Unusual Metal–organic Multicomponent Ni(II) and Mononuclear Zn(II) Compounds Involving Pyridine dicarboxylates: Supramolecular Assemblies and Theoretical Studies
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, <i>viz</i>. [Ni(2,6-PDC)<sub>2</sub>]<sub>2</sub>[Ni(en)<sub>2</sub&...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-10-01
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| Series: | Inorganics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2304-6740/12/10/267 |
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| Summary: | 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, <i>viz</i>. [Ni(2,6-PDC)<sub>2</sub>]<sub>2</sub>[Ni(en)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]<sub>2</sub>[Ni(en)(H<sub>2</sub>O)<sub>4</sub>]·4H<sub>2</sub>O (<b>1</b>) and [Zn(2,6-PDC)(Hdmpz)<sub>2</sub>] (<b>2</b>) (where 2,6-PDC = 2,6-pyridinedicarboxylate, en = ethylene-1,2-diamine, and Hdmpz = 3,5-dimethyl pyrazole). Compound <b>1</b> is found to crystallize as a multicomponent Ni(II) compound with five discrete complex moieties, whereas compound <b>2</b> is isolated as a mononuclear Zn(II) compound. A deep analysis of the crystal structure of <b>1</b> 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 <b>2</b> 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 <b>1</b>, although non-directional electrostatic forces dominate energetically. For compound <b>2</b>, 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. |
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| ISSN: | 2304-6740 |