The approximations made in Hückel theory for conjugated hydrocarbons:
· p orbitals treated separately from s orbitals
· Only p orbitals treated in Hückel theory
· s orbitals treated as a rigid framework
· p orbitals expressed as linear combination of carbon 2p
orbitals (LCAO)
· All carbon
atoms are treated as being identical
· All Coulomb
integrals are set equal (Hrr = a)
· All overlap
integrals between different AOs are set to zero (Srs = 0)
· All resonance
integrals between adjacent carbon atoms set equal (Hrs =b)
· All other
resonance integrals set to zero