LDECAHYDROQUINOLIN-4-ONEDITHIOCARBAMATO)-METAL(II) COMPLEXES - A NEW PREPARATIVE METHOD AND CHARACTERIZATION ALONG WITH C-13 AND H-1-NMR DECOUPLING STUDIES

2-Aryldecahydroquinolin-4-ones, unlike mere piperidines, do not form d ithiocarbamic acids on addition of carbon disulphide under alkaline co ndition. Invariably, xanthates are formed when carbon disulphide is ad ded to the amine in the presence of alcohol. In the present study dith iocarbamato complexes involving 2-aryldecahydroquinolin-4-ones and Ni( II) and Cu(II) metal ions are reported for the first time. The deproto nation of 2-aryldecahydroquinolin-4-ones takes place in a NH3/NH4Cl bu ffer medium (pH=10) in acetonitrile followed by the addition of carbon disulphide and the corresponding aqueous solution of the metal ion. T he isolated complexes were of the formula M(Ldtc)(2); M(II) = Ni(II) a nd Cu(II), Ldtc = 2-aryldecahydroquinolin-4-onedithiocarbamate anion d erivatives. These complexes were characterized by microanalyses, IR, U V, TG and mass spectral studies. A representative nickel(II) complex h as also been subjected to an extensive H-1 NMR decoupling study along with C-13 NMR and mass spectral analysis, clearly indicating the manif estation of complexation on the stereochemistry of the bicyclic ring o f the ligand frame work. H-1 NMR spectral data indicated the significa nce of the 'thioureide' structure contribution to the stability of the present set of complexes which is not available from IR studies. The downfield shift of the H-1 NMR signals and the upfield shift of the C( 2) carbon in C-13 NMR spectra of the complexes indicates that the hete rocyclic ring deviates from the normal chair conformation on complexat ion.