Anion Modified Spin Crossover in [Fe(qsal-4-F)]+ Complexes with a 4-Position Substituted Qsal Ligand.

Four iron(III) complexes, [Fe(qsal-4-F)2]Y·sol (Hqsal-4-F = 4-fluoro-N-(8-quinolyl)salicylaldimine; Y = NO3-, sol = 0.91MeOH·0.57H2O (1NO3); Y = PF6- (2PF6); Y = BF4- (3BF4); Y = OTf-, sol =1.5MeOH (4OTf)), with a new 4-position substituted qsal type ligand Hqsal-4-F have been synthesized and structurally and magnetically characterized. Complexes 1NO3-3BF4 consist of 1D chains formed by the [Fe(qsal-4-F)2]+ cations connected by π-π and C-H···O interactions, which are further linked by more weak interactions to form 2D layers and 3D networks. On the other hand, complex 4OTf has a structure of nearly isolated 1D column where the [Fe(qsal-4-F)2]+ cations are connected by π-π, C-H···π, and C-F···π interactions. Magnetic studies revealed the occurrence of two-step symmetry-breaking SCO in 1NO3 and two-step gradual SCO in 2PF6. Complex 3BF4 undergoes a gradual SCO, whereas 4OTf remains almost high-spin. The smaller anions tend to stabilize the low-spin state, while larger anions tend to stabilize the high-spin state. In addition, the intermediate spin state of 1NO3 could be thermally trapped by quenching from the high temperature, thereby kinetically suppressing the spin transition to the full low-spin state. This work represents a good example that the position of the substituent and the anions plays critical roles in the preparation of SCO materials with tunable properties.

[1]  C. Kepert,et al.  A new spin crossover FeII coordination environment in a two-fold interpenetrated 3-D Hofmann-type framework material. , 2020, Chemical communications.

[2]  John C. McMurtrie,et al.  Three-Way Switchable Single-Crystal-to-Single-Crystal Solvatomorphic Spin Crossover in a Molecular Cocrystal , 2020 .

[3]  Xiaojiang Yu,et al.  Room temperature conductance switching in a molecular iron(iii) spin crossover junction , 2020, Chemical science.

[4]  Qianqian Yang,et al.  Hydrazone based spin crossover complexes: Behind the extra flexibility of the hydrazone moiety to switch the spin state , 2020 .

[5]  J. Clegg,et al.  Structural Origin of Magnetic Hysteresis in an Iron(III) Spin-Crossover Material , 2020 .

[6]  P. Harding,et al.  Spin Crossover in Iron(III) Quinolylsalicylaldiminates: The Curious Case of [Fe(qsal-F)2](Anion). , 2020, Inorganic chemistry.

[7]  H. Ohta,et al.  The Impact of the Next-Nearest Neighbor Dispersion Interactions on Spin Crossover Transition Enthalpy Evidenced by Experimental and Computational Analyses of Neutral π-Extended Heteroleptic Fe(III) Complexes. , 2020, Inorganic Chemistry.

[8]  Quanjun Li,et al.  Variable Cooperative Interactions in the Pressure and Thermally Induced Multistep Spin Transition in a Two-Dimensional Iron(II) Coordination Polymer. , 2020, Inorganic chemistry.

[9]  Jonathan A. Kitchen,et al.  Hydrophobic tail length in spin crossover active iron(ii) complexes predictably tunes T½ in solution and enables surface immobilisation , 2020 .

[10]  Song Gao,et al.  High temperature Fe(iii) spin crossover behaviours in three unprecedented FeIII–MII–FeIII (M = Fe, Cd) linear trinuclear complexes , 2020 .

[11]  J. Pavlik,et al.  Heteronuclear Iron(III)-Schiff Base Complexes with the Hexacyanidocobaltate(III) Anion: On the Quest To Understand the Governing Factors of Spin Crossover. , 2020, Inorganic chemistry.

[12]  J. Tao,et al.  Bistable molecular materials with dynamic structures. , 2020, Chemical communications.

[13]  R. Clérac,et al.  Slow Dynamics of the Spin-Crossover Process in an Apparent High-Spin Mononuclear Fe(II) Complex. , 2019, Angewandte Chemie.

[14]  Charlotte S. Kirk,et al.  Heteroatom substitution effects in spin crossover dinuclear complexes. , 2019, Dalton transactions.

[15]  B. Heinrich,et al.  Bi-stable spin-crossover characteristics of a highly distorted [Fe(1-BPP-COOC2H5)2](ClO4)2·CH3CN complex. , 2019, Dalton transactions.

