Reactions of 2-(Arylazo) Aniline with RhCl₃: Synthesis and Structure of New Cyclometalated Complexes of Rh(III) and Recognition of RhCl₃ Assisted Azo (NN) Cleavage

The reactions of 2-(arylazo) anilines, HL (1) [where HL is 2-(ArNN)C6H4NH2; Ar is C6H5 (for HL1, 1a) and p-MeC6H4 (for HL2, 1b); H of HL represents the proton of Ar which gets dissociated upon orthometalation] with RhCl3 in methanol afforded new orthometalated complexes of composition (L)(HL)RhIIICl2 (2) and (L)(ArNH2)RhIIICl2 (3). The anionic L- binds the metal in tridentate (C, N, N) manner in both the complexes, while HL and ArNH2 bind the metal of 2 and 3 in monodentate fashion through the amino nitrogen. The ArNH2 of 3 was formed in situ due to cleavage of azo (NN) function of monodentate HL of 2. The scission of NN has been authenticated.