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81.
Istvan Bakk Dietrich Gudat Stefan Hp Martin Nieger Lszl Nyulaszi Lszl Szarvas 《无机化学与普通化学杂志》2005,631(1):47-54
Reactions of the phosphonio‐benzophospholide π‐complexes 3a, b[Cr] with [M(CO)5(olefin)] or of the σ‐complexes 2a, b[M] (M = Cr, Mo, W) with [M(CO)3(aren)] lead to the first binuclear complexes 4a, b[CrM] featuring phosphonoio‐benzophospholides as μ‐bridging 8e‐donor ligands to two group 6 metal atoms. The constitution of the products was determined by spectroscopic and X‐ray diffraction studies. Mixed complexes with both group 6 and 7 metals were not accessible. Mechanistic studies showed that the reactions follow a complicated mechanism whose single steps may involve transfer of either M(CO)n fragments or single CO ligands between complexes; the latter are associated with a σ/π‐coordination isomerization of the benzophospholide unit. Competition between both reaction channels can lead to the formation of product mixtures whose composition is controlled by the relative thermodynamic stabilities of the products. Computational studies suggest that in the more stable isomer of heterobimetallic complexes 4a, b[MM′] end‐on coordination to the heavier and side‐on coordination to the lighter metal atom is preferred. 相似文献
82.
Energy transfer in solution of lanthanide complexes 总被引:1,自引:0,他引:1
S. Lis M. Elbanowski B. M
kowska Z. Hnatejko 《Journal of photochemistry and photobiology. A, Chemistry》2002,150(1-3):233-247
The lanthanides with their well-defined energy levels provide an excellent basis to study different Ln(III)-specific energy transfer processes in a variety of chemical environments. The studies concerning intramolecular and intermolecular energy transfer processes with participation of Ln(III) ions and a variety of ligand groups in solution are reviewed. Phenomena of energy transfer from ligands to Ln(III) ions, resulting consequently in a great enhancement of the Ln(III) ion luminescence (ligand sensitized luminescence), as well as from Ln(III) to other species and between Ln(III) ions are presented. 相似文献
83.
84.
Griffiths PC Fallis IA Willock DJ Paul A Barrie CL Griffiths PM Williams GM King SM Heenan RK Görgl R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(8):2022-2028
The morphology of micelles formed by two novel metallosurfactants has been studied by small-angle neutron scattering (SANS) and small-angle-X-ray scattering (SAXS). The two surfactants both contain a dodecyl chain as the hydrophobic moiety, but differ in the structure of the head group. The surfactants are Cu(II) complexes of monopendant alcohol derivatives of a) the face-capping macrocycle 1,4,7-triazacyclanonane (tacn), and b) an analogue based upon the tetraazamacrocycle 1,4,7,10-tetraazacyclododecane. Here, neutron scattering has been used to study the overall size and shape of the surfactant micelles, in conjunction with X-ray scattering to locate the metal ions. For the 1,4,7,10-tetraazacyclododecane-based surfactant, oblate micelles are observed, which are smaller to the prolate micelles formed by the 1,4,7-triazacyclononane analogue. The X-ray scattering analysis shows that the metal ions are distributed throughout the polar head-group region, rather than at a well-defined radius; this is in good agreement with the SANS-derived dimensions of the micelle. Indeed, the same model for micelle morphology can be used to fit both the SANS and SAXS data. 相似文献
85.
Qiang Xu Prof. Dr. Nobuko Tsumori Prof. Dr. Ling Jiang Masanobu Kondo Ryuichi Arakawa Prof. Dr. 《化学:亚洲杂志》2007,2(5):599-608
Carbonyldinitrosyltris(fluorosulfato)tungstate(II) and ‐molybdate‐(II) anions, [fac‐M(CO)(NO)2(SO3F)3]? (M=W, Mo), which are novel weakly coordinating anions that contain a metal carbonyl/nitrosyl moiety, have been generated in fluorosulfonic acid and completely characterized by multinuclear NMR, IR, and Raman spectroscopy as well as ESI mass spectrometry. ESI MS measurements performed for the first time on a superacidic solution system unambiguously reveal the formation of the monoanionic, mononuclear W and Mo complexes formulated as [M(CO)(NO)2(SO3F)3]? (M=W, Mo). Multinuclear NMR spectroscopic studies at natural abundance and 13C and 15N enrichment clearly indicate the presence of one CO ligand, two equivalent NO ligands, and two types of nonequivalent SO3F? groups in a 2:1 ratio. The IR and Raman spectra reveal that the two equivalent NO ligands have a cis conformation, thus indicating a fac structure. Density functional calculations at the B3LYP level of theory predict that these anions have a singlet ground state (1A′) with a Cs symmetry along with C–O and N–O vibrational frequencies that are in agreement with the experimental observations. Mulliken population analysis shows that the monovalent negative charge is dispersed on the bulky sphere, the surface of which is covered by all the negatively charged O and F atoms with charge densities much lower than SO3F?, suggesting that [fac‐M(CO)(NO)2(SO3F)3]? (M=W, Mo) are weakly nucleophilic and poorly coordinating anions. 相似文献
86.
