51
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Belkova NV, Revin PO, Besora M, Baya M, Epstein LM, Lledós A, Poli R, Shubina ES, Vorontsov EV. Hydrogen Bonding and Proton Transfer to the Trihydride Complex [Cp*MoH3(dppe)]: IR, NMR, and Theoretical Investigations. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200600093] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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52
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Algarra AG, Basallote MG, Feliz M, Fernández-Trujillo MJ, Llusar R, Safont VS. New Insights into the Mechanism of Proton Transfer to Hydride Complexes: Kinetic and Theoretical Evidence Showing the Existence of Competitive Pathways for Protonation of the Cluster [W3S4H3(dmpe)3]+ with Acids. Chemistry 2006; 12:1413-26. [PMID: 16294357 DOI: 10.1002/chem.200500695] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The reaction of the hydride cluster [W3S4H3(dmpe)3]+ (1, dmpe = 1,2-bis(dimethylphosphanyl)ethane) with acids (HCl, CF3COOH, HBF4) in CH2Cl2 solution under pseudo-first-order conditions of excess acid occurs with three kinetically distinguishable steps that can be interpreted as corresponding to successive formal substitution processes of the coordinated hydrides by the anion of the acid (HCl, CF3COOH) or the solvent (HBF4). Whereas the rate law for the third step changes with the nature of the acid, the first two kinetic steps always show a second-order dependence on acid concentration. In contrast, a single kinetic step with a first-order dependence with respect to the acid is observed when the experiments are carried out with a deficit of acid. The decrease in the T1 values for the hydride NMR signal of 1 in the presence of added HCl suggests the formation of an adduct with a W-H...H-Cl dihydrogen bond. Theoretical calculations for the reaction with HCl indicate that the kinetic results in CH2Cl2 solution can be interpreted on the basis of a mechanism with two competitive pathways. One of the pathways consists of direct proton transfer within the W-H...H-Cl adduct to form W-Cl and H2, whereas the other requires the presence of a second HCl molecule to form a W-H...H-Cl...H-Cl adduct that transforms into W-Cl, H2 and HCl in the rate-determining step. The activation barriers and the structures of the transition states for both pathways were also calculated, and the results indicate that both pathways can be competitive and that the transition states can be described in both cases as a dihydrogen complex hydrogen-bonded to Cl- or HCl2(-).
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Affiliation(s)
- Andrés G Algarra
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Universidad de Cádiz, Apartado 40, Puerto Real, 11510 Cádiz, Spain
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53
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Donghi D, Beringhelli T, D'Alfonso G, Mondini M. NMR Investigation of the Dihydrogen-Bonding and Proton-Transfer Equilibria between the Hydrido Carbonyl Anion [HRe2(CO)9]− and Fluorinated Alcohols. Chemistry 2006; 12:1016-25. [PMID: 16267862 DOI: 10.1002/chem.200500920] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The interaction of fluorinated alcohols with the anionic hydrido complex [HRe2(CO)9]- (1) has been investigated by NMR spectroscopy. According to the acidic strength of the alcohols, the interaction may result not only in the formation of dihydrogen-bonded ROH...[HRe2(CO)9]- adducts 2, but also in proton transfer to give the neutral species [H2Re2(CO)9] (3). With the weaker acid trifluoroethanol (TFE) evidence for the occurrence of the dihydrogen-bonding equilibrium was obtained by 2D 1H NOESY. The dependence of the hydride chemical shift on TFE concentration at different temperatures provided values for the constants of this equilibrium, from which the thermodynamic parameters were evaluated as deltaH(degrees) = -2.6(2) kcal mol(-1), deltaS(degrees) = -9.3(2) cal mol(-1) K(-1). This corresponds to a rather low basicity factor (E(j) = 0.64). Variable-temperature T1 measurements allowed the proton-hydride distance in adduct 2 a to be estimated (1.80 angstroms). In the presence of hexafluoroisopropyl alcohol (HFIP) simultaneous occurrence of both dihydrogen-bonding and proton-transfer equilibria was observed, and the equilibria shifted versus the protonated product 3 with increasing HFIP concentration and decreasing temperature. Reversible proton transfer between the alcohol and the hydrido complex occurs on the NMR timescale, as revealed by a 2D 1H EXSY experiment at 240 K. For the more acidic perfluoro-tert-butyl alcohol (PFTB) the protonation equilibrium was further shifted to the right. Thermal instability of 3 prevented the acquisition of accurate thermodynamic data for these equilibria. The occurrence of the proton-transfer processes (in spite of the unfavorable pK(a) values) can be explained by the formation of homoconjugated RO...HOR- pairs which stabilize the alcoholate anions.
