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)Rh(III)Cl2 (2) and (L)(ArNH2)Rh(III)Cl2 (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.