The lack of direct correlation between dimer HOMO shifts and dimer dipole moments imply that other factors are involved in this trend, but there is an obvious tendency for dimers with very high dipole moments to exhibit unusual shifts in HOMO energy after monomer combination. This is consistent with charge transfer interactions dominating molecular orbital energies. Incorporation of the (𝛽 #' 2343 ) + , (𝛽 #' 5643 ) + , Δ 2343 , Δ 5643 , HOMO shift, LUMO shift, or dimer dipole moment parameters into the statistical models of Table failed to improve their predictive power.