1,4 Addition of hexafluorobut-2-yne to rhodium(I)–β–ketoneolate rings

Abstract

Hexafluorobut-2-yne reacts with the β-ketoenolate rhodium(I) complexes Rh(O–O)L₂(O–O = acac or dpm; L₂= cyclo-octa-1,5-diene or 1,2,3,4,7,7-hexachlorobicyclo[2·2.1]hepta-2,5-diene) to give complexes in which the fluorocarbon adds 1,4 to the rhodium(I)β-ketoenolate ring. Also the hexafluorobut-2-yne is trimerised to hexakis(trifluoromethyl)benzene which remains co-ordinated to the rhodium so that the diene ligand is displaced. However, although a similar reaction occurs with Rh(dpm)(nbd), norbornadiene is not displaced from Rh(acac)-(nbd) and the diene becomes linked to the rhodium by the acetylene to form a rhodacyclopentene ring.

Hexafluorobut-2-yne reacts with Rh(acac)(C₂H₄)₂ and Rh(acac)(C₂H₄)(C₂F₄) to give a complex which contains a 1,4 adduct of the acetylene and rhodium–acetylacetonate ring and a 1,2,3,4-tetrakistrifluoromethylcyclohexa-1,3-diene ligand. Attempts to isolate similar 1,4 addition products with Rh(CF₃COCHCOCF₃)(cod), and Rh(CF₃COCHCOCF₃)(nbd), have not been successful.