19F NMR studies on positional variations of trifluoromethyl groups in CF3-substituted aromatic group 15 trivalent chlorides

Abstract Several Group 15 trivalent chlorides with CF 3 -substituted aromatic groups R present, including at least one ortho -CF 3 substituent, R n ECl 3-n ( n  = 1 or 2; E  = P, As, Sb or Bi) have been studied by 19 F solution-state NMR spectroscopy. In compounds with both ortho - and para -CF 3 groups, the chemical shifts of the para -CF 3 fluorines are very similar, irrespective of the central element E. Much more variation is found in the shifts of the ortho -CF 3 fluorines, which may be correlated with the nature of the aromatic group, the electronegativity of E and the occurrence of short E–F contacts, as demonstrated by previous crystallographic studies of some of these compounds.