Rhodium vinylidene and alkyne complexes containing a pendant uracil group

Reaction of HCCUr (Ur = uracil) with [RhCl(PiPr3)2] results in the formation of the vinylidene complex [RhCl(PiPr3)2(CC{H}Ur)]. In the solid state this complex forms a hydrogen bonded network which consists of complementary interactions between uracil groups on neighbouring rhodium complexes and with the methanol of crystallisation. The η2-alkyne complexes [RhCl(PiPr3)2(η2-PhCCUr)] and [Rh(η5-C5H5)(PiPr3)(η2-PhCCUr)] have also been prepared. In contrast to the behaviour of [Rh(η5-C5H5)(PiPr3)(η2-PhCCUr)], [RhCl(PiPr3)2(η2-PhCCUr)] shows little evidence for the formation of hydrogen bonded aggregates in solution. The difference in behaviour between the two species is rationalised on the basis of steric effects.

A series of rhodium complexes containing pendant uracil groups are described. A vinylidene complex is reported in which the nucleobase mediates the formation of a hydrogen bonded array in the solid state. Alkyne complexes are also described in which steric effects appear to control the extent of aggregation in solution.Figure optionsDownload as PowerPoint slide