scholarly journals Iron(III) Azadiphenolate Compounds in a New Family of Spin Crossover Iron(II)–Iron(III) Mixed-Valent Complexes

2019 ◽  
Vol 5 (2) ◽  
pp. 37 ◽  
Author(s):  
Wasinee Phonsri ◽  
David S. Macedo ◽  
Barnaby A. I. Lewis ◽  
Declan F. Wain ◽  
Keith S. Murray
Keyword(s):  
Crystal Structures ◽  
Spin Crossover ◽  
Crystal Packing ◽  
Spin Transition ◽  
Double Salt ◽  
Magnetic Studies ◽  
Cationic Precursor ◽  
New Family ◽  
Double Spin ◽  
Crystal Design

A new family of mixed valent, double salt spin crossover compounds containing anionic FeIII and cationic FeII compounds i.e., [FeII{(pz)3CH}2][FeIII(azp)2]2·2H2O (4), [FeII(TPPZ)2][FeIII(azp)2]2]·H2O (5) and [FeII(TPPZ)2][FeIII(azp)2]2]·H2O·3MeCN (6) (where (pz)3CH = tris-pyrazolylmethane, TPPZ = 2,3,5,6, tetrapyridylpyrazine and azp2− = azadiphenolato) has been synthesized and characterised. This is the first time that the rare anionic spin crossover species, [FeIII(azp)2]−, has been used as an anionic component in double salts complexes. Single crystal structures and magnetic studies showed that compound 6 exhibits a spin transition relating to one of the FeIII centres of the constituent FeII and FeIII sites. Crystal structures of the anionic and cationic precursor complexes were also analysed and compared to the double salt products thus providing a clearer picture for future crystal design in double spin crossover materials. We discuss the effects that the solvent and counterion had on the crystal packing and spin crossover properties.

Amphiphilic iron(ii) spin crossover coordination polymers: crystal structures and phase transition properties

2019 ◽  
Vol 7 (5) ◽  
pp. 1151-1163 ◽  
Author(s):  
Johannes Weihermüller ◽  
Stephan Schlamp ◽  
Wolfgang Milius ◽  
Florian Puchtler ◽  
Josef Breu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Crystal Structures ◽  
Coordination Polymers ◽  
Spin Crossover ◽  
Spin Transition ◽  
Spin Crossover Complexes ◽  
Platelet Formation

A cooperative spin transition and thin platelet formation is observed for 1D coordination polymers of amphiphilic iron(ii) spin crossover complexes.

Double spin crossovers: a new double salt strategy to improve magnetic and memory properties

2019 ◽  
Vol 55 (93) ◽  
pp. 14031-14034 ◽  
Author(s):  
Wasinee Phonsri ◽  
Barnaby A. I. Lewis ◽  
Guy N. L. Jameson ◽  
Keith S. Murray
Keyword(s):  
Spin Crossover ◽  
Complex Anion ◽  
Complex Cation ◽  
Double Salt ◽  
Double Spin

The first example of a “double spin crossover” material, [FeII(3,5-Me2 tris(pyrazolyl)methane)(tris(pyrazolyl)methane)][FeIII azodiphenolate]ClO4·2MeCN was synthesised by reacting a spin crossover FeII complex cation with a spin crossover FeIII complex anion.

Non-isothermal kinetics of spin crossover

2017 ◽  
Vol 19 (26) ◽  
pp. 16955-16959 ◽  
Author(s):  
Mark B. Bushuev ◽  
Elena B. Nikolaenkova ◽  
Viktor P. Krivopalov
Keyword(s):  
Activation Energy ◽  
Spin Crossover ◽  
Spin Transition ◽  
Isothermal Kinetics ◽  
Magnetic Studies ◽  
Kinetics Of

Non-isothermal magnetic studies can be used to estimate the activation energy of cooperative spin transition.

