X-ray crystal structures of novel platinum(II) and palladium(II) complexes of dialkyl phosphonated phosphines

Two diethyl phosphonated phosphine ligands of formula Ph2P(CH2)3PO3Et2 (ligand L) and Ph2P(4-C6H4PO3Et2) (ligand L′) were used to prepare different complexes of platinum(II) (1, cis-PtCl2L2; 2, trans-PtCl2L2·H2O; 3A and 3B, cis- and trans-PtCl2L′2) and palladium(II) (4, [PdCl2L]2; 5, trans-PdCl2L2·H2O; 6, trans-PdCl2L′2·CH2Cl2). The single-crystal X-ray structure analyses of complexes 1, 2, 4–6 indicate that complexation involved only the phosphine end, whereas the strong polarization of the PO bond was highlighted by the formation of hydrogen bonds with a water molecule in 2 and 5, and with a dichloromethane molecule in 6, with an exceptionally short CH⋯O hydrogen bond length (C⋯O separation 3.094(3) Å).