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A cluster containing copper(I), l-cysteine and chloride ions was synthesized and characterized by X-ray diffraction and FTIR spectroscopy., The title hydrated copper(I)–l-cysteine–chloride complex has a polymeric structure of composition {[Cu16(CysH2)6Cl16]·xH2O}n [CysH2 = HO2CCH(NH3 +)CH2S− or C3H7NO2S], namely, poly[[tetra-μ3-chlorido-deca-μ2-chlorido-di­chlorido­hexa­kis­(μ4-l-cysteinato)hexa­deca­copper] polyhydrate]. The copper atoms are linked by thiol­ate groups to form Cu12S6 nanoclusters that take the form of a tetra­kis cubocta­hedron, made up of a Cu12 cubo-octa­hedral subunit that is augmented by six sulfur atoms that are located symmetrically atop of each of the Cu4 square units of the Cu12 cubo-octa­hedron. The six S atoms thus form an octa­hedral subunit themselves. The exterior of the Cu12S6 sphere is decorated by chloride ions and trichlorocuprate units. Three chloride ions are coordinated in an irregular fashion to trigonal Cu3 subunits of the nanocluster, and four trigonal CuCl3 units are bonded via each of their chloride ions to a copper ion on the Cu12S6 sphere. The trigonal CuCl3 units are linked via Cu2Cl2 bridges covalently connected to equivalent units in neighboring nanoclusters. Four such connections are arranged in a tetra­hedral fashion, thus creating an infinite diamond-like net of Cu12S6Cl4(CuCl3)4 nanoclusters. The network thus formed results in large channels occupied by solvent mol­ecules that are mostly too ill-defined to model. The content of the voids, believed to be water mol­ecules, was accounted for via reverse Fourier-transform methods using the SQUEEZE algorithm [Spek (2015 ▸). Acta Cryst. C71, 9–18]. The protonated amino groups of the cysteine ligands are directed away from the sphere, forming N—H⋯Cl hydrogen bonds with chloride-ion acceptors of their cluster. The protonated carb­oxy groups point outwards and presumably form O—H⋯O hydrogen bonds with the unresolved water mol­ecules of the solvent channels. Disorder is observed in one of the two crystallographically unique [Cu16(CysH2)6Cl16] segments for three of the six cysteine anions.

Complex formation of nickel(II) with benzoic, para-methoxybenzoic acid hydrazides, and L-histidine have been studied by the methods of pH-metric titrimetry, spectrophotometry, and mathematical modelling in aqueous solutions with 1.0 mol dm–3 KNO3 as background at 298 K. Dissociation constants of ligands, as well as composition, formation constants, and spectral parameters of homo- and heteroligand complexes have been determined. It has been shown that stability of the complexes formed with para-methoxybenzoic acid hydrazide is higher than with benzoic acid hydrazide, which is consistent with the electron-donor properties of the methoxy group. Extra stabilization of the nickel(II) heteroligand complexes with benzoic (para-methoxybenzoic) acid hydrazide and L-histidine has been discovered and interpreted.