, although transition metals were not incorporated into the compound. Its structure indicated a possibility that it would show non-linear optical properties and thus pulsed laser light with the wavelength of 800 nm was irradiated, resulting in the observation of second harmonic generation. In parallel with these studies, the investigator has installed and upgraded diffractometers at two synchrotron facilities : SPring-8 and Photon Factory of High Energy Accelerator Research Organization. These efforts have profited the precise structure analyses of abovementioned NLO active silicotungstate crystals as well as the structural elucidation of the molecular growth and intermolecular condensation of mixed valence molybdenum giant clusters with nanometer sized ring shape. Less