Crystal structures of two mononuclear complexes of terbium(III) nitrate with the tripodal alcohol 111-tris­(hy­droxy­meth­yl)propane

摘要

Two new mononuclear cationic complexes in which the Tb^III ion is bis-chelated by the tripodal alcohol 1,1,1-tris­(hy­droxy­meth­yl)propane (H3 L ^Et, C6H14O3) were prepared from Tb(NO3)3·5H2O and had their crystal and mol­ecular structures solved by single-crystal X-ray diffraction analysis after data collection at 100 K. Both products were isolated in reasonable yields from the same reaction mixture by using different crystallization conditions. The higher-symmetry complex dinitratobis[1,1,1-tris­(hy­droxy­meth­yl)propane]­terbium(III) nitrate di­meth­oxy­ethane hemisolvate, [Tb(NO3)2(H3 L ^Et)2]NO3·0.5C4H10O2, >1, in which the lanthanide ion is 10-coordinate and adopts an s-bicapped square-anti­prismatic coordination geometry, contains two bidentate nitrate ions bound to the metal atom; another nitrate ion functions as a counter-ion and a half-mol­ecule of di­meth­oxy­ethane (completed by a crystallographic twofold rotation axis) is also present. In product aqua­nitratobis[1,1,1-tris­(hy­droxy­meth­yl)propane]­terbium(III) dinitrate, [Tb(NO3)(H₃ L ^Et)₂(H₂O)](NO₃)₂, >2, one bidentate nitrate ion and one water mol­ecule are bound to the nine-coordinate terbium(III) centre, while two free nitrate ions contribute to charge balance outside the tricapped trigonal-prismatic coordination polyhedron. No free water mol­ecule was found in either of the crystal structures and, only in the case of >1, di­meth­oxy­ethane acts as a crystallizing solvent. In both mol­ecular structures, the two tripodal ligands are bent to one side of the coordination sphere, leaving room for the anionic and water ligands. In complex >2, the methyl group of one of the H₃ L ^Et ligands is disordered over two alternative orientations. Strong hydrogen bonds, both intra- and inter­molecular, are found in the crystal structures due to the number of different donor and acceptor groups present.