Synthesis and 19F Nuclear Magnetic Resonance Spectra of Fluorosubstituted Bis(arene)chromium Complexes

A series of substituted bis(fluorobenzene)chromium complexes, (C 6 H 4 FX) 2 Cr, where X is H, F, Cl, CH 3 , or CF 3 , have been synthesized by cocondensing Cr atoms and fluoroarenes. The 19 F chemical shifts of these compounds correlate well with those of the corresponding C 6 F 5 X system suggesting that the overall electron-withdrawing effect of a π-bonded Cr on each ring is similar to the effect of four ring fluorine substituents.