[16]  B. Dittrich,et al.  Kinetic Trapping Effects in Amphiphilic Iron(II) Spin Crossover Compounds. , 2019, Inorganic chemistry.

[17]  F. Ragon,et al.  Guest-Adaptable Spin Crossover Properties in a Dinuclear Species Underpinned by Supramolecular Interactions. , 2018, Inorganic chemistry.

[18]  Anna J. McConnell.  Spin-state switching in Fe(II) helicates and cages , 2018 .

[19]  R. Hogue,et al.  Spin crossover in discrete polynuclear iron(ii) complexes. , 2018, Chemical Society reviews.

[20]  A. Hauser,et al.  Very Long-Lived Photogenerated High-Spin Phase of a Multistable Spin-Crossover Molecular Material. , 2018, Journal of the American Chemical Society.

[21]  Haonan Peng,et al.  Recent advances in self-assembly of spin crossover materials and their applications , 2018 .

[22]  W. Nicolazzi,et al.  Spin Crossover Nanomaterials: From Fundamental Concepts to Devices , 2018, Advanced materials.

[23]  M. Ruben,et al.  Emerging trends in spin crossover (SCO) based functional materials and devices , 2017 .

[24]  P. Harding,et al.  Hysteretic spin crossover driven by anion conformational change. , 2017, Chemical communications.

[25]  S. Telfer,et al.  Solvent modified spin crossover in an iron(iii) complex: phase changes and an exceptionally wide hysteresis , 2017, Chemical science.

[26]  P. Harding,et al.  Spin crossover in iron(III) complexes , 2016 .

[27]  V. Gómez,et al.  Easy Excited-State Trapping and Record High TTIESST in a Spin-Crossover Polyanionic Fe(II) Trimer. , 2015, Journal of the American Chemical Society.

[28]  P. Rosa,et al.  Detailed Investigation of the Interplay Between the Thermal Decay of the Low Temperature Metastable HS State and the Thermal Hysteresis of Spin-Crossover Solids , 2015 .

[29]  L. Pereira,et al.  Thermal hysteresis in a spin-crossover Fe(III) quinolylsalicylaldimine complex, Fe(III)(5-Br-qsal)2Ni(dmit)2·solv: solvent effects. , 2015, Inorganic chemistry.

[30]  M. Halcrow.  The foundation of modern spin-crossover. , 2013, Chemical communications.

[31]  S. Telfer,et al.  Abrupt spin crossover in an iron(III) quinolylsalicylaldimine complex: structural insights and solvent effects. , 2013, Chemical communications.

[32]  H. Adams,et al.  Anionic Tuning of Spin Crossover in FeIII–Quinolylsalicylaldiminate Complexes , 2013 .

[33]  Yann Garcia,et al.  Spin state switching in iron coordination compounds , 2013, Beilstein journal of organic chemistry.

[34]  H. Adams,et al.  Fe(III) quinolylsalicylaldimine complexes: a rare mixed-spin-state complex and abrupt spin crossover. , 2013, Chemistry.

[35]  Azzedine Bousseksou,et al.  Molecular spin crossover phenomenon: recent achievements and prospects. , 2011, Chemical Society reviews.

[36]  Marinela M. Dîrtu,et al.  Insights into the origin of cooperative effects in the spin transition of [Fe(NH2trz)3](NO3)2: the role of supramolecular interactions evidenced in the crystal structure of [Cu(NH2trz)3](NO3)2.H2O. , 2010, Inorganic chemistry.

[37]  L. Pereira,et al.  Synthesis and characterization of Fe(III)(3-CH3O-qsal)2PF6 · nH2O (n = 0, 2) , 2009 .

[38]  H. Oshio,et al.  Spin crossover iron(III) complexes , 2007 .

[39]  J. Real,et al.  Dinuclear iron(II) spin crossover compounds: singular molecular materials for electronics , 2006 .

[40]  D. Morineau,et al.  Spin transition with a large thermal hysteresis near room temperature in a water solvate of an iron(III) thiosemicarbazone complex , 2003 .

[41]  A. Fujishima,et al.  Iron(III) spin-crossover compounds with a wide apparent thermal hysteresis around room temperature. , 2001, Journal of the American Chemical Society.

[42]  A. Bousseksou,et al.  Two-step spin crossover in the new dinuclear compound [Fe(bt)(NCS)2]2bpym, with bt = 2,2'-Bi-2-thiazoline and bpym = 2,2'-bipyrimidine : experimental investigation and theoretical approach , 1992 .

[43]  H. Adams,et al.  Substituent-Influenced Spin Cross­over in FeIII Quinolylsalicylaldimin­ates , 2016 .