151
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Sheu CF, Pillet S, Lin YC, Chen SM, Hsu IJ, Lecomte C, Wang Y. Magnetostructural Relationship in the Spin-Crossover Complex t-{Fe(abpt)2[N(CN)2]2}: Polymorphism and Disorder Phenomenon. Inorg Chem 2008; 47:10866-74. [DOI: 10.1021/ic800879c] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chou-Fu Sheu
- Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, and LCM3B, UMR CNRS 7036, Nancy-Université, BP 239, 54506 Vandoeuvre-les-Nancy, France
| | - Sébastien Pillet
- Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, and LCM3B, UMR CNRS 7036, Nancy-Université, BP 239, 54506 Vandoeuvre-les-Nancy, France
| | - Yen-Chen Lin
- Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, and LCM3B, UMR CNRS 7036, Nancy-Université, BP 239, 54506 Vandoeuvre-les-Nancy, France
| | - Szu-Miao Chen
- Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, and LCM3B, UMR CNRS 7036, Nancy-Université, BP 239, 54506 Vandoeuvre-les-Nancy, France
| | - I-Jui Hsu
- Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, and LCM3B, UMR CNRS 7036, Nancy-Université, BP 239, 54506 Vandoeuvre-les-Nancy, France
| | - Claude Lecomte
- Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, and LCM3B, UMR CNRS 7036, Nancy-Université, BP 239, 54506 Vandoeuvre-les-Nancy, France
| | - Yu Wang
- Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan, and LCM3B, UMR CNRS 7036, Nancy-Université, BP 239, 54506 Vandoeuvre-les-Nancy, France
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152
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Quesada M, Prins F, Bill E, Kooijman H, Gamez P, Roubeau O, Spek A, Haasnoot J, Reedijk J. Counterion Effect on the Spin-Transition Properties of the Cation [Fe(btzx)3]2+(btzx=m-Xylylenebis(tetrazole)). Chemistry 2008; 14:8486-99. [DOI: 10.1002/chem.200800990] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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153
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The interaction between the spin transition and a crystallographic phase transition in the spin-crossover compound [Fe(bbtr)3](ClO4)2: Nucleation, formation of domains and fluctuations. Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2008.03.064] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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154
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Genre C, Jeanneau E, Bousseksou A, Luneau D, Borshch S, Matouzenko G. First Dicyanamide-Bridged Spin-Crossover Coordination Polymer: Synthesis, Structural, Magnetic, and Spectroscopic Studies. Chemistry 2008; 14:697-705. [DOI: 10.1002/chem.200700998] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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155
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Bonnet S, Siegler MA, Costa JS, Molnár G, Bousseksou A, Spek AL, Gamez P, Reedijk J. A two-step spin crossover mononuclear iron(ii) complex with a [HS–LS–LS] intermediate phase. Chem Commun (Camb) 2008:5619-21. [DOI: 10.1039/b811746b] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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156
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Bhattacharjee A, van Koningsbruggen PJ, Hibbs W, Miller JS, Gütlich P. Study of thermal spin crossover in [Fe(II)(isoxazole)(6)](BF(4))(2) with Mössbauer spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:406202. [PMID: 22049101 DOI: 10.1088/0953-8984/19/40/406202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
(57)Fe Mössbauer spectroscopy of the mononuclear [Fe(II)(isoxazole)(6)](BF(4))(2) compound has been studied to reveal the thermal spin crossover of Fe(II) between low-spin (S = 0) and high-spin (S = 2) states. A temperature-dependent spin transition curve has been constructed with the least-square fitted data obtained from the Mössbauer spectra measured at various temperatures in the 240-60 K range during the cooling and heating cycle. The compound exhibits a temperature-dependent two-step spin transition phenomenon with T(SCO) (step 1) = 92 and T(SCO) (step 2) = 191 K. The compound has three high-spin Fe(II) sites at the highest temperature of study; among them, two have slightly different coordination environments. These two Fe(II) sites are found to undergo a spin transition, while the third Fe(II) site retains the high-spin state over the whole temperature range. Possible reasons for the formation of the two steps in the spin transition curve are discussed. The observations made from the present study are in complete agreement with those envisaged from earlier magnetic and structural studies made on [Fe(II)(isoxazole)(6)](BF(4))(2), but highlights the nature of the spin crossover mechanism.
