Syntheses and characterization of ANi(AsF6)3 (A=H3O~+, O_2~+, NO~+, NH_4~+, K~+, Rb~+, and Cs~+) compounds

摘要

ANi(AsF6)3 (A =O_2~+, NO~+, NH_4~+) compounds could be prepared by reaction between corresponding AAsF6 salts and Ni(AsF6)2. When mixtures of AF (A = Li, Na, K, Rb, Cs) and NiF2 are dissolved in aHF acidified with an excess of AsF5 the corresponding AAsF6 and Ni(AsF6)2 were formed in situ. For A " Li and Na only mixtures of AAsF6 and Ni(AsF6)2 were obtained, while for A = K, Rb and Cs, the final products were ANi(AsF6)3 (A = K-Cs) compounds contaminated with AAsF6 (A = K-Cs) and Ni(AsF6)2. ANi(AsF6)3 (A = H3O~+, O_2~+. NO~+, NH_4~* and K~+) compounds are structurally related to previously known H3OCo(AsF6)3. The main features of the structure of these compounds are rings of NiF6 octahedra sharing apexes with AsF6 octahedra connected into infinite tri-dimensional network. In this arrangement cavities are formed where single charged cations are placed. In O2Ni(AsF6)3 the vibrational band belonging to O_2~+ vibration is found at 1866 cm~(-1), which is according to the literature data one of the highest known values, and it is only 10 cm~(-1) lower than the value for free O_2~+.