Cyclometallated Pd(II) azido complexes containing 6-phenyl-2,2′-bipyridyl or 2-phenylpyridyl derivatives:: synthesis and reactivity toward organic isocyanides and isothiocyanates

Cyclometallated palladium(II) azido complexes containing C,N,N- or C,N-donor ligands, [Pd(N-3)L] (HL = 6-phenyl-2,2'-bipyridine or 2-phenylpyridyl derivatives), showed different reactivities toward organic isocyanides and isothiocyanates. In particular, aryl isocyanides (CN-Ar) underwent insertion into the orthometallated Pd-C bond on the phenyl moiety of the supporting ligand (L) in [Pd(N-3)L] or [Pd(N-3)(PR3)L] to selectively give carbodiimido {[Pd(N=C=N-Ar)L]}, imidoyl {[Pd(N-3)(-C=N-Ar)(PR3)L]}, or imidoyl carbodiimido complexes {[Pd(N=C=N-Ar)(-C=N-Ar)L] or [Pd(N=C=N-Ar)(-C=N-Ar)(PR3)L]}, depending on reaction conditions. Interestingly, reactions of [Pd(N-3)(PR3)L] with organic isothiocyanates gave unusual dinuclear complexes [(mu-SCN4-R)PdL](2), exhibiting the concurrent S- and N-coordinating thio-tetrazole bridge.