Weak Carbon−Hydrogen−Nitrogen Interactions Affect the Heterocyclic Ligand Bonding Modes in Barium Complexes Containing η<sup>2</sup>-Tetrazolato and η<sup>2</sup>-Pentazolato Ligands
收藏资源简介：
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)]2(18-crown-6) contains two 1,2-η2-tetrazolato ligands and one η6-18-crown-6 ligand. The molecular structure of Ba[CN4(NiPr2)]2(18-crown-6) is similar to that of Ba[CN4(NMe2)]2(18-crown-6), except that the tetrazolato ligands exhibit the isomeric 2,3-η2-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-η2-CHN4, 2,3-η2-CHN4, and η2-N5) and demonstrate that the ligand coordination modes are influenced by intramolecular interactions between filled nitrogen orbitals on the azolato ligands and empty C−H σ* orbitals on the 18-crown-6 ligands.
