Synthesis, Single Crystal Structural Investigation, Hirshfeld Surface Analysis, Thermoanalysis and Spectroscopic Study of Two New Cu(II) and Co(II) Transition-Metal Complexes

Abstract

Two new complexes, [Cu(dimpyr)2(H2O)2](NO3)2.2H2O (1) and (Hamdimpy)2[CoCl4].H2O (2), with the monodentate ligand 2-amino-6-methylpyrimidin-4-(1H)-one (dimpyr) and the countercation 4-amino-2,6-dimetylpyrimidium (Hamdimpy), respectively, were prepared and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. In (1), the Cu(II) cation is tetracoordinated, in a square plan fashion, by two nitrogen atoms from the pyrimidine ring of the organic ligand and two oxygen atoms of two coordinated water molecules. In the atomic arrangement, the CuO2N2 square planes are interconnected via the formation of O-H…O hydrogen bonds involving both coordinated and free water molecules and NO3− nitrate anions to form inorganic layers parallel to the (a, b) plane at z = (2n + 1)/4. In (2), the central atom Co(II) is four-coordinated in a distorted tetrahedral fashion by four Cl− ions. The [CoCl4]2− tetrahedra are arranged parallel to the plane (1¯10) at x = (2n + 1)/2 and the organic cations are grafted between them by establishing with them hydrogen bonds of CH…Cl and NH…Cl types. The vibrational absorption bands were identified by infrared and Raman spectroscopy. Intermolecular interactions were investigated via Hirshfeld surfaces and electronic properties such as HOMO and LUMO energies were derived. The two compounds were characterized by thermal analysis to determine their thermal behavior with respect to temperature.

The Use of Hirshfeld Surface Analysis Tools to Study the Intermolecular Interactions in Single Molecule Magnets

“…HS analysis tools meet the basic criterion [8], which a method must satisfy for studying intermolecular interactions in a crystal structure and to be the least biased possible, which was set by Desiraju in 1997 [10]: "To visualize a crystal structure in its entirety, not just look at selected intermolecular interactions that have been deemed to be important". HSs have been used extensively in the study of polymorphic organic materials [11], but recently they have also used in the study of transition metal complexes [12][13][14].…”