Stable isomers of AlC2, AlC3, AlCN, and AlC2N and transition states for AlC2 and AlCN molecules were determined at B3LYP and MP2 levels, and stable isomers:of AlC2 and AlCN land AlNC) were also calculated with he QCISD method. Vibrational frequencies were calculated to define whether the optimized geometry is a true minimum (for stable isomer) or the first-order saddle point (for transition state). These species were calculated to be primarily ionic bonding toward-the Al-C bond and thermodynamically stable. To confirm that the transition states of AlC2 and AlCN molecules connect the correct stationary points, IRC calculations were performed at the B3LYP and MP2 levels.