Systematic Design of Crystal Structure for Hofmann-Like Spin Crossover Fe(L)2[Ag(CN)2]2 Complexes

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 370 ◽  
Author(s):  
Takashi Kosone ◽  
Yoshinori Makido ◽  
Syogo Okuda ◽  
Ayaka Haigo ◽  
Takeshi Kawasaki ◽  
...  
Keyword(s):  
Self Assembly ◽  
Spin Crossover ◽  
Interlayer Space ◽  
Layer Structure ◽  
Spin Transition ◽  
Axial Position ◽  
Systematic Design ◽  
Crystal Design ◽  
Critical Temperature Tc ◽  
Benzyl Nicotinate

The synthesis, crystal structures, and magnetic properties of a new two-dimensional (2D) Hofmann-like series, FeII(L)2[AgI(CN)2]2 (L = 3-cyano-4-methylpyridine (1), allyl isonicotinate (2), phenyl-isonicotinate (3), and benzyl nicotinate (4)) were studied. These compounds have a 2D sheet structure because of their strongly determinate self-assembly process. An octahedral FeII ion is coordinated with the nitrogen atoms of[AgI(CN)2 linear units at equatorial positions and monodentate pyridine derivatives at the axial position. The layers construct a parallel stacking array. Compounds 1–3 show pairs of layers constructed by intermetallic Ag···Ag interactions. Compound 4 shows a mono-layer structure. The substituent bulk of the ligands affects the interlayer space. Compounds 1–4 undergo a 100% spin transition. However, compound 1, incorporating a smaller group, has a relatively lower critical temperature (Tc = 182 K (1), Tc = 221 K (2), Tc = 227 (3) and Tc1 = 236 K, Tc2 = 215 K (4)). We investigated the correlations between our systematic crystal design, substituent size, and the spin crossover profiles.

Towards direct correlations between spin-crossover and structural features in iron(II) complexes

2003 ◽  
Vol 59 (4) ◽  
pp. 479-486 ◽  
Author(s):  
Mathieu Marchivie ◽  
Philippe Guionneau ◽  
Jean-François Létard ◽  
Daniel Chasseau
Keyword(s):  
Crystal Structures ◽  
Room Temperature ◽  
Spin Crossover ◽  
Spin Transition ◽  
Intermolecular Hydrogen Bond ◽  
Structural Features ◽  
Gradual Transition ◽  
Hydrogen Bond Interaction ◽  
First Approximation ◽  
Two Phases

The [Fe(PM-BiA)2(NCS)2] complex, where PM is N-2-pyridylmethylene and BiA is 4-aminobiphenyl, crystallizes in two polymorphs. The two phases, denoted (I) and (II), undergo a spin-crossover when the sample is cooled and present distinct spin-transition features as (I) shows a very abrupt spin transition, while (II) exhibits a gradual transition. The two forms of the complex are used to investigate the correlations that exist between the spin-transition features and structural features. This article presents the crystal structures of polymorph (II) at room temperature (high spin) and at 120 K (low spin), including a comparison with those of polymorph (I). This study reveals that the packing, in a first approximation, is similar in both forms. In order to look at the crystal structures in more detail, a new angular parameter, denoted θNCS, as well as a particular type of intermolecular hydrogen-bond interaction, which involves the S atoms of the NCS ligands, are investigated. Interestingly, this angle and this intermolecular interaction can be directly connected to the cooperativity of the spin transition. Such a result is extended to all the SCO iron(II) complexes belonging to the same family of the general formula [Fe(PM-L)2(NCS)2].

scholarly journals Crystal structures of two copper(I)–6,6′-dimethyl-2,2′-bipyridyl (dmbpy) compounds, [Cu(dmbpy)2]2[MF6]·xH2O (M = Zr, Hf; x = 1.134, 0.671)

2021 ◽  
Vol 77 (8) ◽  
pp. 819-823
Author(s):  
Yiran Wang ◽  
Matthew L. Nisbet ◽  
Kenneth R. Poeppelmeier
Keyword(s):  
Water Molecule ◽  
Crystal Structures ◽  
Copper Complexes ◽  
Crystal Packing ◽  
Steric Effects ◽  
Stacking Interactions ◽  
Coulombic Interactions ◽  
Copper Compounds ◽  
Crystal Design ◽  
Molecular Compounds

The syntheses and crystal structures of two bimetallic molecular compounds, namely, bis[bis(6,6′-dimethyl-2,2′-bipyridine)copper(I)] hexafluoridozirconate(IV) 1.134-hydrate, [Cu(dmbpy)2]2[ZrF6]·1.134H2O (dmbpy = 6,6′-dimethyl-2,2′-bipyridyl, C12H12N2), (I), and bis[bis(6,6′-dimethyl-2,2′-bipyridine)copper(I)] hexafluoridohafnate(IV) 0.671-hydrate, [Cu(dmbpy)2]2[HfF6]·0.671H2O, (II), are reported. Apart from a slight site occupany difference for the water molecule of crystallization, compounds (I) and (II) are isostructural, featuring isolated tetrahedral cations of copper(I) ions coordinated by two dmbpy ligands and centrosymmetric, octahedral anions of fluorinated early transition metals. The tetrahedral environments of the copper complexes are distorted owing to the steric effects of the dmbpy ligands. The extended structures are built up through Coulombic interactions between cations and anions and π–π stacking interactions between heterochiral Δ- and Λ-[Cu(dmbpy)2]+ complexes. A comparison between the title compounds and other [Cu(dmbpy)2]+ compounds with monovalent and bivalent anions reveals a significant influence of the cation-to-anion ratio on the resulting crystal packing architectures, providing insights for future crystal design of distorted tetrahedral copper compounds.

