Coupling of the palladium-bis(isocyanide) complexes cis-[PdCl 2 (CNR) 2 ] (R = 2,6-Me 2 C 6 H 3 1, 2-Cl-6-MeC 6 H 3 2) with benzene-1,3diamine (BDA1) leads to the diaminocarbene species cis-[PdCl 2 (CNR){C-(NHR)NH(1,3-C 6 H 4 NH 2 )}] (5 and 6, respectively). In this reaction, BDA1 behaves as a monofunctional nucleophile that adds to one of the RNC ligands by one amino group. By contrast, the reaction of 1 and 2 with benzene-1,4-diamine (BDA2) involves both amino functionalities of the diamine and leads to the binuclear species [cis-PdCl 2 (CNR){μ-C(NHR)NH(1,4-C 6 H 4 )NHC-(NHR)}-(cis)-PdCl 2 (CNR)] (6 and 7) featuring two 1,4-bifunctional diaminocarbene ligands. The reaction of cis-[PdCl 2 (CNR) 2 ] (R = cyclohexyl 3) with either BDA1 or BDA2 does not afford any isolable carbene derivatives. The most versatile chemistry was observed when 1−3 were treated with benzene-1,2diamine (BDA3) and the relevant substituted 1,2-diamines, viz., 4,5-dimethylbenzene-1,2-diamine (BDA4) and 4,5-dichlorobenzene-1,2-diamine (BDA5). The addition of these diamines brings about the formation of the monocarbene cationic complexes cis-[PdCl(CNR){C(NHR) NHC 6 H 2 X 2 NH 2 }]Cl (X = H, Me, Cl) (8−16), the Chugaev-type C,C-bound bis-carbenes cis-[PdCl 2 {C(NHR) NHC 6 H 2 X 2 NHC(NHR)}] (17, 18), and the bis(C,N-chelated)carbene complexes cis-[Pd{C(NHR)NHC 6 H 2 X 2 NH 2 } 2 ]Cl 2 (19−24). All prepared complexes (with the exception of 17 and 18) were isolated as colorless or pale yellow solids and characterized by elemental analyses (C, H, N), HRESI ± -MS, IR, 1 H and 13 C{ 1 H} NMR spectroscopies, and 4, 7, 13, 16, and 24 by X-ray diffraction. Complexes 17 and 18 were characterized by HRESI ± -MS and IR spectroscopy, and their structures were established by X-ray crystallography.
