Treatment of Ba[N(SiMe3)(2)](2)(THF)(2) with 2 equiv of dimethylaminotetrazole or diisopropylaminotetrazole and 1 equiv of 18-crown-6 afforded Ba[CN4(NMe2)](2)(18-crown-6) (87%) and Ba[CN4(NiPr2)](2-)(18-crown-6) (79%) as colorless crystalline solids. Ba[CN4(Nme2)12(18-crown-6) contains two 1,2-eta(2)-tetrazolato ligands and one eta(6)- 18-crown-6 ligand. The molecular structure of Ba[CN4(NiPr2)12(18-crown-6) is similar to that of Ba[CN4(NMe2)12(18-crown-6), except that the tetrazolato ligands exhibit the isomeric 2,3-eta(2)-Coordination mode and the tetrazolato ligand CN4 cores are bent significantly toward the 18-crown-6 ligands. Molecular orbital calculations were carried out on the model complexes Ba(azolate)(2)(18-crown-6) (azolate = 1,2-eta(2)-CHN4, 2,3-eta(2)-CHN4, and eta(2)-N-5) and demonstrate that the ligand coordination modes are influenced by intramolecular interactions between filled nitrogen orbitals on the azolato ligands and empty C-H sigma* orbitals on the 18-crown-6 ligands.