The reaction of the Ru-VI nitride (LRuVI)-Ru-oEt(N)Cl-2 (1; L-OEt- = [CO(eta(5)-C5H5){P(O)(OEt)(2)}(3)](-)) with Ru (mes)(3) (mes = mesityl) results in insertion of the Ru N group into the Rh-C bonds and formation of trinuclear (L-oEt)ClRuIV(mu-Cl)(mu-2-CH2-4,6-Me2C6H2N)-Rh-III (mu-Nmes)(mu-Cl)(2)Ru-IV(L-OEt) (2), containing a cyclometalated mu-mesitylimido ligand, whereas that with Ir-III(dtbpy)R-3 gives the mu-nitrido complexes (dtbpy)(RIrIII)-Ir-3(mu-N)(RuCl2)-Cl-IV(L-OEt) (dtbpy = 4,4'-di-tert-butyl-2,2'-bipyridyl; R = 2,5-dimethylphenyl (3), 4-methoxy-2-methylphenyl (4)). The crystal structures of 2 and 4 have been determined.