Co(<scp>ii</scp>) molecular complexes as a reference for the spin crossover in Fe(<scp>ii</scp>) analogues

Guionneau, Philippe; Marchivie, Mathieu; Bravic, G.; Létard, Jean‐François; Chasseau, D.

doi:10.1039/b202610d

Cited by 168 publications

(166 citation statements)

References 23 publications

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“…The average Fe-N distances at room temperature and at 10 K ''flash cooled'' are in the range expected for 100% and 50% of the HS iron(II), respectively. 9 This observation is consistent with the presence of a metastable HS state at low temperatures as magnetic data indicate only ca. 30% remaining HS Fe II at low temperature.…”

Section: Scheme 1 Some Examples Of Cyanocabanionssupporting

confidence: 82%

Photoinduced HS state in the first spin-crossover chain containing a cyanocarbanion as bridging ligand

et al. 2009

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A new polymeric approach, based on cyanocarbanion ligands, for the design of spin crossover (SCO) compounds led us to the compound [Fe(abpt) 2 (tcpd)] (1) (tcpd 2À = (C[C(CN) 2 ] 3 ) 2À , abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole) which has been characterised as the first SCO molecular chain involving a cyanocarbanion as bridging ligand.The design of new molecular compounds exhibiting the spin crossover phenomenon (SCO) is one of the most relevant and challenging questions in the field of magnetic molecular materials. 1-4 Iron(II) metal complexes involving the octahedral coordination sphere [FeN 6 ] are the most studied SCO compounds. In such materials, the intermolecular interactions (p-stacking, hydrogen bonding and van der Waals interactions) play a crucial role to transmit the transition. 5 Albeit, the lack of control of these non-covalent interactions hardens their organization in the crystal. To better explore the cooperative effect between the active metal sites, Kahn et al., 2 and others, 3,4 introduced an interesting and alternative approach based on the use of neutral suitable bridging ligands to covalently connect the metal centres. This resulted in the synthesis of several Fe II SCO coordination polymers exhibiting rich and fascinating structural features coupled to their magnetic behaviours. However, these studies concern a limited number of neutral ligands and deal essentially with 4-substituted-1,2,4-triazole and poly-N-donating heterocyclic ligands. [2][3][4] In this context, our strategy is to extend this polymeric approach to anionic ligands involving several potentially donating nitrogen atoms (Scheme 1).In our ongoing work on the new potentially bridging cyanocarbanion ligands, we have shown in the last few years that their structural and electronic characteristics (original coordination modes and high electronic delocalization) can be tuned by slight chemical or electrochemical modifications such as substitution of functional groups or variation of the negative charge. 6 In this context, we have directed our efforts to the preparation of new SCO polymeric systems based on such bridging anions, for which the magnetic properties are essentially governed by subtle structural changes and therefore by the nature of the cyanocarbanion ligand.Recently we have reported the first SCO series based on the tcm À ([C(CN) 3 ] À ), tcnome À and tcnoet À ligands and abpt co-ligand (Scheme 1). 5 In this series, the single charge on the anion induces a terminal coordination mode for the polynitrile unit, resulting in neutral discrete SCO complexes. A further step in this direction would be the preparation of original extended SCO networks bearing the Fe II -abpt complexes by using covalent bonds. Here we show how the use of potentially bridging dianionic ligands bearing different coordination sites constitute a very good and simple method to perform this task. We report herein the first SCO iron(II) molecular neutral chain [Fe(abpt) 2 (tcpd)] (1) involving an anion as bridging ligand. To the best ...

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Section: Scheme 1 Some Examples Of Cyanocabanionssupporting

confidence: 82%

Photoinduced HS state in the first spin-crossover chain containing a cyanocarbanion as bridging ligand

et al. 2009

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“…Additionally, the pressure and temperature dependencies of the geometry of the shortest C...C intermolecular contact clearly shows that the HP-HS crystal packing is closer from the LT-LS crystal packing than the HT-HS or the LT-HS ones (Table 2). This is confirmed by the modification 25 . In this case, the octahedricity was estimated from the structural parameter denoted Θ that represents the deviation of the MnN 6 geometry from a perfect octahedron (O h ) to a trigonal prismatic structure (D 3h ); i.e.…”

Section: Comparison Of the High Pressure And The Low Temperature Cryssupporting

confidence: 69%

Spin crossover in[MnIII(pyrol)3tren]probed by high-pressure and low-temperature x-ray diffraction

et al. 2005

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“…4c, 8 The Σ values for the Fe and Co ions were found to be 18.0 and 63.3°, respectively, which were similar to those (28.7 and 71.6°) of 2 in the HT phase.…”

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confidence: 62%

Abrupt Phase Transition Based on Electron-transfer-coupled Spin Transition in a Cyanide-bridged [Co2Fe2] Tetranuclear Complex

2014

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A cyanide-bridged tetranuclear complex, [Co2Fe2(CN)6(tp*)2(dmbpy)4](PF6)2·4CH3CN (1·4CH3CN) (tp*: hydrotris(3,5-dimethylpyrazol-1-yl)borate and dmbpy: 5,5′-dimethyl-2,2′-bipyridine), was synthesized and its magnetic properties were investigated. Magnetic susceptibility measurements revealed that 1 exhibited an abrupt one-step thermal phase transition based on electron-transfer-coupled spin transition (ETCST) and light-induced ETCST at low temperature.

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Co(ii) molecular complexes as a reference for the spin crossover in Fe(ii) analogues

Cited by 168 publications

References 23 publications

Photoinduced HS state in the first spin-crossover chain containing a cyanocarbanion as bridging ligand

Photoinduced HS state in the first spin-crossover chain containing a cyanocarbanion as bridging ligand

Spin crossover in[MnIII(pyrol)3tren]probed by high-pressure and low-temperature x-ray diffraction

Abrupt Phase Transition Based on Electron-transfer-coupled Spin Transition in a Cyanide-bridged [Co2Fe2] Tetranuclear Complex

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