The synthesis and spectroscopic investigations of some pentacarbonyl(pyridine)metal(0) complexes of group vib elements

Hekzakarbonilmetal(0); M: Cr, Mo, W bilesikleri ile sübstütüye piridin ligandlari(4-metilpiridin, 4-t-bütilpiridin ve 2,6-diaminopiridin) arasinda, 10oC de yapilanfotokimyasal tepkimeler, pentakarbonil-N-piridinmetal(0) bilesikleri ni olusturmaktadir.Sentezlenen bu koordinasyon bilesikleri, yeniden kristallendirme yöntemleriylesaflandirilir ve yapilari IR, ve1H- ve 13C-NMR spektroskopileriyle incelendi. IRspektroskopisi sonuçlarina göre sentezlenen bilesiklerin C4v simetrisindepentakarbonil kompleksleri oldugu anlasilmistir. Bununla birlikte 1H- ve 13C-NMRspektrumlarinda piridinlerin serbest halde ve koordine olduktan sonra farkli birkimyasal kaymaya ugramamasi, ligandlarin komplekse piridin üzerindeki azotatomundan simetrik baglandigini göstermistir.Anahtar sözcükler: piridin, krom, karbonil, fotokimyasal sentez, metal-ligand bagi

The photolysis of hexacarbonylmetal(0); M: Cr, Mo, W, complexes inthe presence of a substituted pyridine ligand (4-methylpyridine, 4-tbutylpyridineand 4-dimethylaminopyridine) at 10oC yields the correspondingpentacarbonyl-N-pyridinemetal(0) complexes. These complexes are purifiedunder high vacuum and their structures are investigated by using IR- ,1H- and13C-NMR spectroscopies.The IR spectroscopy results showed three absorption bands (one instrong, the others in medium intensities). The appearance of three absorptionbands in the carbonyl region of these complexes indicates that the M(CO)5 -unit of the complexes has a local C4v symmetry.The 1:4 ratio of CO peaks in the 13C-NMR spectroscopies proved thatthe symmetry of these complexes is C4v . Besides, the 1H- and 13C-NMRspectroscopies showed that the pyridine ligand bonded to metal complexthrough the pyridine nitrogen atom symmetrically.Keywords: pyridine, chromium, photochemical synthesis, metal-ligand bond