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Aarabi M, Sarka J, Pandey A, Nieman R, Aquino AJA, Eckert J, Poirier B. Quantum Dynamical Investigation of Dihydrogen-Hydride Exchange in a Transition-Metal Polyhydride Complex. J Phys Chem A 2023; 127:6385-6399. [PMID: 37494557 DOI: 10.1021/acs.jpca.3c01863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
The ongoing shift toward clean, sustainable energy is a primary driving force behind hydrogen fuel research. Safe and effective storage of hydrogen is a major challenge (particularly for mobile applications) and requires a detailed understanding of the atomic level interactions of hydrogen with its host materials. The light mass of hydrogen, however, implies that quantum effects are important, so a quantum dynamical treatment is required to properly account for these effects in computational simulations. As one such example, we describe herein the hydrogen exchange dynamics between a hydride and a dihydrogen ligand in the [FeH(H2)(PH3)4]+ model complex. A global three-dimensional (3D) potential energy surface (PES) was constructed by fitting to and interpolating from a discrete set of grid points computed using density functional theory; exact quantum dynamical calculations were then carried out on the 3D PES using discrete variable representation basis sets. Energy levels and their quantum tunneling splittings were computed up to 3000 cm-1 above the ground state. Within that energy range, all three fundamentals have been identified using wave function plots, as well as the first three overtones of the exchange (reaction coordinate) motion and several of its combination bands. From the tunneling splittings, the Boltzmann-averaged tunneling rates were computed. The Arrhenius plot of the total exchange rate shows a clear transition around 150 K, below which the activation energy is essentially zero and above which it is less than half of the electronic structure barrier. This indicates that exchange rates are governed by quantum tunneling throughout the relevant temperature range with the low-temperature regime dominated by a single quantum (ground) state. This work is the first-ever fully quantum dynamical study to investigate the hydrogen exchange dynamics between hydride and dihydrogen ligands coordinated to a transition-metal complex.
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Affiliation(s)
- Mahdi Aarabi
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
| | - János Sarka
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
- Institute of Chemistry, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Ankit Pandey
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
| | - Reed Nieman
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
| | - Adelia J A Aquino
- Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas 79409-1061, United States
| | - Juergen Eckert
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
- Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Bill Poirier
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, United States
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Garaeva VV, Spiridonov KA, Nikovskii IA, Peregudov AS, Kiryutin AS, Yurkovskaya AV, Polezhaev AA, Novikov VV. Spin Order Transfer from a Parahydrogen Molecule to the Counterion in the Iridium Complex under the SABRE Conditions. RUSS J COORD CHEM+ 2022. [DOI: 10.1134/s1070328422080036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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3
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Zero-field nuclear magnetic resonance of chemically exchanging systems. Nat Commun 2019; 10:3002. [PMID: 31278303 PMCID: PMC6611813 DOI: 10.1038/s41467-019-10787-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/24/2019] [Indexed: 12/22/2022] Open
Abstract
Zero- to ultralow-field (ZULF) nuclear magnetic resonance (NMR) is an emerging tool for precision chemical analysis. In this work, we study dynamic processes and investigate the influence of chemical exchange on ZULF NMR J-spectra. We develop a computational approach that allows quantitative calculation of J-spectra in the presence of chemical exchange and apply it to study aqueous solutions of [15N]ammonium (15N\documentclass[12pt]{minimal}
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\begin{document}$${\mathrm{H}}_4^ +$$\end{document}H4+) as a model system. We show that pH-dependent chemical exchange substantially affects the J-spectra and, in some cases, can lead to degradation and complete disappearance of the spectral features. To demonstrate potential applications of ZULF NMR for chemistry and biomedicine, we show a ZULF NMR spectrum of [2-13C]pyruvic acid hyperpolarized via dissolution dynamic nuclear polarization (dDNP). We foresee applications of affordable and scalable ZULF NMR coupled with hyperpolarization to study chemical exchange phenomena in vivo and in situations where high-field NMR detection is not possible to implement. Zero-field nuclear magnetic resonance can identify species and collective behaviors in mixtures without applied magnetic fields. Here the authors demonstrate its use for resolving proton exchange in ammonium and for the detection of hyperpolarized pyruvic acid, an important imaging biomarker.