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Affiliation(s)
- A Bhattacharjee
- Institut für Anorganische Chemie und Analytische Chemie, Johannes-Gutenberg Universität, D-55099 Mainz, Germany
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157
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158
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Nasser J, Topçu S, Chassagne L, Bousseksou A, Guillon T, Alayli Y. 3d Electrons-molecular vibrations coupling in spin conversion compounds molecules: A quantitative study for the [Fe(phen)2(NCS)2] molecules. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.07.109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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159
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Leita BA, Neville SM, Halder GJ, Moubaraki B, Kepert CJ, Létard JF, Murray KS. Anion−Solvent Dependence of Bistability in a Family of Meridional N-Donor-Ligand-Containing Iron(II) Spin Crossover Complexes. Inorg Chem 2007; 46:8784-95. [PMID: 17854174 DOI: 10.1021/ic7010919] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Five mononuclear spin crossover iron(II) bis-meridional ligand complexes of the general formula [Fe(L)(2)](X)(2).solvent, have been synthesized, where X = BF(4)- or ClO(4)-; L = 2-(1-pyridin-2-ylmethyl-1H-pyrazol-3-yl)-pyrazine (picpzpz) or 2-(3-(2-pyridyl)pyrazol-1-ylmethyl)pyridine) (picpypz); solvent = MeOH or EtOH. The magnetic and structural consequences of systematic variation of meridional ligand, solvent, and anion, including a desolvated species, have been investigated. The complex [Fe(picpzpz)(2)](BF(4))(2).MeOH, 1.MeOH, displays several unique properties including a two-step spin transition with a gradual higher-temperature step ((1)T(1/2) = 197 K) and an abrupt low-temperature step with hysteresis ((2)T(1/2) = 91/98 K) and a metastable intermediate spin state below 70 K with quench-cooling. Removal of the solvent methanol results in the loss of the abrupt step and associated hysteresis (T(1/2) = 150 K). The complexes [Fe(picpzpz)(2)](BF(4))(2).EtOH (1.EtOH), [Fe(picpzpz)(2)](ClO(4))(2).MeOH (2.MeOH), [Fe(picpzpz)(2)](ClO(4))(2).EtOH (2.EtOH), and [Fe(picpypz)(2)](BF(4))(2).MeOH (3.MeOH) all show gradual one-step spin transitions with T(1/2) values in the range 210-250 K. Photomagnetic LIESST measurements on 1.MeOH reveal a near-quantitative excitation of high-spin sites and a unique two-step relaxation process related to the two-step thermal spin transition ((1)T(LIESST) = 49 K and (2)T(LIESST) = 70 K). The structural consequences of the unusual spin transition displayed by 1.MeOH have been investigated by single-crystal X-ray diffraction structural analyses between 25 and 293 K. Detailed characterization of the unit cell parameter evolution vs temperature reflects both the gradual high-temperature step and abrupt low-temperature step, including the thermal hysteresis, observed magnetically.
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Affiliation(s)
- Ben A Leita
- School of Chemistry, Building 23, Monash University, Clayton, Victoria 3800, Australia
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160
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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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161
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Guillon T, Salmon L, Molnár G, Zein S, Borshch S, Bousseksou A. Investigation of the Two-Step Spin Crossover Complex Fe[5-NO2-sal-(1,4,7,10)] Using Density Functional Theory. J Phys Chem A 2007; 111:8223-8. [PMID: 17567114 DOI: 10.1021/jp071686l] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A quantum chemical study of the Fe[5-NO2-sal-(1,4,7,10)] ((1,10-bis(5-nitrosalicylaldehyde)-1,4,7,10-tetra-ezdecane-O,O',N,N',N' ',N' '')iron(II)) molecule was performed using density functional theory (DFT). Starting from the different X-ray crystallographic structures, geometry optimizations have been performed. These calculations confirmed the conformational isomerism of this complex in each spin states of the molecule ((1)A(1g) and (5)T(2g)). Each employed DFT method (B3LYP, B3LYP*, BP86, HCTH407) reproduced correctly the structural differences between the two calculated conformers when compared to the experimental structures. Furthermore, electronic polarizabilities have been calculated in each spin state and for each conformer. These calculations revealed a higher polarizability in the singlet state in agreement with the measured higher dielectric constant in this state.
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Affiliation(s)
- Thomas Guillon
- Laboratoire de Chimie de Coordination, UPR 8241 CNRS, 205 route de Narbonne, 31077 Toulouse Cedex, France
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162
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Sun CC. Thermal expansion of organic crystals and precision of calculated crystal density: a survey of Cambridge Crystal Database. J Pharm Sci 2007; 96:1043-52. [PMID: 17455328 DOI: 10.1002/jps.20928] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
True density is a physical property of both fundamental and practical importance to the study of pharmaceutical powders. True density may be calculated from crystal structure. However, precision of such calculated density is not well understood. Furthermore, thermal expansion properties of organic crystals have rarely been characterized. A survey of Cambridge Crystal Database is conducted to assess (1) precision of calculated crystal density from crystal structure; (2) thermal expansion properties of organic crystals. It is shown that calculated crystal density exhibits, on average, a relative standard deviation (RSD) of approximately 0.4%. It is found that crystal density generally increases linearly with decreasing temperature provided no phase change occurs. Slope of the line, termed thermal density gradient, of organic crystals ranges between 0.04 and 1.74 mg cm(-3) K(-1) with an average of approximately 0.2 mg cm(-3) K(-1). It is shown that majority polymorph pairs exhibit significantly different thermal expansion behavior and their density-temperature lines can cross. This likely contributes to the less than perfect prediction of relative stability of polymorphs at ambient temperature using the density rule.
