Transition Metal (II) Coordination Chemistry Ligated by a New Coplanar Tridentate Ligand, 2,6-Bis(5-isopropyl-1<i>H</i>-pyrazol-3-yl)pyridine
Transition metal (II) complexes stabilized by 2,6-di(pyrazol-3-yl)pyridine as a novel coplanar tridentate nitrogen-donor ligand have been reported for their unusual structures and photoluminescent properties. In this work, the ligand 2,6-bis(5-isopropyl-1<i>H</i>-pyrazole-3-yl)pyridine (...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Inorganics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2304-6740/13/6/189 |
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| Summary: | Transition metal (II) complexes stabilized by 2,6-di(pyrazol-3-yl)pyridine as a novel coplanar tridentate nitrogen-donor ligand have been reported for their unusual structures and photoluminescent properties. In this work, the ligand 2,6-bis(5-isopropyl-1<i>H</i>-pyrazole-3-yl)pyridine (denoted as <b>L</b>) and its transition metal (II) halogenido complexes <i>viz</i> [ZnCl<sub>2</sub>(<b>L</b>)] (<b>1</b>), [ZnBr<sub>2</sub>(<b>L</b>)] (<b>2</b>), [CuCl<sub>2</sub>(<b>L</b>)] (<b>3</b>), and [CuCl(<b>L</b>)(thf)](PF<sub>6</sub>) (<b>4</b>) were synthesized and characterized by single crystal X-ray crystal analysis. Its structures contained N–H groups in its pyrazole rings and hydrogen bonds between these N–H donors and the coordinated halogenide ions and lattice solvent molecules. Tautomers between 3-pyridyl and 5-pyridyl substitutes were also observed. In <b>L</b>, the N–H group at the pyrazole nitrogen was located adjacent to the pyridine ring to form hydrogen bonds with adjacent pyrazoles. However, on complexation, the H atoms at the pyrazole nitrogens are shifted remotely to the pyridine. The zinc (II) complexes [ZnCl<sub>2</sub>(<b>L</b>)] (<b>1</b>) and [ZnBr<sub>2</sub>(<b>L</b>)] (<b>2</b>) possessed distorted trigonal pyramidal structures in the solid state. By comparison, the copper (II) complexes [CuCl<sub>2</sub>(<b>L</b>)] (<b>3</b>) and [CuCl(<b>L</b>)(thf)](PF<sub>6</sub>) (<b>4</b>) adopted square pyramidal geometry with a Jahn–Teller distortion resulting from their <i>d</i><sup>9</sup> electron configurations. |
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| ISSN: | 2304-6740 |