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Leshchev D, Harlang TCB, Fredin LA, Khakhulin D, Liu Y, Biasin E, Laursen MG, Newby GE, Haldrup K, Nielsen MM, Wärnmark K, Sundström V, Persson P, Kjær KS, Wulff M. Tracking the picosecond deactivation dynamics of a photoexcited iron carbene complex by time-resolved X-ray scattering. Chem Sci 2018; 9:405-414. [PMID: 29629111 PMCID: PMC5868308 DOI: 10.1039/c7sc02815f] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Accepted: 10/30/2017] [Indexed: 12/14/2022] Open
Abstract
Recent years have seen the development of new iron-centered N-heterocyclic carbene (NHC) complexes for solar energy applications. Compared to typical ligand systems, the NHC ligands provide Fe complexes with longer-lived metal-to-ligand charge transfer (MLCT) states. This increased lifetime is ascribed to strong ligand field splitting provided by the NHC ligands that raises the energy levels of the metal centered (MC) states and therefore reduces the deactivation efficiency of MLCT states. Among currently known NHC systems, [Fe(btbip)2]2+ (btbip = 2,6-bis(3-tert-butyl-imidazol-1-ylidene)pyridine) is a unique complex as it exhibits a short-lived MC state with a lifetime on the scale of a few hundreds of picoseconds. Hence, this complex allows for a detailed investigation, using 100 ps X-ray pulses from a synchrotron, of strong ligand field effects on the intermediate MC state in an NHC complex. Here, we use time-resolved wide angle X-ray scattering (TRWAXS) aided by density functional theory (DFT) to investigate the molecular structure, energetics and lifetime of the high-energy MC state in the Fe-NHC complex [Fe(btbip)2]2+ after excitation to the MLCT manifold. We identify it as a 260 ps metal-centered quintet (5MC) state, and we refine the molecular structure of the excited-state complex verifying the DFT results. Using information about the hydrodynamic state of the solvent, we also determine, for the first time, the energy of the 5MC state as 0.75 ± 0.15 eV. Our results demonstrate that due to the increased ligand field strength caused by NHC ligands, upon transition from the ground state to the 5MC state, the metal to ligand bonds extend by unusually large values: by 0.29 Å in the axial and 0.21 Å in the equatorial direction. These results imply that the transition in the photochemical properties from typical Fe complexes to novel NHC compounds is manifested not only in the destabilization of the MC states, but also in structural distortion of these states.
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Affiliation(s)
- Denis Leshchev
- European Synchrotron Radiation Facility , 71 Avenue des Martyrs , 38000 Grenoble , France .
| | - Tobias C B Harlang
- Department of Chemical Physics , Lund University , P. O. Box 12 4 , 22100 Lund , Sweden
- Molecular Movies Group , Department of Physics , Technical University of Denmark , Lyngby , DK-2800 , Denmark
| | - Lisa A Fredin
- Theoretical Chemistry Division , Lund University , P. O. Box 124 , 22100 Lund , Sweden
| | | | - Yizhu Liu
- Centre for Analysis and Synthesis , Department of Chemistry , Lund University , P. O. Box 12 4 , Lund 22100 , Sweden
| | - Elisa Biasin
- Molecular Movies Group , Department of Physics , Technical University of Denmark , Lyngby , DK-2800 , Denmark
| | - Mads G Laursen
- Molecular Movies Group , Department of Physics , Technical University of Denmark , Lyngby , DK-2800 , Denmark
| | - Gemma E Newby
- European Synchrotron Radiation Facility , 71 Avenue des Martyrs , 38000 Grenoble , France .
| | - Kristoffer Haldrup
- Molecular Movies Group , Department of Physics , Technical University of Denmark , Lyngby , DK-2800 , Denmark
| | - Martin M Nielsen
- Molecular Movies Group , Department of Physics , Technical University of Denmark , Lyngby , DK-2800 , Denmark
| | - Kenneth Wärnmark
- Centre for Analysis and Synthesis , Department of Chemistry , Lund University , P. O. Box 12 4 , Lund 22100 , Sweden
| | - Villy Sundström
- Department of Chemical Physics , Lund University , P. O. Box 12 4 , 22100 Lund , Sweden
| | - Petter Persson
- Theoretical Chemistry Division , Lund University , P. O. Box 124 , 22100 Lund , Sweden
| | - Kasper S Kjær
- Department of Chemical Physics , Lund University , P. O. Box 12 4 , 22100 Lund , Sweden
- Molecular Movies Group , Department of Physics , Technical University of Denmark , Lyngby , DK-2800 , Denmark
| | - Michael Wulff
- European Synchrotron Radiation Facility , 71 Avenue des Martyrs , 38000 Grenoble , France .