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Affiliation(s)
- Changquan Calvin Sun
- Amgen Inc., Materials Science Laboratory, Small Molecule Pharmaceutics, One Amgen Center Dr. 21-2-A, Thousand Oaks, California 91320, USA.
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163
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Grunert CM, Goodwin HA, Carbonera C, Létard JF, Kusz J, Gütlich P. Unusual Spin Transition Behavior in 2,6-Bis((pyrazol-3-yl)-pyridine) Iron(II)-bis-oxalato-platinate(II). J Phys Chem B 2007; 111:6738-47. [PMID: 17439168 DOI: 10.1021/jp068774a] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[Fe(bpp)2][Pt(ox)2].H2O (with bpp=2,6-bis(pyrazol-3-yl)-pyridine and ox=oxalate) was prepared, and its spin crossover behavior was characterized. The two-step spin transition behavior changes over several cycles. The original behavior is restored when the sample is allowed to relax for a week. Furthermore, the ST exhibits a strong dependence on the heating and cooling rate. Heating the compound at 1 K/min leads to a spin transition with a third step and a second plateau at gammaHS approximately 0.8. Quenching the sample to 77 K also affects the spin transition behavior. The kinetic relaxation is followed after quenching and after light-induced excited spin state trapping experiments.
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Affiliation(s)
- C Matthias Grunert
- Institut für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität Mainz, Staudingerweg 9, D-55099 Mainz, Germany
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164
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Zhang W, Zhao F, Liu T, Yuan M, Wang ZM, Gao S. Spin Crossover in a Series of Iron(II) Complexes of 2-(2-Alkyl-2H-tetrazol-5-yl)-1,10-phenanthroline: Effects of Alkyl Side Chain, Solvent, and Anion. Inorg Chem 2007; 46:2541-55. [PMID: 17328541 DOI: 10.1021/ic062062h] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2-(2H-Tetrazol-5-yl)-1,10-phenanthroline (HL0), its alkyl-substituted derivatives (Ln, where n = 1-8, 10, 12, 14, and 16, denoting the carbon atom number of the alkyl chain) at the 2H position of the tetrazole ring, and their iron(II) complexes (a for [Fe(L0)2], na for [Fe(Ln)2](ClO4)2, and nb for [Fe(Ln)2](BF4)2) were synthesized and characterized. The crystal structures of a, a.CH3OH, 1a.CH3OH, 1b.CH3OH.CH3CN, 2a.H2O, 2b.H2O, 4b.CH3OH, 5a.H2O, 5b.H2O, 6a, 6b, 7a, 7b, and 16a are described, along with thermal analyses. a undergoes an abrupt spin crossover (SCO) at 255 K with a hysteresis loop of 6 K. a.CH3OH, 2a.H2O, and 2b.H2O exhibit irreversible SCO behaviors due to the loss of solvent molecules upon heating. 3a, 3b, 4a, and 5a.H2O show simple spin transitions above 350 K. The desolvated samples of 4b.CH3OH and 5b.H2O undergo two-step spin transitions. 16a exhibits a two-step SCO behavior between 100 and 300 K, corresponding to sequential phase transitions from the low-spin (LS) phase to the intermediate phase and then to the high-spin phase, respectively, proved by crystal structure analysis and 57Fe Mössbauer spectroscopy. 1a.CH3OH, 10a, 10b, 12a, 12b, 14a, 14b, and 16b show gradual and incomplete SCO behaviors after cooling down from 400 K. 1b.CH3OH.CH3CN, 6a, 6b, 7a, 7b, 8a, and 8b remain in the LS state even at 400 K. This proves that the alkyl side chains, together with the solvent molecules and anions, play a crucial role in the complicated SCO behaviors in this system.
