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191.
Mixed-metal sulfido cluster [(PdCl2)(Cp*Ir)2(μ3-S)2] (Cp*=η5-C5Me5) dissolved in CH2Cl2 reacted with two equivalent of L (L=nicotinamide, isonicotinamide, or N-methylnicotinamide) in the presence of AgBF4 to give the cationic clusters [(PdL2)(Cp*Ir)2(μ3-S)2][BF4]2. The single-crystal X-ray diffraction studies of these products have disclosed that in the solid state the PdIr2S2 cores are self-assembled to form one-dimensional chains through the intermolecular hydrogen-bonding between the amide groups for L=nicotinamide or two-dimensional sheets via the hydrogen-bonding between the amide groups and the BF4 anions for L=isonicotinamide, whereas no organization of the cluster cores is observed for L=N-methylnicotinamide. 相似文献
192.
Ab initio molecular orbital theory and density functional theory have been employed to study N14 cluster with low spin at the HF/6-31G*, B3LYP/6-31G*, B3PW91/6-31G*, BP86/6-31G*, and BHLYP/6-31G* levels of theory. Twelve isomers were studied, including one previously investigated cage molecule. The most stable isomer of N14 is a C
2h
-symmetric molecule that contains two separated five-membered nitrogen rings connected by a —N=N—N=N— bridge. The second, third, and fifth most stable isomers each have one five-membered nitrogen ring. The theoretical results suggest that the five-membered nitrogen ring gives rise to a particularly stable structural unit, and the more side chains that the five-membered nitrogen ring links with, the less stable the structure will become. 相似文献
193.
Fandos R Hernández C Otero A Rodríguez A Ruiz MJ Terreros P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(3):671-677
Titanium complexes with chelating alkoxide ligands [TiCp*(O(2)Bz)(OBzOH)] (1) and [TiCp*(Me)((OCH(2))(2)Py)] (2) were synthesised by reaction of [TiCp*Me(3)] (Cp*=eta(5)-C(5)Me(5)) with 2-hydroxybenzyl alcohol ((HO)(2)Bz) and 2,6-pyridinedimethanol ((HOCH(2))(2)Py), respectively. Complex 1 reacts with [(M(mu-OH)(cod))(2)] (M=Rh, Ir) to yield the early-late heterobimetallic complexes [TiCp*(O(2)Bz)(2)M(cod)] [M=Rh (3), Ir (4)]. Carbon monoxide readily replaces the COD ligand in 3 to give the rhodium dicarbonyl derivative [TiCp*(O(2)Bz)(2)Rh(CO)(2)] (5). Compound 2 reacts with [(M(mu-OH)(cod))(2)] (M=Rh, Ir) with protonolysis of a Tibond;Me bond to give [TiCp*((OCH(2))(2)Py)(mu-O)M(cod)] [M=Rh (6), Ir (7)]. The molecular structures of complexes 3, 5 and 7 were established by single-crystal X-ray diffraction studies. 相似文献
194.
Koridze A. A. Kuklin S. A. Petrovskii P. V. Dolgushin F. M. Ezernitskaya M. G. 《Russian Chemical Bulletin》2002,51(2):350-353
The Os3(-H)2(CO)7(-C6H4){3-Ph2PCH2P(C6H4)Ph} complex, which was isolated from the products of thermolysis of Os3(CO)10(-dppm) (dppm is Ph2PCH2PPh2) in toluene, was characterized by X-ray diffraction analysis. Protonation of the resulting complex with trifluoroacetic acid afforded the cationic complex [Os3(-H)3(CO)7(-C6H4){3-Ph2PCH2P(C6H4)Ph}]+. 相似文献
195.
Deprotonation of Mn2(μ-H)(μ-PR2)(CO)8 (R = Ph Cy) for Synthesis of Heteronuclear Manganese-Gold Clusters with Mn2Aun Cores (n = 1–3) The dimanganese complexes Mn2(μ-H)(μ-PR2)(CO)8 (R = Ph, Cy) have been deprotonated with 1,8-diazabicyclo[5.4.0]undec-7-en (DBU) in tetrahydrofuran solution at 20°C to give the anions [Mn2(μ-PR2)(CO)8]?, which were isolated as tetraethylammonium salts. Both dimanganese complexes and the related anions were measured by cyclic voltammetry. The treatment of the aforementioned dimanganese complexes in thf solution with Lir' (R =Me, Ph) and subsequently with PPh3AuCl gave at 20°C three types of products: Mn2(μ-PR2(CO)8(AuPPh3),Mn2(μ-PR2)(μ-C(R′)O)(CO)6-(AuPPh3)2 and Mn2(μ-PR2)(CO)6(AuPPh3)3. The newly prepared substances were characterized by means of IR-, UV/VIS, 31P NMR data. The results of single X-ray analyses showed for the three-membered metal ring compound Mn2(μ-PPh2)(CO)8(AuPPh3) an uni-fold bridged σ(Mn? Mn) bond length of 306.7(3) pm, the metallatetrahedron complex Mn2(μ-PPh3)(μ-C(Ph)O(CO)6(AuPPh3)2 a twofold bridged σ(Mn? Mn) bond length of 300.6(4) pm and the trigonal-bipyramidal cluster Mn2(μ-Pph2)(CO)6(AuPPh3)3 an uni-fold bridged π(Mn? Mn) bond length of 274.7(3) pm. The Mn? Au bonds of these substances are accompanyied by semi-bridging CO ligands which are signified through short Au…C contact lengths in the range of 251 to 270 pm. In the substance with the Mn2Au2 metallatetrahedron core exists, additionally, such a contact with the acylic C atom of C(Ph)O bridging group of 263.4(18) pm. Such contact lengths were compared for corresponding dimanganese and dirhenium complexes. 相似文献
196.