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Alvarez S. Distortion Pathways of Transition Metal Coordination Polyhedra Induced by Chelating Topology. Chem Rev 2015; 115:13447-83. [PMID: 26575868 DOI: 10.1021/acs.chemrev.5b00537] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A continuous shape measures analysis of the coordination polyhedra of a host of transition metal complexes with bi- and multidentate ligands discloses the distortion pathway associated with each particular topology of the chelate rings formed. The basic parameter that controls the degree of distortion is the metal-donor atom bond distance that induces nonideal bond angles due to the rigidity of the ligands. Thus, the degree of distortion within each family of complexes depends on the atomic size, on which the high- or low-spin state has a large effect. Special attention is therefore paid to several spin-crossover systems and to the enhanced distortions that go along with the transition from low- to high-spin state affected by temperature, light, or pressure. Several families of complexes show deviations from the expected distortion pathways in the high-spin state that can be associated to the onset of intermolecular interactions such as secondary coordination of counterions or solvent molecules. Also, significant displacement of counterions in an extended solid may result from the changes in metal-ligand bond distances when ligands are involved in intermolecular hydrogen bonding.
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Affiliation(s)
- Santiago Alvarez
- Departament de Química Inorgànica and Institut de Química Teòrica i Computacional, Universitat de Barcelona , Martí i Franquès 1-11, 08028 Barcelona, Spain
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Kusz J, Bronisz R, Zubko M, Bednarek G. On the Role of Intermolecular Interactions on Structural and Spin-Crossover Properties of 2D Coordination Networks [Fe(bbtr)3]A2 (bbtr=1,4-bis(1,2,3-triazol-1-yl)butane; A=ClO4−, BF4−). Chemistry 2011; 17:6807-20. [PMID: 21547970 DOI: 10.1002/chem.201100394] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Indexed: 11/08/2022]
Affiliation(s)
- Joachim Kusz
- Institute of Physics, University of Silesia, Katowice, Poland
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Białońska A, Bronisz R. High Spin and Spin-Crossover Two-Dimensional Coordination Polymers Containing FeII(tetrazol-2-yl)4(solv)2 (solv = Ethanol, Acetonitrile) Cores Linked by Flexible/Elastic Spacers. Inorg Chem 2010; 49:4534-42. [DOI: 10.1021/ic9024603] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Agata Białońska
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland
| | - Robert Bronisz
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland
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Białońska A, Bronisz R, Weselski M. A New Family of Spin-Crossover Complexes Based on a FeII(Tetrazolyl)4(MeCN)2-Type Core. Inorg Chem 2008; 47:4436-8. [DOI: 10.1021/ic8002993] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Agata Białońska
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383, Wrocław, Poland
| | - Robert Bronisz
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383, Wrocław, Poland
| | - Marek Weselski
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383, Wrocław, Poland
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Halcrow MA. The spin-states and spin-transitions of mononuclear iron(II) complexes of nitrogen-donor ligands. Polyhedron 2007. [DOI: 10.1016/j.poly.2007.03.033] [Citation(s) in RCA: 270] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Dova E, Peschar R, Sakata M, Kato K, Schenk H. High-Spin- and Low-Spin-State Structures of [Fe(chloroethyltetrazole)6](ClO4)2 from Synchrotron Powder Diffraction Data. Chemistry 2006; 12:5043-52. [PMID: 16642523 DOI: 10.1002/chem.200501594] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The spin-crossover complex [Fe(teec)(6)](ClO(4))(2) (teec = chloroethyltetrazole) exhibits a 50 % incomplete spin crossover in the temperature range 300-30 K. Time-resolved synchrotron powder diffraction experiments have been carried out to elucidate its structural behavior. We report crystal structure models of this material at 300 K (high spin) and 90 K (low spin), as solved from synchrotron powder diffraction data by using Genetic Algorithm and Parallel Tempering techniques and refined with Rietveld refinement. During short synchrotron powder diffraction experiments (five minutes duration) two distinguishable lattices were observed the quantities of which vary with temperature. The implication of this phenomenon, that is interpreted as a structural phase transition associated with the high-to-low spin crossover, and the structural characteristics of the high-spin and low-spin models are discussed in relation to other compounds showing a similar type of spin-crossover behavior.
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Affiliation(s)
- Eva Dova
- University of Amsterdam, Faculty of Science van't Hoff Institute for Molecular Sciences, Laboratory for Crystallography, Valckenierstraat 65, 1018 XE, Amsterdam, The Netherlands.
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Dova E, Peschar R, Takata M, Nishibori E, Schenk H, Stassen AF, Haasnoot JG. Low-Spin State Structure of [Fe(chloroethyltetrazole)6](BF4)2 Obtained from Synchrotron Powder Diffraction Data. Chemistry 2005; 11:5855-65. [PMID: 16041818 DOI: 10.1002/chem.200500036] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The complex [Fe(teec)6](BF4)2 (teec = chloroethyltetrazole) shows a two-step complete spin-crossover transition in the temperature range 300-90 K. Time-resolved synchrotron powder diffraction experiments have been carried out in this temperature range, and crystal structure models have been obtained from the powder patterns by using the parallel tempering technique. Of these models, the low-spin state structure at 90 K has been refined completely with Rietveld refinement. Its structural characteristics are discussed in relation to the high-spin state model and other spin-crossover compounds. The complex shows a remarkable anisotropic unit-cell parameter contraction that is dependent on the applied cooling rate. In addition, the possible important implications for the interpretation of spin-crossover behavior in terms of structural changes are discussed.
