名称:
Camphopyrazole-based N,N- and N,P-ligands and chiral complexes of Ni, Pd, and Rh: P–N bond activation upon Rh(I) complexation
摘要:
Enantiomerically pure C-1 and C-2-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 C-2-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 NON 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). (C) 2016 Elsevier Ltd. All rights reserved.