Abstract
Two new mononuclear cationic complexes in which the TbIII ion is bis-chelated by the tripodal alcohol 1,1,1-tris-(hy-droxy-meth-yl)propane (H3LEt, C6H14O3) were prepared from Tb(NO3)3·5H2O and had their crystal and mol-ecular 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-(hy-droxy-meth-yl)propane]-terbium(III) nitrate di-meth-oxy-ethane hemisolvate, [Tb(NO3)2(H3LEt)2]NO3·0.5C4H10O2, 1, in which the lanthanide ion is 10-coordinate and adopts an s-bicapped square-anti-prismatic coordination geometry, contains two bidentate nitrate ions bound to the metal atom; another nitrate ion functions as a counter-ion and a half-mol-ecule of di-meth-oxy-ethane (completed by a crystallographic twofold rotation axis) is also present. In product aqua-nitratobis[1,1,1-tris-(hy-droxy-meth-yl)propane]-terbium(III) dinitrate, [Tb(NO3)(H3LEt)2(H2O)](NO3)2, 2, one bidentate nitrate ion and one water mol-ecule 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 mol-ecule was found in either of the crystal structures and, only in the case of 1, di-meth-oxy-ethane acts as a crystallizing solvent. In both mol-ecular 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 H3LEt ligands is disordered over two alternative orientations. Strong hydrogen bonds, both intra- and inter-molecular, are found in the crystal structures due to the number of different donor and acceptor groups present.
Highlights
Two new mononuclear cationic complexes in which the TbIII ion is bis-chelated by the tripodal alcohol 1,1,1-tris(hydroxymethyl)propane (H3LEt, C6H14O3)
Nitrate dimethoxyethane hemisolvate, [Tb(NO3)2(H3LEt)2]NO30.5C4H10O2, 1, in which the lanthanide ion is 10-coordinate and adopts an s-bicapped squareantiprismatic coordination geometry, contains two bidentate nitrate ions bound to the metal atom; another nitrate ion functions as a counter-ion and a halfmolecule of dimethoxyethane is present
In product aquanitratobis[1,1,1-tris(hydroxymethyl)propane]terbium(III) dinitrate, [Tb(NO3)(H3LEt)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
Summary
Our interest in developing synthetic routes for the synthesis of mono- or polynuclear complexes containing lanthanide(III). Ions is based on the possibility that these compounds behave as single-ion (SIM) or single-molecule (SMM) magnets (Benelli & Gatteschi, 2015; Gatteschi et al, 2006; Frost et al., 2016; Meng et al, 2016) In such chemical species, it is usually possible to exploit the strong spin-orbit coupling, the relatively high-spin angular momentum and the large magnetic anisotropy presented by lanthanides to maximize the energy barrier for the reversal of the magnetization (Luzon & Sessoli, 2012; Vieru et al, 2016; Sessoli & Powell, 2009) and increase the technological applicability of these materials. This value, lower than the record figures reported for lanthanide-containing SIM compounds (Liu et al, 2016), still reveals the potential of mixed 3d–4f metal complexes to behave as quantum magnets Despite these good results, most of the experimental procedures employed for the preparation of these polynuclear compounds involve self-assembly reactions, which often compete with the rational design of the desired molecules. 3d and 4f starting materials to give heterometallic products with potentially interesting magnetic properties
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