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

Abstract

Cyclometallated palladium(II) azido complexes containing C,N,N- or C,N-donor ligands, [Pd(N₃)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(N₃)L] or [Pd(N₃)(PR₃)L] to selectively give carbodiimido {[Pd(NCN–Ar)L]}, imidoyl {[Pd(N₃)(–CN–Ar)(PR₃)L]}, or imidoyl carbodiimido complexes {[Pd(NCN–Ar)(–CN–Ar)L] or [Pd(NCN–Ar)(–CN–Ar)(PR₃)L]}, depending on reaction conditions. Interestingly, reactions of [Pd(N₃)(PR₃)L] with organic isothiocyanates gave unusual dinuclear complexes [(μ-SCN₄–R)PdL]₂, exhibiting the concurrent S- and N-coordinating thio–tetrazole bridge.