Reactivity of 4-toluidine (2) and 4,5-dimethylbenzene-1,2-diamine (3) were compared in coupling with the palladium-bis(isocyanide) complex cis-[PdCl2(CNXyl)2] (Xyl=2,6-Me2C6H3, 1), mixed isocyanide/diaminocarbene species cis-[PdCl2(CNXyl)(C(NHXyl)NH(4-C6H4CH3))] (4), and cis-[PdCl(CNXyl)(C(NHXyl)NHC6H2(Me)2 NH2)]Cl (5). In these Pd(II)-mediated reactions, 4,5-dimethylbenzene-1,2-diamine (3) was significantly more reactive than 4-toluidine (2), leading to the first mixed bis(diaminocarbene) complex cis-[PdCl(C(NHR)NHC6H2X2 NH2)(C(NHXyl)NH(4-C6H4CH3))]Cl (6) containing two different diaminocarbene ligands. Complex 6 was isolated and characterized by elemental analyses (C, H, N), HRESI+-MS, IR, 1H and 13C(1H) NMR spectroscopies, and single-crystal X-ray diffraction.