NMR study on the coordination of dibenzylideneacetone to chiral palladium(0) units. Fluxional behaviour including an intramolecular double bond exchange
Fa. Jalon et al., NMR study on the coordination of dibenzylideneacetone to chiral palladium(0) units. Fluxional behaviour including an intramolecular double bond exchange, J CHEM S DA, (16), 2001, pp. 2417-2424
Citations number
53
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
New derivatives with the general formula Pd(L-L)(eta (2)-dba) (dba = dibenz
ylideneacetone), L-L = 1-diphenylphosphino-2,1'-(1-dimethylaminopropanediyl
)ferrocene, PAPF, 1; 2-[1-(dimethylamino)ethyl]-1-(diphenylphosphino)ferroc
ene, PPFA, 2; N,N-dimethyl-1-[1',2-bis(diphenylphosphino)ferrocenyl]ethylam
ine, BPPFA, 3, 1-diphenylphosphino-2,1'-(I-dicyclohexylphosphinopropanediyl
)ferrocene, (PPPF)-P-Cy, 4 were synthesized from Pd-2(dba)(3). CHCl3 and th
e appropriate ferrocenyl ligand. When an excess of PPFA was used, the compl
ex Pd(PPFA)(3) with P-coordinated PPFA ligands was formed. The dba unit pre
ferentially adopts an s-cis,trans conformation with the s-trans alkene coor
dinated to the Pd(L-L) fragment. Several intramolecular dynamic processes w
ere identified: at room temperature a fast rotation of dba about the alkene
-Pd bond, a Pd-N bond rupture process for complex 2 and, at elevated temper
atures, an intramolecular diastereomer interconversion involving an alkene
face exchange accompanied by an interchange between the coordinated and non
-coordinated dba double bonds. The crystal structure of complex 2 was deter
mined by X-ray diffraction.