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Carnevale D, Pelupessy P, Bodenhausen G. Cross-term Splittings Due to the Orientational Inequivalence of Proton Magnetic Shielding Tensors: Do Water Molecules Trapped in Crystals Hop or Tunnel? J Phys Chem Lett 2019; 10:3224-3231. [PMID: 31059264 DOI: 10.1021/acs.jpclett.9b00914] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Water molecules trapped in crystals of barium chlorate monohydrate have been investigated by magic-angle spinning (MAS) proton NMR spectroscopy in the temperature range 110-300 K. At high temperatures, a single spinning sideband pattern is observed. Below 150 K, however, two interleaved spinning sideband manifolds appear, with distinct centerbands that do not coincide with the average isotropic chemical shift seen at high temperatures. This hitherto unknown "cross-term splitting" results from the interplay of the homonuclear dipole-dipole coupling and two anisotropic proton shielding tensors that have identical principal components but nonequivalent orientations. The resulting cross terms cannot be averaged out by rotation about the magic angle. The analysis of the exchange-induced broadening, coalescence, and narrowing of the cross-term splitting in MAS spectra allows one to estimate the rate of exchange of the two protons between 140 and 190 K. The experimental data is compared with 2H and 1H NMR studies of the same sample reported in the literature. Density functional theory methods are utilized to estimate the thermal activation energy for a 2-fold hopping process of proton exchange about the H-O-H bisector. The Bell-Limbach model allows one to take into account contributions due to incoherent quantum tunneling in the low-temperature regime.
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Affiliation(s)
- Diego Carnevale
- Laboratoire des Biomolécules, LBM, Département de Chimie , École Normale Supérieure , PSL University, Sorbonne Université, CNRS, 75005 Paris , France
| | - Philippe Pelupessy
- Laboratoire des Biomolécules, LBM, Département de Chimie , École Normale Supérieure , PSL University, Sorbonne Université, CNRS, 75005 Paris , France
| | - Geoffrey Bodenhausen
- Laboratoire des Biomolécules, LBM, Département de Chimie , École Normale Supérieure , PSL University, Sorbonne Université, CNRS, 75005 Paris , France
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Gonzalez ME, Eckert J, Aquino AJA, Poirier B. A quantum dynamical study of the rotation of the dihydrogen ligand in the Fe(H) 2(H 2)(PEtPh 2) 3 coordination complex. J Chem Phys 2018; 148:154303. [PMID: 29679974 DOI: 10.1063/1.5026637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Progress in the hydrogen fuel field requires a clear understanding and characterization of how materials of interest interact with hydrogen. Due to the inherently quantum mechanical nature of hydrogen nuclei, any theoretical studies of these systems must be treated quantum dynamically. One class of material that has been examined in this context are dihydrogen complexes. Since their discovery by Kubas in 1984, many such complexes have been studied both experimentally and theoretically. This particular study examines the rotational dynamics of the dihydrogen ligand in the Fe(H)2(H2)(PEtPh2)3 complex, allowing for full motion in both the rotational degrees of freedom and treating the quantum dynamics (QD) explicitly. A "gas-phase" global potential energy surface is first constructed using density functional theory with the Becke, 3-parameter, Lee-Yang-Parr functional; this is followed by an exact QD calculation of the corresponding rotation/libration states. The results provide insight into the dynamical correlation of the two rotation angles as well as a comprehensive analysis of both ground- and excited-state librational tunneling splittings. The latter was computed to be 6.914 cm-1-in excellent agreement with the experimental value of 6.4 cm-1. This work represents the first full-dimensional ab initio exact QD calculation ever performed for dihydrogen ligand rotation in a coordination complex.
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Affiliation(s)
- Megan E Gonzalez
- Department of Chemistry and Biochemistry, and Department of Physics, Texas Tech University, P.O. Box 41061, Lubbock, Texas 79409-1061, USA
| | - Juergen Eckert
- Department of Chemistry and Biochemistry, and Department of Physics, Texas Tech University, P.O. Box 41061, Lubbock, Texas 79409-1061, USA
| | - Adelia J A Aquino
- Department of Chemistry and Biochemistry, and Department of Physics, Texas Tech University, P.O. Box 41061, Lubbock, Texas 79409-1061, USA
| | - Bill Poirier
- Department of Chemistry and Biochemistry, and Department of Physics, Texas Tech University, P.O. Box 41061, Lubbock, Texas 79409-1061, USA
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Limbach HH, Pery T, Rothermel N, Chaudret B, Gutmann T, Buntkowsky G. Gas phase 1H NMR studies and kinetic modeling of dihydrogen isotope equilibration catalyzed by Ru-nanoparticles under normal conditions: dissociative vs. associative exchange. Phys Chem Chem Phys 2018; 20:10697-10712. [DOI: 10.1039/c7cp07770j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Exposure of surface H-containing Ru-nanoparticles to D2 gas produces HD via associative adsorption, surface H-transfer and associative desorption.