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Affiliation(s)
- Wen Zhang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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165
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Krivokapic I, Zerara M, Daku ML, Vargas A, Enachescu C, Ambrus C, Tregenna-Piggott P, Amstutz N, Krausz E, Hauser A. Spin-crossover in cobalt(II) imine complexes. Coord Chem Rev 2007. [DOI: 10.1016/j.ccr.2006.05.006] [Citation(s) in RCA: 198] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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166
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Rodríguez-Velamazán JA, Castro M, Palacios E, Burriel R, Kitazawa T, Kawasaki T. A Two-Step Spin Transition with a Disordered Intermediate State in a New Two-Dimensional Coordination Polymer. J Phys Chem B 2007; 111:1256-61. [PMID: 17253737 DOI: 10.1021/jp066010p] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The two-dimensional (2D) polymeric spin crossover (SCO) compound Fe(py)2[Ag(CN)2]2 has been synthesized. The compound shows a two-step spin transition detected by magnetic, heat capacity, and X-ray diffraction measurements. The magnetic moment shows a high-temperature step (step 1) occurring at 146.3 K without hysteresis, while the low-temperature step (step 2) happens at 84 K on cooling and 98.2 K on heating. These measurements reveal a large amount of residual high spin (HS) species (23%) and that HS state trapping occurs at cooling rates of around 1 K min(-1) or higher. The two-step behavior has been confirmed by heat capacity, which gives, for steps 1 and 2, respectively, DeltaH1 = 3.33 kJ mol(-1), DeltaS1 = 22.6 J mol(-1) K(-1), and DeltaH2 = 1.51 kJ mol(-1), DeltaS2 = 15.7 J mol(-1) K(-1). For step 2 a hysteresis of 10 K has been determined with dynamic measurements. Powder X-ray diffraction at room temperature shows that the compound is isostructural to Cd(py)2[Ag(CN)2]2 previously reported. Powder X-ray diffraction indicates that there is only one crystallographic site for iron(II) in the whole temperature range, confirmed by Mössbauer spectroscopy. The X-ray diffraction study at different temperatures do not show any superstructure in the region between the transitions, discarding a crystallographic phase transition as the origin of the two-step behavior. However, an unexpected increase of the thermal factor is detected on lowering the temperature and considered as a manifestation of a disordered state between the two steps, consisting of a mixing of HS and LS species without long-range order.
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Affiliation(s)
- J Alberto Rodríguez-Velamazán
- Instituto de Ciencia de Materiales de Aragón, CSIC - Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
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167
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Gaspar AB, Ksenofontov V, Reiman S, Gütlich P, Thompson AL, Goeta AE, Muñoz MC, Real JA. Mössbauer Investigation of the Photoexcited Spin States and Crystal Structure Analysis of the Spin-Crossover Dinuclear Complex [{Fe(bt)(NCS)2}2bpym] (bt=2,2′-Bithiazoline, bpym=2,2′-Bipyrimidine). Chemistry 2006; 12:9289-98. [PMID: 16991185 DOI: 10.1002/chem.200600559] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The crystal structure of the complex [{Fe(bt)(NCS)(2)}(2)bpym] (1) (bt=2,2'-bithiazoline, bpym=2,2'-bipyrimidine) has been solved at 293, 240, 175 and 30 K. At all four temperatures the crystal remains in the P space group with a=8.7601(17), b=9.450(2), c=12.089(3) A, alpha=72.77(2), beta=79.150(19), gamma=66.392(18) degrees , V=873.1(4) Angstrom(3) (data for 293 K structure). The structure consists of centrosymmetric dinuclear units in which each iron(II) atom is coordinated by two NCS(-) ions in the cis position and two nitrogen atoms of the bridging bpym ligand, with the remaining positions occupied by the peripheral bt ligand. The iron atom is in a severely distorted octahedral FeN(6) environment. The average Fe--N bond length of 2.15(9) Angstrom indicates that compound 1 is in the high-spin state (HS-HS) at 293 K. Crystal structure determinations at 240, 175 and 30 K gave a cell comparable to that seen at 293 K, but reduced in volume. At 30 K, the average Fe--N distance is 1.958(4) Angstrom, showing that the structure is clearly low spin (LS-LS). At 175 K the average Fe--N bond length of 2.052(11) Angstrom suggests that there is an intermediate phase. Mössbauer investigations of the light-induced excited spin state trapping (LIESST) effect (lambda=514 nm, 25 mW cm(-2)) in 1 (4.2 K, H(ext)=50 kOe) show that the excited spin states correspond to the HS-HS and HS-LS pairs. The dynamics of the relaxation of the photoexcited states studied at 4.2 K and H(ext)=50 kOe demonstrate that HS-HS pairs revert with time to both HS-LS and LS-LS configurations. The HS-LS photoexcited pairs relax with time back to the ground LS-LS configuration. Complex [{Fe(0.15)Zn(0.85)(bt)(NCS)(2)}(2)bpym] (2) exhibits a continuous spin transition centred around 158 K in contrast to the two-step transition observed for 1. The different spin-crossover behaviour observed for 2 is due to the decrease of cooperativity (intermolecular interactions) imposed by the matrix of Zn(II) ions. This clearly demonstrates the role of the intermolecular interactions in the stabilization of the HS-LS intermediate state in 1.
