| Abstract |
Coupling of the palladium-bis(isocyanide) complexes cis-[PdCl2(CNR)(2)] (R = 2,6-Me2C6H3 1, 2-Cl-6-MeC6H3 2) with benzene-1,3-diamine (BDA1) leads to the diaminocarbene species cis-[PdCl2(CNR)\C-(NHR)=NH(1,3-C6H4NH2)\\ (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-PdCl2(CNR)\mu-C(NHR)=NH(1,4-C6H4)NH=C-(NHR)\-(cis)-PdCl2(CNR)] (6 and 7) featuring two 1,4-bifunctional diaminocarbene ligands. The reaction of cis-[PdCl2(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-clichlorobenzene-1,2-diamine (BDAS). The addition of these diamines brings about the formation of the monocarbene cationic complexes cis-[PdCl(CNR)\C(NHR)=NHC6H2X2NH2\]Cl (X = H, Me, CO (8-16), the Chugaev-type C,C-bound bis-carbenes cis-[PdCl2\C(NHR)=NHC6H2X2NH=C(NHR)\] (17, 18), and the bis(C,N-chelated)carbene complexes cis-\Pd\C(NHR)=NHC6H2X2NH2\(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, H-1 and C-13\H-1\ 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. |
