Ni2+–Fe3+ cyanometallate structures covalently embedded in silica: Influence of the blocking ligand at Ni2+

Abstract

Ni(II)/Fe(III) cyanometallate structures with Si(OR)3-substituted bis(2-aminoethyl)-1,3-propanediamine or 1,4,8,11-tetraazacyclotetradecane (cyclam) blocking ligands at Ni(II) were prepared and embedded in SiO2 by means of sol-gel processing with Si(OEt)4. The cyanometallates were microcrystalline before sol-gel-processing, and a double-chain structure is proposed for the silyl-substituted [Ni(tetramine)]3[Fe(CN)6]2 derivatives. The 3D arrangement is lost during sol-gel processing, although Fe(III)CNNi(II) structures are retained in the gels, as proven by FTIR and SWAXS studies. The obtained gels show paramagnetic behavior.