2024 : 4 : 20
Hamid Khanmohammadi

Hamid Khanmohammadi

Academic rank: Professor
ORCID: https://orcid.org/0000-0001-5600-4738
Education: PhD.
ScopusId: 22734138900
Faculty: Science
Address: Arak University


Synthesis, crystal structure, NMR and ab initio molecular-orbital studies of some magnesium(II) macrocyclic Schiff-base complexes, with two 2-aminoethyl pendant arms
Magnesium(II) Macrocyclic Complex, Schiff-base, Pendant arm, NMR studies, Seven coordinate, ab initio
Journal Inorganica Chimica Acta
Researchers Hassan Keypour ، Hamid Khanmohammadi ، Kevin P. Wainwright ، Max A. Taylor


Three new Mg(II) bis(pendant arm) macrocyclic Schiff base complexes, [MgLn]2+(n=5,6,7), have been prepared via cyclocondensation of 2,6-diacetylpyridine with branched hexaamines and characterised spectroscopically. In addition, for [MgL5](ClO4)2 the crystal structure is reported. This is the first X-ray structural determination of an Mg(II) complex coordinated by seven nitrogen atoms. The ligands, L, are 15-, 16- and 17-membered pentaaza macrocycles having two 2-aminoethyl pendant arms [L5; 2,13-dimethyl-6,9-bis(aminoethyl)-3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18), 2, 12, 14, 16-pentaene, L6; 2,14-dimethyl-6,10-bis(aminoethyl)-3,6,10,13,19-pentaazabicyclo[13.3.1]nonadeca-1(19), 2, 13, 15, 17-pentaene and L7; 2,15-dimethyl-6,11-bis(aminoethyl)-3,6,11,14,20-pentaazabicyclo[14.3.1]eicosa-1(20),2,14,16,18-pentaene]. The crystal structure of [Mg L5](ClO4)2, was determined by X-ray diffraction and showed that the complex cation that had formed consisted of a pentagonal bipyramidally coordinated Mg(II) ion. All complexes were characterised by IR, 1H NMR,13C NMR, COSY(H, H) and HETCOR(H, C) spectroscopy, and the data indicate that the structure is approximately pentagonal bipyramidal in each case. This structural assignment is also supported by ab initio HF-MO calculations made using the standard 3-21G* basis set.