Tris(tert-butoxy)siloxy Derivatives of Boron, Including the Boronous Acid HOB[OSi(OtBu)3]2and the Metal (Siloxy)boryloxide Complex Cp2Zr(Me)OB[OSi(OtBu)3]2:  A Remarkable Crystal Structure with 18 Independent Molecules in Its Asymmetric Unit

2003 ◽  
Vol 42 (4) ◽  
pp. 1140-1150 ◽  
Author(s):  
Kyle L. Fujdala ◽  
Allen G. Oliver ◽  
Frederick J. Hollander ◽  
T. Don Tilley
2006 ◽  
Vol 62 (4) ◽  
pp. o1319-o1320 ◽  
Author(s):  
Min-Hui Cao ◽  
Sheng-Zhen Xu ◽  
Yang-Gen Hu

The title compound, C15H16N2O2S, contains a five-membered thiophene ring fused to a benzene ring and a substituted pyrimidinone ring. All three rings in each of the independent molecules of the asymmetric unit lie in approximately the same plane. The crystal structure is stabilized by intermolecular C—H...O hydrogen bonding and π–π stacking interactions.


2014 ◽  
Vol 70 (11) ◽  
pp. 379-381
Author(s):  
Brigita Vigante ◽  
Dmitrijs Stepanovs ◽  
Andrejs Pelss ◽  
Anatoly Mishnev

The asymmetric unit of the title compound, C10H14N2O3, contains two independent molecules with similar conformations. In the both molecules, the cyclohexene rings adopt the same envelope conformation with the flap C atoms lying 0.658 (3) and 0.668 (3) Å from the mean planes formed by the remaining atoms. In the crystal, adjacent molecules are connectedviaN—H...O hydrogen bonds and weak C—H...O interactions, forming supramolecular layers parallel to (-101).


2014 ◽  
Vol 70 (11) ◽  
pp. m380-m381
Author(s):  
Rachel E. Hsuan ◽  
Jemma E. Hughes ◽  
Thomas H. Miller ◽  
Nabila Shaikh ◽  
Phoebe H. M. Cunningham ◽  
...  

Two independent molecules of the title solvated complex, [V(C16H14N2O2)O]·CH3OH, also known as [N,N′-bis(salicylidene)ethylenediamine]oxidovanadium(IV) or vanadyl salen, crystallize in the asymmetric unit. Each disordered methanol solvent molecule [occupancy ratios 0.678 (4):0.322 (4) and 0.750 (5):0.250 (5)] is linked to a [N,N′-bis(salicylidene)ethylenediamine]oxidovanadium(IV) molecule by an O—H...O hydrogen bond and to others by C—H...O hydrogen bonds. The resulting extended structure consists of a bilayer of molecules parallel to theabplane. Despite the fact that solvates are common in complexes derived from substituted analogues of theN,N′-bis(salicylidene)ethylenediamine ligand, the title solvate is the first one of [N,N′-bis(salicylidene)ethylenediamine]oxidovanadium(IV) to be structurally characterized. The two vanadyl species have very similar internal geometries, which are best characterized as distorted square-based pyramidal with the vanadium atom displaced from the N2O2basal plane by 0.5966 (9) Å in the direction of the doubly-bonded oxide ligand.


2006 ◽  
Vol 62 (5) ◽  
pp. o2064-o2065 ◽  
Author(s):  
Andrew D. Bond

The crystal structure of the title compound, C7H16O, has been determined at 150 (2) K following in situ crystal growth from the liquid. The structure contains four independent molecules in the asymmetric unit, forming a fourfold cyclic arrangement via O—H...O hydrogen bonds.


