Search Results (2)

In the present work, we reported the synthesis and characterization [single crystal X-ray diffraction technique, spectroscopic, etc.] of two new Ni(II) and Zn(II) coordination compounds, viz. [Ni(2,6-PDC)₂]₂[Ni(en)₂(H₂O)₂]₂[Ni(en)(H₂O)₄]·4H₂O (1) and [Zn(2,6-PDC)(Hdmpz)₂] (2) (where 2,6-PDC = 2,6-pyridinedicarboxylate, en = ethylene-1,2-diamine, and Hdmpz = 3,5-dimethyl pyrazole). Compound 1 is found to crystallize as a multicomponent Ni(II) compound with five discrete complex moieties, whereas compound 2 is isolated as a mononuclear Zn(II) compound. A deep analysis of the crystal structure of 1 unfolds unusual dual enclathration of guest complex cationic moieties within the supramolecular host cavity stabilized by anion–π, π-stacking, N–H⋯O, C–H⋯O, and O–H⋯O hydrogen bonding interactions. Again, the crystal structure of compound 2 is stabilized by the presence of unconventional C–H⋯π(chelate ring) interactions along with C–H⋯O, C–H⋯N hydrogen bonding, π-stacking, and C–H⋯π(pyridyl) interactions. These non-covalent interactions were further studied theoretically using density functional theory (DFT) calculations, molecular electrostatic potential (MEP) surfaces, non-covalent interaction (NCI) plot index, and quantum theory of atoms in molecules (QTAIM) computational tools. The computational study displays that π-stacking or H bonds greatly tune the directionality of compound 1, although non-directional electrostatic forces dominate energetically. For compound 2, a combined QTAIM/NCI plot analysis confirms the presence of unconventional C–H⋯π(chelate ring) interactions along with other weak interactions obtained from the crystal structure analysis. Further, the individual energy contributions of these weak yet significant non-covalent interactions have also been determined computationally. Full article

Two Na(I) coordination polymers, namely, {Na(BA)₂(μ-H₂O)₂}_n{adp}_n (1) and {[Na₂(μ-BA)(μ-fum)(μ-H₂O)₄](BA)}_n (2) (where, BA = boric acid, adp = adipic acid, fum = fumarate),were prepared and characterized using elemental analysis, TGA, FT-IR, and single-crystal X-ray diffraction techniques. Various unconventional supramolecular interactions, i.e., CH∙∙∙HC and parallel CO∙∙∙CO interactions, stabilize the layered assembly of compound 1. Interesting dual enclathration of BA molecules within the supramolecular host cavities formed by O-H∙∙∙O and C-H∙∙∙C interactions stabilizes the crystal structure of compound 2. The H-bonding interactions in 1 and 2 were further studied theoretically using the quantum theory of atoms in molecules (QTAIM) and the noncovalent interaction plot (NCI Plot) computational tools. The energy of the H-bonds was estimated using the potential energy density at the bond critical points. Theoretical calculations confirmed the presence of O-H∙∙∙O H-bonding interactions in both compounds, forming structure-guiding $R_2^2\left(8\right)$ synthons relevant for the stability of the compounds. Full article