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Theoretical Study on the Structures and Magnetic Properties of metal string complexes Containing Rigid Equatorial Ligands [Ni3(L)4(NCS)2] (L = dzp-, mpmpa-, mppda-, mptpa-)

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Chinese Journal of Structural Chemistry 2017年第7期36卷 1077-1085页

作者：班颖陈蓉李波许旋徐志广 School of Chemistry & Environment South China Normal University Guangzhou 510006 China Key Laboratory of Materialsfor Energy Conversion and Storage of Guangzhou Guangzhou 510006 China Key Laboratory of Theoretical Chemistry of Environment Ministry of Education Guangzhou 510006 China

Density functional theory at the BP86 level was used to investigate the influence of equatorial ligands on the Ni–Ni interactions and magnetic coupling properties of metal string complexes [Ni3（L）4（NCS）2] （L represents the rigid equatorial ligands; L = dzp- （1）, mpmpa- （2）, mppda- （3）, mptpa- （4））. The following conclusions can be drawn. （1） With increasing the radius of the connecting atom in the cental ring in equatorial ligands, the two pyridine rings bend down, resulting in the decreasing distance between the two pyridine-nitrogen atoms and the Ni–Ni distance. Therefore, the strength order of the Ni–Ni interaction is 4 〉 2 〉 3 〉 1. The Ni–Ni interactions in 2 and 4 are stronger than those in Ni3（dpa）4（NCS）2 containing no-rigid equatorial ligands. （2） The calculated -Jab is 4 〉 2 〉 3 〉 1. There are two types of magnetic exchange pathways in these complexes： the σ-type pathway through the Ni36＋ chains and the δ-type pathway through the equatorial ligands. The magnetic coupling through the metals is the dominant part. Hence, the magnetic coupling strength increases with increasing the Ni–Ni interaction. Modifying the radius of the connecting atom may be one of the means to fine tuning of magnetic coupling strength of this kind of metal string complexes.

关键词： metal string complex rigid equatorial ligands density functional theory magnetic coupling constant

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FROM metal string complexES TO metal WIRES

FROM METAL STRING COMPLEXES TO METAL WIRES

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第五届尖端科学研讨会

作者： Shie-Ming Peng Department of Chemistry National Taiwan UniversityTaipeiTaiwan

＜正＞ Owing to their fascinating bonding nature, the metal-metal （M-M） multiple bonds in dinuclear metal complexes have been an interesting and vital research topic. During the past decade, our seminal and systematic approaches on the all-syn oligo-（a-pyridyl）amido ligands coordinated metal ions have successfully opened up a new chapter, extending this territory from dinuclear to linear oligonuclear metal complexes. Their unique features in structures and bonding characterization have been thoroughly investigated, which, according to the M-M bonding strength, can be classified into two categories, namely the oligonickel（Ⅱ） complexes lacking an M-M bond and the oligochromium（Ⅱ） complexes with a strong M-M bonding formation. Depending on the specificity and number of metal ions, structures and magnetic behaviors of the corresponding metal complexes are systematically analyzed. Their potential application as a molecular metal wire is conveyed on the basis of the band structures calculated from hypothetical one-dimensional metal strings. Moreover, self-assembled monolayers of n-alkanethiols are employed as a two-dimensional matrix to isolate the metal string complexes, of which the scanning tunneling microscopy （STM） image exhibits remarkable protrusion characteristics. For tricobalt and trichromium complexes, the topographic STM images reveal that the protruding features are, respectively, 0.3 nm and 0.6 nm higher than that of the trinickel complexes. The trend of increasing conductivity correlates well with their associated bond orders, and is also in consistence with qualitative EHMO approaches.

关键词： metal string complex Molecular metalwire STM Spectroscopy

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A Defective Linear Pentachromium complex for the Enhanced Catalysis of the Cycloaddition of CO2 with Propylene Oxide

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Chinese Journal of Structural Chemistry 2018年第8期37卷 1305-1312页

作者：王文珍蔺伟李磊磊刘双拉亚特伊斯梅洛夫李锦祥彭旭明 School of Chemistry and Chemical Engineering Xi'an Shiyou University Institute of Chemical Problems of Azerbaijian Academy of Sciences Department of Chemistry National Taiwan University

Based on the ligand（2,7-bis（α-pyrimidylamino）-1,8-naphthyridine（H2 bpmany））, a linear pentachromium complex [Cr5（μ5-bpmany）4Cl2]PF6（1, μ5-bpmany = 2,7-bis（a-pyrimidylamino）-1,8-naphthyridine） was synthesized. The crystal structure of compound 1 has been characterized by X-ray crystallography. Interestingly, one metal atom in the center is missing in this linear chain, leading to the defective pentachromium metal string structure which is similar with the reported complex [Cr5（μ5-dpznda）4Cl2]（2, dpznda = N^2,N^7-di（pyrazin-2-yl）-1,8-naphthyridine-2,7-diamine）. The central Cr（Ⅲ） ion of 1 is eight-coordinated and is also rare in the chromium complex. The reaction of carbon dioxide with propylene oxide that generates propylene carbonate（PC） when catalyzed by [Cr5（μ5-bpmany）4Cl2]PF6 was investigated. Different reaction conditions including temperature and pressure were studied to optimize the reaction conditions.

关键词： metal string complex pentachromium(Ⅲ) complex extended metal atomic chain

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