Studies on Unusual Properties and New Functions Occurred by the Interaction among Heavy Transition Metal Atoms

多核过渡金属配合物中的金属-金属相互作用主要受中心金属离子的性质、氧化态和几何形状的影响。由于金属-金属相互作用的程度可以通过金属离子氧化态的变化来控制，从而有可能分离出混合价化合物，因此多核过渡金属配合物的氧化还原性能受到了广泛的关注。为了研究具有金属-金属相互作用的分子对外界刺激（如磁场、电势、辐射或热激发）的响应，我们合成了吡唑酸酯和吡啶硫醇的多核配合物，并研究了它们的性质。以下是我们研究结果的摘要。(1)具有分子内氢键的前驱体[Pd_2(μ-Rpz)_2(Rpz)_2(Rpz)_2(Rpzh)_2] （R=3-t-丁基）得到了Pd_2M'_2型的四核配合物（M' = Ag, Au）。详细研究了HT-[Pd_2(μ-3-t-Bupz)_2(3-t-Bupz)_2(3-t-Bupz)_2(3-tBupz…More H)_2]与Ag^I离子和Au^I配合物的反应，分离出了四核配合物的两种连锁异构体，头对头异构体（HH异构体）和头对尾异构体（HT异构体）。由于在高温下观察到键同分异构体容易发生立体化学重排，因此随后进行了^1H核磁共振波谱分析。(2)在环铂三聚体中合成Pt-Pt键，最合适的配合物可能是吡唑啉桥接的三核铂（II）配合物[Pt_3(μ-pz)_6] （pz =吡唑酸酯）。为了回答环铂三聚体中是否能形成Pt-Pt直接键的问题，我们对[Pt_3(μ-pz)_6]进行了氧化，首次成功地分离和表征了双电子氧化产物[Pt_3Br_2(μ-pz)_6]，并对它们的电子能谱进行了分配。非常有趣的是，氧化产物在溶液中表现出“脱价”行为。我们得出结论，在溶液状态下，通过溶剂DMF分子与Br配位Pt中心的结合或Br^-在过量Br^-阴离子存在下与非配位Pt原子的结合方式发生价脱扣。(3)虽然目前已经合成了几种ESBO铼（IV）配合物，但它们都是抗磁性的。我们成功地合成了吡啶-2-硫酸盐的ESBO铼（IV）配合物，该配合物表现出温度依赖的磁性能，表明存在^3（δδ^*）激发态。少

The metal-metal interaction in polynuclear transition metal complex is mainly governed by the nature, oxidation state and geometry of the central metal ion. Because the extent of metal-metal interaction can be controlled by the change of oxidation state of metal ions and therefore there is possibility to isolate mixed-valent compounds, the redox properties of polynuclear transition metal complexes have attracted much attention. In order to study the response of molecules with metal-metal interactions towards external stimuli such as magnetic field, electric potential, excitation by radiation, or heat, we have synthesized polynuclear complexes of pyrazolates and pyridinethiols, and studied their properties. Followings are the summary of our results.(1) The precursor with intramolecular hydrogen bonding, [Pd_2(μ-Rpz)_2(Rpz)_2(Rpzh)_2] (R=3-t-butyl), gave tetranuclear complexes of Pd_2M'_2 type (M' = Ag, Au). The detailed study on the reaction of HT-[Pd_2(μ-3-t-Bupz)_2(3-t-Bupz)_2(3-tBupz … More H)_2] with Ag^I ion and Au^I complex enabled is to isolate two linkage isomers of tetranuclear complexes, head-to-head isomer (HH isomer) and head-to-tail isomer (HT isomer). Because a facile stereochemical rearrangement of the linkage isomers was observed at elevated temperature, it was followed by ^1H NMR spectroscopy.(2) To synthesize Pt-Pt bonds in cyclic platinum trimer, the best-fit complex is probably the pyrazolato-bridged trinuclear platinum(II) complex, [Pt_3(μ-pz)_6] (pz = pyrazolate). In order to give an answer to the question whether direct Pt-Pt bond can be formed in the cyclic platinum trimer or not, we have conducted the oxidation of [Pt_3(μ-pz)_6] and succeeded, for the first time, the isolation and characterization of the two-electron oxidized species, [Pt_3Br_2(μ-Pz)_6], as well as the assignment of the electronic spectra of them. Very interestingly, the oxidized species show "valence-detrapping" behavior in solution. We concluded that the valence-detrapping occurs in the solution state in associative manner via either approach of solvent DMF molecule to the Br-coordinated Pt center or approach of Br^- to the uncoordinated Pt atom in the presence of excess Br^- anion.(3) Although several ESBO rhenium(IV) complexes have been synthesized so far, they are all diamagnetic. We have succeeded in the synthesis of an ESBO rhenium(IV) complex of pyridine-2-thiolate, which exhibits temperature-dependent magnetic properties showing the existence of ^3(δδ^*) excited triplet state. Less