Crystal structure solid interaction products of ε-caprolactam with hydrofluoric asid and copper(II) hexafluorosilicate

Synthesis conditions were developed, new compounds of compositions (HOOC(CH2)5NH3)2SiF6 (1) and [Cu(Cpl)2(H2O)2SiF6]·2Cpl (2), where (Cpl – ɛ-caprolactam, ɛ-C6H11NO, (HOOC(CH2)5NH3)+ – cation 5-carboxypentylammonium) were obtained from aqueous solutions and studied by chemical, IR spectroscopic and X-ray diffraction analyses. In the structure of compound 1, the coordination environment of the Si atom is an almost regular octahedron. Crystals are triclinic sistem, space group P$\overline{1}$. During crystallization, caprolactam undergoes a hydration reaction and protonation. In structure 1, hydrogen bonds F...H–N were found between anions and organic cations, as well as “acidic” hydrogen bonds between carboxyl groups of cations. Compound 2 crystallizes in the triclinic system, space group P$\overline{1}$ and has a polymer chain structure. The coordination polyhedron of two independent copper cations is a tetragonally distorted octahedron formed by the O atoms of two Cpl molecules and two F atoms of hexafluorosilicate anions acting as bridges between neighboring cations. The coordination environment of the Si atom is a slightly distorted octahedron. The structure contains hydrogen bonds between the H atoms of coordinated water molecules and the O atoms of uncoordinated Cpl molecules. The geometry of hexafluorosilicate anions in structures 1 and 2 is identical.