Data to support study of Iron(II) Complexes of 2,4-Dipyrazolyl-1,3,5-Triazine Derivatives ‒ the Influence of Ligand Geometry on Metal Ion Spin State

Seven derivatives of [FeL2]2+ (L = 2,4-di{pyrazol-1-yl}-1,3,5-triazine) are all high-spin. DFT calculations imply this can be attributed to the geometry of the L ligand

Data to support study of The Number and Shape of Lattice Solvent Molecules Controls Spin-Crossover in an Isomorphous Series of Crystalline Solvate Salts

Crystals of [FeL2][BF4]2·nMeCN (L = N-(2,6-di{pyrazol-1-yl}pyrid-4-yl)acetamide; n = 1 or 2), [FeL2][ClO4]2·MeCN and [FeL2]X2·EtCN (X = BF4 or ClO4) are all isomorphous but exhibit a variety of spin state behaviours

Data to Support a Study of Exploring the Influence of Counterions on a Hysteretic Spin-Transition in Isomorphous Iron(II) Complex Salts

The hysteretic spin transition shown by [FeL2][BF4]2 is quenched in its isomorphous perchlorate salt, which reflects more sluggish lattice dynamics in the presence of the larger ClO4 ion

Data to support study of The Structures and Spin States of Iron(II) Complexes of Isomeric 2,6-Di(1,2,3-triazolyl)pyridine Ligands

Different isomers of the title ligands coordinate to iron(II) in monodentate or tridentate fashion, leading to complexes with a variety of spin state properties

Tracking Structural Deactivation of H-Ferrierite Zeolite Catalyst During MTH with XRD

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Data to support study of Spin-Crossover in a New Iron(II)/Di(pyrazolyl)pyridine Complex with a Terpyridine Embrace Lattice

[FeL2]X2 ( L = 2,6-di{4-fluoropyrazol-1-yl}pyridine) exhibit hysteretic spin-transitions at T½ = 164 (X = BF4) and 148 K (X = ClO4). The perchlorate salt shows efficient TIESST below 120 K, and was characterized in its thermally trapped high-spin form, as well as in its thermodynamic high- and low-spin states

Molecular Squares, Coordination Polymers and Mononuclear Complexes Supported by 2,4-Dipyrazolyl-6H-1,3,5-triazine and 4,6-Dipyrazolylpyrimidine Ligands

The Fe[BF4]2 complex of 2,4-di(pyrazol-1-yl)-6H-1,3,5-triazine (L1) is a high-spin molecular square, [{Fe(L1)}4(μ-L1)4][BF4]8, whose crystals also contain the unusual HPzBF3 (HPz = pyrazole) adduct. Three other 2,4-di(pyrazol-1-yl)-6H-1,3,5-triazine derivatives with different pyrazole substituents (L2-L4) are unstable in the presence of first row transition ions, but form mononuclear, polymeric or molecular square complexes with silver(I). Most of these compounds involve bis-bidentate di(pyrazolyl)triazine coordination, which is unusual for that class of ligand, and the molecular squares encapsulate one or two BF4‒, ClO4‒ or SbF6‒ ions through combinations of anion...π, Ag...X and/or C‒H...X (X = O or F) interactions. Treatment of Fe[NCS]2 or Fe[NCSe]2 with 4,6-di(pyrazol-1-yl)-2H-pyrimidine (L5) or its 2-methyl and 2-amino derivatives L6 and L7) yields mononuclear [Fe(NCE)2L2] and/or the 1D coordination polymers catena-[Fe(NCE)2(μ-L)] (E = S or Se, L = L5-L7). Alcohol solvates of isomorphous [Fe(NCS)2L2] and [Fe(NCSe)2L2] compounds show different patterns of intermolecular hydrogen bonding, reflecting the acceptor properties of the anion ligands. These iron compounds are all high-spin, although annealing solvated crystals of [Fe(NCSe)2(L5)2] affords a new phase exhibiting an abrupt, low-temperature spin transition. Catena-[Fe(H2O)2(μ-L5)][ClO4]2 is a coordination polymer of alternating cis and trans iron centres

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

Reaction of 2,4,6-trifluoropyridine with sodium 3,4-dimethoxybenzenethiolate 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 [FeL2][BF4]2 (1a) and [FeL2][ClO4]2 (1b) are high-spin with a highly distorted six-coordinate geometry. This structural deviation from ideal D2d symmetry is common in high-spin [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 D2d 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][CF3SO3]2, which also has a strong angular distortion, is also briefly described and included in the analysis