SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF DIALKYLDITHIOCARBAMATO COMPLEXES OF NIOBIUM

The reaction of alkyne-containing niobium(III) complexes [NbCl3(dme)(R C=CR')] (dme = 1,2-dimethoxyethane) with the appropriate Na(S2CNR2 '') reagents, in a 1:3 molar ratio, afforded the corresponding dialkyldit hiocarbamato complexes [Nb(RC=CR')(S2CNR2 '')(3)] (R = R' = Ph, R '' = Me 1; R = R' = Ph, R '' = Et 2; R = R' = R '' = Me 3; R = R' = Me, R '' = Et 4; R = R' = Et, R '' = Me 5; R = R' = R '' = Et 6; R = R' = Si Me3, R '' = Me 7; R = R' = SiMe3, R '' = Et 8; R = Ph, R' = Me, R '' = Me 9). The same complexes were also prepared from the reaction of the appropriate [NbCl3(bpzm)(RC=CR')][bpzm = bis(pyrazol-1-yl)methane] co mplexes with the corresponding sodium dialkyldithiocarbamates. All com plexes were spectroscopically characterized and the dynamic behaviour of some of them was studied by variable-temperature NMR techniques. Th e molecular structure of complex 9 was also established.