Banca de DEFESA: ALEXSANDRO LIMA DOS ANJOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ALEXSANDRO LIMA DOS ANJOS
DATA : 01/11/2018
HORA: 14:30
LOCAL: Sala de aula do Química I
TÍTULO:

SYNTHESIS AND CHARACTERIZATION OF MOLYBDENUM(VI) COMPLEXES WITH NITROGENATED LIGANDS

PALAVRAS-CHAVES:

Molybdenum; Phenanthroline; Azide; Metformin

PÁGINAS: 117
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Inorgânica
ESPECIALIDADE: Campos de Coordenação
RESUMO:

Molybdenum is a metal that is present in the human body and performs various functions, such as assisting catalytic redox processes and transfer of oxygen atoms between various substrates. In addition, this metal are widely used to obtain new compounds with biological activities or catalysts in epoxidation reactions. Therefore, the present work aims to the synthesis and characterization of cis-dioxo molybdenum(VI) complexes with ligands 1,10-Phenantroline (phen), Azide (N₃­^-) and Metformin (met). Thus, the cis-[Mo(phen)(O)₂Cl₂], cis-[Mo(phen)(O)₂(N₃)₂] and cis- [Mo(met)(O)₂Cl₂] compounds were obtained from the precursor cis-[Mo(DMSO)₂(O)₂ Cl₂]. The compounds were obtained based on methodologies described in the literature and by adaptation of procedures of synthesis of similar complexes. The characterization was performed using spectroscopic (Infrared and Uv-vis), electrochemical techniques and thermal analysis. Based on the analysis of the vibrational spectra it was possible to verify the presence of the characteristic absorptions for compounds containing the oxide ligands, through Mo=O stretch, with bands on 919 and 891 cm^-1 for the precursor, 933 and 896 cm^-1 for complex with the ligand phen, 915 and 885 cm^-1 for azido complex and 947 and 891 cm^-1 for complex with metformin. In addition to variation in the main absorptions of the other ligands, showing coordination with the metal. The electronic spectra, obtained in water, did not present d-d transitions, the molybdenum is in maximum oxidation state (6+). Only the LMCT bands for chlorines at 213 and 234 nm were verified, in addition to other LMCT at 272 nm for for the DMSO. The complexes containing the phenanthroline ligand presented characteristic intraligand bands for the system. The Cyclic Voltammetry analysis showed irreversible and quasi- reversible processes corresponding to the one- and two-electron sequencial transfers, as well as the variation of the metal redox potential due to the exchange of ligands depending on the π-donor or π-acceptor character of the ligand. Based on the thermal analysis, it was possible to evaluate the stability of the compounds and the influence of the ligands on the main characteristics of the system, especially the initial decomposition temperature of the complexes formed. Thus, the set of techniques provided a correlation between the donor capacity of the oxo groups and the influence of ligands with different characteristics, showing how the electronic density around the metal can vary.

MEMBROS DA BANCA:
Presidente - 1530500 - ANA CRISTINA FACUNDO DE BRITO PONTES
Interno - 1945343 - FRANCISCO ORDELEI NASCIMENTO DA SILVA
Externo à Instituição - CLEIDE MARIA DA SILVA LEITE - UNILAB