共查询到20条相似文献,搜索用时 12 毫秒
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Glaser T Heidemeier M Strautmann JB Bögge H Stammler A Krickemeyer E Huenerbein R Grimme S Bothe E Bill E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(33):9191-9206
A series of trinuclear Cu(II) complexes with the tris(tetradentate) triplesalen ligands H(6)talen, H(6)talen(tBu(2) ), and H(6)talen(NO(2) ), namely [(talen)Cu(II) (3)] (1), [(talen(tBu(2) ))Cu(II) (3)] (2), and [(talen(NO(2) ))Cu(II) (3)] (3), were synthesized and their molecular and electronic structures determined. These triplesalen ligands provide three salen-like coordination environments bridged in a meta-phenylene arrangement by a phloroglucinol backbone. The structure of [(talen)Cu(II) (3)] (1) was communicated recently. The structure of the tert-butyl derivative [(talen(tBu(2) ))Cu(II) (3)] (2) was established in three different solvates. The molecular structures of these trinuclear complexes show notable differences, the most important of which is the degree of ligand folding around the central Cu(II)-phenolate bonds. This folding is symmetric with regard to the central phloroglucinol backbone in two structures, where it gives rise to bowl-shaped overall geometries. For one solvate two trinuclear triplesalen complexes form a supramolecular disk-like arrangement, hosting two dichloromethane molecules like two pearls in an oyster. The FTIR spectra of these complexes indicate the higher effective nuclear charge of Cu(II) in comparison to the trinuclear Ni(II) complexes by the lower C--O and higher C=N stretching frequencies. The UV/Vis/NIR spectra of 1-3 reflect the stronger ligand folding in the tert-butyl complex 2 by an intense phenolate-to-Cu(II) LMCT. This absorption is absent in 1 and is obscured by the nitro chromophore in 3. The more planar molecular structures cause orthogonality of the Cu(II) d(x(2)-y(2) ) orbital and the phenolate O p(z) orbital, which leads to small LMCT dipole strengths. Whereas 1 and 3 exhibit only irreversible oxidations, 2 exhibits a reversible one-electron oxidation at +0.26 V, a reversible two-electron oxidation at +0.59 V, and a reversible one-electron oxidation at +0.81 V versus Fc(+)/Fc. The one-electron oxidized form 2(+) is strongly stabilized with respect to reference mononuclear salen-like Cu complexes. Chemical one-electron oxidation of 2 to 2(+) allows the determination of its UV/Vis/NIR spectrum, which indicates a ligand-centered oxidation that can be assigned to the central phloroglucinol unit by analogy with the trinuclear Ni triplesalen series. Delocalization of this oxidation over three Cu(II)-phenolate subunits causes the observed energetic stabilization of 2(+). Temperature-dependent magnetic susceptibility measurements reveal ferromagnetic couplings for all three trinuclear Cu(II) triplesalen complexes. The trend of the coupling constants can be rationalized by two opposing effects: 1) electron-withdrawing terminal substituents stabilize the central Cu(II)-phenolate bond, which results in a stronger coupling, and 2) ligand folding around the central Cu(II)-phenolate bond opens a bonding pathway between the magnetic Cu(II) d(x(2)-y(2) ) orbital and the phenolate O p(z) orbital, which results in a stronger coupling. Density functional calculations indicate that both spin-polarization and spin-delocalization are operative and that slight geometric variations alter their relative magnitudes. 相似文献
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Cover Picture: Combining Topological and Steric Constraints for the Preparation of Heteroleptic Copper(I) Complexes (Chem. Eur. J. 38/2014) 下载免费PDF全文
Dr. Meera Mohankumar Dr. Filippo Monti Dr. Michel Holler Dr. Frédéric Niess Dr. Béatrice Delavaux‐Nicot Dr. Nicola Armaroli Dr. Jean‐Pierre Sauvage Dr. Jean‐François Nierengarten 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(38):11957-11957
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Cover Picture: Coordination Chemistry of N‐Heterocyclic Nitrenium‐Based Ligands (Chem. Eur. J. 19/2015) 下载免费PDF全文
Dr. Yuri Tulchinsky Dr. Sebastian Kozuch Dr. Prasenjit Saha Assaf Mauda Dr. Gennady Nisnevich Dr. Mark Botoshansky Dr. Linda J. W. Shimon Prof. Mark Gandelman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):6965-6965
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Dr. Emilio Pardo Jesús Ferrando‐Soria Dr. Marie‐Claire Dul Dr. Rodrigue Lescouëzec Dr. Yves Journaux Dr. Rafael Ruiz‐García Dr. Joan Cano Prof. Dr. Miguel Julve Prof. Dr. Francesc Lloret Dr. Laura Cañadillas‐Delgado Dr. Jorge Pasán Prof. Dr. Catalina Ruiz‐Pérez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(43):12762-12762
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Cover Picture: Peptoid‐Ligated Pentadecanuclear Yttrium and Dysprosium Hydroxy Clusters (Chem. Eur. J. 7/2015) 下载免费PDF全文
Dr. Dominique T. Thielemann Anna T. Wagner Dr. Yanhua Lan Dr. Pascual Oña‐Burgos Prof. Dr. Ignacio Fernández Prof. Dr. Esther S. Rösch Dr. Dominik K. Kölmel Prof. Dr. Annie K. Powell Prof. Dr. Stefan Bräse Prof. Dr. Peter W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2709-2709
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Conformational Tuning of the Intramolecular Electronic Coupling in Molecular‐Wire Biruthenium Complexes Bridged by Biphenyl Derivatives 下载免费PDF全文
Dan‐Dan Kong Lu‐Sha Xue Rui Jang Dr. Bin Liu Dr. Xiang‐Gao Meng Prof. Dr. Shan Jin Ya‐Ping Ou Xiao Hao Prof. Dr. Sheng‐Hua Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9895-9904
The synthesis and characterization of a series of biphenyl‐derived binuclear ruthenium complexes with terminal {RuCl(CO)(PMe3)3} moieties and different structural arrangements of the phenyl rings are reported. Electrochemical studies revealed that the two metal centers of the binuclear ruthenium complexes interact with each other through the biphenyl bridge, and the redox splittings ΔE1/2 show a strong linear correlation with cos2 ?, where ? is the torsion angle between the two phenyl rings. A combination of electrochemical, UV/Vis/NIR, and in situ IR differential spectroelectrochemical analysis clearly showed that: 1) the intramolecular electronic couplings in the binuclear ruthenium complexes could be modulated by changing ?; 2) the electronic ground state of the mixed‐valent cations changes from delocalized to localized through the biphenyl bridge with increasing torsion angle ?, that is, the redox processes of these complexes change from significant involvement of the bridging ligand to an oxidation behavior with less participation of the bridge. 相似文献
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Da‐Yu Wu Osamu Sato Yasuaki Einaga Chun‐Ying Duan 《Angewandte Chemie (International ed. in English)》2009,48(8):1337-1337
A spin‐crossover cluster with the {FeII4O4} core structure is presented by D. Y. Wu, O. Sato et al. in their Communication on page 1475 ff. The cluster is synthesized by self‐assembly and shows an abrupt spin transition, giving two high‐spin and two low‐spin states. It exhibits complete light‐induced excited spin‐state trapping effects. Importantly, synergy effects between the magnetic interaction and spin transition operate in the cluster.