Retrospect of Se and Te Chemistry

Retrospect of organoselenium and tellurium chemistry for these 30 years is described focusing on our novel findings in this field: (1) telluroxide elimination leading to alkenes and allylic compounds, (2) Pd-catalyzed or –mediated carbodetelluration for a new C–C bond formation, (3) synthesis of chiral diferrocenyl dichalcogenides and their use as chiral auxiliaries, (4) asymmetric selenoxide elimination for making optically active allenes and alkenes, (5) meta chloroperbenzoic acid (MCPBA) oxidation of organic selenides and tellurides leading to a substitution of a PhSe or PhTe moiety, as well as (6) preparation of chalcogen-bridged diruthenium complexes and their catalytic use for propargylic substitution reactions.     

The First Heteropentanuclear Extended Metal‐Atom Chain: [Ni+Ru25+Ni2+Ni2+(tripyridyldiamido)4(NCS)2]

This study develops the first heteropentametal extended metal atom chain (EMAC) in which a string of nickel cores is incorporated with a diruthenium unit to tune the molecular properties. Spectroscopic, crystallographic, and magnetic characterizations show the formation of a fully delocalized Ru₂⁵⁺ unit. This [Ru₂]‐containing EMAC exhibits single‐molecule conductance four‐fold superior to that of the pentanickel complex and results in features of negative differential resistance (NDR), which are unobserved in analogues of pentanickel and pentaruthenium EMACs. A plausible mechanism for the NDR behavior is proposed for this diruthenium‐modulated EMAC.     

Enantioselectivity in Ruthenium-Catalyzed Propargylic Substitution Reactions of Propargylic Alcohols with Acetone: A DFT Study

The enantioselectivity in the propargylic substitution reactions of propargylic alcohols with acetone catalyzed by optically active thiolate-bridged diruthenium complexes was examined via ωB97X-D level DFT calculations. Some structures with intramolecular dispersion interactions between ligands were found for the ruthenium-allenylidene complex, which is the key intermediate in the catalytic reaction, and it was determined that the structure corresponding to the X-ray crystal structure, which had provided the transition state model for the enantioselectivity in previous studies, was not the most stable among the obtained structures. Then, a variety of transition-state structures for the nucleophilic attack of prop-1-ene-2-ol, which is the enol isomer of acetone, on the γ-carbon of the ruthenium-allenylidene complex were explored. Among the transition-state structures with lower energies, the number of structures leading to the major (R) product was found to be larger than that of structures leading to the minor (S) product, providing enantioselectivity in terms of probability distributions. The introduction of a phenyl group in the thiolate ligand was suggested to increase the selectivity. Thus, we propose the novel transition state model for the asymmetric catalytic reaction system.     

C-C bond formation at polynuclear metal centers

Studies on C-C bond formation between simple hydrocarbon species such as CH₂, C=CH₂, CH=CH₂, CH₂=CH₂, CH₂=C=CH₂ and CHCH at a diruthenium center suggest that the process is promoted when the dimetal center can readily compensate for the two electrons lost in the formation of the new C-C bond. Thus, whereas -CH₂ and ethene combine only under forcing conditions, the combination of -CH₂ with allene or ethyne, which have additional -electrons available for coordination, occurs readily at room temperature. Likewise, the availability of uncoordinated -electrons in -C=CH₂ allows vinylidene to link rapidly with ethene at room temperature. Alkyne complexes [Ru₂(CO)(-RCCR)(-C₅H₅)₂] (R=CF₃ or Ph) react only under vigorous conditions with additional alkyne to give [Ru₂(CO)(-C₄R₄) (-C₅H₅)₂], but give these same species at room temperature in the presence of acid, shown to be due to the intermediacy of highly reactive 30-electron -vinyl cations. Thermally, alkyne linking proceedsvia three-alkyne species [Ru₂(-C₆R₆)(-C₅H₅)₂] to a four-alkyne complex [Ru₂(-C₈R₈)(-C₅H₅)₂], containing an unprecedented C₈ ligand composed of a C₆ ring with a C₂ tail. Treatment of [Ru₂(CO)(-RCCR)(-C₅H₅)₂] with unsaturated metal fragments gives trimetal complexes such as [Ru₃(CO)₅(₃-CF₃CCCF₃) (-C₅H₅)₂]. The MeCN derivative of this species undergoes unusual linking processes on reaction with additional alkyne to giveinter alia [Ru₃(CO)₃(₃-CCF₃){₃-C₃(CF₃)₃}(-C₅H₅)₂], arising from alkyne cleavage, and [Ru₃(CO)₃{₃-C₄(CF₃)₂(CO₂Me)₂}(-C₅H₅)₂], a closo-pentagonal bipyramidal Ru₃C₄ cluster.     

双核钌-DMBA双芳香炔化合物的合成和电化学性质

在弱碱性条件下,双核钌（Ⅲ）配合物Ru₂（DMBA）₄（NO₃）₂（DMBA=tetrakis-N,N''-dimethylbenzamidinate）与不同芳香炔反应（其中芳香基团包括：NAP^me,N-甲基-1,8-萘二甲酰亚胺;NAP^iso,N-异丙基-1,8-萘二甲酰亚胺;Naphth,萘;Ant,蒽）,制备了相应的端基炔取代配合物trans-Ru₂（DMBA）₄（C₂Ar）₂（Ar=NAP^me,1;NAP^iso,2;Naphth,3;Ant,4）。利用X射线晶体衍射测定了它们的结构。所有化合物的Ru-Ru 键长处于单键范围（0.245 0~0.249 1 nm）,它们均是抗磁性物质。进一步通过¹H NMR和UV-Vis-NIR光谱进行了表征。电化学研究表明,所有化合物显示出与芳香基团有关的2个可逆的单电子氧化还原过程（包括一个氧化过程和一个还原过程）。     

双核钌-DMBA双芳香炔化合物的合成和电化学性质

在弱碱性条件下,双核钌(III)配合物Ru₂（DMBA）₄（NO₃）₂（DMBA=tetrakis-N,N''-dimethylbenzamidinate）与不同芳香炔反应（其中芳香基团包括：NAP^me,N-甲基-1,8-萘二甲酰亚胺;NAP^iso,N-异丙基-1,8-萘二甲酰亚胺;Naphth,萘;Ant,蒽）,制备了相应的端基炔取代配合物trans-Ru₂（DMBA）₄（C₂Ar）₂（Ar=NAP^me,1;NAP^iso,2;Naphth,3;Ant,4）。利用X射线晶体衍射测定了它们的结构。所有化合物的Ru-Ru键长处于单键范围（0.2450~0.2491 nm）,它们均是抗磁性物质。进一步通过¹H NMR和UV-Vis-NIR光谱进行了表征。电化学研究表明,所有化合物显示出与芳香基团有关的2个可逆的单电子氧化还原过程（包括一个氧化过程和一个还原过程）。