Chemical Review and Letters

Complexation of Co(II), Ni(II), Cu(II), and Zn(II) with some hydroxy aromatic and heteroaromatic carboxylic acids: Unusual coordination mode of Zn2+ in chloro-bis(1,10-phenanthroline) zinc(II) 3,5-dinitro salicylate

Document Type : Research Article

Authors

Rana Abdulillah Abbas 1
Dui Ling Han 2
Andrey Utenyshev 3, 4
Olga Kovalchukova 3, 5

1 Department of Chemical and Petroleum Industries Engineering Technologies, Polytechnic College of Engineering Specializations-Baghdad, Middle Technical University, Baghdad, Iraq.

2 Department of Environmental Analytical, Institute of Environmental Chemistry Vietnam - Russia Tropical Center, Hanoi, Vietnam.

3 Kosygin Russian State University (Technology. Design. Arts), Moscow, Russia.

4 Laboratory of Structural Chemistry, Federal Research Center of Problem of Chemical Physics and Medicinal Chemistry RAS, Chernogolovka, Moscow Region, Russia.

5 Department of General and Inorganic Chemistry, Science Faculty, Peoples’ Friendship University of Russia (RUDN University), Moscow, Russia.

https://doi.org/10.22034/crl.2025.544285.1682
Abstract

Ten complex compounds of Co(II), Ni(II), Cu(II) and Zn(II) with a number of aromatic and heteroaromatic hydroxy acids were isolated and studied by spectral and structural analysis methods. Potentiometric and spectrophotometric titration methods indicated that the processes of complexation ate accompanied by ionization of the ligands. The ML and ML2 complexes of medium and high stability are formed in neutral and slightly alkaline solutions. The organic ligands coordinate in the form of mono anions and are coordinated through an O-atom of carboxylic groups of the molecules. Crystal structures of three complexes are reported. Introduction of 1,10-phenanthroline to the reactional mixture containing ZnCl2 and 3,5-dinitrosalicylic acid leaded to formation of complex compound with unexpected five-coordinated Zn-atom. The coordination polyhedron is square pyramidal, the donating atoms are four N atoms of two phenanthroline moieties and a chloride anion. The 3,5-dinitrosalicylic acid in the form of monoanion deprotonated by the hydroxy group acts as an outer sphere anion.

Graphical Abstract

Complexation of Co(II), Ni(II), Cu(II), and Zn(II) with some hydroxy aromatic and heteroaromatic carboxylic acids: Unusual coordination mode of Zn2+ in chloro-bis(1,10-phenanthroline) zinc(II) 3,5-dinitro salicylate

Keywords

Keywords: complex compounds
hydroxy aromatic and heteroaromatic acids
spectrophotometric titration
stability constants
crystal structure

Subjects

Chemical Review and Letters
Volume 8, Issue 6 - Serial Number 6
November and December 2025
Pages 1179-1187

  • Receive Date 26 August 2025
  • Revise Date 27 September 2025
  • Accept Date 01 October 2025

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