Palladium(II) complexes with hemilabile amphiphilic phosphines

A series of trans-PdCl2L2 complexes were prepared and characterized with th e following hemilabile amphiphilic phosphines: R-(C6H4)-(OCH2CH2)(n)-PPh2 { 1 (R = tert-octyl, n = 1), 2 (R = tert-octyl, (n) over bar = 5), 3 (R = ter t-octyl, (n) over bar = 13), 4 (R = n-nonyl, (n) over bar = 1.4), 5 (R = n- nonyl, (n) over bar = 5), 6 (R = n-nonyl, (n) over bar = 11)}, CH3(OCH2CH2) (3)PPh2 (7), CH3(OCH2CH2)(3)PPhR (8, R = isopentyl) and HOCH2CH2(OCH2CH2)(2 )PPhR (9, R=n-octyl). The molecular structure of trans-PdCl2(1)(2) was dete rmined by X-ray crystallography. The reaction between the trans-PdCl2L2 com plexes and Ag+. was studied by P-31-NMR spectroscopy. The formation of chel ated P boolean ANDO species in tetrahydrofuran solution was observed in com plexes with ligands 2, 3, 5, 6, 7, 8 and 9. However, with ligand 1 the form ation of chelated species was only observed in the less coordinating solven t dichloromethane. This different behavior can be attributed to the electro nic 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. (C) 2001 Elsevier Scien ce B.V. All rights reserved.