The title compound, C7H14N2Si, crystallizes in a tetra-gonal space group and exists as an N-H⋯N hydrogen-bonded tetra-mer, formed around the crystallographic fourfold rotoinversion axis. The mol-ecular identity is clearly the 5-tri-methyl-silyl-3-methyl-1H-pyrazole tautomer and the structure is isomorphous with that of 5-tert-butyl-3-methyl-1H-pyrazole [Foces-Foces & Trofimenko (2001 ▶). Acta C...

Two Co(II) and Mn(II) coordination polymers, which have been synthesized under hydrothermal conditions, are isomorphous with magnetic Δ-chains containing trinuclear triangular [M(3)(μ(3)-OH)] clusters. The Δ-chains are bridged by isonicotinic spacers to generate a two-dimensional scalariform layer structure. Magnetic investigations indicate that Co(II) compound exhibits not only spin canting bu...

isomorphous replacements, for clarification and possible decision among the several structures proposed. tRNA has long been known to be rich in minor base modifications (6, 20), of which the most common is methylation, and this occurs on all 4 major bases. Data presented at this symposium by Stulberg and Shugart (72) support the logical inference that these base modifications change the tertiar...

The two title isostructural and isomorphous complexes, [M(C6H10N4)2(H2O)2](NO3)2 (M is Co or Ni), contain the transition metal in a distorted octahedral geometry, coordinated by four N atoms of two neutral bidentate organic ligands in the equatorial plane and two water O atoms molecules in the axial positions. The cation is centrosymmetric, with the transition metal located on an inversion cent...

The 35C1 NQR frequencies o f A 2PdCl6 were studied. For A = (CH3)4N + a clathrate [(CH3)4N]2PdCl6 Cl2 was found and its crystal structure was determined (F d3c, Z = 32, a = 2554.5 pm, R = 0.062). The clathrate [(CH3)4N]2SnCl6 Cl2 was prepared, too. It is isomorphous with the corresponding palladium salt. The results o f the 35C1 NQR studies are discus­ sed on the basis o f the crystal structure.

The structure of the 7Fe ferredoxin from Azotobacter vinelandii has been solved from a 3.0-A multiple isomorphous replacement map. The crystals belong to space group P43212 with a = 55.22, c = 95.20 A, and Z = 1. Heavy-atom derivatives were prepared with K2PtCl4,K2[OsO2(OH)4], and Na3RhCl6. Anomalous scattering data were collected for native (Fe) and Pt derivative crystals. The figure of merit ...

The crystal structures of five 6-mercaptopurine derivatives, viz. 2-[(9-acetyl-9H-purin-6-yl)sulfan-yl]-1-(3-meth-oxy-phen-yl)ethan-1-one (1), C16H14N4O3S, 2-[(9-acetyl-9H-purin-6-yl)sulfan-yl]-1-(4-meth-oxy-phen-yl)ethan-1-one (2), C16H14N4O3S, 2-[(9-acetyl-9H-purin-6-yl)sulfan-yl]-1-(4-chloro-phen-yl)ethan-1-one (3), C15H11ClN4O2S, 2-[(9-acetyl-9H-purin-6-yl)sulfan-yl]-1-(4-bromo-phen-yl)etha...

Protein powder diffraction is shown to be suitable for obtaining de novo solutions to the phase problem at low resolution via phasing methods such as the isomorphous replacement method. Two heavy-atom derivatives (a gadolinium derivative and a holmium derivative) of the tetragonal form of hen egg-white lysozyme were crystallized at room temperature. Using synchrotron radiation, high-quality pow...

Recrystallization of [PdCl2([9]aneS2O)] ([9]aneS2O = 1-oxa-4,7-dithiacyclononane), 1, and [PtCl2([9]aneS2O)], 2, by diffusion of Et2O vapor into solutions of the complexes in MeNO2 yielded three phases of 1 and two phases of 2. The known phase of 1, herein designated α-1, was obtained under ambient conditions. A second phase, designated β-1, was initially also obtained by this method; however, ...