화학공학소재연구정보센터
Inorganic Chemistry, Vol.55, No.24, 12531-12543, 2016
Synthesis and Coordination Chemistry of Hexadentate Picolinic Acid Based Bispidine Ligands
The synthesis and Cu-II, Ni-II, Zn-II, Co-II, and Ga-III coordination chemistry of the two isomeric hexadentate N5O ligands 6-[[9-hydroxy-1,5-bis(methoxycarbony1)-7-methyl-6,8-bis(pyridin-2-yl)-3,7-diazabicyclo[3.3.1]nonan-3-yl]methyl] picolinic acid (Hbispa(1a)) and 6-[[9-hydroxy-1,5-bis(methoxycarbony1)-7-methyl-2,4-bis(pyridin-2-yl)-3,7-diazabicyclo[3.3.1]nonan-3-yl]methyl]picolinic acid (Hbispa(1b)), picolinic acid-appended bispidines, are described. The two ligands are highly preorganized for octahedral coordination geometries and are particularly well suited for tetragonal symmetries, i.e., for Jahn-Teller labile ground states. This is confirmed by all data presented: solid-state structures, solution spectroscopy, electrochemistry, and CuII complex stabilities. Differences in the preorganization of the two isomers for the Jahn-Teller labile Cu-II centers are thoroughly analyzed on the basis of the crystal structures and an angular-overlap-model-based ligand-field analysis.