Electronic Excitations and Lattice Dynamics of Coordinatively “Unsaturated” Complex Transition Metal Compounds

Abstract

Single crystal polarized Raman and infrared spectra of the series Na(5)[MO(2)][X] with M = Co(I), Ni(I), and Cu(I) and X = S(2-) and CO(3)(2-), are reported. All phonon modes are assigned to the lattice eigenmodes based on the group theory analysis and first principles lattice dynamics calculations. The energies of the fundamental symmetric and asymmetric vibrations of the [MO(2)](3-) complex are discussed on the basis of their electronic structure and variation in M-O interatomic distances. Electronic Raman scattering and luminescence are observed for the magnetic members of the series (Co(I), d(8), and Ni(I), d(9)). Ligand field theory is employed to account for the electronic effects which originate from states split by spin-orbit coupling.

Reactivity of FeMoO4 in CsCl Fluxes and Formation of the Salt-Inclusion Type of Compounds

“…Multi-anionic compounds are fascinating because of the potential to control the transition metal’s coordination sphere as well as their mutual connectivity with access to low-dimensional structures and tunable physical properties. − Synthesis protocols span from solid-state to widely explored solvothermal approaches: (i) TiOCl is a prominent example for a chemical vapor transport reaction and has gained attention due to an incommensurate Spin–Peierls phase transition with interchain frustration; (ii) redox chemistry in the presence of alkaline-metal oxides has been fruitful in exploring coordinatively “unsaturated″ compounds, such as Na 5 [MO 2 ]­[X] with M = Co I or Ni I (C.N. 2) and X = CO 3 2– or S 2– ; and (iii) a triple-anionic compound, [Ba 2 X]­Cu­(OH)­[V 2 O 7 ] with X = Cl, Br, containing well-isolated magnetic chains, has been obtained from solvothermal reactions.…”