Preparation and crystal structure of hydrated crystalline complex of ciprofloxacin and copper tetrachloride

Synthesis of a complex formed by ciprofloxacin (cfH) and copper(II) chloride is described; its crystal structure is reported and analyzed in comparison to related compounds. The obtained compound (cfH3)CuCl4·H2O (cfH 3 2+ — double protonated cfH molecule) crystallizes as platelets of P21/c symmetry having the unit cell parameters a = 13.491(1) A, b = 11.0459(7) A, c = 16.299(1) A; β = 111.392(7)°. Carbonyl oxygen O(1) is protonated, and hydrogen atom combined with it forms an intramolecular hydrogen bond with carboxylic O(2) oxygen (O(1)⋯O(2) = 2.642(5) A). Terminal nitrogen atom N(3) of the piperazinyl group is also protonated, and two its hydrogen atoms participate in hydrogen bonds of N-H⋯Cl type. The structure also has hydrogen bonds O-H⋯O, O-H⋯Cl with the participation of water molecules which occupy hydrophilic channels. Molecular ions cfH 3 2+ make couples with intrapair π⋯π interactions.