Three 3D Cu(II) Isonicotinamide Complexes with Carboxylates: Synthesis, Spectral, Structural, and Thermogravimetric Analysis

Three novel isonicotinamide(inic)-based Cu(II) complexes [Cu(inic)2(cbba)2] (inic is isonicotinamide, cbba is 2-(p-chlorobenzoyl)benzoate) (1), [Cu(inic)2(mpa)2] (mpa is 4-methoxyphenylacetate) (2), and [Cu(inic)2(tmca)2(H2O)]2⋅CH2Cl2 (tmca is 3,4,5-trimethoxycinnamate) (3) have been acquired by the injection of the carboxylates as the auxiliary ligands and characterized by using the X-ray crystallography, together with the elemental analysis, FT-IR, and thermogravimetric analysis techniques. In all the complexes, the Cu(II) ions are coordinated through two monodentate carboxylates to the two anions, forming approximately a plane. Each Cu(II) ion is then coordinated with the pyridine N atom of the inic molecules that behave as the monodentate ligands. The amide groups of the inic create the H-bonds with other amide and carboxylate residues, engendering a molecular crystal with the three-dimensional H-bond arrangement of the mononuclear units. The X-ray diffraction studies displayed that these complexes possessed mononuclear structures with the square planar/square-pyramidal coordination modes at the Cu(II) ions. The pair of the complementary N–H···O H-bonds between the amides of the inic molecules were set up in compounds 1 and 3, making the dimer motif of inic, while there found the catemer motif of the inic molecules through using the intermolecular single N–H···O H-bond between the CONH2 in 2. The CH–O contacts derived from the py CH of the inic molecules were built in all the compounds. The intricate intra- and intermolecular classical H-bonds, O–C, O–O, Cl–Cl, CH3–CH/CH–CH, CH3–C, CH–O/CH2–O/CH3–O, CH–Cl/CH3–Cl, C–π, O–π, CH–π, and π–π associates are elucidated by using the X-ray crystallographic studies, driving the isolated complexes into the high-dimensional ordered supramolecular structures.