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61.
Lithio-1,3-diarylformamidines undergo reaction with the monomeric and dimeric carbonyl chlorides of manganese and rhenium, [M(CO)5Cl] and [M(CO)4Cl2] to yield respectively the carbamoyl-formamidino [M(CO)4-CON(R)CHNR] and the formamidino [M(CO)4RNCHNR] types of complex. The carbamoyl complexes undergo decarbonylation to produce the formamidino complexes in low yield. 相似文献
62.
Darbost U Rager MN Petit S Jabin I Reinaud O 《Journal of the American Chemical Society》2005,127(23):8517-8525
The host-guest properties of calix[6]tren 1 have been evaluated. The receptor is based on a calix[6]arene that is covalently capped at the narrow rim by a tren unit. As a result, the system presents a concave hydrophobic cavity with, at its bottom, a grid-like nitrogenous core. Despite its well-defined cavity and opening to the outside at the large rim, 1 did not behave as a good receptor for neutral molecules in chloroform. However, it exhibited efficient endo-complexation of ammonium guests. By contrast, the per-protonated host, 1.4H(+), behaved as a remarkable receptor for small organic molecules. The complexation is driven by a strong charge-dipole interaction and hydrogen bonds between the polar guest and the tetracationic cap of the calixarene. Finally, coordination of Zn(2+) to the tren core led to the asymmetrization of calixarene cavity and to the strong but selective endo-binding of neutral ligands. This study emphasizes the efficiency of a receptor presenting a concave hydrophobic cavity that is polarized at its bottom. The resulting combination of charge-dipole, hydrogen bonding, CH-pi, and van der Waals interactions highly stabilizes the supramolecular architectures. Also, importantly, the tren cap allows the tuning of the polarization, offering either a basic (1), a highly charged and acidic (1.4H(+)), or a coordination (1.Zn(2+)) site. As a result, the system proved to be highly versatile, tunable, and interconvertible in solution by simple addition of protons, bases, or metal ions. 相似文献
63.
Nina Ulrich 《Analytical and bioanalytical chemistry》1998,360(7-8):797-800
An on-line method for the analysis of Sb(III), Sb(V) and trimethylstiboxide (TMSbO) is presented. The separation is performed
using ion chromatography (IC) on a strong anion-exchange column with phthalic acid plus 2% acteone at pH 5 as mobile phase.
The chromatographic system is coupled to an ICP-MS as detector. The influence of different complexing agents on the chromatographic
behavior of the antimony species is studied. Rather stable complexes of Sb(III) seem to be formed with citrate and tartrate
under the experimental conditions. TMSbO forms a dianionic species with citrate in contrast to the otherwise monoanionic complex.
Received: 31 Juli 1997 / Revised: 8 December 1997 / Accepted: 11 December 1997 相似文献
64.
65.
N(SCl)2⊕ [MoCl5(NSCl)]?, a Chlorothionitrene Complex of Molybdenum (VI) . The title compound is formed together with MoCl3(N3S2) by the reaction of MoCl4 or MoCl5 with (NSCl)3 in CH2Cl2. The black, crystalline compound was characterized by its i.r. spectrum and an X-ray crystal structure determination. N(SCl)2⊕[MoCl5(NSCl)]? crystallizes in the monoclinic space group P21/n with four formula units per unit cell. The lattice constants are a = 716.3, b = 1627.4, c = 1178.9 pm and β = 100.90°. The [MoCl5(NSCl)]? ion posseses an almost linear Mo = N = S grouping with bond lengths that can be interpreted as double bonds. Crystal data for AsPh4[MoCl5(NSCl)] are reported. 相似文献
66.
The mer‐octahedral complexes(2‐carbonyl)(4‐Me)(6‐tBu)phenolato[C,O]hydridotris(trimethylphosphine)cobalt(III) ( 1 ) or ‐(1‐carbonyl)(2‐oxo)(1,2‐diphenylethene)[C,O]hydridotris(trimethylphosphine)cobalt(III) ( 2 ) via formal insertion of propynoic acid ethyl ester into Co‐H functions afford pentacoordinate vinylcobalt(III) 3 and 4 , respectively, that are diamagnetic and attain a square pyramidal structure as exemplified by an X‐ray diffraction analysis of 3 . 相似文献
67.
