Molecular and crystal structure of bis(Lidocaine) tetrachlorozincate(II)

The present paper reports on the synthesis, molecular and crystal structure of bis(2-(diethylamino)N-(2,6-dimethylphenyl)acetamide) tetrachlorozincate(II). The complex with the formula (C₁₄H₂₃ON₂)₂ZnCl₄ (or (LidH)₂ZnCl₄), crystallizes in the monoclinic space group P2₁/c with a = 8.8921(2), b = 19.2650(3), c = 19.3211(3) Å, β = 95.026(2)°, V = 3297.10(10) ų, Z = 4, and D_c = 1.366 Mg/m³. In molecular structure the coordination of the Zn²⁺ ion with chlorine atoms generates slightly distorted tetrahedral anion ZnCl₄^2–, while two protonated cations LidH⁺ remain in an outer coordination sphere. The anion and cations are associated by hydrogen bonds formed by two chlorine atoms with amido nitrogen atoms, the conformation of the flexible chain of lidocaine molecules provides for the formation of an intramolecular hydrogen bond between the protonated nitrogen atom of the amino group and the oxygen atom of the carboxamide group. Protonated amino nitrogen atoms also form intermolecular hydrogen bonds with the oxygen atoms of neighboring molecules of the charge-transfer complex, combining them in pairs 2[(LidH)₂ZnCl₄]. Each pair forms intermolecular N–H···Cl hydrogen bonds with four adjacent pairs, arranging them into endless sheets lying in the bc plane.