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

多核过渡金属络合物中的金属-金属相互作用主要由中心金属离子的性质、氧化态和几何构型决定。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，因此有可能分离出混价化合物，因此多核过渡金属络合物的氧化还原性质引起了人们的广泛关注。为了研究具有金属-金属相互作用的分子对磁场、电势、辐射激发或热等外界刺激的响应，我们合成了吡唑类化合物和吡啶硫醇多核配合物，并研究了它们的性质。主要研究结果如下：(1)以具有分子内氢键的前驱体[Pd_2(μ-rpz)_2(Rpz)_2(Rpzh)_2](R=3-叔丁基)为原料，合成了Pd_2m‘_2型四核配合物(M’=Ag，Au)。HT-[Pd_2(μ-3-t-Bupz)_2(3-t-Bupz)_2(3-tBupz…)]反应的详细研究[More H)_2]通过启用Ag^I离子和Au^I络合物来分离四核络合物的两个键合异构体，即头到头异构体(HH异构体)和头到尾异构体(HT异构体)。(2)要合成环状铂三聚体中的铂-铂键，最合适的络合物可能是吡唑桥联的三核铂(II)配合物[Pt3(μ-Pz)6](PZ=吡唑啉)。为了回答环状铂三聚体中是否能形成直接的铂-铂键的问题，我们进行了[Pt_3(μ-PZ)_6]的氧化反应，首次成功地分离和表征了被氧化的双电子物种[PT_3Br2(μ-PZ)_6]，并对其电子光谱进行了指认。有趣的是，被氧化的物种在溶液中表现出“价脱陷阱”行为。我们的结论是，在溶液状态下，通过溶剂DMF分子靠近溴配位的铂中心，或者在过量的溴阴离子存在的情况下，溴^-靠近非配位的铂原子，价脱陷态发生。(3)虽然到目前为止已经合成了几种ESBO-Re(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-Re(IV)配合物，该配合物具有随温度变化的磁性，表明存在^3(δδ^*)激发的三重态。较少

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