Hirshfeld Surface Analysis, Crystal Structure and Spectroscopic Studies of a New Cu(II) Halocuprate Salt with Protonated N-Amino-Ethyl-Piperazine

Abstract

(C₆H₁₈N₃)₄[CuCl₅]₂[CuCl₄]₃·1.42H₂O is prepared and characterized by various physicochemical techniques. The single crystal X-ray diffraction structural analysis reveals that the title compound belongs to the orthorhombic system with the space group Cmca. Its unit cell dimensions are: a = 24.286(2) Å, b = 14.3082(14) Å, c = 16.6160(16) Å, Z = 4, V = 5773.8(10) ų. Its crystal structure is determined and refined down to R = 0.024 and wR(F²) = 0.059. The structure contains three crystallographically independent Cu²⁺ ions coordinated to chlorine anions in various fashions. Cu1 is five-coordinated in a distorted square pyramidal fashion, while Cu2 and Cu3 are four-coordinated in square planar and distorted tetrahedral fashions, respectively. The entities are interconnected by means of the hydrogen bonding [O(W)–H…Cl, N–H…Cl, C–H…Cl and C–H…O(W)], forming a three-dimensional network. Intermolecular interactions are investigated by Hirshfeld surfaces and the contacts of the eight different chloride atoms are notably compared. The vibrational absorption bands are identified by infrared spectroscopy. The optical study is performed by UV-vis absorption.