VARIANTS OF SOLID-STATE AND SOLUTION STRUCTURES OF PHINO)PHENYL]-4,5-DIHYDROOXAZOLE-P,N)PALLADIUM(II) HEXAFLUOROPHOSPHATES AND TETRAPHENYLBORATES

Crystal and solution structures of the enantiomerically pure and the r acemic pairs of (eta(3)-allyl) enylphosphino)phenyl]-4,5-dihydro-4-phe nyloxazole} palladium(II) hexafluorophosphates (1, and rac-1, resp.) a nd tetraphenylborates (2, and rac-2, resp.) as well as enyl]-4,5-dihyd ro-4-isopropyloxazole}palladium(II) tetraphenylborate (3) were charact erized by X-ray crystallography and H-1-NMR spectroscopy. In the solid slate, rac-1 and, rac-2 proved to be disordered with both diastereois omeric complexes in the crystal. The complexes 2 and 3 exist only in t he 'exo' form. The X-ray structures show that the [Pd-II(eta(3)-allyl) ] moiety may adopt different configurations between a nearly symmetric al three-electron Pd(pi-allyl) system and an asymmetrical allyl group with a eta(1) and a eta(2)-bonding to the metal center. The [Pd-II(eta (3)-allyl)] system of rac-1 and of 'endo' rac-2 is closer to the forme r, and that of 2, 'exo'-rac-2, and 3 closer to the later geometry. The H-1-NMR spectra of the hexafluorophosphates 1 and rac-1 show two sets of signals of the allylic protons in an 'exo'/'endo' ratio of 2:3. Th e tetraphenylborates 2, rac-2, and 3 give only one set of broad signal s of the allylic protons.