New copper(II) complexes of the hydrazone ligands H2salhyhb, H2salhyhp, and H2salhyhh, derived from salicylaldehyde and ω‐hydroxy carbonic acid hydrazides, have been synthesized and physically characterized. Two fundamental structures were found in solid state depending on the pH‐value of the reaction solution. Acidic conditions lead to the formation of the di‐μ‐phenoxo‐bridged dicationic complex dimers [{Cu(Hsalhyhb)}2]2+ ( 1a ), [{Cu(Hsalhyhp)}2]2+ ( 2a ), and [{Cu(Hsalhyhh)}2]2+ ( 3a ), isolated as perchlorate salts. The dimeric complexes show strong antiferromagnetic coupling with J = ?399 ( 1a ), ?410 ( 2a ), and ?311 cm?1 ( 3a ). Higher pH‐values resulted in the aggregation of neutral copper ligand fragments to the one‐dimensional coordination polymers [{Cu(salhyhb)}n] ( 1b ), [{Cu(salhyhp)}n] ( 2b ), and [{Cu(salhyhh)}n] ( 3b ). 3b has been examined by means of X‐ray crystallography and represents the first example of a structurally characterized neutral copper(II) N‐salicylidenehydrazide complex without additional ligands. The magnetic interactions in the polymers are also antiferromagnetic with J = ?125 ( 1b ), ?136 ( 2b ), and ?148 cm?1 ( 3b ), but strongly reduced compared to the corresponding dimeric complexes. The two basic structure types can be reversibly interconverted simply by pH‐control. 相似文献
87.
Woods M Zhang S Ebron VH Sherry AD 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(19):4634-4640
The lanthanide(III) complexes of three tetraamide DOTA bearing pyridyl, phenolic and hydroxypyridyl substituents have been studied by NMR, luminescence and cyclic voltammetry. The relaxivity profiles of the gadolinium complexes of the pyridyl and phenolic ligands were flat and essentially the same between pH 2 and 8. The hydroxypyridyl ligand, however, exhibited two regions of enhanced relaxivity. The small relaxivity enhancement (25 %) at lower pH (pH 2-4) has been attributed to an increase in the prototropic exchange of the coordinated water molecule while the slightly larger enhancement (84 %) at higher pH (pH 6-9) reflects deprotonation of the ligand amide protons. Deprotonation of the amides results in the formation of an intramolecular acid-base pair interaction with the phenolic protons and this, in turn, causes a highly organized second hydration sphere to come into effect, thereby increasing the relaxivity. The water relaxivity of the Gd(3+)-hydroxypyridyl complex is further enhanced upon binding to serum albumin. 相似文献
88.
The oxidative electrochemistry of 11 chiral bis-phosphinoferrocene ligands, all within the Josiphos class of ligands, was examined in methylene chloride. The oxidation of these ligands displays multiple waves of varying chemical reversibility. Palladium(II) and platinum(II) complexes with the general formula [MCl2(P-P)] (M = Pd or Pt; P-P = Josiphos) were prepared, characterized by NMR and cyclic voltammetry. The electrochemistry simplifies greatly upon coordination of the Josiphos ligands. The X-ray structures of a palladium(II) and platinum(II) complex of the same Josiphos ligand are reported. 相似文献
89.
Complexes of Vanadium and Titanium with Salicylaldehyde benzoylhydrazone and 2-(2′-Hydroxyphenyl)-8-quinolinol. Crystal Structure of μ-Oxo-bis[oxo{2-(2′-hydroxyphenyl)-8-quinolinato(2-)}-vanadium(V)] . By reaction of titanium(IV)-isopropoxide and bis(acetylacetonato)-oxovanadium(IV) with salicylaldehyde benzoylhydrazone and 2-(2′hydroxyphenyl)-8-quinolinol, respectively, the metal complexes of the tridentate diacidic ligands were synthesized and characterized mass spectrometrically. The mass spectra of the titanium compounds correspond to the expected bisligand complexes whereas several species are demonstrable in the case of vanadium. Crystals of μ-oxo-bis[oxo{2-(2′-hydroxyphenyl)-8-quinolinolato(2-)}-vanadium(V)] were isolated and characterized by X-ray structural analysis. The complex exhibits C2 symmetry, accordingly the μ2-oxygen atom is situated on the 4 axis. The VOV bridge is angular with the unusually small bond angle of 107.3°. The coordination polyhedron is distorted octahedral. The compound additionally contains one molecule of chloroform per formula unit which is disordered in two positions. Crystallographic data see “Inhaltsübersicht”. 相似文献
90.
The reactions of CpRu(dppf)Cl (1) with the sulfur-containing ligands, thiophenol HSPh, 2-mercaptopyridine C5H4N(SH), thiourea SC(NH2)2, vinylene trithiocarbonate SCS(CH)2S and ethylene trithiocarbonate SCS(CH2)2S, yielded chloro-substituted derivatives, viz. the mono-ruthenium(II) complexes CpRu(dppf)(SPh) (2), [CpRu(dppf)(SC5H4NH)]BPh4 (3)BPh4, [CpRu(dppf)(SC(NH2)2]PF6 (4)PF6, [CpRu(dppf)(SCS(CH)2S)]Cl (5)Cl and [CpRu(dppf)(SCS(CH2)2S)]Cl (6)Cl, respectively. Treatment of 1 with AuCl(SMe2) in the presence of NH4PF6 gave [(CpRu(dppf)(SMe2)]PF6 (7)PF6. The reaction of 1 or 6 with SnCl2 resulted in cleavage of chloro and dithiocarbonate ligands, respectively, to give CpRu(dppf)SnCl3 (8). All complexes were spectroscopically characterized and the structures of 2 and cationic complexes 4-7 were determined by single-crystal diffraction analyses. 相似文献