The reactions of Re2X4(-dppm)2 (X=Cl or Br; dppm=Ph2PCH2PPh2) with H2S in THF afford the dirhenium (III) complexes Re2(-H)(-SH)X4(-dppm)2, the first examples of the oxidative addition of an S-H unit across an electron-rich metal-metal triple bond. The bromide complex Re2(-H)(-SH)Br4(-dppm)2 (C2H5)2O crystallizes in the space group P21/n witha=16.631(2) Å,b=15.967(3) Å,c=19.904(2) Å, =92.698(7)°,V=5279(2) Å3, andZ=4. The structure which was refined toR=0.053 (R
w=0.070) for 4903 data withI>3.0(I), shows the presence of an edge-shared bioctahedral geometry with a very short Re-Re distance of 2.4566(7) Å. While the hydrogen atoms of the -H and -SH ligands were not located in the X-ray structure determination, their presence is confirmed by IR and1H NMR spectroscopy. 相似文献
197.
Yu. G. Yatluk N. A. Zhuravlev O. V. Koryakova L. K. Neudachina Yu. A. Skorik 《Russian Chemical Bulletin》2005,54(8):1836-1841
A series of new hybrid organo-inorganic sorbents with the 3-aminopropionate chelating group was synthesized. The synthesis
includes the copolycondensation (sol—gel method) of tetraethoxysilane, 3-aminopropyltriethoxysilane, and several modifiers
(MeSi(OEt)3, EtSi(OEt)3, Ti(OEt)4, AlONO3, ZrOCl2) followed by carboxyethylation with acrylic acid. The obtained chelating sorbents were characterized by elemental analysis,
FT-IR and 1H NMR spectroscopy, and thermogravimetry. The N-carboxylated sorbents have a higher sorption capacity with respect to metal ions (0.5–0.9 mmol g−1, pH 6.3, NH4OAc, 20 °C) than the starting sorbents with the primary amino group (0.05–0.2 mmol g−1) and manifest high selectivity for copper(II) ion extraction.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1783–1788, August, 2005. 相似文献
198.
Dimitri E Khoshtariya Achim Zahl Tina D Dolidze Anton Neubrand Rudi van Eldik 《Chemphyschem》2004,5(9):1398-1404
Difference and double-difference near-infrared DO-D and HO-H stretching overtone (2nuOD and 2nuOH) spectroscopy and a rigorous (physically substantiated) band deconvolution technique were applied to reveal three different kinds of inherent (interstitial) structures of liquid water, which determine its high density (compared to ice lh under ambient conditions), its compressibility (under hydrostatic pressure, up to 300MPa), and its high fragility (manifested under temperature variation). Our data processing allowed the rigorous discrimination of up to six vibrational components. On the basis of an extensive comparative analysis combined with available structural data (X-ray and neutron scattering) and molecular dynamics (MD) simulations for liquid water, as well as with experimental and computed data for small non-tetrahedrally arranged water clusters, the major four components could be ascribed to: i) The basic lh icelike substructure; ii) the temperature-dependent remote interstitial "defects" due to tetrahedral displacements (primarily responsible for transport properties); iii) the interstitial "defects" most probably arranged in quasiplanar noncyclic tetramers (totally absent in the ice structure); and iv) the interstitial "defects" formed with increasing pressure, probably arranged in cubic water octamers and composed of two pairs of noncyclic and cyclic tetramer fragments. The latter structures include, essentially, bent hydrogen bonds stabilized by resonance effects. 相似文献
199.
Serdar Öğüt Juan C. Idrobo Julius Jellinek Jinlan Wang 《Journal of Cluster Science》2006,17(4):609-626
We examine low-energy isomeric forms, static polarizabilities, and optical absorption spectra of Ag
n
, n = 2–8, and Au
n
, n = 2–3, clusters using first principles computations within the static and time-dependent versions of the density functional theory. The noticeable decrease in the static polarizabilities of Ag7 and Ag8 compared to the values characteristic of Ag
n
, n = 2–6, is correlated with the transition from two-dimensional to three-dimensional structures at n = 7. The optical spectra computed within the time-dependent local density approximation for the most stable structures are in good agreement with the available experimental data and the results of earlier theoretical studies. Optical spectra of higher-energy isomers typically present features that are not observed in the experimental spectra. The d electrons affect the spectra of noble metal clusters by quenching the oscillator strengths through screening of the s electrons and by getting directly involved in the excitations. Due to the larger s–d hybridization in Au compared to Ag, these effects are more pronounced in Au
n
clusters. 相似文献
200.
IntroductionItiswellknownthatmetallocenesactivatedwithmethylaluminoxane (MAO)arehighlyactivehomogeneousZiegler Nattacatalyststhatproducepolyolefinwithcon trolledstereoregularityandnarrowmolecularweightdistri bution ,1 4 however,themolecularweightofthepolym… 相似文献