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Affiliation(s)
| | - Tal Pery
- Institut für Chemie und Biochemie
- Freie Universität Berlin
- D-14195 Berlin
- Germany
| | - Niels Rothermel
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie
- Technische Universität Darmstadt
- D-64287 Darmstadt
- Germany
| | - Bruno Chaudret
- Laboratoire de Physique et Chimie des Nano Objets
- LPCNO
- Institut National des Sciences Appliquées
- Toulouse 31077
- France
| | - Torsten Gutmann
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie
- Technische Universität Darmstadt
- D-64287 Darmstadt
- Germany
| | - Gerd Buntkowsky
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie
- Technische Universität Darmstadt
- D-64287 Darmstadt
- Germany
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Pravdivtsev AN, Ivanov KL, Yurkovskaya AV, Petrov PA, Limbach HH, Kaptein R, Vieth HM. Spin polarization transfer mechanisms of SABRE: A magnetic field dependent study. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2015; 261:73-82. [PMID: 26529205 DOI: 10.1016/j.jmr.2015.10.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/05/2015] [Accepted: 10/09/2015] [Indexed: 06/05/2023]
Abstract
We have investigated the magnetic field dependence of Signal Amplification By Reversible Exchange (SABRE) arising from binding of para-hydrogen (p-H2) and a substrate to a suitable transition metal complex. The magnetic field dependence of the amplification of the (1)H Nuclear Magnetic Resonance (NMR) signals of the released substrates and dihydrogen, and the transient transition metal dihydride species shows characteristic patterns, which is explained using the theory presented here. The generation of SABRE is most efficient at low magnetic fields due to coherent spin mixing at nuclear spin Level Anti-Crossings (LACs) in the SABRE complexes. We studied two Ir-complexes and have shown that the presence of a (31)P atom in the SABRE complex doubles the number of LACs and, consequently, the number of peaks in the SABRE field dependence. Interestingly, the polarization of SABRE substrates is always accompanied by the para-to-ortho conversion in dihydride species that results in enhancement of the NMR signal of free (H2) and catalyst-bound H2 (Ir-HH). The field dependences of hyperpolarized H2 and Ir-HH by means of SABRE are studied here, for the first time, in detail. The field dependences depend on the chemical shifts and coupling constants of Ir-HH, in which the polarization transfer takes place. A negative coupling constant of -7Hz between the two chemically equivalent but magnetically inequivalent hydride nuclei is determined, which indicates that Ir-HH is a dihydride with an HH distance larger than 2Å. Finally, the field dependence of SABRE at high fields as found earlier has been investigated and attributed to polarization transfer to the substrate by cross-relaxation. The present study provides further evidence for the key role of LACs in the formation of SABRE-derived polarization. Understanding the spin dynamics behind the SABRE method opens the way to optimizing its performance and overcoming the main limitation of NMR, its notoriously low sensitivity.
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Affiliation(s)
- Andrey N Pravdivtsev
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Konstantin L Ivanov
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
| | - Alexandra V Yurkovskaya
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - Pavel A Petrov
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia; Nikolaev Institute of Inorganic Chemistry SB RAS, Acad. Lavrentiev Ave., 3, Novosibirsk 630090, Russia
| | - Hans-Heinrich Limbach
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, Berlin 14195, Germany
| | - Robert Kaptein
- Utrecht University, Bijvoet Center, Padualaan 8, NL-3584 CH Utrecht, The Netherlands
| | - Hans-Martin Vieth
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia; Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
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9
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Tsapatsaris N, Kolesov BA, Fischer J, Boldyreva EV, Daemen L, Eckert J, Bordallo HN. Polymorphism of Paracetamol: A New Understanding of Molecular Flexibility through Local Methyl Dynamics. Mol Pharm 2014; 11:1032-41. [DOI: 10.1021/mp400707m] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | - Boris A. Kolesov
- Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090, Russia
- REC-008 Novosibirsk State University, ul. Pirogova 2, Novosibirsk 630090, Russia
| | | | - Elena V. Boldyreva
- REC-008 Novosibirsk State University, ul. Pirogova 2, Novosibirsk 630090, Russia
- Institute of Solid-State Chemistry and Mechanochemistry SB RAS, Kutateladze 18, Novosibirsk 630128, Russia
| | - Luke Daemen
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Juergen Eckert
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- Department
of Chemistry, University of South Florida, Tampa, Florida 33620, United States
| | - Heloisa N. Bordallo
- European Spallation Source ESS AB, P.O. Box 176, Lund 221 00, Sweden
- Niels Bohr Institute, Universitetsparken
5, Copenhagen 2100, Denmark
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10
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Horsewill AJ, Goh K, Rols S, Ollivier J, Johnson MR, Levitt MH, Carravetta M, Mamone S, Murata Y, Chen JYC, Johnson JA, Lei X, Turro NJ. Quantum rotation and translation of hydrogen molecules encapsulated inside C₆₀: temperature dependence of inelastic neutron scattering spectra. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20110627. [PMID: 23918709 DOI: 10.1098/rsta.2011.0627] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The quantum dynamics of a hydrogen molecule encapsulated inside the cage of a C60 fullerene molecule is investigated using inelastic neutron scattering (INS). The emphasis is on the temperature dependence of the INS spectra which were recorded using time-of-flight spectrometers. The hydrogen endofullerene system is highly quantum mechanical, exhibiting both translational and rotational quantization. The profound influence of the Pauli exclusion principle is revealed through nuclear spin isomerism. INS is shown to be exceptionally able to drive transitions between ortho-hydrogen and para-hydrogen which are spin-forbidden to photon spectroscopies. Spectra in the temperature range 1.6≤T≤280 K are presented, and examples are given which demonstrate how the temperature dependence of the INS peak amplitudes can provide an effective tool for assigning the transitions. It is also shown in a preliminary investigation how the temperature dependence may conceivably be used to probe crystal field effects and inter-fullerene interactions.
