Options
Synthesis and characterisation of chromium (II) and copper (II) carboxylato complexes
Author
Tan, Keai Fong
Supervisor
Yan, Yaw Kai
Abstract
This thesis describes the synthesis and characterization of chromium(II) and copper(II) carboxylato complexes. Five polymers with pendant carboxyl groups were chosen to react with CrC12 to produce air-stable chromium(II)-polymer complexes 1-6. All the chromium(II)-polymer complexes were moderately air-sensitive except that obtained from the reaction with poly(methacrylic acid, sodium salt) with the molar ration 1:20 (complex 1), which was surprisingly stable in the solid state (stable for at least 1 month). Comparative investigation on copper(II)-polymer complexes 7-11 was also carried out by reacting copper(II) sulphate with the same five polymers as in the case of chromium(II) chloride.
All the chromium(II) carboxylate complexes 15-21 are air-sensitive in both solid and solution states, except chromium(II) D-gluconate (12), chromium(II)-glycylglycinate (13) and chromium(II)-glycylglycylglycinate (14), which are surprisingly stable in both solid and solution states (stable for weeks), compared to the others, which are stable for few seconds to a few minutes. The crystal structure of chromium(II) 4-aminobenzoate (20) revealed the presence of intermolecular hydrogen bonds, resulting in infinite chains. Investigation on copper(II) carboxylate complexes 22-29 showed that both mononuclear and dinuclear structures are possible, depending on the chelation ability of the carboxylate ligand. Crystal structures were also determined for the complexes 22, 25, 26 and 29.
Chromium(II) and copper(II)-polymer complexes (complexes 1-11) were characterized by DSC, TGA and IR spectrum. The chromium(II) complex from the 1:20 molar ratio reaction with poly(methacrylic acid, sodium salt) was also investigated by UV-vis spectroscopy and inductively-coupled plasma optical emission spectrometry. The rest of the chromium(II) and copper(II) carboxylate complexes were characterized by IR spectroscopy. All the copper(II) carboxylate complexes were characterized by elemental analysis. The air-sensitive chromium(II) carboxylate complexes gave inaccurate elemental analysis.
All the chromium(II) carboxylate complexes 15-21 are air-sensitive in both solid and solution states, except chromium(II) D-gluconate (12), chromium(II)-glycylglycinate (13) and chromium(II)-glycylglycylglycinate (14), which are surprisingly stable in both solid and solution states (stable for weeks), compared to the others, which are stable for few seconds to a few minutes. The crystal structure of chromium(II) 4-aminobenzoate (20) revealed the presence of intermolecular hydrogen bonds, resulting in infinite chains. Investigation on copper(II) carboxylate complexes 22-29 showed that both mononuclear and dinuclear structures are possible, depending on the chelation ability of the carboxylate ligand. Crystal structures were also determined for the complexes 22, 25, 26 and 29.
Chromium(II) and copper(II)-polymer complexes (complexes 1-11) were characterized by DSC, TGA and IR spectrum. The chromium(II) complex from the 1:20 molar ratio reaction with poly(methacrylic acid, sodium salt) was also investigated by UV-vis spectroscopy and inductively-coupled plasma optical emission spectrometry. The rest of the chromium(II) and copper(II) carboxylate complexes were characterized by IR spectroscopy. All the copper(II) carboxylate complexes were characterized by elemental analysis. The air-sensitive chromium(II) carboxylate complexes gave inaccurate elemental analysis.
Date Issued
2004
Call Number
QD474 Tan
Date Submitted
2004