63498-27-1Relevant articles and documents
Preparation and NMR Properties of Tricarbonylchromium(0) Derivatives of Dithiacyclophanes. An Estimate of the Reduction in Ring Current of an Aromatic Ring on Tricarbonylchromium Complexation
Mitchell, Reginald H.,Vinod, Thottumkara K.,Bodwell, Graham J.,Bushnell, Gordon W.
, p. 5871 - 5879 (2007/10/02)
The tricarbonylchromium(0) complexes 9-16 of 2,11-dithiametacyclophane (1) its 6,15-dimethyl (2), syn- and anti-9,18-dimethyl (6,7), 5,7,14,16-tetramethyl (3), 9-fluoro (4), and 9,18-difluoro (5) derivatives, the complex 17 from 2,11-dithiaparacyclophane (8), and the bis complex 18 of 1 were prepared in 20-80percent yields by reaction of the cyclophane with either 1.6 or 6 equiv of Cr(CO)6 or Cr(CO)3(CH3CN)3.The IR, UV, and 1H, 19F, and 13C NMR spectra of the complexes are reported and discussed.Characteristically different spectra are obtained for the syn- and anti-cyclophanes, and some shifts are reversed in the thiacyclophanes from the cyclophanes themselves.Analysis of their NMR spectra indicates that the time-averaged conformation of the tricarbonylchromium umbrella is eclipsing the cyclophane bridges.The reduction of ring current of an arene on complexation with a tricarbonylchromium moiety is estimated at 40percent by analysis of the shift data of these cyclophanes.The complexation shifts in these dithiacyclophanes for protons is 1.6-2.0 ppm and for carbons is 32-39 ppm (tertiary carbons) and 26-29 ppm ( quaternary carbons).