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Affiliation(s)
- Ana B Gaspar
- Institut de Ciència Molecular/Departament de Química Inorgánica, Universitat de València, Edifici de Instituts de Paterna, Apartat de Correus 22085, 46071 València, Spain
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168
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Malassa A, Görls H, Buchholz A, Plass W, Westerhausen M. Pyridylmethylamines as Ligands in Iron Halide Complexes – Coordination Behaviour Depending on the Halide, the Denticity of the Amino Ligand and the Oxidation State of Iron. Z Anorg Allg Chem 2006. [DOI: 10.1002/zaac.200600200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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169
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The Role of Binary and Many-Centre Molecular Interactions in Spin Crossover in the Solid State. Part IV. Ordering in Systems with Many-Body Interactions. MONATSHEFTE FUR CHEMIE 2006. [DOI: 10.1007/s00706-006-0533-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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170
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Bréfuel N, Imatomi S, Torigoe H, Hagiwara H, Shova S, Meunier JF, Bonhommeau S, Tuchagues JP, Matsumoto N. Structural−Electronic Correlation in the First-Order Phase Transition of [FeH2L2-Me](ClO4)2 (H2L2-Me = Bis[((2-methylimidazol-4-yl)methylidene)-3- aminopropyl]ethylenediamine). Inorg Chem 2006; 45:8126-35. [PMID: 16999410 DOI: 10.1021/ic060674w] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis and detailed study of the new mononuclear spin crossover complex [Fe(II)H2L(2-Me)](ClO4)2 (where H2L(2-Me) = bis[((2-methylimidazol-4-yl)methylidene)-3-aminopropyl]ethylenediamine) are reported. Variable-temperature magnetic susceptibility measurements show the occurrence of a steep spin crossover centered at 171.5 K with a hysteresis loop of ca. 5 K width (T(/2)(increasing) = 174 K and T(1/2)(decreasing) = 169 K, for increasing and decreasing temperatures, respectively). The crystal structure has been resolved for the high-spin (HS) and low-spin (LS) states at 200 and 123 K, respectively, revealing a crystallographic phase transition that occurs concomitantly to the spin crossover: at 200 K, the complex crystallizes in the monoclinic system, space group P2(1)/n, while the space group is P2(1) at 123 K. The mean Fe-N distances are shortened by 0.2 A, but the thermal spin crossover is accompanied by significant structural changes: the rearrangement of the central atom C12 of a six-membered chelate ring of [Fe(II)H2L(2-Me)]2+ to two positions (C12A and C12B) and, consequently, the lack of an inversion center at 123 K (P2(1) space group). Both HS and LS supramolecular structures involve all possible hydrogen bonds between imidazole and amine NH functions, and perchlorate anions; however, the HS supramolecular structure is a one-dimensional (1D) network, and the LS phase may better be described as a two-dimensional (2D) extended structure of A and B molecules. The structural phase transition of [FeH2L(2-Me)](ClO4)2 seems to trigger the steep and hysteretic spin crossover. Discontinuities in the temperature dependence of the Mössbauer parameters (isomer shift and quadrupole splitting) at the spin crossover temperature confirmed the occurrence of a structural phase transition. The experimental enthalpy and entropy variations were determined by differential scanning calorimetry (DSC) as 7.5 +/- 0.4 kJ/mol and 45 +/- 3 J K(-1) mol(-1), respectively. The regular solution theory was applied to the experimental data, yielding an interaction parameter of Gamma = 3.36 kJ/mol, which is larger than 2RT(1/2), which fulfills the condition for observing hysteresis.
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Affiliation(s)
- Nicolas Bréfuel
- Department of Chemistry, Faculty of Sciences, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan.
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171
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Törnroos KW, Hostettler M, Chernyshov D, Vangdal B, Bürgi HB. Interplay of Spin Conversion and Structural Phase Transformations: Re-Entrant Phase Transitions in the 2-Propanol Solvate of Tris(2-picolylamine)iron(II) Dichloride. Chemistry 2006; 12:6207-15. [PMID: 16841350 DOI: 10.1002/chem.200600547] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Crystal structures, magnetic and thermodynamic properties of the spin-crossover compound tris(2-picolylamine)iron(II) dichloride (with 2-propanol solvent molecules) have been measured in the temperature range from 15 to 293 K. X-ray diffraction, SQUID, and calorimetric experiments all showed two first-order phase transitions with hysteresis loops, a narrow one at T(1) approximately 196 K and a broad, triangular one covering the range 153<T(2)<166 K. Crystal structures were analysed at fourteen temperatures in a cooling cycle and at seven temperatures in a heating cycle. They reveal a complex, temperature-dependent ordering behaviour of both the complex cations and the alcohol molecules. A phenomenological model accounting for spin conversion, solvent ordering and coupling between the two processes describes the observed phase transitions and ordering phenomena reasonably well. Similarities and differences in the behaviour of the corresponding ethanol solvate with the same crystal architecture are discussed. It is concluded that spin-crossover behaviour depends as much on molecular properties as it does on intermolecular interactions, both of the spin active and the spin inactive components.
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Affiliation(s)
- Karl W Törnroos
- Department of Chemistry, University of Bergen, Allégt. 41, 5007 Bergen, Norway.
