ALBERT

Description: Organic Letters DOI: 10.1021/acs.orglett.5b03154

Description: The chiral title compound, [CeNi6(C3H6NO2)12][Ce(NO3)3(OH)3(H2O)], comprises a complex heterometallic Ni/Ce cation and a homonuclear Ce anion. Both the cation and anion exhibit point group symmetry 3. with the CeIIIatom situated on the threefold rotation axis. The cation metal core consists of six NiIIatoms coordinated in a slightly distorted octahedral N2O4configuration by N and O atoms of 12 deprotonated L-alaninate ligands exhibiting both bridging and chelating modes. This metal–organic coordination motif encapsulates one CeIIIatom that shows an icosahedral coordination by the O-donor atoms of the L-alaninate ligands, with Ce—O distances varying in the range 2.455 (5)–2.675 (3) Å. In the anion, the central CeIIIion is bound to three bidentate nitrate ligands, to three hydroxide ligands and to one water molecule, with Ce—O distances in the range 2.6808 (19)–2.741 (2) Å. The H atoms of the coordinating water molecule are disordered over three positions due to its location on a threefold rotation axis. Disorder is also observed in fragments of two L-alaninate ligands, with occupancy ratios of 0.608 (14):0.392 (14) and 0.669 (8):0.331 (8), respectively, for the two sets of sites. In the crystal, the complex cations and anions assemble through O—H...O and N—H...O hydrogen bonds into a three-dimensional network with large voids of approximately 1020 Å3. The contributions of highly disordered ethanol and water solvent molecules to the diffraction data were removed with the SQUEEZE procedure [Spek (2015).Acta Cryst.C71, 9–18]. The given chemical formula and other crystal data do not take into account the unknown amount of these solvent molecules.

Description: The asymmetric unit in the structure of the title compound, C25H22NO2+·Br−·0.5CH2Cl2·0.5H2O, comprises two pseudosymmetry-related cations, two bromide anions, a dichloromethane molecule and a water molecule of solvation. The two independent cations are conformationally similar with the comparative dihedral angles between the central pyridine ring and the three benzene substituent rings being 3.0 (2), 36.4 (1) and 24.2 (1)°, and 3.7 (2), 36.5 (1) and 24.8 (1)°, respectively. In the crystal, the cations, anions and water molecules are linked through O—H...O and O—H...Br hydrogen bonds, forming an insular unit. Within the cations there are also intramolecular N—H...O hydrogen bonds. Adjacent centrosymmetrically related aggregates are linked by π–π stacking interactions between the pyridine ring and a benzene ring in both cations [ring-centroid separations = 3.525 (3) and 3.668 (3) Å], forming chains extending across theacdiagonal. Voids between these chains are filled by dichloromethane molecules.

Description: The coordination polyhedron at the silicon atom in the title compound, C26H37Cl2NO2Si·0.25C7H8, is typical for pentacoordinated silicon derivatives and represents a slightly distorted trigonal bipyramid with an N atom and a Cl atom in the apical positions and the two O atoms and the other Cl atom occupying the equatorial sites. There are two independent molecules in the asymmetric unit. The N–Si–Cl fragment in each is close to linear [178.24 (5) and 178.71 (5)°], in good agreement with 4e–3ctheory, as is the elongation of the apical bond lengths [Si—Cl = 2.1663 (7) and 2.1797 (7) Å] in comparison with the equatorial bonds [Si—Cl = 2.0784 (7) and 2.0748 (7) Å]. Orthogonal least-squares fitting of the two independent molecules resulted in r.m.s. deviation of 0.017 Å. The conformations of the two molecules are almost the same, with corresponding torsion angles differing by less than 5.5°. The toluene solvent molecule is disordered about an inversion centre.