Variants of Solid-State and Solution Structures of (η3-Allyl)- {2-[2′-(diphenylphosphino)phenyl]-4,5-dihydrooxazole-P,N}palladium(II) hexafluorophosphates and tetraphenylborates

✍ Scribed by Silvia Schaffner; Ludwig Macko; Markus Neubufger; Margareta Zehnder

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: German
• Weight: 510 KB
• Volume: 80
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19970800211

✦ Synopsis

1 9.VIII.96) Crystal and solution structures of the enantiomerically pure and the racemic pairs of (q3-allyl) { 2-[2'-(diphenylphosphino)phenyl]-4,5-dihydro-4-phenyloxazole}palladium(II) hexafluorophosphates (1, and rac-1, resp.) and tetraphenylborates (2, and ruc-2, resp.) as well as (q3-ally1){2-[2'-(diphenylphosphino)phenyl]-4,5-dihydro-4-isopropyloxazole}palladium(II) tetraphenylborate (3) were characterized by X-ray crystallography and 'H-NMR spectroscopy. In the solid state, rac-1 and ruc-2 proved to be disordered with both diastereoisomeric complexes in the crystal. The complexes 2 and 3 exist only in the 'exo' form. The X-ray structures show that the [Pd"(q3-allyl)] moiety may adopt different configurations between a nearly symmetrical three-electron Pd(n-allyl) system and an asymmetrical ally1 group with a q l -and a $-bonding to the metal center. The [Pd"(q3-allyl)] system of rac-1 and of 'endo' rac-2 is closer to the former, and that of 2, 'exo'-rac-2, and 3 closer to the later geometry. The 'H-NMR spectra of the hexafluorophosphates 1 and rac-1 show two sets of signals of the allylic protons in an 'exo'l'endo' ratio of 2: 3 . The tetraphenylborates 2, ruc-2, and 3 give only one set of broad signals of the allylic protons.

') H, and H, are the protons in trans-and cis-position, respectively, to H-C(2) of the allyl group