Electronic structure calculations for the mer and fac-isomers of aluminum tris (8-hydroxyquinoline) (Alq3) and the methyl-substituted series, nMeq3Al (n = 3 - 7) are presented. From these data, we estimate their relative abundances in Alq3 thin films and the resultant trap state energies. Ab initio computations performed at the SCF level suggest a significantly higher stability (6 - 7.5 kcal/mol) of the mer-isomer over the facial form, whereas MP2 treatment of electron correlation effects lowers the difference to (4 - 4.5 kcal/mol). Substitution of the Al+3 metal ion with the larger ions Ga+3 and In+3 increases the energetic preference of the meridianal form by 2.7 kcal/mol and decreases it by 0.8 kcal/mol, respectively. Trap state energies calculated by previously proposed methodologies show little difference between mer and fac trap states. These results suggest that the existence of the facial isomer in thin films of metal trisquinolates is unlikely to significantly affect charge conduction.