Synthesis and properties of arylpalladium(II) azido complexes PdAr(N3)(PR3)2.: Nucleophilic reactions of the azido ligand with CO and with isocyanides to afford Pd(II) isocyanate, C-tetrazolate and carbodiimide complexes

The tmeda ligand in the complexes, PdAr(N-3)(tmeda) is easily replaced by addition of tertiary phosphine or chelated phosphine to give the corresponding palladium(II) azido complexes with the phosphines ligand, PdAr(N-3)L-2 (1: Ar = Ph, L = PMe3; 2: Ar = Ph, L = PEt3; 3: Ar = tolyl, L = PMe3; 4: Ar = naphthyl, L = PMe3; 5: L-2 = dppe). Complex 3 was characterized by X-ray crystallography. Complexes 1-2 react with CO (1 atm) to afford Pd(II) isocyanates, PdPh(NCO)L-2 (6, L = PMe3; 7: L = PEt3), in 98 and 76% yields, respectively. In contrast, the reaction of trans-PdMe(N-3)(PMe3)(2) with CO gives acetylpalladium isocyanate, trans-Pd(COMe)(NCO)(PMe3)(2) (8) in 96% yield, which is characterized by X-ray crystallography. Reactions of 1 with an equal amount of tert-butyl and cyclohexyl isocyanides cause 1,3-dipolar addition of the isocyanides to the azido ligand, to give the complexes, trans-PdPh[CN4(R)](PMe3)(2) (R = C(CH3)(3), 9; C6H11, 10) with a five-membered heterocyclic ring (C-coordinated tetrazolato group). However, similar reactions of 1 and 3 with 2,6-dimethylphenyl isocyanide result in the unusual formation of Pd(II) complexes containing carbodiimido ligand, trans-(p-Y-C6H4)Pd(NCN-2,6-Me2C6H3)(PMe3)(2) (Y = H, 11; Y = Me, 12) in 51 and 94% yields, respectively. Reactions of 1 with protonating agents such as benzenthiol and phenylacetylene are also described. (C) 2000 Elsevier Science S.A. All rights reserved.