Grup VI B elementlerinin bazı pentakarbonil(pirimidintiyol)metal(0) komplekslerinin sentezi, spektroskopik incelenmesi, termal davranışı ve DFT hesaplamaları

The photochemical reaction of hexacarbonylmetal(0); M: Cr, Mo, W, complexes in the presence of a substituted pyrimidinethiol (mercaptopyrimidine) ligand (4,6-dimethyl-2-mercaptopyrimidine) at 10 ºC yields the corresponding pentacarbonyl-N-pyrimidinethiolmetal(0) complexes. These synthesized organometallic complexes are purified under high vacuum by recrystallization and their structures are investigated by using IR-,1H- and 13C-NMR spectroscopies. The IR spectroscopy results showed three absoption bands (one in strong, the other two in medium intensities). These three absorption bands in the carbonyl region of the complexes indicates thatthe pentacarbonyl metal unit of the complexes has a local C4v symmetry. The 1H- and 13C-NMR spectroscopies showed that the pyrimidinethiol ligand bonded to metal complex through the pyrimidinethiol nitrogen atom symmetrically. Also, the 13C-NMR spectroscopy results showed 1:4 ratio of peaks in the CO-region, the ratio of the peaks proved the C4v symmetry of these complexes. The thermal behaviour of these organometallic complexes is investigated by using DTA/TGA methods. The results of the analysis showed that the complexes decomposed in three different temperatures. The density functional theory, DFT, calculations are made in Becke?s three parameters (B32YP, B3PW91, B31PBE functionals) and Perdew/Wang 91, B3PW91 is used throughout this computation performed by Gaussian03W Software (Gaussian 03W single, CPU Serial number: PC 99997441 W-5042N) by this way all datas of experimental studies ( IR, UV, NMR, TGA ) are compared with the theoretical values.