title: High-pressure spin-crossover in a dinuclear Fe(II) complex.
abstract: The effect of pressure on the dinuclear spin crossover material [{Fe(bpp)(NCS)(2)}(2)(4,4'-bipy)]·2MeOH (where bpp = 2,6-bis(pyrazol-3-yl)pyridine and 4,4'-bipy = 4,4'-bipyridine, 1) has been investigated with single crystal X-ray diffraction and Raman spectroscopy using diamond anvil cell techniques. The very gradual pressure-induced spin crossover occurs between 7 and 25 kbar, and shows no evidence of crystallographic phase transitions. The pressure-induced spin transition leads to a complete LS state which is not thermally accessible. This structural evolution under pressure is in stark contrast to the previously reported thermal spin crossover behaviour, in which a symmetry-breaking, purely structural phase transition results in only partial conversion to the low spin state. This observation is attributed to the symmetry-breaking phase transition becoming unfavourable under pressure.
authors.affiliation: Laboratoire de Chimie de Coordination, CNRS UPR-8241, and Université de Toulouse, UPS, INP, Toulouse, France.
authors.forename: Helena J
authors.initials: HJ
authors.lastname: Shepherd
authors.forename: Patrick
authors.initials: P
authors.lastname: Rosa
authors.forename: Laure
authors.initials: L
authors.lastname: Vendier
authors.forename: Nicola
authors.initials: N
authors.lastname: Casati
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Létard
authors.forename: Azzedine
authors.initials: A
authors.lastname: Bousseksou
authors.forename: Philippe
authors.initials: P
authors.lastname: Guionneau
authors.forename: Gábor
authors.initials: G
authors.lastname: Molnár