Coordination chemistry of platinum(II) and rhodium(I) complexes containing chiral monophosphacrown ether ligands

Abstract

Coordination properties of recently synthesized chiral phospha-modified crown ethers were studied in the presence of platinum(II) and rhodium(I) precursors. The prepared and in situ formed complexes were characterized by 1H and 31P NMR spectroscopies. Platinum(II)-complexes were dominantly formed as transPP arrangements, even in the case of diphosphines, possessing large bite angles, enabling to act as trans-chelating ligands. Isomers of trans-complexes were identified and explained by ligand back-bone interactions, supported by DFT calculations. Basically different complexes were formed in the presence of rhodium(I) precursors, since only one of the two phosphorous donor atoms was coordinated to the metal centre. The addition of Na[BPh4] was also examined showing dramatically different effects: sodium ion coordination to the crown ether moiety can be supposed in case of platinum complexes, while the use of rhodium(I) precursors brought about the formation of ionic complexes.