3,5-Bis(diphenylphosphinoethyl)pyrazolate ligand (PNNPC2) and its dirhodium complexes: Comparison with related quadridentate dinucleating diphenylphosphinomethyl (PNNPPy) and phthalazine derivatives (PNNPPh)

► Dirhodium carbonyl complexes with the quadridentate ligands. ► Effects of the ring size of the chelate rings and the charge of the dirhodium adducts. ► Dependence of the structures of the related dirhodium-carbonyl complexes on the dqadridentate ligands.