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Affiliation(s)
- Daniela Donghi
- Università degli Studi di Milano, Facoltà di Farmacia, Dipartimento di Chimica Inorganica, Metallorganica e Analitica, Via Venezian 21, 20133 Milano, Italy
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54
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Kovács G, Ujaque G, Lledós A, Joó F. Theoretical Investigation of the Selective CC Hydrogenation of Unsaturated Aldehydes Catalyzed by [{RuCl2(mtppms)2}2] in Acidic Media. Organometallics 2006. [DOI: 10.1021/om050929y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gábor Kovács
- Institute of Physical Chemistry, University of Debrecen, Debrecen 10, H-4010 Hungary, Research Group of Homogeneous Catalysis, Hungarian Academy of Sciences, Debrecen 10, P.O. Box 7, H-4010 Hungary, and Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
| | - Gregori Ujaque
- Institute of Physical Chemistry, University of Debrecen, Debrecen 10, H-4010 Hungary, Research Group of Homogeneous Catalysis, Hungarian Academy of Sciences, Debrecen 10, P.O. Box 7, H-4010 Hungary, and Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
| | - Agustí Lledós
- Institute of Physical Chemistry, University of Debrecen, Debrecen 10, H-4010 Hungary, Research Group of Homogeneous Catalysis, Hungarian Academy of Sciences, Debrecen 10, P.O. Box 7, H-4010 Hungary, and Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
| | - Ferenc Joó
- Institute of Physical Chemistry, University of Debrecen, Debrecen 10, H-4010 Hungary, Research Group of Homogeneous Catalysis, Hungarian Academy of Sciences, Debrecen 10, P.O. Box 7, H-4010 Hungary, and Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
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55
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Kovács G, Schubert G, Joó F, Pápai I. Theoretical Mechanistic Study of Rhodium(I) Phosphine-Catalyzed H/D Exchange Processes in Aqueous Solutions. Organometallics 2005. [DOI: 10.1021/om0501529] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gábor Kovács
- Institute of Physical Chemistry, University of Debrecen, 4010 Debrecen, P.O.Box 7, Hungary, Chemical Research Centre of the Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary, and Research Group of Homogeneous Catalysis, Hungarian Academy of Sciences−University of Debrecen, 4010 Debrecen, P.O. Box 7, Hungary
| | - Gábor Schubert
- Institute of Physical Chemistry, University of Debrecen, 4010 Debrecen, P.O.Box 7, Hungary, Chemical Research Centre of the Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary, and Research Group of Homogeneous Catalysis, Hungarian Academy of Sciences−University of Debrecen, 4010 Debrecen, P.O. Box 7, Hungary
| | - Ferenc Joó
- Institute of Physical Chemistry, University of Debrecen, 4010 Debrecen, P.O.Box 7, Hungary, Chemical Research Centre of the Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary, and Research Group of Homogeneous Catalysis, Hungarian Academy of Sciences−University of Debrecen, 4010 Debrecen, P.O. Box 7, Hungary
| | - Imre Pápai
- Institute of Physical Chemistry, University of Debrecen, 4010 Debrecen, P.O.Box 7, Hungary, Chemical Research Centre of the Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary, and Research Group of Homogeneous Catalysis, Hungarian Academy of Sciences−University of Debrecen, 4010 Debrecen, P.O. Box 7, Hungary
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Czerwiński M, Narbutt J. Outer‐Sphere Hydration and Liquid−Liquid Partition of Metal(
III
) Chelates − Density Functional Calculations. Eur J Inorg Chem 2005. [DOI: 10.1002/ejic.200400267] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Marian Czerwiński
- Jan Dlugosz University, Institute of Chemistry and Environmental Protection, Al. Armii Krajowej 13/15, 42200 Czestochowa, Poland
| | - Jerzy Narbutt
- Department of Radiochemistry, Institute of Nuclear Chemistry and Technology, Dorodna 16, 03‐195 Warsaw, Poland, Fax: (internat.) + 48‐22‐8111‐532
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58
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Bakhmutov VI. Proton Transfer to Hydride Ligands with Formation of Dihydrogen Complexes: A Physicochemical View. Eur J Inorg Chem 2005. [DOI: 10.1002/ejic.200400697] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Vladimir I. Bakhmutov
- Department of Chemistry, Texas A&M University, College Station, Texas 77843‐3255, USA
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59
