Relevance of supramolecular interactions, texture and lattice occupancy in the designer iron(II) spin crossover complexes

Journal Article · Mon Jun 15 00:00:00 EDT 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2009.02.035· OSTI ID:21370423

Naik, Anil D ^[1]; Tinant, Bernard ^[2]; Muffler, Kai; Wolny, Juliusz A; Schuenemann, Volker ^[3]; Garcia, Yann ^[1]

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1. Unite de Chimie des Materiaux Inorganiques et Organiques, Departement de Chimie, Universite Catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve (Belgium)
2. Unite de Chimie Structurale et des Mecanismes Reactionnels, Departement de Chimie, Universite Catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve (Belgium)
3. Technische Universitaet Kaiserslautern, Fachbereich Physik, Erwin-Schroedinger-Str. 56, 67663 Kaiserslautern (Germany)

New Fe{sup II} complexes of formula [Fe(3-Br-phen){sub 2}(NCS){sub 2}].Solvent (Solvent=0.5 CH{sub 3}OH (1), 2 CH{sub 2}Cl{sub 2} (2), desolvation of 2 (3), 0.5 CH{sub 3}COCH{sub 3} (4) and 0 (5)) have been synthesized. {sup 57}Fe Moessbauer and magnetic investigation reveal unique features atypical of classic [Fe(phen){sub 2}(NCS){sub 2}] polymorphs. Complex 1, prepared by precipitation in MeOH, undergoes upon cooling below room temperature an incomplete and gradual thermally induced spin conversion, while 4 prepared by an extraction method remains mostly in the low-spin state. The non solvated compounds 3 and 5, display a more abrupt spin crossover on cooling around T{sub 1/2}=175 K and T{sub 1/2}=198 K, respectively. Defects/soft lattice inclusion due to different methods of material synthesis, extent of aging, reaction medium and associated solvent molecules have enormous influence on the particle size and magnetic properties of these complexes. Scanning electron micrographs helps to establish a logical relationship among methods employed for synthesis, texture of materials and their effect on magnetic properties. The crystal structure of 2 determined in the monoclinic space group P2/c (100 K) reveals a mononuclear complex consisting of a distorted FeN{sub 6} octahedron in the low-spin state, constructed from two 3-bromo-1, 10-phenanthroline and two isothiocyanato anions in cis position. Intermolecular interactions between mononuclear units of the S...Br, S...C(H) and pi-pi type afford a 2D supramolecular network. DFT calculations for the single molecule 2 reveals an energy difference between high-spin and low-spin isomers of 7 kJ/mol suggesting a slight destabilization of the low-spin state compared to [Fe(phen){sub 2}(NCS){sub 2}]. Normal co-ordinate analysis was also carried out for 3 and compared with experimental temperature dependent Raman spectra for 5. - Graphical abstract: New Fe{sup II} complexes of formula [Fe(3-Br-phen){sub 2}(NCS){sub 2}].Solvent have been synthesized by precipitation (1) and extraction (4) methods. {sup 57}Fe Moessbauer and magnetic investigation reveal unique features atypical of classic [Fe(phen){sub 2}(NCS){sub 2}] polymorphs. Complex 1, undergoes upon cooling below room temperature an incomplete and gradual thermally induced spin conversion, while 4 remains mostly in the low-spin state. Role of supramolecular interactions, particles size, lattice solvents have profound influence on magnetic properties.

• OSTI ID: 21370423
• Journal Information: Journal of Solid State Chemistry, Vol. 182, Issue 6; Other Information: DOI: 10.1016/j.jssc.2009.02.035; PII: S0022-4596(09)00096-6; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AGING
COOLING
CRYSTAL DEFECTS
EXTRACTION
INTERACTIONS
IRON COMPLEXES
MAGNETIC PROPERTIES
METHANOL
METHYLENE CHLORIDE
MOESSBAUER EFFECT
MONOCLINIC LATTICES
PARTICLE SIZE
PHENANTHROLINES
PRECIPITATION
RAMAN SPECTRA
SCANNING ELECTRON MICROSCOPY
SOLVENTS
SPACE GROUPS
SPIN
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
ALCOHOLS
ANGULAR MOMENTUM
AROMATICS
AZAARENES
COMPLEXES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
MICROSCOPY
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
SEPARATION PROCESSES
SIZE
SPECTRA
SYMMETRY GROUPS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPLEXES