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Camphopyrazole-based N,N- and N,P-ligands and chiral complexes of Ni, Pd, and Rh: P–N bond activation upon Rh(I) complexation


Herrera, Alberto; Briceño, Alexander; Gonzalez, Teresa; Linden, Anthony; Heinemann, Frank W; Agrifoglio, Giuseppe; Pastrán, Jesús; Dorta, Romano (2016). Camphopyrazole-based N,N- and N,P-ligands and chiral complexes of Ni, Pd, and Rh: P–N bond activation upon Rh(I) complexation. Tetrahedron: Asymmetry, 27(16):759-767.

Abstract

Enantiomerically pure C1 and C2-symmetric bidentate N,N- and N,P-ligands are accessible from (+)-camphor in good yields (60–90%). Modified syntheses of precursors 1 and 2 are disclosed as well as the crystal structures of three hydroxy-pyrazoline intermediates. Ligands 3, 4, 6, and 11 were fully characterized including an X-ray crystal structure of C2-symmetric 6, which showed an E-configuration in the solid state. These ligands form complexes with Ni(II), Pd(II), and Rh(I) in good yields (84–96%); the X-ray crystal structures of complexes 12, 14, and 16 confirmed the bidentate coordination modes of ligands 4, 6, and 11 and distorted tetrahedral [for Ni(II)] and square planar [for Rh(I)] coordination geometries. Furthermore, the structure of the Rh(I) complex 16 revealed the presence of a Ph2PCl ligand, which, along with spectroscopic data, is proof of an almost quantitative P–N bond cleavage upon coordination of ligand 11 to [RhCl(COD)]2.

Abstract

Enantiomerically pure C1 and C2-symmetric bidentate N,N- and N,P-ligands are accessible from (+)-camphor in good yields (60–90%). Modified syntheses of precursors 1 and 2 are disclosed as well as the crystal structures of three hydroxy-pyrazoline intermediates. Ligands 3, 4, 6, and 11 were fully characterized including an X-ray crystal structure of C2-symmetric 6, which showed an E-configuration in the solid state. These ligands form complexes with Ni(II), Pd(II), and Rh(I) in good yields (84–96%); the X-ray crystal structures of complexes 12, 14, and 16 confirmed the bidentate coordination modes of ligands 4, 6, and 11 and distorted tetrahedral [for Ni(II)] and square planar [for Rh(I)] coordination geometries. Furthermore, the structure of the Rh(I) complex 16 revealed the presence of a Ph2PCl ligand, which, along with spectroscopic data, is proof of an almost quantitative P–N bond cleavage upon coordination of ligand 11 to [RhCl(COD)]2.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Uncontrolled Keywords:camphopyrazole, chiral complexes, rhodium complexes, N,N-ligands, N,P-ligands
Language:English
Date:2016
Deposited On:08 Sep 2016 13:04
Last Modified:08 Dec 2017 20:20
Publisher:Elsevier
ISSN:0957-4166
Funders:FONACIT (project S1-2001000851), DID-USB (project S1-IC-CB-034-2014)
Publisher DOI:https://doi.org/10.1016/j.tetasy.2016.06.013

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