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172
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Matouzenko GS, Luneau D, Molnár G, Ould-Moussa N, Zein S, Borshch SA, Bousseksou A, Averseng F. A Two-Step Spin Transition and Order–Disorder Phenomena in the Mononuclear Compound [Fe(Hpy-DAPP)](BF4)2. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200600068] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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173
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Hauser A, Enachescu C, Daku ML, Vargas A, Amstutz N. Low-temperature lifetimes of metastable high-spin states in spin-crossover and in low-spin iron(II) compounds: The rule and exceptions to the rule. Coord Chem Rev 2006. [DOI: 10.1016/j.ccr.2005.12.006] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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174
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Papanikolaou D, Margadonna S, Kosaka W, Ohkoshi SI, Brunelli M, Prassides K. X-ray Illumination Induced Fe(II) Spin Crossover in the Prussian Blue Analogue Cesium Iron Hexacyanochromate. J Am Chem Soc 2006; 128:8358-63. [PMID: 16787101 DOI: 10.1021/ja061650r] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effect of X-ray illumination on the structural properties of the mixed valence Prussian blue analogue CsFe(II)[Cr(III)(CN)6] has been studied by time-dependent high-resolution synchrotron X-ray diffraction. Abrupt isosymmetric phase transitions, accompanied by dramatic volume collapse, were found in the temperature range 245-265 K, induced by sudden Fe(II) spin transitions from the high spin (HS) (4t(2g)2e(g), S = 2) to the low spin (LS) (6t(2g)0e(g), S = 0) configuration. Absorption of X-ray photons generates photoexcited Fe(II)(LS) domains whose size rapidly grows with time until the percolation threshold is reached and the structure collapse is triggered. The persistent character of the optically excited spin crossover states derives from the strong electron-phonon coupling, associated with the large lattice relaxations, which accompany the internal spin rearrangements. It is thus possible to use X-ray light in a controllable and efficient way to induce photoswitching between the ground and hidden or inaccessible excited states in suitably selected multistable materials in the bulk.
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175
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Two-step spin-crossover phenomenon under high pressure in the coordination polymer Fe(3-methylpyridine)2[Ni(CN)4]. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.03.053] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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176
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Koudriavtsev AB, Linert W. The Role of Binary and Many-center Molecular Interactions in Spin Crossover in the Solid State. Part III. Expressing Many-body Interactions. MONATSHEFTE FUR CHEMIE 2006. [DOI: 10.1007/s00706-005-0454-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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177
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Sorai M, Nakano M, Miyazaki Y. Calorimetric Investigation of Phase Transitions Occurring in Molecule-Based Magnets. Chem Rev 2006; 106:976-1031. [PMID: 16522015 DOI: 10.1021/cr960049g] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michio Sorai
- Research Center for Molecular Thermodynamics, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
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178
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Gaspar AB, Muñoz MC, Real JA. Dinuclear iron(ii) spin crossover compounds: singular molecular materials for electronics. ACTA ACUST UNITED AC 2006. [DOI: 10.1039/b603488h] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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179
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Spin-crossover in dimeric hydrogen-bonded iron(II) 2-(pyrazolyl)-pyridine and 2-(imidazolyl)-pyridine complexes. Polyhedron 2005. [DOI: 10.1016/j.poly.2005.03.033] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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180
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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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181
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Pillet S, Lecomte C, Sheu CF, Lin YC, Hsu IJ, Wang Y. Light induced modulated structure of the spin crossover compound {Fe(abpt)2[N(CN)2]2}. ACTA ACUST UNITED AC 2005. [DOI: 10.1088/1742-6596/21/1/037] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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182
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Ortega-Villar N, Thompson AL, Muñoz MC, Ugalde-Saldívar VM, Goeta AE, Moreno-Esparza R, Real JA. Solid- and Solution-State Studies of the Novel μ-Dicyanamide-Bridged Dinuclear Spin-Crossover System {[(Fe(bztpen)]2[μ-N(CN)2]}(PF6)3⋅n H2O. Chemistry 2005; 11:5721-34. [PMID: 16028299 DOI: 10.1002/chem.200500171] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The mononuclear diamagnetic compound {Fe(bztpen)[N(CN)2]}(PF6)CH3OH (1) (bztpen = N-benzyl-N,N',N'-tris(2-pyridylmethyl)ethylenediamine) has been synthesized and its crystal structure studied. Complex 1 can be considered to be the formal precursor of two new dinuclear, dicyanamide-bridged iron(II) complexes with the generic formula {[(Fe(bztpen)]2[mu-N(CN)2]}(PF6)3 x n H2O (n = 1 (2) or 0 (3)), which have been characterized in the solid state and in solution. In all three complexes, the iron atoms have a distorted [FeN6] octahedral coordination defined by a bztpen ligand and a terminal (1) or a bridging dicyanamide ligand (2 and 3). In the solid state, 2 and 3 can be considered to be molecular isomers that differ by the relative position of the phenyl ring of the two {Fe(bztpen)[N(CN)2]}+ halves (cis and trans, respectively). Depending on the texture of the sample, 2 exhibits paramagnetic behavior or displays a very incomplete spin transition at atmospheric pressure. Complex 3 undergoes a gradual two-step spin transition with no observed hysteresis in the solid state. Both steps are approximately 100 K wide, centered at approximately 200 K and approximately 350 K, with a plateau of approximately 80 K separating the transitions. The crystal structure of 3 has been determined in steps of approximately 50 K between 400 K and 90 K, which provides a fascinating insight into the structural behavior of the complex and the nature of the spin transition. Order-disorder transitions occur in the dicyanamide bridge and the PF6(-) ions simultaneously, with the spin-crossover behavior suggesting that these transitions may trigger the two-step character. In solution, 2 and 3 display very similar continuous spin conversions. Electrochemical studies of 2 and 3 show that the voltammograms are typical of dimeric systems with electronic coupling of the metals through the dicyanamide ligand.
