Synthesis, characterization and crystal structures of monocyclopalladated and biscyclopalladated 1,1′-bisferrocenylpyrimidine–monophosphine complexes

A new 1,1′-bisferrocenylpyrimidine ligand [{(η5-C5H4)–N2C4H–2CH3}2Fe] 1 was conveniently prepared via the coupling reaction of 1,1′-dichloromercuriferrocene and 4,6-dimethyl-2-iodopyrimidine, and its monophosphine–palladacycle complexes 2–3 were also readily obtained from the cyclopalladation reactions and bridge-splitting reactions. These compounds have been characterized by 1H NMR, IR, ESI-MS, and elemental analysis. The complex 2 was found to be a biscyclopalladated complex, while the complex 3 was a monocyclopalladated complex. Additionally, their detailed structures have been determined by X-ray single-crystal diffraction. The most striking common feature of the structures of 2–3 is intermolecular C–H···Cl hydrogen bonds, which are attributed to construct the 1D chain structures.