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Belkova NV, Collange E, Dub P, Epstein LM, Lemenovskii DA, Lledós A, Maresca O, Maseras F, Poli R, Revin PO, Shubina ES, Vorontsov EV. Experimental and Computational Studies of Hydrogen Bonding and Proton Transfer to [Cp*Fe(dppe)H]. Chemistry 2004; 11:873-88. [PMID: 15580590 DOI: 10.1002/chem.200400700] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The present contribution reports experimental and computational investigations of the interaction between [Cp*Fe(dppe)H] and different proton donors (HA). The focus is on the structure of the proton transfer intermediates and on the potential energy surface of the proton transfer leading to the dihydrogen complex [Cp*Fe(dppe)(H2)]+. With p-nitrophenol (PNP) a UV/Visible study provides evidence of the formation of the ion-pair stabilized by a hydrogen bond between the nonclassical cation [Cp*Fe(dppe)(H2)]+ and the homoconjugated anion ([AHA]-). With trifluoroacetic acid (TFA), the hydrogen-bonded ion pair containing the simple conjugate base (A-) in equilibrium with the free ions is observed by IR spectroscopy when using a deficit of the proton donor. An excess leads to the formation of the homoconjugated anion. The interaction with hexafluoroisopropanol (HFIP) was investigated quantitatively by IR spectroscopy and by 1H and 31P NMR spectroscopy at low temperatures (200-260 K) and by stopped-flow kinetics at about room temperature (288-308 K). The hydrogen bond formation to give [Cp*Fe(dppe)H]HA is characterized by DeltaH degrees =-6.5+/-0.4 kcal mol(-1) and DeltaS degrees = -18.6+/-1.7 cal mol(-1) K(-1). The activation barrier for the proton transfer step, which occurs only upon intervention of a second HFIP molecule, is DeltaH(not equal) = 2.6+/-0.3 kcal mol(-1) and DeltaS(not equal) = -44.5+/-1.1 cal mol(-1) K(-1). The computational investigation (at the DFT/B3 LYP level with inclusion of solvent effects by the polarizable continuum model) reproduces all the qualitative findings, provided the correct number of proton donor molecules are used in the model. The proton transfer process is, however, computed to be less exothermic than observed in the experiment.
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Affiliation(s)
- Natalia V Belkova
- Nesmeyanov Institute of Organoelement Compounds (INEOS) Russian Academy of Sciences, Vavilov Street 28, 119991 Moscow, Russia
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Belkova N, Filippov O, Filin A, Teplitskaya L, Shmyrova Y, Gavrilenko V, Golubinskaya L, Bregadze V, Epstein L, Shubina E. Interaction of the [GaH4]− Anion with Weak XH Acids− A Spectroscopic and Theoretical Study. Eur J Inorg Chem 2004. [DOI: 10.1002/ejic.200400084] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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61
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Gil A, Sodupe M, Bertran J. Unusual hydrogen bonds in [AH3–H3O]+ radical cations (A=C, Si, Ge, Sn and Pb). Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.07.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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62
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Novel platinum-catalysed cascade reactions: cyclisation, ring expansion and 1,2-oxygen shift reaction of a camphor-derived diyne. Tetrahedron 2004. [DOI: 10.1016/j.tet.2004.03.078] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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63
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Basallote MG, Besora M, Durán J, Fernández-Trujillo MJ, Lledós A, Máñez MA, Maseras F. The Effect of the “Inert” Counteranions in the Deprotonation of the Dihydrogen Complex trans-[FeH(η2-H2)(dppe)2]+: Kinetic and Theoretical Studies. J Am Chem Soc 2004; 126:2320-1. [PMID: 14982432 DOI: 10.1021/ja039844j] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Kinetic studies indicate that trans-[FeH(H2)(dppe)2]+ reacts with an excess of NEt3 to form cis-[FeH2(dppe)2] in a single kinetic step. The second-order rate constant is strongly affected by the presence of added salts, an acceleration being observed with BF4- and PF6- salts and a deceleration with BPh4-. Theoretical calculations indicate that the role of the accelerating anions consists of the formation of ion pairs that provide a more effective reaction pathway for deprotonation. However, for the ion pair with the bulky BPh4- anion, steric crowding in the proximities of the dihydrogen ligand hinders the approach of the base, and the reaction is decelerated.
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Affiliation(s)
- Manuel G Basallote
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Universidad de Cádiz, Apartado 40, Puerto Real, 11510 Cádiz, Spain.
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