Crystal chemistry of zinc quinaldinate complexes with pyridine-based ligands

Abstract

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.

Keywords

kompleksi cinka(II);kinaldinska kislina;piridin;hidroksilna skupina;kristalna struktura;vodikova vez;zinc(II) complexes;quinaldinic acid;pyridine;hydroxyl group;crystal structure;hydrogen bond;

Data

Language:	English
Year of publishing:	2018
Typology:	1.01 - Original Scientific Article
Organization:	UL FKKT - Faculty of Chemistry and Chemical Technology
UDC:	546.47:547.82:548
COBISS:	1538074819
ISSN:	2073-4352
Views:	220
Downloads:	72
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	Slovenian
Secondary keywords:	kompleksi cinka(II);kinaldinska kislina;piridin;hidroksilna skupina;kristalna struktura;vodikova vez;
Type (COBISS):	Article
Pages:	str. 1-22
Volume:	ǂVol. ǂ8
Issue:	ǂiss. ǂ1
Chronology:	2018
DOI:	10.3390/cryst8010052
ID:	13646707