14890-41-6Relevant academic research and scientific papers
Excitonic two-phonon progressions in transition metal compounds
Pollini
, p. 281 - 286 (2000)
Evidence of two-phonon structures is reported for some intra-configurational crystal field transitions in layered V- and Cr-halides. In particular, the crystal field spectrum of CrBr2 (3d4) has been shown for the first time, since the exciton-phonon interaction, despite its unfilled e(g) orbitals, vanishes to first order yielding a two-phonon sequence in the 3A1(G) + 3A2(F) band. It is suggested that the main mechanism for the occurrence of two-phonon progressions consists in the direct coupling of the incident photon to a two-phonon state via the second-order dipole moment operator. (C) 2000 Elsevier Science B.V.
MAGNETIC SUSCEPTIBILITIES OF THE FRUSTRATED TRIANGULAR LATTICE ANTIFERROMAGNETS CsVCl3 3 AND VX2 (X equals Cl, Br AND I): APPEARANCE OF MAGNETIC LIQUID IN THE ORDERED STATE.
Hirakawa,Ikeda,Kadowaki,Ubukoshi
, p. 2882 - 2887 (1983)
Magnetic susceptibilities chi have been measured by means of the conventional Faraday-type as well as SQUID magnetometers. The chi -T curve of CsVCl//3 shows a typical 1D-like character in agreement with the early work by M. Niel et al. No anisotropy could be detected below T//n. This suggests that the transition is quite different from the conventional one for the non-frustrated antiferromagnetic systems and a magnetic liquid state is formed in the ordered state.
Redox reactions with bis(η6-arene) derivatives of early transition metals
Calderazzo, Fausto,Englert, Ulli,Pampaloni, Guido,Volpe, Manuel
, p. 3321 - 3332 (2007/10/03)
The reactivity of M(η6-arene)2 derivatives of early transition metals (M = Ti, Cr, Mo, arene = MeC6H5; M = V, Nb, arene = 1,3,5-Me3C6H3) has been investigated and the syntheses of new and known compounds are described. The derivatives M(CH3COO)3, M = Ti, V, Nb, Cr; M(CF 3COO)3, M = Ti, Nb, Cr; M(acac)3, M = Ti, V, Mo, acac = acetylacetonato, and M(F6acac)3, F 6acac = hexafluoroacetylacetonato, M = V, Nb have been prepared by reaction of the metal bis(arene) derivatives with the appropriate Lewis acid. The crystal and molecular structure of V(F6acac)3 has been determined. Hydrogen halides or halogens react with M(η6-arene) 2 with formation of metal halides, a highly reactive form of VCl 3 being obtained from V(η6-1,3,5-Me3C 6H3)2 and hydrogen chloride in heptane. TiCl4 oxidizes Ti(η6-arene)2 with complete loss of the arene ligands. An electron transfer process affording ionic derivatives of formula [M(η6-MeC6H5) 2][TiCl4(THF)2], M = Cr (structurally characterized), Mo, has been observed between the THF-adduct of TiCl4 and the appropriate metal-arene derivative of Group 6.
Vaporization reactions of vanadium(III) bromide. Dissociation and disproportionation equilibria, and the formation of vanadium(IV) bromide
Mccarley, Robert E.,Roddy, James W.
, p. 54 - 59 (2008/10/08)
The equilibria VBr3(s) = VBr2(s) + 1/2Br2(g) (1) and 2VBr3(s) = VBr2(s) + VBr4(g) (2) were studied over the range 644 to 805°K. by transpiration in helium. For (1) ΔH° = 23.1 ± 0.9 kcal./mole and ΔS° = 10.6 ± 0.4 e.u., while for (2) ΔH° = 37.7 ± 1.3 kcal./mole and ΔS° = 34.7 ± 1.2 e.u. Both transpiration in bromine vapor and static pressure measurements using a glass diaphragm gage showed that VBr3(s) vaporized as VBr4(g) in the presence of bromine according to VBr3(s) + 1/2Br2(g) = VBr4(g) (3). The transpiration measurements gave for (3) ΔF° = 15.80 × 103 - 23.9T for T = 515-585°K. Solid VBr4 was isolated by condensation of the vapor at -78° and was found to be stable at -45°. At higher temperatures the solid decomposed to VBr3(s) and bromine.
The vapor pressures of vanadium(II) chloride, vanadium(III) chloride, vanadium(II) bromide, and vanadium(III) bromide by Knudsen effusion
Mccarley, Robert E.,Roddy, James W.
, p. 60 - 63 (2008/10/08)
The vapor pressures of crystalline VCl2, VBr2, VCl3, and VBr3 have been measured by the Knudsen effusion method. Only the simple vaporization was observed for VCl2 and VBr2 over the interva