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Affiliation(s)
- A J Horsewill
- School of Physics and Astronomy, University of Nottingham, , Nottingham NG7 2RD, UK.
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11
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Molecular flexibility and structural instabilities in crystalline l-methionine. Biophys Chem 2013; 180-181:76-85. [PMID: 23886538 DOI: 10.1016/j.bpc.2013.06.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 06/14/2013] [Accepted: 06/14/2013] [Indexed: 11/22/2022]
Abstract
We have investigated the dynamics in polycrystalline samples of l-methionine related to the structural transition at about 307K by incoherent inelastic and quasielastic neutron scattering, X-ray powder diffraction as well as ab-initio calculations. l-Methionine is a sulfur amino acid which can be considered a derivative of alanine with the alanine R-group CH3 exchanged by CH3S(CH2)2. Using X-ray powder diffraction we have observed at ~190K an anomalous drop of the c-lattice parameter and an abrupt change of the β-monoclinic angle that could be correlated to the anomalies observed in previous specific heat measurements. Distinct changes in the quasielastic region of the neutron spectra are interpreted as being due to the onset and slowing-down of reorientational motions of the CH3-S group, are clearly distinguished above 130K in crystalline l-methionine. Large-amplitude motions observed at low frequencies are also activated above 275K, while other well-defined vibrations are damped. The ensemble of our results suggests that the crystalline structure of l-methionine is dynamically highly disordered above 275K, and such disorder can be linked to the flexibility of the molecular thiol-ether group.
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Abstract
Abstract
The five-fold coordinated ruthenium (II) catalyst RuCl2(PPh3)3 is heterogenized on the surface of amine functionalized mesoporous silica material SBA-3 and studied by BET, XRD and 31P CP-MAS solid-state NMR. The spectra indicate the replacement of one or two of the triphenyl-phosphine groups in the course of the grafting. To distinguish between both possibilities two-dimensional J-resolved 31P MAS solid-state NMR combined with quantum chemical calculations is employed. The changes of the scalar coupling pattern between the neat catalyst and the immobilized catalyst suggest the replacement of two of the PPh3-groups by coordinative bonds to the amine-functions of the linker. DFT calculations reveal the absence of two chemically and magnetically equivalent phosphines and confirm the replacement of two PPh3-groups. This finding is similar to the results observed for the binding of the rhodium in the Wilkinson's catalyst, despite the different coordination of the metals (four-fold versus five-fold), the presence of two chlorine ligands and the different transition metal.
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13
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Gutmann T, del Rosal I, Chaudret B, Poteau R, Limbach HH, Buntkowsky G. From Molecular Complexes to Complex Metallic Nanostructures-2H Solid-State NMR Studies of Ruthenium-Containing Hydrogenation Catalysts. Chemphyschem 2013; 14:3026-33. [DOI: 10.1002/cphc.201300200] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Indexed: 11/08/2022]
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14
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Espino G, Caballero A, Manzano BR, Santos L, Pérez-Manrique M, Moreno M, Jalón FA. Experimental and Computational Evidence for the Participation of Nonclassical Dihydrogen Species in Proton Transfer Processes on Ru–Arene Complexes with Uncoordinated N Centers. Efficient Catalytic Deuterium Labeling of H2 with CD3OD. Organometallics 2012. [DOI: 10.1021/om300015j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gustavo Espino
- Departamento de Quı́mica, Facultad de Ciencias, Universidad de Burgos, Plaza Misael Bañuelos
s/n, 09001 Burgos, Spain
| | - Agustín Caballero
- Departamento de Quı́mica
Inorgánica, Orgánica
y Bioquı́mica, Facultad de Quı́micas, Universidad de Castilla-La Mancha, Avda. Camilo J.
Cela 10, 13071 Ciudad Real, Spain
| | - Blanca R. Manzano
- Departamento de Quı́mica
Inorgánica, Orgánica
y Bioquı́mica, Facultad de Quı́micas, Universidad de Castilla-La Mancha, Avda. Camilo J.
