A novel bis-1,2,4-benzothiadiazine pincer ligand: synthesis, characterization and first row transition metal complexes

Pringouri, Konstantina; Anwar, Muhammad U.; Mansour, Liz; Doupnik, Nathan P; Beldjoudi, Yassine; Gavey, Emma L.; Pilkington, Melanie; Rawson, Jeremy M.

doi:10.1039/c8dt03346c

Cited by 6 publications

(3 citation statements)

References 74 publications

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“…While the distortion is most prevalent in [Fe(bpp) 2 ] 2+ chemistry, it also occurs in high-spin iron(II) complexes of other tris -heterocyclic ligands, − and in related complexes of high-spin iron(III), − manganese(II), − cobalt(II), − and zinc(II). − In high-spin iron(II) complexes, the distortion electronically resembles a Jahn–Teller distortion of a 5 E ground state (in D 2d symmetry), which is favored in complexes of tridentate ligands with a narrow bite angle. , However, distortion also occurs in complexes with an orbital singlet ground state. In that case, the absence of a ligand field stabilization energy makes their coordination geometry more susceptible to deformations induced by crystal packing.…”

Section: Introductionmentioning

confidence: 99%

A Survey of the Angular Distortion Landscape in the Coordination Geometries of High-Spin Iron(II) 2,6-Bis(pyrazolyl)pyridine Complexes

Capel Berdiell,

Michaels,

Munro

et al. 2024

Inorg. Chem.

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Reaction of 2,4,6-trifluoropyridine with sodium 3,4dimethoxybenzenethiolate and 2 equiv of sodium pyrazolate in tetrahydrofuran at room temperature affords 4-(3,4-dimethoxyphenylsulfanyl)-2,6-di(pyrazol-1-yl)pyridine (L), in 30% yield. The iron(II) complexes [FeL 2 ][BF 4 ] 2 (1a) and [FeL 2 ][ClO 4 ] 2 (1b) are high-spin with a highly distorted six-coordinate geometry. This structural deviation from ideal D 2d symmetry is common in highspin [Fe(bpp) 2 ] 2+ (bpp = di{pyrazol-1-yl}pyridine) derivatives, which are important in spin-crossover materials research. The magnitude of the distortion in 1a and 1b is the largest yet discovered for a mononuclear complex. Gas-phase DFT calculations at the ω-B97X-D/6-311G** level of theory identified four minimum or local minimum structural pathways across the distortion landscape, all of which are observed experimentally in different complexes. Small distortions from D 2d symmetry are energetically favorable in complexes with electron-donating ligand substituents, including sulfanyl groups, which also have smaller energy penalties associated with the lowest energy distortion pathway. Natural population analysis showed that these differences reflect greater changes to the Fe−N{pyridyl} σ-bonding as the distortion proceeds, in the presence of more electron-rich pyridyl donors. The results imply that [Fe(bpp) 2 ] 2+ derivatives with electron-donating pyridyl substituents are more likely to undergo cooperative spin transitions in the solid state. The high-spin salt [Fe(bpp) 2 ][CF 3 SO 3 ] 2 , which also has a strong angular distortion, is also briefly described and included in the analysis.

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Section: Introductionmentioning

confidence: 99%

A Survey of the Angular Distortion Landscape in the Coordination Geometries of High-Spin Iron(II) 2,6-Bis(pyrazolyl)pyridine Complexes

Capel Berdiell,

Michaels,

Munro

et al. 2024

Inorg. Chem.

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“…, and n = 0-6) show various SCO behaviors generating incomplete or gradual SCO curves. [45][46][47][48][49][50] The SCO behavior can be significantly influenced by counter anions and lattice solvent. [51][52][53][54][55][56] Inspired by the above, we introduce an auxiliary ligand of 1,10-phenanthroline (phen) and 2,2 0 : 6 0 ,2 00 -terpyridine (terpy) on the basis of previous mixed-valence cobalt trinuclear complexes…”

Section: Introductionmentioning

confidence: 99%

“…44 Relevant research results show that the SCO cobalt( ii ) complexes, [Co(terpy) 2 ]X 2 ·nH 2 O (X = Br − , Cl − , I − , F − , ClO 4 − , NCS − , NO 3 − , [Co(CN) 4 ] − , SO 4 − , BPh 4 − , and n = 0–6) show various SCO behaviors generating incomplete or gradual SCO curves. 45–50 The SCO behavior can be significantly influenced by counter anions and lattice solvent. 51–56…”

Section: Introductionmentioning

confidence: 99%

Slow magnetic relaxation and spin crossover behavior in two mixed-valence Co(ii)/Co(iii) complexes

Zhong

et al. 2022

New J. Chem.

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Elucidating the Structural Chemistry of a Hysteretic Iron(II) Spin‐Crossover Compound From its Copper(II) and Zinc(II) Congeners

Pask

Greatorex

Kulmaczewski

et al. 2020

Chemistry A European J

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Annealing [FeL2][BF4]2⋅2 H2O (L=2,6‐bis‐[5‐methyl‐1H‐pyrazol‐3‐yl]pyridine) affords an anhydrous material, which undergoes a spin transition at T1/2=205 K with a 65 K thermal hysteresis loop. This occurs through a sequence of phase changes, which were monitored by powder diffraction in an earlier study. [CuL2][BF4]2⋅2 H2O and [ZnL2][BF4]2⋅2 H2O are not perfectly isostructural but, unlike the iron compound, they undergo single‐crystal‐to‐single‐crystal dehydration upon annealing. All the annealed compounds initially adopt the same tetragonal phase but undergo a phase change near room temperature upon re‐cooling. The low‐temperature phase of [CuL2][BF4]2 involves ordering of its Jahn–Teller distortion, to a monoclinic lattice with three unique cation sites. The zinc compound adopts a different, triclinic low‐temperature phase with significant twisting of its coordination sphere, which unexpectedly becomes more pronounced as the crystal is cooled. Synchrotron powder diffraction data confirm that the structural changes in the anhydrous zinc complex are reproduced in the high‐spin iron compound, before the onset of spin‐crossover. This will contribute to the wide hysteresis in the spin transition of the iron complex. EPR spectra of copper‐doped [Fe0.97Cu0.03L2][BF4]2 imply its low‐spin phase contains two distinct cation environments in a 2:1 ratio.

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A novel bis-1,2,4-benzothiadiazine pincer ligand: synthesis, characterization and first row transition metal complexes

Abstract: The synthesis and coordination chemistry of ligand LH2 to first row transition metals is described in which it acts as a tridentate N,N′,N′′-donor.

Cited by 6 publications

References 74 publications

A Survey of the Angular Distortion Landscape in the Coordination Geometries of High-Spin Iron(II) 2,6-Bis(pyrazolyl)pyridine Complexes

A Survey of the Angular Distortion Landscape in the Coordination Geometries of High-Spin Iron(II) 2,6-Bis(pyrazolyl)pyridine Complexes

Slow magnetic relaxation and spin crossover behavior in two mixed-valence Co(ii)/Co(iii) complexes

Elucidating the Structural Chemistry of a Hysteretic Iron(II) Spin‐Crossover Compound From its Copper(II) and Zinc(II) Congeners

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