Reaction of HCCUr (Ur=uracil) with [RhCl(PiPr 3 ) 2 ] results in the formation of the vinylidene complex [RhCl(PiPr 3 ) 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 η 2 -alkyne complexes [RhCl(PiPr 3 ) 2 (η 2 -PhCCUr)] and [Rh(η 5 -C 5 H 5 )(PiPr 3 )(η 2 -PhCCUr)] have also been prepared. In contrast to the behaviour of [Rh(η 5 -C 5 H 5 )(PiPr 3 )(η 2 -PhCCUr)], [RhCl(PiPr 3 ) 2 (η 2 -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.