Cela 10, 13071 Ciudad Real, Spain
| | - Lucía Santos
- Departamento de Quı́mica
Fı́sica, Facultad de Quı́micas, Universidad de Castilla-La Mancha, Avda. Camilo J. Cela s/n, 13071
Ciudad Real, Spain
| | - Mercedes Pérez-Manrique
- Departamento de Quı́mica, Facultad de Ciencias, Universidad de Burgos, Plaza Misael Bañuelos
s/n, 09001 Burgos, Spain
| | - Miquel Moreno
- Departament de Quı́mica, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra,
Spain
| | - Félix A. Jalón
- Departamento de Quı́mica
Inorgánica, Orgánica
y Bioquı́mica, Facultad de Quı́micas, Universidad de Castilla-La Mancha, Avda. Camilo J.
Cela 10, 13071 Ciudad Real, Spain
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15
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Schulz F, Sumerin V, Heikkinen S, Pedersen B, Wang C, Atsumi M, Leskelä M, Repo T, Pyykkö P, Petry W, Rieger B. Molecular Hydrogen Tweezers: Structure and Mechanisms by Neutron Diffraction, NMR, and Deuterium Labeling Studies in Solid and Solution. J Am Chem Soc 2011; 133:20245-57. [DOI: 10.1021/ja206394w] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Victor Sumerin
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
| | - Sami Heikkinen
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
| | | | - Cong Wang
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
| | - Michiko Atsumi
- Department of Physical and Analytical Chemistry, Quantum Chemistry, Uppsala University, P.O. Box 518, SE-75120 Uppsala, Sweden
| | - Markku Leskelä
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
| | - Timo Repo
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
| | - Pekka Pyykkö
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
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Došlić N, Gomzi V, Mališ M, Matanović I, Eckert J. Fluxionality of Hydrogen Ligands in Fe(H)2(H2)(PEtPh2)3. Inorg Chem 2011; 50:10740-7. [DOI: 10.1021/ic201248z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nađa Došlić
- Department of Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Vjeran Gomzi
- Department of Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Momir Mališ
- Department of Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Ivana Matanović
- Department of Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Juergen Eckert
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States
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Jiménez-Tenorio M, Puerta MC, Valerga P, Moncho S, Ujaque G, Lledós A. Proton-Transfer Reactions to Half-Sandwich Ruthenium Trihydride Complexes Bearing Hemilabile P,N Ligands: Experimental and Density Functional Theory Studies†Dedicated to Prof. Serafin Bernal in recognition of his contribution to inorganic chemistry, on the occasion of his retirement. Inorg Chem 2010; 49:6035-57. [DOI: 10.1021/ic100710d] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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18
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Limbach HH, Schowen KB, Schowen RL. Heavy atom motions and tunneling in hydrogen transfer reactions: the importance of the pre-tunneling state. J PHYS ORG CHEM 2010. [DOI: 10.1002/poc.1663] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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19
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Macholl S, Matthes J, Limbach HH, Sabo-Etienne S, Chaudret B, Buntkowsky G. High-resolution 2H MAS NMR applied to deuterium analogs of hydrido eta2-dihydrogen complexes. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2009; 36:137-143. [PMID: 19781918 DOI: 10.1016/j.ssnmr.2009.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2009] [Revised: 08/03/2009] [Accepted: 08/14/2009] [Indexed: 05/28/2023]
Abstract
(2)H solid-state, variable temperature magic angle spinning (MAS) NMR spectra of precipitated samples of the deutero dideuterium complexes Ru(D)(2)(eta(2)-D(2))(2)(PCy(3))(2) and RuD(eta(2)-D(2))I(PCy(3))(2) [Cy=cyclohexyl] are presented. They show that even at moderate MAS speed, high resolution is achieved at 7 and 14T allowing (2)H chemical shifts and quadrupole couplings to be obtained and assigned to different solid and gaseous (2)H species. These two parameters allow identifying chemically different hydrogen species in the material. The analysis of these parameters in this study reveals the presence of three different species in the sample, namely the complexes RuD(eta(2)-D(2))I(PCy(3))(2) and RuD(eta(2)-D(2))(2)I(PCy(3))(2), and highly mobile HD/D(2). These assignments are supported by (2)H T(1) relaxation times and (31)P MAS NMR spectra. Moreover, variable temperature MAS NMR spectra reveal temperature-dependent line-shape changes, which are clear indications of intramolecular hydrogen exchange of the deutero and the dideuterium ligands and which give an estimate for the activation energy of this process.
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Affiliation(s)
- Sven Macholl
- Freie Universität Berlin, Institut für Chemie und Biochemie, Takustr. 3, 14195 Berlin, Germany.
