Chlorodicarbonylrhodium(I) dimer reacts with 3,5,7-triphenyl-4H-1,2-diazepine without cleavage of the N–N bond of the diazepine to yield chloro-cis-dicarbonyl (3,5,7-triphenyl-4H-1,2-diazepine)rhodium(I) in which the diazepine (in a twisted boat conformation) is co-ordinated to the rhodium(I) atom via only one nitrogen atom.