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.

Graphical abstractA 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 full-size imageDownload as PowerPoint slide