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Buntkowsky G, Limbach HH, Walaszek B, Adamczyk A, Xu Y, Breitzke H, Schweitzer A, Gutmann T, Wächtler M, Amadeu N, Tietze D, Chaudret B. Mechanisms of Dipolar Ortho/Para-H2O Conversion in Ice. Z PHYS CHEM 2009. [DOI: 10.1524/zpch.2008.5359] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
In this paper a possible explanation for an unexpected ortho/para-water ratio in the gas clouds of comets is given. The description is based on the quantum-mechanical density matrix formalism and the spin temperature concept. Only the nuclear spin system is treated quantum-mechanically. Employing the model of a four spin system, created by two nearest neighbour water molecules, spin eigenstates and their dynamics under the influence of their mutual dipolar interactions are studied. It is shown that a fast conversion between ortho- and para-states occurs on a msec time scale, caused by the intermolecular homonuclear magnetic dipolar interaction. Moreover the spin eigenstates of water in an ice crystal are determined by magnetic dipolar interactions and are not given by normal ortho- and para-H2O states of gaseous water. As a result of this the spin temperature of gaseous water evaporated from ice depends strongly on its evaporation history and the ortho/para-ratio of water molecules are only an indirect measure of the temperature of ice crystals from where they descend. This result could explain the unexpected experimentally observed ortho/para-ratios in the clouds of comets.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Bruno Chaudret
- Laboratoire de Chimie de Doordination du CNRS, Toulouse Cedex 04, Frankreich
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Adamczyk A, Xu Y, Walaszek B, Roelofs F, Pery T, Pelzer K, Philippot K, Chaudret B, Limbach HH, Breitzke H, Buntkowsky G. Solid State and Gas Phase NMR Studies of Immobilized Catalysts and Catalytic Active Nanoparticles. Top Catal 2008. [DOI: 10.1007/s11244-008-9054-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Lee YJ, Murakhtina T, Sebastiani D, Spiess HW. 2H Solid-State NMR of Mobile Protons: It Is Not Always the Simple Way. J Am Chem Soc 2007; 129:12406-7. [PMID: 17887682 DOI: 10.1021/ja0754857] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Young Joo Lee
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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Perutz RN, Sabo-Etienne S. The sigma-CAM Mechanism: sigma complexes as the basis of sigma-bond metathesis at late-transition-metal centers. Angew Chem Int Ed Engl 2007; 46:2578-92. [PMID: 17380532 DOI: 10.1002/anie.200603224] [Citation(s) in RCA: 478] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Complexes in which a sigma-H--E bond (E=H, B, Si, C) acts as a two-electron donor to the metal center are called sigma complexes. Clues that it is possible to interconvert sigma ligands without a change in oxidation state derive from C--H activation reactions effecting isotope exchange and from dynamic rearrangements of sigma complexes (see Frontispiece). Through these pathways, metathesis of M--E bonds can occur at late transition metals. We call this process sigma-complex-assisted metathesis, or sigma-CAM, which is distinct from the familiar sigma-bond metathesis (typical for d(0) metals and requiring no intermediate) and from oxidative-reductive elimination mechanisms (inherently requiring intermediates with changed oxidation states and sometimes involving sigma complexes). There are examples of sigma-CAM mechanisms in catalysis, especially for alkane borylation and isotope exchange of alkanes. It may also occur in silylation and alkene hydrogenation.
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Affiliation(s)
- Robin N Perutz
- Department of Chemistry, University of York, York, YO10 5DD, UK.
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Perutz R, Sabo-Etienne S. Der σ-CAM-Mechanismus: σ-Komplexe als Schlüssel der σ-Bindungsmetathese bei späten Übergangsmetallen. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200603224] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Limbach HH, Buntkowsky G, Matthes J, Gründemann S, Pery T, Walaszek B, Chaudret B. Novel Insights into the Mechanism of the Ortho/Para Spin Conversion of Hydrogen Pairs: Implications for Catalysis and Interstellar Water. Chemphyschem 2006; 7:551-4. [PMID: 16493700 DOI: 10.1002/cphc.200500559] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The phenomenon of exchange coupling is taken into account in the description of the magnetic nuclear spin conversion between bound ortho- and para-dihydrogen. This conversion occurs without bond breaking, in contrast to the chemical spin conversion. It is shown that the exchange coupling needs to be reduced so that the corresponding exchange barrier can increase and the given magnetic interaction can effectively induce a spin conversion. The implications for related molecules such as water are discussed. For ice, a dipolar magnetic conversion and for liquid water a chemical conversion are predicted to occur within the millisecond timescale. It follows that a separation of water into its spin isomers, as proposed by Tikhonov and Volkov (Science 2002, 296, 2363), is not feasible. Nuclear spin temperatures of water vapor in comets, which are smaller than the gas-phase equilibrium temperatures, are proposed to be diagnostic for the temperature of the ice or the dust surface from which the water was released.
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Affiliation(s)
- Hans-Heinrich Limbach
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany.
