Cyclometallation of a pyrrole ring of 2-(1-pyrrolyl)pyridine with palladium(II) and rhodium(III)

2-(1-Pyrrolyl)pyridine (Hplp) is cyclometallated with lithium tetrachloropalladate(II) and hexahalogenotetrakis(tri-n-butylphosphine)dirhodium(III) to give PdCl(plp)]₂ and RhX₂(plp(PBu₃)₂] (X = Cl, Br; PBu₃ = tri-n-butylphosphine), respectively, where deprotonated plp is coordinated via the pyridine-N and pyrrole-2C atoms forming a five-membered metallacycle. PdCl(plp)]₂ reacts with pyridine (py) and with PBu₃ to form the adducts PdCl(plp)L] (L = py, PBu₃) and with acetylacetone (Hacac) to afford the complex Pd(plp)(acac)]. Metathesis of RhCl₂(plp)(PBu₃)₂] with excess lithium iodide gives a mixed halogeno complex RhClI(plp)(PBu₃)₂]. These complexes are characterized spectroscopically.