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Symmetry breaking and light-induced spin-state trapping in a mononuclear Fe<sup>II</sup> complex with the two-step thermal conversion

hal.structure.identifierInstitut de Physique de Rennes [IPR]
dc.contributor.authorBURON-LE COINTE, Marylise
hal.structure.identifierInstitut de Physique de Rennes [IPR]
hal.structure.identifierLaboratoire de chimie de coordination [LCC]
dc.contributor.authorOULD-MOUSSA, Nawell
hal.structure.identifierInstitut de Physique de Rennes [IPR]
dc.contributor.authorTRZOP, E.
hal.structure.identifierInstitut de Physique de Rennes [IPR]
dc.contributor.authorMORÉAC, Alain
hal.structure.identifierLaboratoire de chimie de coordination [LCC]
dc.contributor.authorMOLNÁR, Gábor
hal.structure.identifierInstitut de Physique de Rennes [IPR]
dc.contributor.authorTOUPET, Loïc
hal.structure.identifierLaboratoire de chimie de coordination [LCC]
dc.contributor.authorBOUSSEKSOU, Azzedine
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorLETARD, Jean-François
hal.structure.identifierLaboratoire de Chimie - UMR5182 [LC]
dc.contributor.authorMATOUZENKO, Galina
dc.date.issued2010
dc.identifier.issn1098-0121
dc.description.abstractEnCrystallographic, magnetic, and Raman investigations of the mononuclear [Fe<sup>II</sup>(Hpy-DAPP)](BF<sub>4</sub>)<sub>2</sub> complex are presented. Its particular feature is a two-step thermal spin conversion in spite of a unique symmetry-independent iron site per unit cell. The plateau around 140 K is associated with a symmetry breaking visible by the appearance of weak (0k0) k odd Bragg peaks. Symmetries of the high-temperature high-spin state and of the low-temperature low-spin state are both monoclinic P2<sub>1</sub>/c, so that the symmetry breaking on the plateau is associated with a reentrant phase transition. It is discussed in relation with Ising-type microscopic models. At the plateau level, the two symmetry-independent molecules differ both by their spin state and the conformation (chair versus twist-boat) of one metallocycle. At low-temperature photoinduced phenomena have been investigated: a partial phototransformation [light-induced excited spin-state trapping (LIESST) effect] is observed under visible red irradiation. Raman spectroscopy shows that the molecular photoinduced state is the high-spin one. Nevertheless, as no macroscopic symmetry breaking is observed, the unique average cationic [Fe<sup>II</sup>(Hpy-DAPP)] state of the unit cell is intermediate between pure low-spin and high-spin states and presents a conformational disorder for one metallocycle. Reverse-LIESST has also been evidenced using near infrared excitation. Thus, the mononuclear [Fe(Hpy-DAPP)](BF<sub>4</sub>)<sub>2</sub> compound offers the opportunity to discuss the interplay between spin conversion, molecular conformational change, and ordering processes.
dc.language.isoen
dc.publisherAmerican Physical Society
dc.title.enSymmetry breaking and light-induced spin-state trapping in a mononuclear Fe<sup>II</sup> complex with the two-step thermal conversion
dc.typeArticle de revue
dc.identifier.doi10.1103/PhysRevB.82.214106
dc.subject.halChimie/Matériaux
bordeaux.journalPhysical Review B: Condensed Matter and Materials Physics (1998-2015)
bordeaux.page214106 (11 p.)
bordeaux.volume82
bordeaux.issue21
bordeaux.peerReviewedoui
hal.identifierhal-00569998
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00569998v1
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