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Gutsul EI Belkova NV Sverdlov MS Epstein LM Shubina ES Bakhmutov VI Gribanova TN Minyaev RM Bianchini C Peruzzini M Zanobini F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(10):2219-2228
The reactions of the octahedral dihydrido complexes [MH(2)(PP(3))] [M=Fe, Ru, Os; PP(3)=P(CH(2)CH(2)PPh(2))(3)] with a variety of weak ROH acids have been studied by IR and NMR methods in either CH(2)Cl(2) or THF in the temperature range from 190 to 290 K. This study has allowed the determination of the spectral and thermodynamic properties associated with the formation of dihydrogen bonds (DHB) between the terminal hydrides and the OH group. Both the DHB enthalpy values and the hydride basicity factors (E(j)) have been found to increase in the order Fe < Ru < Os. The proton transfer process, leading to the DHB complexes, and eventually to eta(2)-H(2) products, has been found to depend on the acidic strength of the alcohol as well as the nature of the solvent. Low temperature IR and NMR techniques have been used to trace the complete energy profile of the proton transfer process involving the osmium complex [OsH(2)(PP(3))] with trifluoroethanol. 相似文献
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Shubina ES Tikhonova IA Bakhmutova EV Dolgushin FM Antipin MY Bakhmutov VI Sivaev IB Teplitskaya LN Chizhevsky IT Pisareva IV Bregadze VI Epstein LM Shur VB 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(17):3783-3790
It has been shown by IR and NMR spectroscopy that cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4-Hg)3 (1) is capable of binding closo-[B10H10]2- and closo-[B12H12]2- anions to form complexes [[(o-C6F4Hg)3](B10-H10)]2- (2), [[(o-C6F4Hg)3]2(B10H10)]2-(3), [[(o-C6F4Hg)3](B12H12)]2- (4), and [[(o-C6F4Hg)3]2(B12H12)]2- (5). According to IR data, the bonding of the [B10H10]2- and [B12H12]2- ions to the macrocycle in these complexes is accomplished through the formation of B-H-Hg bridges. Complexes 2, 3, and 5 have been isolated in analytically pure form and have been characterized by spectroscopic means. X-ray diffraction studies of 3 and 5 have revealed that these compounds have unusual sandwich structures, in which the polyhedral di-anion is located between the planes of two molecules of 1 and is bonded to each of them through two types of B-H-Hg bridges. One type is the simultaneous coordination of a B-H group to all three Hg atoms of the macrocycle. The other type is the coordination of a B-H group to a single Hg atom of the cycle. According to X-ray diffraction data, complex 2 has an analogous but half-sandwich structure. The obtained complexes 2-5 are quite stable; their stability constants in THF/acetone (1:1) at 20 degrees C have been determined as 1.0 x 10(2)Lmol(-1), 2.6 x 10(3)L(2)mol(2), 0.7 x 10(2)Lmol(-1), and 0.98 x 10(3)L(2)mol(-2), respectively. 相似文献
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Pavel A. Dub Vladislava A. Levina Elena S. Shubina 《Journal of organometallic chemistry》2011,696(6):1174-6773
Compound trans-PtBr2(C2H4)(NHEt2) (1) has been synthesized by Et2NH addition to K[PtBr3(C2H4)] and structurally characterized. Its isomer cis-PtBr2(C2H4)(NHEt2) (3) has been obtained from 1 by photolytic dissociation of ethylene, generating the dinuclear trans-[PtBr2(NHEt2)]2 intermediate (2), followed by thermal re-addition of C2H4, but only in low yields. The addition of further Et2NH to 1 in either dichloromethane or acetone yields the zwitterionic complex trans-Pt(−)Br2(NHEt2)(CH2CH2N(+)HEt2) (4) within the time of mixing in an equilibrated process, which shifts toward the product at lower temperatures (ΔH° = −6.8 ± 0.5 kcal/mol, ΔS° = 14.0 ± 2.0 e.u., from a variable temperature IR study). 1H NMR shows that free Et2NH exchanges rapidly with H-bonded amine in a 4·NHEt2 adduct, slowly with the coordinated Et2NH in 1, and not at all (on the NMR time scale) with Pt-NHEt2 or -CH2CH2N(+)HEt2 in 4. No evidence was obtained for deprotonation of 4 to yield an aminoethyl derivative trans-[PtBr2(NHEt2)(CH2CH2NEt2)]− (5), except as an intermediate in the averaging of the diasteretopic methylene protons of the CH2CH2N(+)HEt2 ligand of 4 in the higher polarity acetone solvent. Computational work by DFT attributes this phenomenon to more facile ion pair dissociation of 5·Et2NH2+, obtained from 4·Et2NH, facilitating inversion at the N atom. Complex 4 is the sole observable product initially but slow decomposition occurs in both solvents, though in different ways, without observable generation of NEt3. Addition of TfOH to equilibrated solutions of 4, 1 and excess Et2NH leads to partial protonolysis to yield NEt3 but also regenerates 1 through a shift of the equilibrium via protonation of free Et2NH. The DFT calculations reveal also a more favourable coordination (stronger Pt-N bond) of Et2NH relative to PhNH2 to the PtII center, but the barriers of the nucleophilic additions of Et2NH to the C2H4 ligand in 1 and of PhNH2 to trans-PtBr2(C2H4)(PhNH2) (1a) are predicted to be essentially identical for the two systems. 相似文献
15.
Tsupreva VN Titov AA Filippov OA Bilyachenko AN Smol'yakov AF Dolgushin FM Agapkin DV Godovikov IA Epstein LM Shubina ES 《Inorganic chemistry》2011,50(8):3325-3331
Interaction of the copper, {[3,5-(CF(3))(2)Pz]Cu}(3), and silver, {[3,5-(CF(3))(2)Pz]Ag}(3), macrocycles [3,5-(CF(3))(2)Pz = 3,5-bis(trifluoromethyl)pyrazolate] with cyclooctatetraeneiron tricarbonyl, (cot)Fe(CO)(3), was investigated by IR and NMR spectroscopy for the first time. The formation of 1:1 complexes was observed at low temperatures in hexane. The composition of the complexes (1:1) and their thermodynamic characteristics in hexane and dichloromethane were determined. The π-electron system of (cot)Fe(CO)(3) was proven to be the sole site of coordination in solution and in the solid state. However, according to the single-crystal X-ray data, the complex has a different (2:1) composition featuring the sandwich structure. The complexes of ferrocene with copper and silver macrocycles have a columnar structure (X-ray data). 相似文献
16.
Acid-base interaction between transition-metal hydrides: dihydrogen bonding and dihydrogen evolution
17.
Shubina E. S. Krylov A. N. Muratov D. V. Fil'chikov A. A. Epstein L. M. 《Russian Chemical Bulletin》1993,42(11):1919-1920
The interaction of Cp*M(CO)2 (M=Ir or Rh) with CF3COOH in low polar media results in partial protonation of these compounds giving molecular (M...HO) and ionic (MH+...O–) hydrogen-bonded complexes. According to IR spectral data, a decrease in temperature results in a shift of the equilibrium toward the ionic forms. These compounds react with phenol to give molecular complexes only.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2002–2003, November, 1993. 相似文献
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V. N. Rodionov B. V. Chernyaev I. A. Levandovskii T. E. Shubina A. A. Fokin 《Theoretical and Experimental Chemistry》2005,41(1):1-6
The chromatographic behavior of a series of dialkyl-cis-9,10-dihydroanthracene-9,10-endofumarates on a silver-containing stationary phase with various mobile phase compositions and at various temperatures was investigated by liquid chromatography. The observed relationships indicate reorientation of the analytes on the surface of the adsorbent with increase in temperature. This is explained by the formation of two types of chelate complexes similar in energy between the analytes and the silver ions. It agrees well with data calculated by the B3LYP/LANL2DZ method.__________Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol. 41, No. 1, pp. 1–6, January–February, 2005. 相似文献