Mikhail A. Kinzhalov, Galina L. Starova, Vadim P. Boyarskiy
“Interaction of benzene-1,2-diamines with isocyanide complexes of palladium(II): Insight into the mechanism”
Inorganica Chimica Acta, 2017, 455, 607–612
DOI:10.1016/j.ica.2016.05.014
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)double bond; length as m-dashNH(4-C6H4CH3)}] (4), and cis-[PdCl(CNXyl){C(NHXyl)double bond; length as m-dashNHC6H2(Me)2NH2}]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)double bond; length as m-dashNHC6H2X2NH2}{C(NHXyl)double bond; length as m-dashNH(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.