Conformational analysis of meso- and (±)-2,3-dicyano-2,3- dicyclopropylbutane and 1,2-dicyanotetracyclopropylethane

Synthesis and Structural Characterization of Nonanuclear Lanthanide Complexes

“…For complex 3 (Ln = Gd), the plot of χ M -1 vs T obeys the Curie−Weiss law [χ = C /( T − θ)] with Curie constant, χ, of 77.3 cm 3 K mol -1 , and with Weiss constant, θ, of −4.06. The μ eff value per molecule of 3 is 23.6 μ B at room temperature, close to the expected value of 23.8 μ B for nine free noninteracting Gd 3+ ions, decreases gradually to 22.8 μ B at 50 K, and then drops rapidly below 50 K to 15.2 μ B at 2 K. The dramatic decrease of μ eff at low temperature is mainly attributed to the weak intra- and intermolecular antiferromagnetic coupling between the Gd 3+ ions and may also partially arise from the very small splitting of the 8 S 7/2 multiplet at zero field . Similar varieties of the temperature dependence of μ eff can also be found in complexes 4 and 5 .…”

“…Four Ln1 metal ions in each square base are planar and are linked by one μ 4 -O, which is slightly above the basal face. The shift of the μ 4 -O [0.253(6)−0.275(8) Å for 1 − 5 ] above the Ln 4 basal plane is significantly shorter than that observed in the tetradecanuclear [Ln 14 (μ 4 -OH) 2 (μ 3 -OH) 16 ( o -O 2 NC 6 H 4 O) 24 (Ln = Er, Yb)] [0.52 Å], whereas the in-planar μ 4 -oxo was observed for [Y 9 (μ 4 -O) 2 (μ 3 -OH) 8 (AAA) 16 ], [M 4 L 2 (NO 3 ) 4 (MeOH) 2 (μ 4 -O)] [M = Gd, Tb; L = 1,3-bis(2-hydroxy-3-methoxy-benzylamino)propan-2-ol], and [Er 8 (μ 4 -O)(μ 3 -OH) 12 (thd) 12 ] (Hthd = 2,2,6,6-tetramethylheptane-3,5-dione) . The Ln 9 core is surrounded by 16 peripheral BA ligands (Figure b), which are divided into two classes, eight terminal chelate ( t -BA) and eight bridging chelate (μ-BA), according to the coordination behavior of the ligand (Scheme ).…”

Evolution of C2B4Carborane Chemistry: from Early Years to the Present

“…Although oxygen coordination numbers ranging from 3 to 6 have been observed for f-block metal complexes, , there does not seem to be any consistency in either the precursor or the synthetic procedures. Clusters with a similar tetrahedral Ln 4 O core were found for [Ln 4 (μ 4 -O)(NHPh) 3 (OSiMe 2 NPh) 6 ·Na 6 (THF) 7 ] (Ln = Gd, Yb), which were obtained in low yields (8.9%) by the reaction of LnBr 3 , NaNHPh, and (Me 2 SiO) 3 in THF, while the planar Ln 4 O core in Na 6 {[(C 6 H 5 SiO 2 ) 8 ] 2 Nd 4 (μ 4 -O)} was obtained in 16% yield by the reaction of anhydrous NdCl 3 and sodium oligo(phenylsiloxanolate) in an n -butanol solution 126a. The planar Ln 4 O core cluster in [Tb 4 L 2 (NO 3 ) 4 (MeOH) 2 (μ 4 -O)] (H 3 L = 1,3-bis(2-hydroxy-3-methoxybenzylamino)propan-2-ol) was obtained by the reaction of hydrated Tb(NO 3 ) 3 ·5H 2 O with H 3 L in a 2:1 ratio in methanol 126b.…”

“…Clusters with a similar tetrahedral Ln 4 O core were found for [Ln 4 (μ 4 -O)(NHPh) 3 (OSiMe 2 NPh) 6 ·Na 6 (THF) 7 ] (Ln = Gd, Yb), which were obtained in low yields (8.9%) by the reaction of LnBr 3 , NaNHPh, and (Me 2 SiO) 3 in THF, while the planar Ln 4 O core in Na 6 {[(C 6 H 5 SiO 2 ) 8 ] 2 Nd 4 (μ 4 -O)} was obtained in 16% yield by the reaction of anhydrous NdCl 3 and sodium oligo(phenylsiloxanolate) in an n -butanol solution 126a. The planar Ln 4 O core cluster in [Tb 4 L 2 (NO 3 ) 4 (MeOH) 2 (μ 4 -O)] (H 3 L = 1,3-bis(2-hydroxy-3-methoxybenzylamino)propan-2-ol) was obtained by the reaction of hydrated Tb(NO 3 ) 3 ·5H 2 O with H 3 L in a 2:1 ratio in methanol 126b. On the other hand, the butterfly form of Ce 4 O in the cerium complex Ce 4 O(O i Pr) 13 ( i PrOH) was obtained from the photoreduction of Ce 2 (O i Pr) 8 ( i PrOH) in a 2:1 mixture of MeOC 2 H 4 OMe/ i -PrOH .…”

An Oxide Ion Encapsulating Tetraholmium Tetrahedron Stabilized by Complexation with the “Carbons Apart” C2B4-Carborane Ligands

“…This is similar to compound 2 , except that these have more complex geometries with polydentate oxadimethylsilyl- N -phenylamido ligands over all edges and anilido ligands on three of the four vertexes. On the other hand, both [Tb 4 L 2 (NO 3 ) 4 (MeOH) 2 (μ 4 -O)] (H 3 L = 1,3-bis(2-hydroxy-3-methoxybenzylamino)propan-2-ol) and Na 6 {[(C 6 H 5 SiO 2 ) 8 ] 2 Nd 4 (μ 4 -O) show planar Ln 4 O cores, , while Ce 4 (μ 4 -O)(μ 3 -O i Pr) 2 (μ 3 -O i Pr) 4 (O i Pr) 7 ( i PrOH) has a butterfly core, as does [Y 4 (μ 3 -OCMe 3 ) 2 (μ-OCMe 3 ) 4 (OCMe 3 ) 4 (μ 4 -O)(μ-Cl) 2 Li 4 (μ-OCMe 3 ) 2 ] 2 . All of these structures are complex, and it is difficult to assess the forces that dictate the geometry of the Ln 4 O core.…”