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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2025-06-01
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| author | Kiyoshi Fujisawa Yurika Minakawa David James Young |
| author_facet | Kiyoshi Fujisawa Yurika Minakawa David James Young |
| author_sort | Kiyoshi Fujisawa |
| collection | DOAJ |
| description | 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. |
| format | Article |
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| institution | Matheson Library |
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| language | English |
| publishDate | 2025-06-01 |
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| spelling | doaj-art-f528052cf601452bb368c6cbcaeb99742025-06-25T13:58:01ZengMDPI AGInorganics2304-67402025-06-0113618910.3390/inorganics13060189Transition Metal (II) Coordination Chemistry Ligated by a New Coplanar Tridentate Ligand, 2,6-Bis(5-isopropyl-1<i>H</i>-pyrazol-3-yl)pyridineKiyoshi Fujisawa0Yurika Minakawa1David James Young2Department of Chemistry, Ibaraki University, Mito 310-8512, Ibaraki, JapanDepartment of Chemistry, Ibaraki University, Mito 310-8512, Ibaraki, JapanJames Watt School of Engineering, University of Glasgow, University Avenue, Glasgow G12 8QQ, UKTransition 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.https://www.mdpi.com/2304-6740/13/6/189N3 type ligandplanar ligandcoppercrystal structuresphysicochemical properties |
| spellingShingle | Kiyoshi Fujisawa Yurika Minakawa David James Young 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 Inorganics N3 type ligand planar ligand copper crystal structures physicochemical properties |
| title | 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 |
| title_full | 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 |
| title_fullStr | 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 |
| title_full_unstemmed | 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 |
| title_short | 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 |
| title_sort | 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 |
| topic | N3 type ligand planar ligand copper crystal structures physicochemical properties |
| url | https://www.mdpi.com/2304-6740/13/6/189 |
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