A phosphino,oxazoline P,N-bidentate ligand, 4, containing 3,5-di-tert-butylphenyl groups has been prepared. In the Heck arylation of dihydrofuran, 4 is shown to afford higher ee's than either 2 or 3, the unsubstituted and m-dimethylphenyl analogues, respectively. Several Pd(0) complexes of 4 are reported. The exchange dynamics of Pd(4)(dba) are shown to involve an interconversion of diastereomers via an intramolecular process. The X-ray structure for PdCl2(4), 8, was determined by X-ray diffraction methods. Comparison of data with PdCl2(2), 9, and PdCl2(3), 10, suggests that differing amounts of stacking influence the structures of these relatively simple Pd complexes, with 9 and 10 revealing the strongest, pi-pi interactions. An estimation of the van der Waals energies involved in the interaction supports a ca. 4 kcal/mol stabilization via pi-pi stacking.

Dialkyl effect on enantioselectivity : pi-stacking as a structural feature in P,N complexes of palladium(II) / P. Dotta, A. Magistrato, U. Rothlisberger, P. Pregosin, A. Albinati. - In: ORGANOMETALLICS. - ISSN 0276-7333. - 21:14(2002 Jul 08), pp. 3033-3041.

Dialkyl effect on enantioselectivity : pi-stacking as a structural feature in P,N complexes of palladium(II)

A. Albinati
Ultimo
2002

Abstract

A phosphino,oxazoline P,N-bidentate ligand, 4, containing 3,5-di-tert-butylphenyl groups has been prepared. In the Heck arylation of dihydrofuran, 4 is shown to afford higher ee's than either 2 or 3, the unsubstituted and m-dimethylphenyl analogues, respectively. Several Pd(0) complexes of 4 are reported. The exchange dynamics of Pd(4)(dba) are shown to involve an interconversion of diastereomers via an intramolecular process. The X-ray structure for PdCl2(4), 8, was determined by X-ray diffraction methods. Comparison of data with PdCl2(2), 9, and PdCl2(3), 10, suggests that differing amounts of stacking influence the structures of these relatively simple Pd complexes, with 9 and 10 revealing the strongest, pi-pi interactions. An estimation of the van der Waals energies involved in the interaction supports a ca. 4 kcal/mol stabilization via pi-pi stacking.
Heck reaction; P,N ligands; X-ray crystallography; DFT; weak interactions
Settore CHIM/03 - Chimica Generale e Inorganica
Article (author)
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/252936
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