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Buntkowsky G, Walaszek B, Adamczyk A, Xu Y, Limbach HH, Chaudret B. Mechanism of nuclear spin initiated para-H2 to ortho-H2 conversion. Phys Chem Chem Phys 2006; 8:1929-35. [PMID: 16633680 DOI: 10.1039/b601594h] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this paper a quantitative explanation for a diamagnetic ortho/para H2 conversion is given. The description is based on the quantum-mechanical density matrix formalism originally developed by Alexander and Binsch for studies of exchange processes in NMR spectra. Only the nuclear spin system is treated quantum-mechanically. Employing the model of a three spin system, the reactions of the hydrogen gas with the catalysts are treated as a phenomenological rate process, described by a rate constant. Numerical calculations reveal that for nearly all possible geometrical arrangements of the three spin system an efficient spin conversion is obtained. Only in the chemically improbable case of a linear group H-X-H no spin conversion is obtained. The efficiency of the spin conversion depends strongly on the lifetime of the H-X-H complex and on the presence of exchange interactions between the two hydrogens. Even moderate exchange couplings cause a quench of the spin conversion. Thus a sufficiently strong binding of the dihydrogen to the S spin is necessary to render the quenching by the exchange interaction ineffective.
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Affiliation(s)
- G Buntkowsky
- FSU Jena, Institut für Physikalische Chemie, Helmholtzweg 4, 07743, Jena, Germany.
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Matthes J, Pery T, Gründemann S, Buntkowsky G, Sabo-Etienne S, Chaudret B, Limbach HH. Bridging the gap between homogeneous and heterogeneous catalysis: ortho/para H(2) conversion, hydrogen isotope scrambling, and hydrogenation of olefins by Ir(CO)Cl(PPh(3))(2). J Am Chem Soc 2004; 126:8366-7. [PMID: 15237979 DOI: 10.1021/ja0475961] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Some transition metal complexes are known to catalyze ortho/para hydrogen conversion, hydrogen isotope scrambling, and hydrogenation reactions in liquid solution. Using the example of Vaska's complex, we present here evidence by NMR that the solvent is not necessary for these reactions to occur. Thus, solid frozen solutions or polycrystalline powdered samples of homogeneous catalysts may become heterogeneous catalysts. Comparative liquid- and solid-state studies provide novel insight into the reaction mechanisms.
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Affiliation(s)
- Jochen Matthes
- Institute of Chemistry, Freie Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany
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Aneetha H, Jiménez Tenorio M, Puerta M, Valerga P. Ruthenium hydrides bearing SbPh3 and AsPh3 ligands: characterization of the bis(dihydrogen) complexes [Cp*Ru(H2)2(EPh3)]+ (Cp*=C5Me5; E=Sb, As). J Organomet Chem 2002. [DOI: 10.1016/s0022-328x(02)01965-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Wehrmann F, Albrecht J, Gedat E, Kubas GJ, Eckert J, Limbach HH, Buntkowsky G. Hydrogen Deuterium Isotope Effect on Exchange Rates in η2 Bond Transition Metal Dihydrogen Complexes Revealed by 2H Solid State NMR Spectroscopy. J Phys Chem A 2002. [DOI: 10.1021/jp012087w] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- F. Wehrmann
- Institut für Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, and LANSCE, Los Alamos National Laboratory, Mail Stop H805, Los Alamos, New Mexico 87545
| | - J. Albrecht
- Institut für Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, and LANSCE, Los Alamos National Laboratory, Mail Stop H805, Los Alamos, New Mexico 87545
| | - E. Gedat
- Institut für Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, and LANSCE, Los Alamos National Laboratory, Mail Stop H805, Los Alamos, New Mexico 87545
| | - G. J. Kubas
- Institut für Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, and LANSCE, Los Alamos National Laboratory, Mail Stop H805, Los Alamos, New Mexico 87545
| | - J. Eckert
- Institut für Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, and LANSCE, Los Alamos National Laboratory, Mail Stop H805, Los Alamos, New Mexico 87545
| | - H.-H. Limbach
- Institut für Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, and LANSCE, Los Alamos National Laboratory, Mail Stop H805, Los Alamos, New Mexico 87545
| | - G. Buntkowsky
- Institut für Chemie der Freien Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany, and LANSCE, Los Alamos National Laboratory, Mail Stop H805, Los Alamos, New Mexico 87545
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Yandulov DV, Huang D, Huffman JC, Caulton KG. Structural distortions in mer-M(H)3(NO)L2 (M = Ru, Os) and their influence on intramolecular fluxionality and quantum exchange coupling. Inorg Chem 2000; 39:1919-32. [PMID: 11428112 DOI: 10.1021/ic991452j] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecules of the type mer-M(H)3(NO)L2 [M = Ru (1), Os (2); L = PR3] are characterized on the basis of 1H NMR T1min values and IR spectra as pseudo-octahedral trihydrides significantly distorted by compression of the cis H-M-H angles to approximately 75 degrees. The distortion, uncharacteristic of six-coordinate d6 complexes, is rationalized with DFT (B3LYP) calculations as being driven by increased H-to-M sigma donation and by the exceptional pi-accepting ability of linear NO+. In both 1 and 2, hydrides undergo intramolecular site exchange with delta HHH++(1) = 10-11 kcal/mol and delta HHH++(2) = 16-20 kcal/mol, depending on L, whereas for mer-Ru(H)3(NO)(PtBu2Me)2 (1b), moderate exchange couplings (up to 77 Hz) are featured in the low-temperature 1H NMR spectra, in addition to chemical exchange. On the basis of experimental and theoretical results, a dihydrogen intermediate is suggested to mediate hydride site exchange in 1. The cis H-M-H distortion shortens the tunneling path for the exchanging hydrides in 1, thereby increasing the tunneling rate; diminishes the "conflict" between trans hydrides in the mer geometry; and decreases the nucleophilicity of the hydrides. The generality of the observed structural distortion and its dependence on the ligand environment in late transition metal tri- and dihydrides are discussed. A less reducing metal center is generally characterized by greater distortion.