E. Abel 《Monatshefte für Chemie / Chemical Monthly》1954,85(1):227-234
Zusammenfassung Don Geschwindigkeitsbeziehungen, die unter zeitlicher Verfolgung der Autoxydation von Ferroion erhalten worden sind, werden Rektionsmechanismen zugeordnet: der charakteristische Aciditätseinfluß sei durch einen Primärschritt bedingt, der in electron transfer zwischen O2 und OH-Ion besteht, unter gleichzeitiger Anlagerung von OH; eine entsprechende Struktur wird auch jenem Mechanismus zuzuordnen versucht, der zu quadratischer Abhängigkeit der Autoxydationsgeschwindigkeit von der Ferroionkonzentration führt. 相似文献
68.
The synthesis of the indoles 7 , 15 , 16 with a 3-methoxyphenyl group, attached via an α-side chain of 1,2,or 3 CH2 units, is reported. These compounds, after appropriate protection at C(3), were transformed into the N-[(dimethylamino)methyl]indoles 22 , 23 , and 24 , respectively. When treated with AcCl, these N-Mannich bases gave, in two cases, stable N-(chloromethyl)indoles 25 and 26 . In the presence of SnCl4, ring closure occurred via electrophilic attack of 1-methylideneindolium ions on the methoxyphenyl group. Formation of seven-membered rings (→ 27 , 28 ) and eight-membered rings (→ 29 ) was found to be a favorable process. Cyclization to six-membered rings did not occur within this series. 相似文献
69.
Sila-analoguesA 2 andB 2 of two drugs from the benzhydryl ether class, chlorphenoxamine and clofenetamine, were synthesized for the first time by the steps shown in scheme 1. They and their precursors I–VI were characterized by their physical (Table 1) and chemical properties and their structures confirmed by n.m.r., mass and infrared spectrocopy (Tables 2–5). Their physiological effects were investigated and compared with those of the carbon analogues (Chapter 5).
1. Mitt.:R. Tacke undU. Wannagat, Mh. Chem.106, 1005 (1975).
Mit Auszügen aus der DissertationR. Tacke, Techn. Univ. Braunschweig 1974. 相似文献
1. Mitt.:R. Tacke undU. Wannagat, Mh. Chem.106, 1005 (1975).
Mit Auszügen aus der DissertationR. Tacke, Techn. Univ. Braunschweig 1974. 相似文献
70.
The systems AeAl(2-x)Mgx (Ae = Ca, Sr, Ba) display electron concentration induced Laves phase structural changes. However, the complete sequence MgCu2 --> MgNi2 --> MgZn2 with increasing x (decreasing electron count) is only observed for Ae = Ca. Compounds SrAl(2-x)Mgx (0 < x < or = 2) and BaAl(2-x)Mgx (x = 0.85 and 2.0) were synthesized and structurally characterized by X-ray diffraction experiments. For the Sr system the structural sequence CeCu2 --> MgNi2 --> MgZn2 occurs with increasing Mg content x. Thus, larger Sr does not allow the realization of the MgCu2 structure at low x. For Ae = Ba a binary compound BaAl2 does not exist, but more Ba-rich Ba7Al13 forms. The reinvestigation of the crystal structure of Ba7Al13 by selected area and convergent beam electron diffraction in a transmission electron microscope revealed a superstructure, which subsequently could be refined from single X-ray diffraction data. The formula unit of the superstructure is Ba21Al40 (space group P31m, Z = 1, a = 10.568(1) angstroms, c = 17.205(6) angstroms). In Ba21Al40 a size match problem between Ba and Al present in Ba7Al13 is resolved. The structure of Ba7Al13 (Ba21Al40) can be considered as a Ba excess variant of the hexagonal MgNi2 Laves phase type structure. An incommensurately modulated variant of the MgNi2 structure is obtained for phases BaAl(2-x)Mgx with x = 0.8-1. At even higher Mg concentrations a structural change to the proper MgZn2 type structure takes place. 相似文献