Electronic Energy Diagram for Cyclobutadiene ·Following Hund's π4 rule,two electrons are in separate nonbonding T2 nonbonding line molecular orbitals. ·This diradical would be very reactive. π1 Copyright 2010 Pearson Prentice Hall.Inc. Chapter 16 18 Chapter 16 18 Electronic Energy Diagram for Cyclobutadiene • Following Hund’s rule, two electrons are in separate nonbonding molecular orbitals. • This diradical would be very reactive