Chemical bonding and magnetic exchange in two dimensional [M(TCNE) (NCMe)2] X (M=Fe, Mn;X=FeCI4, SbF6) magnets: a pressure study
Abstract not provided
Engineering topics
Publications and source records attributed to Pokhodnya, K.
Abstract not provided
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{sup II}(TCNE) (NCMe){sub 2}[SbF{sub 6}] [M = Mn, Fe, Ni] composition is discussed in conjunction with their magnetic behavior and newly resolved crystal structures. The vibrational properties of the isolated TCNE{sup {sm_bullet}-} anion in the paramagnetic Bu{sub 4}N [TCNE{sup {sm_bullet}-}] salt and recently characterized 2D layered magnet Fe{sup II}(TCNE)(NCMe){sub 2}[FeCl{sub 4}] are also reported for comparison. Additionally, a linear correlation between {nu}{sub c=c} (a{sub g}) frequency of the TCNE ligand and its formal charge Z (the spin density on the {pi}* orbital), Z = [1571 - {nu}{sub C=C} (ag)]/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.
Amorphous silicon nanowires (a-SiNWs) were prepared by electrospinning cyclohexasilane (Si{sub 6}H{sub 12}) admixed with polymethylmethacrylate (PMMA) in toluene. Raman spectroscopy characterization of these wires (d {approx} 50-2000 nm) shows 350 C treatment yields a-SiNWs. Porous a-SiNWs are obtained using a volatile polymer.