1H NMR studies of Cr(III)–imidazole complexes: can 1H NMR be used as a probe of Cr–guanine DNA adducts?

The mono and dimetallic cyclometallated ruthenium complexes of dibenzo[a:c](dipyrido[2,3-h:2ʹ,3ʹ-j])phenazine (dbdpzH2) have been prepared. The monocyclometallation of this potentially dicyclometallating bridging ligand in the dimetallic complex: [(tpy)Ru (dbdpzH)Ru(H2O)(tpy)]3+ has been attributed to the distortion of the ligand upon binding to the first metal ion, which increases the size of the second binding site, inhibiting the second cyclometallation. The mono and dimetallic cyclometallated ruthenium complexes of dibenzo[a:c](dipyrido[2,3-h:2ʹ,3ʹ-j]) phenazine (dbdpzH2) have been prepared. The monocyclometallation of this potentially dicyclometallating bridging ligand in the dimetallic complex has been attributed to distortion of the second chelating site by the first complexation which inhibits the second cyclometallation.