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Affiliation(s)
- Norma Ortega-Villar
- Institut de Ciencia Molecular/Departament de Química Inorgánica, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Spain
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183
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Real JA, Gaspar AB, Muñoz MC. Thermal, pressure and light switchable spin-crossover materials. Dalton Trans 2005:2062-79. [PMID: 15957044 DOI: 10.1039/b501491c] [Citation(s) in RCA: 538] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This article reviews the most relevant chemical and structural aspects that influence the spin-crossover phenomenon (SCO). Special attention is focussed on the recent development of SCO coordination polymers. The different approaches currently being explored in order to achieve multifunctionality in SCO materials are discussed.
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Affiliation(s)
- Jośe Antonio Real
- Institut de Ciència Molecular/Departament de Química Inorgánica, Universitat de València, Doctor Moliner 50, 46100, Burjassot, Spain.
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184
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Niel V, Thompson AL, Goeta AE, Enachescu C, Hauser A, Galet A, Muñoz MC, Real JA. Thermal- and Photoinduced Spin-State Switching in an Unprecedented Three-Dimensional Bimetallic Coordination Polymer. Chemistry 2005; 11:2047-60. [PMID: 15693059 DOI: 10.1002/chem.200400930] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The compound {Fe(pmd)[Ag(CN)2][Ag2(CN)3]} (pmd=pyrimidine) was synthesized and characterized. Magnetic, calorimetric and single crystal visible spectroscopic studies demonstrate the occurrence of a two-step high-spin (HS) right arrow over left arrow low-spin (LS) transition. The critical temperatures are T(c1)=185 and T(c2)=148 K. Each step involves approximately 50 % of the iron centers, with the low-temperature step showing a hysteresis of 2.5 K. The enthalpy and entropy variations associated with the two steps are DeltaH(1)=3.6+/-0.4 kJ mol(-1) and DeltaS(1)=19.5+/-3 J K(-1) mol(-1); DeltaH(2)=4.8+/-0.4 kJ mol(-1) and DeltaS(2)=33.5+/-3 J K(-1) mol(-1). Photomagnetic and visible spectroscopy experiments show that below 50 K, where the LS state is the thermodynamically stable state, the compound can be switched quantitatively to the HS state using green-red light (550-650 nm). HS-to-LS relaxation experiments in the dark at temperatures between 15 and 55 K show that the relaxation takes place via a two-step cooperative process, which was analyzed in the context of the mean field theory. The crystal structure has been studied at 290, 220, 170, 90 and 30 K together with 30 K after irradiation. The compound adopts monoclinic symmetry (P2(1)/c, Z=16) at all temperatures. There are five [FeN6] pseudo-octahedral sites linked by pmd, [Ag(CN)2]- and [Ag2(CN)3]- bridging ligands to form an unprecedented three-dimensional (6,6) topology. The structural analysis allows for an understanding of the microscopic mechanism of the two-step behavior of the thermally induced spin transition as well as the corresponding relaxation of the photoexcited compound based on the individual changes of the five sites. Synergy between metallophilic interactions and the spin transition is also shown by the variation of the AgAg distances. Correlations between the variation of the unit-cell volume and the change of AgAg interactions within each step with the asymmetric change of the anomalous heat capacity have also been inferred.
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Affiliation(s)
- Virginie Niel
- Institut de Ciencia Molecular/Departament de Química Inorgánica, Universitat de València, Doctor Moliner 50, 46100 Burjassot, Spain
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185
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Reger DL, Gardinier JR, Gemmill WR, Smith MD, Shahin AM, Long GJ, Rebbouh L, Grandjean F. Formation of Third Generation Poly(pyrazolyl)borate Ligands from Alkyne Coupling Reactions of Fe[(p-IC6H4)B(3-Rpz)3]2 (R = H, Me; pz = Pyrazolyl): Pathways toward Controlling an Iron(II) Electronic Spin-State Crossover. J Am Chem Soc 2005; 127:2303-16. [PMID: 15713110 DOI: 10.1021/ja044900h] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sonogashira coupling reactions of terminal alkynes with Fe[(p-IC6H4)B(3-Mepz)3]2 (pz = pyrazolyl ring) yield Fe[(p-PhC2C6H4)B(3-Mepz)3]2 (2), Fe[(p-Me3SiC2C6H4)B(3-Rpz)3]2 (R = H, 3a, R = Me, 3b), and Fe[(p-HC2C6H4)B(3-Mepz)3]2 (R = H, 4a, R = Me, 4b), a series of new complexes containing "third generation" poly(pyrazolyl)borate ligands. Complex 2 undergoes a fairly gradual iron(II) electronic spin-state crossover with a 30 K hysteresis, whereas complex 3b is an unusual example of a complex with equivalent iron(II) sites in the high-spin form that shows an abrupt 50% spin crossover. For complex 4b, 50% of the iron(II) sites undergo a gradual spin-state transition between 185 and 350 K with an activation energy of 1590 +/- 30 cm(-1) and a T(1/2) = 280 K and, for the remaining iron(II) sites, an abrupt cooperative spin-state crossover between 106 and 114 K. The crystal structures of 4b obtained for each of the three distinct electronic spin states reveal two crystallographically different iron(II) sites, and analysis of the molecular/supramolecular structures indicates that the difference in the degree of pyrazolyl ring tilting in the ligands between the two sites, rather than the strength of the intermolecular forces, play a prominent role in determining the temperature of the spin-state crossover.
