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Phase transition in bis(ethyldimethylammonium) pentachloroantimonate(III)
1999
The crystal structure of a new member of the alkylammonium chloroantimonate family, namely bis-(ethyldimethylammonium) pentachloroantimonate(III), [C 2 H 5 NH(CH 3 ) 2 ] 2 [SbCl 5 ], was determined at room temperature. The anionic sublattice consists of isolated distorted square-pyramidal [SbCl 5 ] 2- units and two crystallographically inequivalent disordered ethyldimethylammonium cations connected to anions by NH...Cl hydrogen bonds. The disorder is realised by the presence of two positions for all C, N and H atoms, and is explained as being a result of the overall reorientation of cations along the long axis of the molecule. One second-order phase transition was found at ca 160 K and resu…
Methyl 4-[5-(4-fluorophenyl)-4-(pyridin-4-yl)-1H-imidazol-2-ylsulfanyl]butanoate
2008
The title compound, C19H18FN3O2S, was synthesized in the course of studies on 2-alkylsufanylimidazoles as p38 mitogen-activated protein kinase inhibitors. The synthesis was achieved by nucleophilic substitution of 4-(4-fluorophenyl)-5-(pyridin-4-yl)-1,3-dihydroimidazole-2-thione with methyl 4-bromobutanoate. The five-membered heterocycle makes dihedral angles of 32.4 (2) and 18.3 (2)° with the fluorophenyl and pyridinyl rings, respectively, indicating a low degree of conjugation between these rings. Intramolecular C—H...N and intermolecular N—H...N hydrogen bonds as well as C—H...π interactions seem to be effective in stabilization of the crystal stru…
Charge-density analysis of 1-nitroindoline: refinement quality using free R factors and restraints. Corrigendum
2011
The D e (dissociation energy) values in Table 6 of the article by Zarychta et al. [(2011). Acta Cryst. B67, 250–262] are corrected.
Spin Transitions in Iron(II) Complexes
1996
Iron(II) has the 3d6 outer electronic configuration and hence its octahedral complexes may be either high-spin or low-spin. The high-spin configuration, t 2g 4 e g 2 , is adopted when relatively weak-field ligands are coordinated while the low-spin, t 2g 6 e g 0 , is obtained when strong-field ligands are involved. In Oh symmetry the ground states are 5T2g and lA1g, for the high-spin and low-spin configurations, respectively. While in most iron(II) six-coordinate complexes the symmetry is lower than Oh, these designations are generally adopted in the following sections for convenience. [Fe(H2O)6]2+ and [Fe(en)3]2+ (en = ethylenediamine) are typical examples of high-spin complexes, while [Fe…
N,N,N',N'‐Tetramethylguanidinium tetrachloroantimonate(III) at 295 and 92K
1999
The crystal structure of N,N,N',N'-tetramethylguanidinium tetrachloroantimonate(III), (C 5 H 14 N 3 )[SbCl 4 ], has been determined at 295 and 92 K. Each Sb atom is surrounded by six Cl atoms forming an irregular [SbCl 6 ] 3- octahedron. The octahedra are connected with each other in infinite zigzag chains. There is one crystallographically independent N,N,N',N'-tetramethylguanidinium cation in the crystal structure. It is linked to the [SbCl 6 ] 3- octahedra through N-H...Cl hydrogen bonds. The deformation of the octahedral coordination of the Sb III atom is related to the presence of N-H...Cl hydrogen bonds.
2-(2,3,5,6-Tetramethylbenzylsulfanyl)pyridine N-oxide
2008
In the title compound, C16H19NOS, the durene ring and the oxopyridyl ring form a dihedral angle of 82.26 (7)°. The crystal structure is stabilized by intermolecular C—H...O hydrogen bonds, weak C—H...π interactions and π–π interactions [centroid–centroid distance of 3.4432 (19) Å], together with intramolecular S...O [2.657 (2) Å] short contacts.
Tetrakis{2,4-bis[(1-oxo-2-pyridyl)sulfanylmethyl]mesitylene} acetone hemisolvate 11.5-hydrate
2009
In the crystal structure of the title compound, 4C21H22N2O2S2·0.5C3H6O·11.5H2O, there are four crystallographically independent molecules (A, B, C, D) with similar geometries, 11 water molecules and a solvent acetone molecule which is disordered with a water molecule with occupancy factors of 0.5:0.5. The dihedral angles formed by the mesitylene ring with the two pyridyl rings are 82.07 (3) and 78.39 (3)° in molecule A, 86.20 (3) and 82.29 (3)° in molecule B, 81.05 (3) and 76.0 (4)° in molecule C, 86.0 (3) and 80.9 (3)° in moleule D. The two pyridyl rings form dihedral angles of 41.17 (4), 64.01 (3), 8…
Unprecedented Hexa- and Undecanuclear Frameworks of Two New Tin(IV) Oxo Clusters Resulting from Partial Debenzylation Reactions
2010
A new and facile synthetic route to the known neutral cluster ((PhCH2)2SnO)6[((PhCH2)2SnOH)2- (CO3)]2 (2) as well as its reactivity toward trifluoromethanesulfonic acid (HO3SCF3, TfOH) are reported. The solid-state structure of the new solvate 2·6C7H8 has been determined by single-crystal X-ray diffraction. The core of 2 can be described as a pair of coplanar pentanuclear [(PhCH2)2SnO]5 ladders bridged at their ends by two carbonate groups. Successive additions of TfOH to a suspension of 2 in CD3CN were monitored by 119Sn{1H} NMR spectroscopy showing the transformation of the fingerprint of 2 (δ = −244, −246, −306 ppm), via new upfield signals, to a final broad resonance located at δ = −474…
Why betaine crystallizes in high local C s symmetry. An ab initio MO and DFT study of anhydrous betaine and betaine monohydrate
1999
A theoretical study of the structure, charge distribution, rotational barrier and fundamental vibrations of anhydrous betaine (CH3)3NCH2COO (trimethylglycine) was carried out and compared with available experimental data. Calculations were carried out at HF, MP2 and B3LYP levels using a 6-31+G(d,p) basis set. The calculated rotational barrier of the betaine carboxylic group is 40.5 kJ/mol at the MP4(SDQ)/6-311G(d,p)//HF/6-31+G(d,p) level of theory. The rotation of the carboxylic group changes the molecule from a highly symmetric (C s ) conformation into a twisted conformation resulting in shortening of the molecule by about 50 pm. Natural population analysis (NPA) indicates intramolecular i…
Alternating cationic–anionic layers in the [Mii(H2O)6][Cuii(mal)2(H2O)] complexes linked through hydrogen bonds (M = Mn, Co, Ni, Cu and Zn; H2mal = m…
2002
The compounds of formula [MII(H2O)6][CuII(mal)2(H2O)2] [M = Mn (1), Co (2), Ni (3), Cu (4), Zn (5) and H2mal = malonic acid] have been prepared and structurally characterised. Each compound adopts a structure where the layers of [Cu(mal)2(H2O)2]2− anions alternate with layers of [M(H2O)6]2+ cations. The layers are linked to each other through hydrogen bonds affording a three-dimensional network. A quasi-Curie law behaviour is observed for the complexes 1–5 in the temperature range 2.0–298 K.