scholarly journals 2D Layer Arrangement of Solely [HS-HS] or [LS-LS] Molecules in the [HS-LS] State of a Dinuclear Fe(II) Spin Crossover Complex

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 448
Author(s):  
Fabian Fürmeyer ◽  
Luca M. Carrella ◽  
Eva Rentschler
Keyword(s):  
Crystal Structure ◽  
Spin Crossover ◽  
Crystal Packing ◽  
Spin Transition ◽  
High Spin State ◽  
Crystal Structure Analysis ◽  
Magnetic Data ◽  
The Novel ◽  
Layer Arrangement ◽  
Dinuclear Iron

Herein we report the synthesis and characterization of three new dinuclear iron(II) complexes [FeII2(I4MTD)2](F3CSO3)4 (C1), [FeII2(I4MTD)2](ClO4)4 (C2) and [FeII2(I4MTD)2](BF4)4 (C3) based on the novel ligand (I4MTD = 2,5-bis{[(1H-imidazol-4-ylmethyl)amino]methyl}-1,3,4-thiadiazole). Magnetic susceptibility measurements and single-crystal structure analysis show that the iron(II) spin centers for all complexes are in the high spin state at high temperatures. While the magnetic data of air-dried samples confirm the [HS-HS] state for C1 and C2 down to very low temperature, for C3, a gradual spin crossover is observed below 150 K. The crystal structure of C3·THF at 100 K shows that a spin transition from [HS-HS] to an intermediate state takes place, which is a 1:1 mixture of discrete [HS-HS] and [LS-LS] molecules, as identified unambiguously by crystallography. The different SCO properties of C1–C3 can be attributed to crystal packing effects in the solid state.

Kinetics of spin crossover with thermal hysteresis

2018 ◽  
Vol 20 (8) ◽  
pp. 5586-5590 ◽  
Author(s):  
Mark B. Bushuev
Keyword(s):  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Spin Transition ◽  
Reaction Model ◽  
Magnetic Studies ◽  
Kinetics Of

Non-isothermal magnetic studies allow establishing a reaction model of hysteretic spin transition.

Abrupt spin crossover in iron(iii) complexes with aromatic anions

2019 ◽  
Vol 48 (41) ◽  
pp. 15515-15520 ◽  
Author(s):  
Sharon E. Lazaro ◽  
Adil Alkaş ◽  
Seok J. Lee ◽  
Shane G. Telfer ◽  
Keith S. Murray ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Spin Crossover ◽  
Spin Transition ◽  
Halogen Bonds ◽  
Aromatic Anions

Two iron(iii) complexes, [Fe(qsal-X)2]OTs·nH2O, are found to exhibit abrupt spin crossover with the spin transition temperature substituent dependent, and X⋯O halogen bonds linking the spin centres.

Structural, magnetic and Mössbauer spectroscopic studies of the [Fe(3-bpp)2](CF3COO)2 complex: role of crystal packing leading to an incomplete Fe(ii) high spin ⇋ low spin transition

CrystEngComm ◽  
2021 ◽  
Vol 23 (15) ◽  
pp. 2854-2861
Author(s):  
Kristian Handoyo Sugiyarto ◽  
Djulia Onggo ◽  
Hiroki Akutsu ◽  
Varimalla Raghavendra Reddy ◽  
Hari Sutrisno ◽  
...  
Keyword(s):  
High Spin ◽  
Crystal Packing ◽  
Spin Transition ◽  
Spectroscopic Studies ◽  
Mononuclear Complex

Mononuclear complex [Fe(3-bpp)2](CF3COO)2 exhibits a thermal (HS + HS) ⇋ (HS + LS) transition at ∼226 K which is not associated with any crystallographic transition.

Sign in / Sign up

Export Citation Format

Share Document