American Chemical Society
ao7b00457_si_002.txt (2.92 MB)

Synthesis and Structural Analysis of Palladium(II) Complexes Containing Neutral or Anionic C2‑Symmetric Bis(oxazoline) Ligands: Effects of Substituents in the 5‑Position

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posted on 2017-07-25, 14:18 authored by Ken Tsutsumi, Koji Itagaki, Kotohiro Nomura
A series of neutral and cationic palladium­(II) complexes containing C2-symmetric bis­(oxazoline) (BOX) ligands, (BOX)­PdCl2 (2ad), (BOX)­Pd­(Me)Cl (3ad), and [(BOX)­PdMe­(2,6-Me2C5H3N)]+PF6 (4ad) [BOX: 2,2′-(2-propylidene)­bis­{(4R)-4-phenyl-5,5-dimethyl-2-oxazoline}, 2,2′-methylenebis­{(4R)-4-phenyl-5,5-dimethyl-2-oxazoline}, 2,2′-methylenebis­{(4R)-4,5,5-triphenyl-2-oxazoline}, and 2,2′-methylenebis­{(4R,5S)-4,5-diphenyl-2-oxazoline}], were prepared, and their structures were determined by X-ray crystallography. It was found that substituents at the 5-position (Ph, Me) in addition to substituents on the bridgehead carbon directly affect the structure around palladium, especially the BOX bite angle and the dihedral angles between the phenyl rings at the 4-position and the N2Pd plane. Treatment of the bridged methylene proton in the BOX ligand (1bd) with KH afforded the anionic BOX ligand; also, the neutral Pd complexes, (BOX)­PdMe­(2,6-Me2C5H3N) (5bd), could thus be prepared by reaction with Pd­(Me)­Cl­(cod) (cod = 1,5-cyclooctadiene); 5bd showed strong coordination to Pd, as demonstrated by X-ray crystallographic analysis.