Das erste quaternäre Oxocobaltat(I): CsK₂[CoO₂]

Abstract

The First Quaternary Oxide of Monovalent Cobalt: CsK2(CoO2).-Dark-red single crystals of CsK2(CoO2) are prepared by heating pretempered Cs2K2Cd3O5 powder in a sealed Co cylinder 48 d at 500 . degree.C. According to the four-circle diffractometer data, the compound crystallizes in the tetragonal space group I4/mmm with Z = 2. The structure is isotypic with RbNa2(NiO2). Maple calculations, investigations of magnetism and EPR measurements give evidence for the monovalence of Co. CsK2(CoO2) exhibits Curie-Weiss behavior in the temp. range 5 K

Synthesis, Crystal Structure, and Spectroscopic Characterization of Na5[NiO2][CO3], containing the Linear [NiO2]3- Group with Monovalent Nickel

“…3). All known monovalent oxometallates with the linear [MO 2 ] 3± complex (M = Fe, Co, Ni) are of an intense ruby-red colour [1,3,5]. These bands are shifted some 650 cm ±1 to lower wavenumbers compared to single crystal data obtained for K 3 [NiO 2 ] [5].…”

“…d xz , d yz = 2 e p (2) e eff r = e r ± 2 e ds (3) The extent of the d-s interaction, eq. (3) and in consequence the relative orbital energies determines the ground state to be either 2 R g (d 2 z ) with the d-orbital sequence of d 2 z > d xz , d yz > d x 2 Ày 2 , d xy or 2 P g (d xz , d yz ) corresponding to d xz , d yz > d 2 z > d x 2 Ày 2 , d xy .…”

“…Theoretical approaches, pronouncing a stronger d-s mixing of the 3 d-and 4 s-metal orbitals, lead to a different ground state, 2 P g [6]. Therefore, we have intensified our efforts and can now report Na 5 3 ] is sensitive to moisture and decomposes immediately when exposed to air. Therefore, we have intensified our efforts and can now report Na 5 3 ] is sensitive to moisture and decomposes immediately when exposed to air.…”

“…Na 5 [NiO 2 ][CO3 ] has been obtained from redox reactions between Cd 2+ and nickel metal, giving Ni + and Cd in the presence of Na 2 O (from reactions of NaOH (p. a. Merck) with sodium metal (98% Riedel-de Hae È n))[7]. Na 5 [NiO 2 ][CO3 ] has been obtained from redox reactions between Cd 2+ and nickel metal, giving Ni + and Cd in the presence of Na 2 O (from reactions of NaOH (p. a. Merck) with sodium metal (98% Riedel-de Hae È n))[7].…”

“…For the incommensurate/modulated structure of c-Na 2 CO 3 similar crystallographic problems of a disordered [CO 3 ] 2± were observed[8].Each sodium atom in Na 5 [NiO 2 ][CO3 ] has the C.N. 4).…”