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Affiliation(s)
- Daniel L Reger
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA.
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186
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Simaan AJ, Boillot ML, Carrasco R, Cano J, Girerd JJ, Mattioli TA, Ensling J, Spiering H, Gütlich P. Electronic, Vibrational, and Structural Properties of a Spin-Crossover Catecholato-Iron System in the Solid State: Theoretical Study of the Electronic Nature of the Doublet and Sextet States. Chemistry 2005; 11:1779-93. [PMID: 15669047 DOI: 10.1002/chem.200400484] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
As a functional model of the catechol dioxygenases, [(TPA)Fe(Cat)]BPh4 (TPA = tris(2-pyridylmethyl)amine and Cat = catecholate dianion) exhibits the purple-blue coloration indicative of some charge transfer within the ground state. In contrast to a number of high-spin bioinspired systems, it was previously shown that, in the solid state, [(TPA)Fe(Cat)]BPh4 undergoes a two-step S = 1/2 = S = 5/2 spin-crossover. Therefore, the electronic and vibrational characteristics of this compound were investigated in the solid state by UV/Vis absorption and resonance Raman spectroscopies over the temperature range of the transition. This allowed the charge-transfer transitions of the low-spin (LS) form to be identified. In addition, the vibrational progression observed in the NIR absorption of the LS form was assigned to a five-membered chelate ring mode. The X-ray crystal structure solved at two different temperatures, shows the presence of highly distorted pseudo-octahedral ferric complexes that occupy two nonequivalent crystalline sites. The variation of the molecular parameters as a function of temperature strongly suggests that the two-step transition proceeds by a successive transition of the species in the two nonequivalent sites. The thermal dependence of the high-spin fraction of metal ions determined by Mössbauer experiments is consistent with the magnetic data, except for slight deviations in the high temperature range. The optimized geometries, the electronic transitions, vibrational frequencies, and thermodynamic functions were calculated with the B3LYP density functional method for the doublet and the sextet states. The finding of a ground state that possesses a significant mixture of Fe(III)-catecholate and FeII-semiquinonate configurations is discussed with regard to the set of experimental and theoretical data.
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Affiliation(s)
- A Jalila Simaan
- Laboratoire de Chimie Inorganique, UMR 8613, ICMMO, Bât 420, Université Paris-Sud, 91405 Orsay, France
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187
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Juhász G, Seto M, Yoda Y, Hayami S, Maeda Y. NRIS study on the [FeN6] core in photo-induced high-spin state of [Fe(2-pic)3]Cl2·EtOH. Chem Commun (Camb) 2004:2574-5. [PMID: 15543286 DOI: 10.1039/b409025j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A comparison is reported for thermally and photo-induced high-spin phases of [Fe(2-pic)3]Cl2.EtOH (2-pic: 2-picolylamine) using the nuclear resonant inelastic scattering (NRIS) technique.
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Affiliation(s)
- Gergely Juhász
- Department of Chemistry, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka, 812-8581, Japan.
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188
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Nakano K, Kawata S, Yoneda K, Fuyuhiro A, Yagi T, Nasu S, Morimoto S, Kaizaki S. Direct two-step spin-crossover through [HS–HS]⋯[LS–LS] at the plateau in dinuclear diiron(ii) complex [{Fe(NCBH3)(4phpy)}2(μ-bpypz)2]. Chem Commun (Camb) 2004:2892-3. [PMID: 15599459 DOI: 10.1039/b411190g] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The variable temperature magnetic susceptibility, X-ray crystallography, and IR and Raman spectra of a new dinuclear complex [{Fe(II)(NCBH(3))(4-phpy)}(2) mu-bpypz)(2)] demonstrated the first two-step spin-crossover associated with a 1 : 1 mixture of high-spin pair [HS-HS] and low-spin pair [LS-LS] at the plateau.
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Affiliation(s)
- Keisaku Nakano
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka Osaka, 560-0043, Japan
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