Anion-dependent spin crossover in solution for an iron(ii) complex of a 1H-pyrazolyl ligand

Barrett, Simon; Halcrow, Malcolm A.

doi:10.1039/c4ra00230j

Cited by 39 publications

(30 citation statements)

References 35 publications

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“…Titrating halide or other more associating anions into chloroform solutions of [Fe(bip)2L][BPh4]2, around the SCO temperature for each complex, causes a steady high→low spin conversion associated with anion binding to the bip ligands. A comparable effect was also noted in different salts of [Fe(3-bpp)2] 2+ (Scheme 2), whose SCO was shifted by up to 15 K higher temperature in the presence of more associating counterions, at NMR concentrations in a 9:1 (CD3)2CO:D2O solvent mixture [106]. While studies of [Fe(tacn)2] 2+ [99] or [Fe(pic)3] 2+ [100] reported no measurable response to different anions in solution, that might reflect the aqueous solvents used for those measurements, which would disfavor intermolecular hydrogen-bonding and ion pairing [107].…”

Section: Effect Of Secondary Bonding Interactions On Metal Ion Spin Smentioning

confidence: 58%

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

2016

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Abstract:The relationship between chemical structure and spin state in a transition metal complex has an important bearing on mechanistic bioinorganic chemistry, catalysis by base metals, and the design of spin crossover materials. The latter provide an ideal testbed for this question, since small changes in spin state energetics can be easily detected from shifts in the spin crossover equilibrium temperature. Published structure-function relationships relating ligand design and spin state from the spin crossover literature give varied results. A sterically crowded ligand sphere favors the expanded metal-ligand bonds associated with the high-spin state. However, steric clashes at the molecular periphery can stabilize either the high-spin or the low-spin state in a predictable way, depending on their effect on ligand conformation. In the absence of steric influences, the picture is less clear since electron-withdrawing ligand substituents are reported to favor the low-spin or the high-spin state in different series of compounds. A recent study has shed light on this conundrum, showing that the electronic influence of a substituent on a coordinated metal ion depends on its position on the ligand framework. Finally, hydrogen bonding to complexes containing peripheral N-H groups consistently stabilizes the low-spin state, where this has been quantified.

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Section: Effect Of Secondary Bonding Interactions On Metal Ion Spin Smentioning

confidence: 58%

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

2016

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“…The desired product L 3 was purified from this material by silica column chromatography (9:1 ethyl acetate:methanol eluent ), 7.62 (m, 3H, Py H [3][4][5] ). 13 …”

Section: Synthesis Of 26-di(5-amino-1h-pyrazol-3-yl)pyridine Hemihydmentioning

confidence: 99%

“…For example, hydrogen bonding to water strongly stabilises the low spin state of the complex, in the solid state 10,11 and in solution. 12 The solution-phase spinequilibrium in 2 ] 2+ is similarly responsive to the presence of different anions, 13 while cation…anion hydrogen bonding may also play a role in the cooperative spin-crossover transitions shown by some 2 ] 2+ salts. 8 While [Fe(3-bpp) 2 ] 2+ itself has been well studied, the synthesis of substituted analogues of 3-bpp is poorly developed.…”

Section: Introductionmentioning

confidence: 99%

Iron(ii) complexes of 2,6-di(1H-pyrazol-3-yl)-pyridine derivatives with hydrogen bonding and sterically bulky substituents

et al. 2014

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aSyntheses of 2,6-di(5-aminopyrazol-3-yl)pyridine (L 1 ), 2,6-di(5-tertbutylcarboxamido-pyrazol-3-reported. Iron complex salts of the first four ligands were crystallographically characterised. The structures exhibit intermolecular hydrogen bonding between the cations and the anions and/or solvent, leading to a fluorite (flu) net, a 1D ladder structure, and a homochiral self-penetrating helical network related to the (10,3)-a (srs) topology. All the complexes are high-spin in the crystal, and bulk samples are also fully or predominantly high-spin at room temperature and below although two of the dried materials exhibit partial spin-state transitions on cooling.

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“…showing the distorted trigonal prismatic coordination sphere of the Fe atom and the oxygen atoms from two perchlorate anions that cap two rectangular faces (bottom). [53]. The white data points are from Goodwin et al's original publication, and were also measured in a D 2 O:(CD 3 ) 2 CO mixed solvent (Fig.…”

Section: Supplementary Datamentioning

confidence: 99%

Spin state behavior of iron(II)/dipyrazolylpyridine complexes. New insights from crystallographic and solution measurements

Cook

Mohammed

Sherborne

et al. 2015

Coordination Chemistry Reviews

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Anion-dependent spin crossover in solution for an iron(ii) complex of a 1H-pyrazolyl ligand

Cited by 39 publications

References 35 publications

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

Iron(ii) complexes of 2,6-di(1H-pyrazol-3-yl)-pyridine derivatives with hydrogen bonding and sterically bulky substituents

Spin state behavior of iron(II)/dipyrazolylpyridine complexes. New insights from crystallographic and solution measurements

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