Palladium(II) complexes with hemilabile amphiphilic phosphines

Article abstract of DOI:10.1016/S0022-328X(01)00663-5

A series of trans-PdCl₂L₂ complexes were prepared and characterized with the following hemilabile amphiphilic phosphines: R-(C₆H₄)-(OCH₂CH₂) _n-PPh₂ {1 (R=tert-octyl, n=1), 2 (R=tert-octyl, n?=5), 3 (R=tert-octyl, n?=13), 4 (R=n-nonyl, n?=1.4), 5 (R=n-nonyl, n?=5), 6 (R=n-nonyl, n?=11)}, CH₃(OCH₂CH₂)₃PPh₂ (7), CH₃(OCH₂CH₂)₃PPhR (8, R=isopentyl) and HOCH₂CH₂(OCH₂CH₂)₂PPhR (9, R=n-octyl). The molecular structure of trans-PdCl₂(1)₂ was determined by X-ray crystallography. The reaction between the trans-PdCl₂L₂ complexes and Ag⁺ was studied by ³¹P-NMR spectroscopy. The formation of chelated P∩O species in tetrahydrofuran solution was observed in complexes with ligands 2, 3, 5, 6, 7, 8 and 9. However, with ligand 1 the formation of chelated species was only observed in the less coordinating solvent dichloromethane. This different behavior can be attributed to the electronic and steric effects of the aryl group bonded to the oxygen atom. Ligand 4 is a mixture of a molecule similar to 1 and molecules with more than one oxygen atom and thus displays both characteristics.