Crystal Chemistry of Zinc Quinaldinate Complexes with Pyridine-Based Ligands
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Bibliographic record
Abstract
Substitution of methanol in [Zn(quin)2(CH3OH)2] (quin− denotes an anionic form of quinoline-2-carboxylic acid, also known as quinaldinic acid) with pyridine (Py) or its substituted derivatives, 3,5-lutidine (3,5-Lut), nicotinamide (Nia), 3-hydroxypyridine (3-Py-OH), 3-hydroxymethylpyridine (3-Hmpy), 4-hydroxypyridine (4-Py-OH) and 4-hydroxymethylpyridine (4-Hmpy), afforded a series of novel heteroleptic complexes with compositions [Zn(quin)2(Py)2] (1), [Zn(quin)2(3,5-Lut)2] (2), [Zn(quin)2(Nia)2]·2CH3CN (3), [Zn(quin)2(3-Py-OH)2] (4), [Zn(quin)2(3-Hmpy)2] (5), [Zn(quin)2(4-Pyridone)] (6) (4-Pyridone = a keto tautomer of 4-hydroxypyridine), and [Zn(quin)2(4-Hmpy)2] (7). In all reactions, the {Zn(quin)2} structural fragment with quinaldinate ions bound in a bidentate chelating manner retained its structural integrity. With the exception of [Zn(quin)2(4-Pyridone)] (6), all complexes feature a six-numbered coordination environment of metal ion that may be described as a distorted octahedron. The arrangement of ligands is trans. The coordination sphere of zinc(II) in the 4-pyridone complex consists of only three ligands, two quinaldinates, and one secondary ligand. The metal ion thereby attains a five-numbered coordination environment that is best described as a distorted square-pyramid (τ parameter equals 0.39). The influence of substituents on the pyridine-based ligand over intermolecular interactions in the solid state is investigated. Since pyridine and 3,5-lutidine are not able to form hydrogen-bonding interactions, the solid state structures of their complexes, [Zn(quin)2(Py)2] (1) and [Zn(quin)2(3,5-Lut)2] (2), are governed by π···π stacking, C–H∙∙∙π, and C–H∙∙∙O intermolecular interactions. With other pyridine ligands possessing amide or hydroxyl functional groups, the connectivity patterns in the crystal structures of their complexes are governed by hydrogen bonding interactions. Thermal decomposition studies of novel complexes have shown the formation of zinc oxide as the end product.
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Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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