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91.
Rojo I Teixidor F Viñas C Kivekäs R Sillanpää R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(21):5376-5385
The anionic chelating ligand [1,1'-(PPh2)2-3,3'-Co(1,2-C2B9H10)2]- has been synthesized from [3,3'-Co(1,2-C2B9H11)2]- in very good yield in a one-pot process with an easy work-up procedure. The coordinating ability of this ligand has been studied with Group 11 metal ions (Ag, Au) and with transition-metal ions (Pd, Rh). The two dicarbollide halves of the [1,1'-(PPh2)2-3,3'-Co(1,2-C2B9H10)2]- ligand can swing about one axis in a manner analogous to the constituent parts of BINAP and ferrocenyl phosphine derivatives. All these ligands function as hinges, with the most important property in relation to the coordination requirements of the metal being the PP distance. [1,1'-(PPh2)2-3,3'-Co(1,2-C2B9H10)2]-, BINAP, ferrocenyl phosphine derivatives, and other hinge ligands present a range of different PP separations, and consequently different coordination spheres and dispositions around metal cations. To account for these differences, the equation Dphi2 = D02 + 4 R2cos2(90-phi/2) has been developed. It relates the PP distance (Dphi) in a complex with the minimum PP distance (D0) that is characteristic of the hinge-type ligand. 相似文献
92.
Baxter PN 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(11):2531-2541
The new twistophane 4 has been synthesised, which comprises a conjugated dehydropyridoannulene-type macrocyclic scaffold with outwardly projecting nitrogen-donor sites for the purpose of metal ion coordination. The macrocyclíc structure of 4 was assigned by using spectroscopic methods, and shown to exist in a twisted and chiral ground state conformation by semi-empirical theoretical calculations. A detailed spectroscopic investigation into the metal ion binding properties of 4 and precursor 11 revealed that they functioned as selective complexants, affording a fluorescence quenching output response characteristic of Pd(II) and Hg(II) ions. Furthermore, 4 also signalled the presence of Fe(II), Co(II), Ni(II) and Ag(I) ions by the precipitation of coordination polymers, and exhibited reversible proton-triggered fluorescence quenching behaviour. Macrocycle 4 thus represents a unique type of molecular sensory platform, which may find a wealth of potential applications such as the detection of heavy-metal pollutants, as well as for the fabrication of proton-switchable materials and coordination polymers with novel electronic and magnetic properties. 相似文献
93.
In this paper we study theoretically the molecular structure of [Be(C5Me5)2], with special interest in similarities and differences found in the computed geometric parameters, depending on the treatment of the electron correlation used. Given the low energy differences found between the different configurations studied (less than 4 kcal mol−1), and the high fluxionality found in experimental studies for this compound, we analyzed the dynamics of the system by means of first principles molecular dynamics calculations. A complex dynamics is found and analyzed in terms of two molecular rearrangement processes: 1,2-sigmatropic intraring rearrangement and a ring inversion mechanism that interchanges the roles (with regard to their coordination to the central Be atom) of the two rings.Dedicated to Dr. Jeal Paul Malrieu on occasion of his 65th birthday. 相似文献
94.
Based on an analysis of previously reported structures and a potential geometry fit with substrates, a new family of chiral dioxocyclam derivatives have been designed. The synthesis of those ligands was accomplished starting from l-proline and α-d-amino acids (converted to β-amino acids) with a key step of macrocyclization reaction of amino esters. All ligands were converted into neutral copper(II) complexes (amide groups underwent deprotonation of upon treatment of ligands with copper(II) acetate). The complexes exhibit the desired shape of their active surfaces, as proved by X-ray analysis. 相似文献
95.
Helmut Bahrmann Klaus Bergrath Han -Jerg Kleiner Peter Lappe Christoph Naumann Dieter Peters Dieter Regnat 《Journal of organometallic chemistry》1996,520(1-2):97-100
BINAS is a new, very efficient ligand for propylene hydroformylation. BINAS is made by the sulfonation of NAPHOS. Different synthetic routes to NAPHOS are discussed. A new two step synthesis starting from 2,2′-bis(bromomethyl)-1,1′-binaphthyl is described. 相似文献
96.
