Synthesis and Spectrothermal Studies of Thermochromic Diamine Complexes of Cobalt(III), Nickel(II) and Copper(II) Squarate. Crystal Structure of [Co(en)3](sq)1.5 · 6H2O

Abstract

New adducts of ethylenediamine (en), N,N-dimethylethylenediamine (ndmen) and N,N¢-dimethylethylenediamine (dmen) with squarate as counter-ions were synthesized and characterized by physico-chemical methods (IR and UV/ vis spectroscopy, magnetic susceptibility and thermoanalytical measurements). The crystal structure of tris(ethylenediamine)cobalt(III) 1.5 squarate hexahydrate, [Co(en) 3 ](sq) 1.5 AE 6H 2 O, was determined by single crystal X-ray diffraction. Co(III), Ni(II) and Cu(II) ions in the monomeric octahedral tris(ethylenediamine)cobalt(III) 1.5 squarate hexahydrate (1), tris(ethylenediamine)nickel(II) squarate 0.5 hydrate (2) and diaquabis(ethylenediamine)copper(II) squarate dihydrate (3) are chelated by ethylenediamines through two amine nitrogen atoms. Cu(II) atoms in the diaquabis(ndmen)copper(II) squarate (4) and diaquabis(dmen)copper(II) squarate (5) monomeric octahedral complexes are coordinated by ndmen and dmen molecules through two amine nitrogen atoms in a bidentate chelating manner. Water molecules complete the octahedral coordination. The orange (1), violet (4) and violet (5) complexes upon heating transform to claret, green and green species on dehydration, respectively, which revert immediately after cooling in the open atmosphere. The violet (3) complex upon heating loses water molecules yielding a deep blue dehydrated species, which on further heating undergoes an exothermic phase transition accompanied by thermochromism, deep blue to brown in the solid state. The decomposition mechanism and thermal stability of the solid complexes are interpreted in terms of their structures. The final decomposition products -the respective metal oxides -were identified by IR spectroscopy.

Synthesis, structural characterization, antimicrobial, antioxidant and DNA binding studies of some novel homo‐binuclear Schiff base metal (II) complexes

“…The free ligand showed a strong band characteristic of the azomethine ν(C═ N) group at 1617 cm −1 , which was diagnostic for Schiff base condensation, while no bands attributable to C═ O group were detected. The two bands at 3467 and 3352 cm −1 were attributed to the ν(NH 2 ) mode of diamines . The chelation of the Schiff base ligand could be easily detected by monitoring the position of the ligand bands which shifted to lower or higher energy upon complexation.…”

“…The two bands at 3467 and 3352 cm −1 were attributed to the ν(NH 2 ) mode of diamines. [37] The chelation of the Schiff base ligand could be easily detected by monitoring the position of the ligand bands which shifted to lower or higher energy upon complexation. For all complexes, the ν(C═ N) band underwent a change in frequency and intensity, caused by complexation, shifted by 2-10 cm −1 to higher frequency.…”

Synthesis, thermal, spectroscopic and structural properties of di(aqua)bis(N, N′-dimethylethylenediamine-κ 2 N, N′)copper(II) acesulfamate

“…Copper(II) and nickel(II) complexes with the bidentate diamine ligand were studied extensively due to their thermochromic properties [7][8][9][10][11][12][13][14][15]. The investigations revealed that the nature of the diamine ligand and counter anion are crucial for the thermochromism.…”

Synthesis, Crystal Structure, and Hydrogen Bonding of μ‐Hydroxo‐μ‐peroxo‐bis[bis(ethylenediamine)cobalt(III)] Squarate

“…The absorption band at 1049 cm -1 is due the C-C vibration. [35,53] The weak band at 889 cm -1 is mainly caused by the peroxo group. [54,55] , and 542 nm (band III).…”

“…Supramolecular structures, in which the squarate dianion acts as a counterion were found using N-donor ligands. [24][25][26][27][28][29][30][31][32][33][34] Yesilel et al [35] reports on the reaction of cobalt(II) squarate with ethylenediamine (en) at elevated temperature leading to a tris(ethylenediamine)cobalt(III) squarate, in which the squarate dianions act exclusively as counterions and hydrogen bonds between the anions and the complex [Co(en)] 3+ cations build up a three-dimensional supramolecular network.…”