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Affiliation(s)
- D V Yandulov
- Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405-4001, USA
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Maseras F, Lledós A, Clot E, Eisenstein O. Transition metal polyhydrides: from qualitative ideas to reliable computational studies. Chem Rev 2000; 100:601-36. [PMID: 11749246 DOI: 10.1021/cr980397d] [Citation(s) in RCA: 312] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- F Maseras
- LSDSMS (UMR 5636) CC 014, Université de Montpellier II, 34095 Montpellier Cedex 05, France
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Facey GA, Fong TP, Gusev D, Macdonald PM, Morris RH, Schlaf M, Xu W. Probing the motion of the η2-dideuterium ligand by solution and solid-state 2H NMR spectroscopy. CAN J CHEM 1999. [DOI: 10.1139/v99-184] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Variable temperature 2H NMR is used to measure the T1min values of the η2-D2 and D ligands in trans-[M(η2-D2)(D)(dppe)2]+, M = Ru (1) and Os (2) in solution. The rapid spinning motion of the η2-D2 ligand results in a much longer T1min than that of the terminal deuteride. The quadrupole coupling constant (CQ) for the terminal deuteride is calculated to be 79 kHz for 1 and 81 kHz for 2 while motion-reduced coupling constant (CQeff) for the D in the η2-D2 ligands in 1 and 2 are in the range 19-22 and 27-31 kHz, respectively. The actual CQ for these ligands with short D-D distances (<1 Å) should be at least 2CQeff and probably greater than that of the terminal deuteride but less than that of D2(g), 227 kHz. A fast spinning (>>61 MHz) and tilting of the primary electric field gradient component of between 90° and 60° or between 50° and 40° with respect to the axis of D2 rotation is an explanation for the small CQeff. Therefore neither D-D nor M-D bonding dominates the electric field gradient direction in these M(η2-D2) bonds. The complex [RuD2(C5Me5)(dppm)]+ 3, which exists in solution as a 3.3:1 mixture of Ru(D···D) (3a) and Ru(D)2 (3b) tautomers, has T1min(D) values that provide CQeff values of 66 kHz for 3a and 71 kHz for 3b. The elongated D···D ligand in 3a with d(D···D) ~ 1.10 Å may be "static" compared to the 61.4 MHz 2H spectrometer frequency and therefore have "compressed dihydride" character and display similar Ru-D bonds as in 3b. However, it is more likely that the static CQ for the D of 3a is much larger than that of a terminal Ru-D but averaged to 66 kHz by a 180° flip of the D2 as observed in 7. The complexes trans-[M(D···D)(Cl)(dppe)2]PF6, M = Ru (4), Os (5), and Ru(η2-D2)(dppb)(µ-Cl)3RuCl(dppb) (6) also have motion-reduced CQ values. Some 2H NMR quadrupole echo wide-line spectra of 1, 4, and Os(D···D)(Cl)2(CO)(PiPr3)2 (7) (contaminated with 20% Os(H···D)) were recorded in the solid phase from 293 to 123 K. These also indicate that the CQeff of the D in the D2 ligands are motion-reduced. Simulation of the spectra of 7 are suggestive of a twofold reorientation of a D2 ligand with a static CQ value in the range of 120-167 kHz, a tilt angle of the electric field gradient of about 50°, and an asymmetry parameter near to zero. Significantly, the MAS 2H spectrum of 7 has a broad doublet, possibly due to a non-averaged D-D dipolar/quadrupolar interference phenomenon; this is first time this has been observed. Variable temperature T1 data for solid 7 are also reported, which allow the evaluation of the activation barrier to the twofold flipping motion of the D2; the only other way of quantifying such an energy barrier is by use of an inelastic neutron scattering method.Key words: dihydrogen, deuterium, NMR, ruthenium, osmium, complexes, dynamics, hydride, bonding.
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