Yu. G. Budnikova A. G. Kafiyatullina Yu. M. Kargin O. G. Sinyashin 《Russian Chemical Bulletin》2003,52(7):1504-1511
Electrochemical reduction of cobalt(ii) complexes containing -acceptor ligands (L = bpy, Ph2Ppy) proceeds through three consecutive reversible steps: one-electron transfer to form a more stable CoIL complex, transfer of two electrons at more negative potentials to form an anionic [NiL]– complex, and reduction of the ligand to the radical anion. The stability of the cobalt complexes with different ligands decreases in the series Ph2Ppy > Ph3P > bpy. 相似文献
97.
通过1-环庚烯基锂与6,6-二烷基富烯发生环外双键的加成反应形成的大取代茂锂试剂与MCl4(M=Ti,Zr)反应,合成了12个含或不含手性碳的大位阻取代茂金属有机化合物,并研究了它们的1HNMR,EIMS和IR. 相似文献
98.
Summary A potentially heptadentated ligand (apytren) was obtained by condensation of 2-acetylpyridine andtris-(2-aminoethyl)-amine in the presence of lanthanoid(III) cations. Complexes of the formulaLn(apytren)(NO3)3·H2O (Ln=La, Eu, Gd, and Tb) have been isolated and characterized, both in the solid state and in solution, by means of vibrational and electronic spectroscopy and of conductometric measurements. Their photophysical properties, including emission quantum yields and lifetimes, were studied and are discussed.
Synthese und Lumineszenzuntersuchungen an Lanthanoid(III)-Komplexen mit einer aus 2-Acetylpyridin undtris-(2-Aminoethyl)-amin hergeleitetenSchiffschen Base
Zusammenfassung Durch Kondensation von 2-Acetylpyridin undtris-(2-Aminoethyl)-amin in der Gegenwart von Lanthanoid(III)-Kationen wurde ein potentiell siebenzähniger Ligand (apytren) erhalten. Komplexe der ZusammensetzungLn(apytren)(NO3)3·H2O (Ln=La, Eu, Gd und Tb) wurden isoliert und sowohl im festen Zustand als auch in Lösung mittels IR-und UV-Vis-Spektroskopie und Leitfähigkeitsmessungen charakterisiert. Ihre photophysikalischen Eigenschaften, einschließlich Emissionsquantenausbeute und Lebensdauer, wurden untersucht und werden diskutiert.相似文献
99.
Hubert Schmidbaur 《Angewandte Chemie (International ed. in English)》1985,24(11):893-904
Arene complexes of main-group metals were, until recently, rare species—in contrast to the now classical, analogous complexes of transition metals. In systematic investigations, it has been possible to prepare and structurally characterize arene complexes of the univalent elements gallium, indium, and thallium, which directly follow the d-block elements in the periodic table. This new type of compound is characterized by centric (η6) coordination of the metal to the arene; both mono- and bis(arene) complexes are known. The interaction can be explained by the perfect agreement between the HOMO/LUMO symmetry of the arene and of the low-valent metal. The electronic states of the nd10(n + 1)s2 configuration, which are partially modified by relativistic effects, play a particularly important role. The relationship to the few known complexes of the neighboring elements (SnII, PbII) becomes plausible via the isoelectronic principle. The arene/GaI, InI, TlI systems are of potential significance as homogeneous reducing agents and as agents for the activation of aromatic compounds, the purification of metals, and the separation of metals from nonaqueous media. 相似文献
100.
Norma A. Cortez 《Tetrahedron letters》2007,48(25):4335-4338
Monosulfonamide ligands with heteroatom/heterocyclic systems were derived from trans-(1R,2R)-cyclohexane-1,2-diamine and complexed with [Ru(benzene)Cl2]2, [Cp∗RhCl2]2 in situ and used in the ATH of aromatic ketones with aqueous sodium formate as the hydrogen source. The chiral secondary alcohols were obtained with >93% enantioselectivity and >89% yield. Reduction in water was faster than in isopropanol/KOH. Addition of surfactants showed little or no effects. 相似文献