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Novel heteroleptic Pd0 complexes with an N‐heterocyclic carbene (NHC) ligand [(Me3P)Pd(NHC)] (NHC = IPr, 1; SIPr, 2) were obtained from [Pd(CH2=CHPh)(PMe3)2] and an equivalent of NHC [NHC = 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene (IPr) or 1,3‐bis(2,6‐diisopropylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene (SIPr)]. Further treatments of complexes 1 and 2 with an additional equimolar NHCafforded the corresponding bis(NHC)–Pd0 complexes [Pd(NHC)2] (NHC = IPr, 3; SIPr, 4). Complexes 1–4 readily reacted with dichloromethane or chloroform to give C–Cl oxidative addition products. In addition, the reactivity of complex 2 toward other organic halides such as bromobenzene, trans‐1,2‐dichloroethylene, and 5,5′‐dibromo‐2,2′‐bithiophene to produce the corresponding oxidative addition products was investigated. Finally, the ligand replacement of complex 1 with a chelating phosphane was examined.

Cyclopalladated azido dimers having various C,N-donor ligands, [Pd(mu-N3)(C,N-Ln)]2 (L1H = 2-(2'-thienyl)pyridine; L2H = azobenzene; L3H = 3,3'-dimethylazobenzene; L4H = N,N'-dimethylbenzylamine; L5H = 2-phenylpyridine), underwent cleavage with tertiary (or chelating) phosphines to form the cyclopalladated [Pd(N3)(PR3)(C,N-L)], the sigma-bonded [Pd(N3)(PR3)2(C-L)], or the dinuclear-cyclopalladated [PdN3(PR3)(C,N-L)]2(mu-P approximately P) complexes. In particular, treating [Pd(mu-N3)(C,N-L)]2 with the basic chelating phosphine (depe or dmpe) produced the homoleptic bis(chelating) complex [Pd(C,N-Ln)2] (n = 1-3). Complex [Pd(N3)(PR3)(C,N-L4)] or [Pd(N3)(PR3)2(C-L4)] reacted with aryl isocyanides to selectively give the imidoyl [Pd(N3)(-C=N-Ar)(PR3)(N-L4)] or the imidoyl carbodiimido complex [Pd(N=C=N-Ar)(-C=N-Ar)(PR3)(N-L4)], which was formed by the CN-Ar insertion into the orthometallated Pd-C bond on the phenyl moiety or the interaction into the Pd-N3 bond of the supporting ligand. In addition, reactions of [Pd(N3)(PR3)2(C-Ln)] (n = 1, 2, 4) with R-NCS {R = i-Pr, C6H4-NCS, (CH3)3Si} gave the S-coordinated tetrazole-thiolato Pd(II) complexes. Finally, the catalytic activity of the cyclopalladated azido complexes was evaluated.

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