title: Spectroscopic study of (two-dimensional) molecule-based magnets: [M(II)(TCNE)(NCMe)2][SbF6] (M = Fe, Mn, Ni).
abstract: The M-[TCNE] (M = 3d metal; TCNE = tetracyanoethylene) system is one of the most interesting classes of molecule-based magnets, exhibiting a plethora of compositions and structures (inorganic polymer chains, 2D layers, 3D networks, and amorphous solids) with a wide range of magnetic ordering temperatures (up to 400 K). A systematic study of vibrational (both infrared and, for the first time, Raman) properties of the family of new TCNE-based magnets of M(II)(TCNE) (NCMe)(2)[SbF(6)] [M = Mn, Fe, Ni] composition is discussed in conjunction with their magnetic behavior and newly reso-lved crystal structures. The vibrational properties of the isolated TCNE(●-) anion in the paramagnetic Bu(4)N [TCNE(●-)] salt and recently characterized 2D layered magnet Fe(II)(TCNE)(NCMe)(2)[FeCl(4)] are also reported for comparison. Additionally, a linear correlation between ν(C=C) (a(g)) frequency of the TCNE ligand and its formal charge Z (the spin density on the π* orbital), Z = [1571 - ν(C=C) (a(g))]/154.5 [e], is presented. It is shown that monitoring Z by Raman spectroscopy is of great use in providing information that allows understanding the peculiarity of the superexchange interaction in M-[TCNE] magnets and establishing the structure-magnetic properties correlations in this class of magnetic material.
authors.affiliation: Center for Nanoscale Science and Engineering, North Dakota State University, Fargo, North Dakota 58102, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Olson
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Heth
authors.forename: Saul H
authors.initials: SH
authors.lastname: Lapidus
authors.forename: Peter W
authors.initials: PW
authors.lastname: Stephens
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Halder
authors.forename: Konstantin
authors.initials: K
authors.lastname: Pokhodnya