2-merkaptopirimidin ve 4-dimetilaminopiridin ligandlarının 6B metal-karbonil bileşiklerinin sentezi, yapısal incelenmesi ve DFT hesaplamaları

The number of studies concerning the interaction modes and reactivity of transition metal complexes containing pyridine, pyridinethiolate and pyrimidinethiolate ligands is growing rapidly such ligands are especially interesting because the pyridine group is a constituent of nucleic acids and they have ability to chelate and bridge transition metals.The photolysis of hexacarbonyl metal(0) (M; Cr, Mo, W) complex in the presence of 2-mercaptopyrimidine ligand at 10 °C yields the corresponding pentacarbonyl-N-pyrimidinethiol metal(0) complex. These organometallic complexes were purified by recrystallization under high vacuum and stored at very low temperatures. The structure of these complexes have been investigated using IR, 1H-NMR, 13C-NMR and UV spectroscopic methods. The appearance of three absorption bands in the carbonyl region of these complexes IR spectra is the best indication for the formation M(CO)5 part of the molecule with C4V local symmetry. The spectroscopic results showed that the 2-mercaptopyrimidine ligand exhibit tautomeric equilibrium between thiol and thione as a consequence of the highly mobile protons that it possess and exhibits a predominant thione form in solid state. However, the IR data obtained from the polar dichloromethane solution implies that both free ligand and coordinated ligand exist in the thiol form. Moreover, 2-mercaptopyrimidine coordinated to the metal ion through its nitrogen atom lone pair of the aromatic ligand.The thermal behaviour of pentacarbonyl(2-mercaptopyrimidine) metal(0) complexes were also investigated by using DTA/TGA methods. At each temperature corresponding to TG/DTA curve the complex tittled has been subjected to X-ray powder diffraction(XRD) and infrared spectroscopic techniques. The results of the analysis showed that the complexes decomposed in four different temperatures.Disubstituted carbonyl complexes of 4-dmap ligand was done also to produce the unfavored cis-tetracarbonyl(4-dmap)metal(0) (M; W) complexes as the major product from the reaction of metal-hexacarbonyls and excess ligand. The structure of the complex was investigated using IR and NMR spectroscopies.In addition the theoritical calculations, including bond angles, bond distances and vibrational frequencies have also performed with the calculation of their NMR and UV spectral data using the Gaussian 03 DFT calculation method(Gaussian 03W single, CPU serial number; PC99997441W-5042N) at different basis sets. Finally these theoritical results have been compared with their experimental values. It has been shown that there is a good agreement between the theoritical and experimental results.Keywords: Pentacarbonyl, Tetracarbonyl, 2-mercaptopyrimidine, 4-(dimethylamino)pyridine Thermal analysis, DFT calculations