Synthesis, spectral, thermal, crystal structure, Hirschfeld analysis of [bis(triamine)Cadimium(II)][Cadimum(IV)tetra-bromide] complexes and their thermolysis to CdO nanoparticles

Abstract

Background: The coordination chemistry of cadmium(II) with diamine ligands is of particular interest. The most common structure around cadmium(II) center in their complexes is tetrahedral, that is due the octet rule obeyed. Nevertheless, five and six-coordinated complexes are also well known. Now a day, many cadmium(II) complexes with chelate ligands were synthesized for their structural or applications properties. Antibacterial activities and DNA binding affinity of this class of cadmium complexes have attracted considerable interest.

Results: Cadmium(II) complexes in dicationic form with general formula [Cd(dien)2]CdBr4 complex 1 (dien = diethylenetriamine) and [Cd(dipn)2]CdBr4 complex 2 (dipn = diproylenetriamine) were prepared and elucidated there chemical structures by elemental analysis, UV-Vis, IR, TG and NMR, additionally complex 1 structure was solved by X-ray diffraction study. The Cd(II) cation is located in a slightly distorted octahedral geometry while Cd(IV) anion is in tetrahedral geometry. High stability of the synthesized complexes confirmed by TG. Thermolysis of complex 1 revealed the formation of pure cubic nanoparticles CdO which was deduced by spectral analysis. The average size of CdO nanoparticles was found to be ~60 nm.

Conclusions: Two new Cd(II) complexes of general formula [Cd(N3)2]CdBr4 were made available. The structure of [Cd(dien)2]CdBr4 was confirmed by X-ray diffraction. Thermal, electro and spectral analysis were also investigated in this study. The direct thermolysis of such complexes formed a cubic CdO regular spherical nanoparticle with the ~60 nm average particle size.Graphical abstractORTEP for the complex 1.

Keywords: Cadmium(II) complexes; CdO nanoparticles; Triamine; XRD.

Graphical abstract

ORTEP for the complex 1

Scheme 1

Synthesis of the desired complexes

Fig. 1

ORTEP of the complex 1 with atom labelling. Thermal ellipsoids are drawn at the 50 % probability level

Fig. 2

Elongation of bond length of Br3 atom due to hydrogen bonding. The dotted lines indicate hydrogen bonds

Fig. 3

A crystal packing of complex 1 exhibiting layered stacking when viewed (perspective) along the crystallographic a axis. The dotted lines indicate hydrogen bonds

Fig. 4

IR-KBr disk spectra of the complex 1

Fig. 5

UV–Vis spectrum of the complex 1 in water at RT

Fig. 6

¹H NMR spectrum of the complex 1 in DMSO at RT

Fig. 7

TG thermal curve of complex 1

Fig. 8

IR spectra of CdO nanoparticles produced by thermolysis of complex 1

Fig. 9

Powder XRD pattern of CdO prepared by direct thermolysis of the complex 1

Fig. 10

The SEM image of complex 1 a before and b after calcination to produce CdO nanoparticles

Fig. 11

TEM image of CdO nanoparticles of an average diameter of ~60 nm

Fig. 12

d _norm mapped on hirshfeld surface for visualizing the intercontacts of complex 1

Fig. 13

Hirshfeld surface fingerprint of complex 1, a H_inside…all atoms_outside 64.6 %, b Br_inside…all atoms_outside 34.6 %, c Cd_inside…all atoms_outside ~0 %, d all atoms_inside…all atoms_outside 100 %, total interactions