Which of the following is an electrophile?
Electrophilic reagent or electrophile: A positively charged species of neutral molecule with electron-deficient centre. They act as Lewsi acids, e.g.
⊕H,.B⊕r,C⊕l,⊕l⊕NO2 R3⊕C,H3,⊕O,⊕NH4,⊕NO,R ⊕N=N,
SO3,BF3,AlCl3,ZnCl2,FeCl3,RCOCl,(RCO)2O(anhydride).