title: Chemical bonding and magnetic exchange in two-dimensional [M(TCNE)(NCMe)2]X (M = Fe, Mn; X = FeCl4, SbF6) magnets: a pressure study.
abstract: Pressure-dependent X-ray diffraction studies reveal the bulk modulus and compression anisotropy of the 2D magnet [Mn(TCNE)(NCMe)(2)]SbF(6). The Raman response of this and the similar [Fe(TCNE)(NCMe)(2)]FeCl(4) layered magnet, shows that the evolution of the a(g) ν(C=C) frequency correlates well with the magnetic exchange and T(c) variations of these materials under pressure. There is a significantly more complex correlation between the a(g) ν(C≡N) frequency and T(c) despite the fact that some unpaired π* electron density (~0.125 e) is localized on each of TCNE nitrile N≡C group. The shortening of the M-NC bond with pressure (<0.5 GPa) does not result in a T(c) increase, which suggests a more complex bond length magnetic exchange relationship.
authors.affiliation: Department of Physics and Astronomy, University of Missouri-Kansas City, Kansas City, Missouri 64110, USA.
authors.forename: Alex E
authors.initials: AE
authors.lastname: Midgley
authors.forename: Christopher
authors.initials: C
authors.lastname: Olson
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Heth
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Caruso
authors.forename: Michael B
authors.initials: MB
authors.lastname: Kruger
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Halder
authors.forename: John A
authors.initials: JA
authors.lastname: Schlueter
authors.forename: Konstantin
authors.initials: K
authors.lastname: Pokhodnya