DOUBLE CYCLOPALLADATION OF N,N,N',N'-TETRAMETHYLFERROCENE-1,1'-DICARBOTHIOAMIDE

A method was developed for one-pot synthesis of N,N,N',N'-tetramethylferrocene-1,1'-dicarbothioamide (H(2)fdt); ferrocene was lithiated with n-butyl lithium and then treated with N,N-dimethylthiocarbamoyl chloride. The structure of H(2)fdt was confirmed by X-ray analysis. The H(2)fdt molecule had a twofold axis and the two thioamide groups were nearly stacked. The twist angle of two cyclopentadienyl rings was 22.5(2)degrees. H(2)fdt was easily cyclopalladated with lithium tetrachloropalladate to give a mixture of isomers of the composition, Pd-2(fdt)Cl-2. The product reacted with bidentate ligands (L-L) to afford a mixture of meso and racemic isomers, Pd-2(fdt)(L-L)(2) (L-L=acetylacetonate, dipivaloylmethanate, N,N-diethyldithiocarbamate and N,N-diisopropyldithiocarbamate (pdc)ions). The mixtures were separated into the two isomers by chromatography on a silica-gel column and the racemic isomer of Pd-2(fdt)(pdc)(2) was identified by X-ray analysis. In the complex, one Pd coordination subunit was placed nearly upon the other and the twist angle of two cyclopentadienyl rings was 19.1(8)degrees.