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Affiliation(s)
- Eva Dova
- University of Amsterdam, Faculty of Science, van't Hoff Institute for Molecular Sciences, Laboratory of Crystallography, Valckenierstraat 65, 1018XE Amsterdam, The Netherlands.
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Grunert CM, Weinberger P, Schweifer J, Hampel C, Stassen AF, Mereiter K, Linert W. Synthesis and characterisation of tetrazole compounds: 3 series of new ligands representing versatile building blocks for iron(II) spin-crossover compounds. J Mol Struct 2005. [DOI: 10.1016/j.molstruc.2004.07.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Hibbs W, van Koningsbruggen PJ, Arif AM, Shum WW, Miller JS. One- and two-step spin-crossover behavior of [Fe(II)(isoxazole)(6)](2+) and the structure and magnetic properties of triangular [Fe(III)(3)O(OAc)(6)(isoxazole)(3)][ClO(4)]. Inorg Chem 2003; 42:5645-53. [PMID: 12950213 DOI: 10.1021/ic034226p] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structure and spin-crossover magnetic behavior of [Fe(II)1(6)][BF(4)](2) (1 = isoxazole) and [Fe(II)1(6)][ClO(4)](2) have been studied. [Fe(II)1(6)][BF(4)](2) undergoes two reversible spin-crossover transitions at 91 and 192 K, and is the first two-step spin transition to undergo a simultaneous crystallographic phase transition, but does not exhibit thermal hysteresis. The single-crystal structure determinations at 260 [space group P3, a = 17.4387(4) A, c = 7.6847(2) A] and at 130 K [space group P1, a = 17.0901(2) A, b = 16.7481(2) A, c = 7.5413(1) A, alpha = 90.5309(6) degrees, beta = 91.5231(6) degrees, gamma = 117.8195(8) degrees ] reveal two different iron sites, Fe1 and Fe2, in a 1:2 ratio. The room-temperature magnetic moment of 5.0 mu(B) is consistent with high-spin Fe(II). A plateau in mu(T) having a moment of 3.3 mu(B) centered at 130 K suggests a mixed spin system of some high-spin and some low-spin Fe(II) molecules. On the basis of the Fe-N bond distances at the two temperatures, and the molar fraction of high-spin molecules at the transition plateau, Fe1 and Fe2 can be assigned to the 91 and 192 K transitions, respectively. [Fe(II)1(6)][ClO(4)](2) [space group P3, a = 17.5829(3) A, c = 7.8043(2) A, beta = 109.820 (3) degrees, T = 295 K] also possesses Fe1:Fe2 in a 1:2 ratio, and magnetic measurements show a single spin transition at 213 K, indicating that both Fe1 and Fe2 undergo a simultaneous spin transition. [Fe(II)1(6)][ClO(4)](2) slowly decomposes in solutions containing acetic anhydride to form [Fe(III)(3)O(OAc)(6)1(3)][ClO(4)] [space group I2, a = 10.1547(7) A, b = 16.5497(11) A, c = 10.3205(9) A, beta = 109.820 (3) degrees, T = 200 K]. The isosceles Fe(3) unit contains two Fe.Fe distances of 3.2844(1) A and a third Fe.Fe distance of 3.2857(1) A. The magnetic data can be fit to a trinuclear model with H = -2J(S(1)xS(2) + S(2)xS(3)) - 2J(13)(S(1)xS(3)), where J = -27.1 and J(13) = -32.5 cm(-1).
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Affiliation(s)
- Wendy Hibbs
- Department of Chemistry, University of Utah, 315 S. 1400 E. RM Dock, Salt Lake City, Utah 84112-0850, USA
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Alvarez S. Relationships between temperature, magnetic moment, and continuous symmetry measures in spin crossover complexes. J Am Chem Soc 2003; 125:6795-802. [PMID: 12769591 DOI: 10.1021/ja0283450] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A study of the changes in the symmetry of the metal coordination sphere that accompany spin crossover transitions has been carried out. Changes in symmetry have been calibrated by using the continuous symmetry measures approach. Different behaviors have been found for several families of complexes, depending on the nature of their ligands. The most remarkable changes take place for trischelate complexes, for which octahedricity, trigonal prismacity, chirality, bite angle, bond distance, tempeature, pressure, magnetic moment, and density are correlated.
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Affiliation(s)
- Santiago Alvarez
- Departament de Química Inorgànica and Centre de Recerca en Química Teòrica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain.
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Spin crossover in hexakis(1-(2-chloroethyl)-tetrazole)iron(II) complexes; synthesis and magnetic properties. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(02)00759-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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