Experimental and theoretical studies of a triazole ligand and complexes formed with the lanthanides

The crystal structure of 2DBTZP . H2O [DBTZP=2,6-bis(5-butyl-1,2,4-triazol-3-yl)pyridine] has been determined and shows a dimeric structure in which two ligands, with different protonation patterns, form four hydrogen bonds with an enclosed water molecule. Several crystal structures have been determined of lanthanide complexes with the corresponding 5-methyl derivative (DMTZP) which cover the lanthanide series. Four different structural types are reported: La-III forms [La(DMTZP)(NO3)(H2O)(5)][NO3)(2); Nd-III, Sm-III and Tb-III in the first part of the lanthanide series form [M(DMTZP)(NO3)(3)(H2O)] which is crystallographically disordered over a two-fold axis, Ho-III forms [Ho(DMTZP)(NO3)(3)(H2O)], with one monodentate nitrate giving nine co-ordination, while Er-III and Yb-III form [M(DMTZP)(NO3)(3)] complexes which are also nine-co-ordinate.