Pentadienyl cation C 5 H 7   Charge = +1   Real ion. Gram formula weight (molecular mass) = 67.109 Pentadienyl cation is defined with respect to the entities below: The entities below are defined with respect to: Pentadienyl cation Pentadieny FMO (generic) pi-LUMO Lewis acid (generic) Real complex ion (generic) chemical compound molecule metal molecular science reaction mechanism ionic material acid base geometry reactivity synthesis science knowledge chemistry Lewis