ChemInform Abstract: Crystal Structure and Raman Spectroscopy of FeVMoO₇ and CrVMoO₇ with Mo=O Double Bonds.

Abstract

structure structure (solids and liquids) D 2000 -003Crystal Structure and Raman Spectroscopy of FeVMoO 7 and CrVMoO 7 with Mo=O Double Bonds.-Single crystals of the title compounds are grown by a flux method from Fe 2 O 3 -V 2 O 5 -MoO 3 and Cr 2 O 3 -V 2 O 5 -MoO 3 melts. Both compounds crystallize in the triclinic space group P1 with Z = 2. FeVMoO 7 and CrVMoO 7 are isostructural, in which V 5+ and Mo 6+ ions in the [VMoO 7 ] 3− units are crystallographically distinct, and one type of oxygen is bonded only to molybdenum, forming a Mo=O double bond. These rare structural features are also studied by infrared and Raman spectroscopy. -(WANG, X.; HEIER, K. R.; STERN, C. L.; POEPPELMEIER, K. R.; Inorg. Chem. 37 (1998) 13, 3252-3256; Dep. Chem., Northwest. Univ., Evanston, IL 60208, USA; EN)

Magnetism of the antiferromagnetic spin- 32 dimer compound CrVMoO7 having an antiferromagnetically ordered state

“…3(b) show the T dependence of χ(T ) of CrVMoO 7 powder in H = 0.1 T. The broad maximum of χ(T ) around 35 K indicates a low-dimensional AF spin system. The susceptibility seems to approach a finite value (∼ 0.012 emu/mol Cr) at 0 K. The magnetic order results in the probable finite susceptibility at 0 K. The susceptibility obtained by us is close to that reported in literature [19,22].…”

“…The refined crystal structure parameters are presented in Table I. The atomic positions in our results are similar to those in the literature [19,20]. Figure 6(a) shows neutron powder diffraction patterns of CrVMoO 7 at 5 and 35 K. The two patterns nearly overlap each other except for around 2θ = 20 • .…”

“…Only the Cr 3+ ion (3d 3 ) has a localized spin- 3 2 . The shortest distance between two Cr 3+ ions is 3.01Å at 153 K, whereas the other Cr-Cr distances are larger than 4.96Å [19]. We found an antiferromagnetically ordered state below T N = 26.5 ± 0.8 K. We investigated magnetism of CrVMoO 7 using magnetization, specific heat, electron spin resonance, neutron diffraction, and inelastic neutron scattering experiments.…”

“…The unit cell of CrVMoO7 [19,20]. An AF spin-3 2 dimer is formed by two neighboring Cr 3+ ions (3d 3 electron configuration) with the distance of 3.01Å.…”

“…We can expect an interacting AF spin-3 2 dimer model in CrVMoO 7 from its crystal structure as shown in Fig. 1(a) [19,20]. Only the Cr 3+ ion (3d 3 ) has a localized spin- 3 2 .…”