Question

when is no2 considered -M or -I group?​

Answer 1

Answer:

important to know that M effect always dominates I effect !

Explanation:

MESOMERIC effect is directional in nature it only operates in one direction which is permanent shift of pie electron cloud !

NOTE it is independent of distance .

whereas in INDUCTIVE it is wasn't directional ( it can operates in any direction) in operates through shifting of sigma electron cloud !

NOTE it depends on the distance .

so if there is change that delocalisation can be done only in one direction then consider M effect other than it will be I effect but if the distance is greater then inductive wont operate ! it is negligible after 2-3 atoms

there are more molecules like NO2 which -I as well -M eg. -CN, -CHO, -COR etc