PSEUDOHALOGEN CHEMISTRY .13. NMR AND IR STUDIES OF SUBSTITUENT EFFECTS IN 3-SUBSTITUTED AND 3,5-SUBSTITUTED THIOCYANATOBENZENES

H-1 and C-13 NMR chemical shifts and IR SCN stretching frequencies for 3- and 3,5-substituted thiocyanatobenzenes have been measured at high dilution in an inert solvent. Substituent effects are additive for de lta C of the SCN group. delta H and vSCN in the two series. but not fo r the ring delta C. Most data sets gave excellent correlations (r>0.99 ) with substituent effects using single,dual and triple parameter appr oaches. The SCN carbon experiences a reverse substituent effect throug h both polar and resonance pathways of the electronic effect of tile s ubstituent(s), with sigma(F) accounting for 96% of it. In contrast, vS CN shows a normal substituent effect through both pathways. with sigma (F) accounting for 92% of it. delta C-1, under the influence of the ip so SCN, shows complete dependency on sigma(F) while delta C-6 (ortho S CN) shows a low rho(F) value; the other carbon shifts show typical rho (F) and rho(F) values. All delta H show a normal substituent effect th rough both pathways.