Crystal chemistry of zinc quinaldinate complexes with pyridine-based ligands

Modec, Barbara (author)

Substitution of methanol in [Zn(quin)$_2$(CH$_3$OH)$_2$] (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)$_2$]·2CH$_3$CN (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.

• Language: English
• Keywords: zinc(II) complexes, quinaldinic acid, pyridine, hydroxyl group, crystal structure, hydrogen bond
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2018
• Number of pages: 22 str.
• Numbering: Vol. 8, iss. 1, art. 52
• PID: 20.500.12556/RUL-131879
• UDC: 546.47:547.82:548
• ISSN on article: 2073-4352
• DOI: 10.3390/cryst8010052
• COBISS.SI-ID: 1538074819
• Publication date in RUL: 05.10.2021

Record is a part of a journal

• Title: Crystals
• Shortened title: Crystals
• Publisher: MDPI
• ISSN: 2073-4352
• COBISS.SI-ID: 36677893

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 19.01.2018

Secondary language

• Language: Slovenian
• Keywords: kompleksi cinka(II), kinaldinska kislina, piridin, hidroksilna skupina, kristalna struktura, vodikova vez

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P1-0134
• Name: Kemija za trajnostni razvoj