2014 ◽  
Vol 70 (6) ◽  
pp. o696-o697
Author(s):  
Md. Lutfor Rahman ◽  
H. T. Srinivasa ◽  
Mashitah Mohd. Yusoff ◽  
Huey Chong Kwong ◽  
Ching Kheng Quah

The asymmetric unit of the title compound, C17H18O3, comprises three independent molecules with similar geometries. In each molecule, the carbonyl group is twisted away from the napthalene ring system, making dihedral angles of 1.0 (2), 1.05 (19)° and 1.5 (2)°. The butene group in all three molecules are disordered over two sets of sites, with a refined occupancy ratio of 0.664 (6):0.336 (6). In the crystal, molecules are oriented with respect to their carbonyl groups, forming head-to-head dimersviaO—H...O hydrogen bonds. Adjacent dimers are further interconnected by C—H...O hydrogen bonds into chains along thea-axis direction. The crystal structure is further stabilized by weak C—H...π interactions.


Author(s):  
Yegor Yartsev ◽  
Vitaliy Palchikov ◽  
Alexandr Gaponov ◽  
Svitlana Shishkina

The title compound, C15H13ClN4, crystallizes with two independent molecules (AandB) in the asymmetric unit, which are far from planar as a result of steric repulsion between the rings. The benzene and phenyl rings are inclined to the central pyrazole ring by 46.64 (10) and 17.87 (10)° in moleculeA, and by 40.02 (10) and 14.18 (10)° in moleculeB. The aromatic rings are inclined to one another by 58.77 (9)° in moleculeA, and 36.95 (8)° in moleculeB. In the crystal, theAandBmolecules are linked by two pairs of N—H...N hydrogen bonds formingA–Bdimers. These are further linked by a fifth N—H...N hydrogen bond, forming tetramer-like units that stack along thea-axis direction, forming columns, which are in turn linked by C—H...π interactions, forming layers parallel to theacplane.


1983 ◽  
Vol 36 (11) ◽  
pp. 2269 ◽  
Author(s):  
RA Wood ◽  
VJ James ◽  
AD Rae ◽  
JD Stevens ◽  
FH Moore

The crystal structure of 5-O-acetyl-1,2:3,4-di-O-isopropylidene-α-D-glucoseptanose [P212121, Z 8, a 14.329(5), b 22.075(5), c 10.012(5) �] has been determined by X-ray and neutron diffraction analyses. For the neutron diffraction analysis, the acetate group and the trans-O-isopropylidene group were deuterated. Constrained refinement was used in the neutron diffraction analysis to counter over parameterization in the block-diagonal least-squares refinement. Final unweighted R-values were 0.038 [X-ray for 3070 reflections with [Fo > 2.58σ (Fo)] and 0.061 [neutron for 1118 reflections with Fo > 4σ ([Fo)]The neutron refinement revealed a disordering of the acetate methyl group in each of the two independent molecules in the asymmetric unit. The septanose ring in each molecule adopted the same twist-chair conformation but the dioxolan rings assumed different twist and envelope conformations.


1976 ◽  
Vol 29 (9) ◽  
pp. 1905 ◽  
Author(s):  
CL Raston ◽  
AH White ◽  
SB Wild

The crystal structure of the title compound has been determined by direct methods from X-ray diffraction data and refined by least squares to a residual of 0.071 for 2647 'observed' reflections. Crystals are monoclinic, C2/c, a = 36.81(1), b = 11.181(2), c = 20.369(5) �, β = 95.28(3)�, Z = 32. There are four independent molecules in the asymmetric unit, all with the cis disposition of ligands (<Fe-Hg), 2.498 �; <Hg-Fe-Hg), 80.9�); in one of the molecules one of the carbonyl sites is occupied by a more substantial moiety, possibly a result of partial occupancy of HgCl as a result of disorder or decomposition.


2007 ◽  
Vol 63 (11) ◽  
pp. o4439-o4439
Author(s):  
Hao Shi

The title compound, C22H26O8, prepared from the natural diterpenoid Macrocalyxin J, is built up from five fused rings. Cyclohenane ring A adopts a chair conformation, ring B exists in a screw-boat conformation and ring C adopts a boat conformation; the two five membered rings adopt envelope conformations. Two unique molecules are present in the asymmetric unit; both independent molecules have the same absolute configuration, the absolute configuration being deduced from the chirality of Macrocalyxin A, which was isolated from the same plant (i.e. Rabdosia macrocalyx) as Macrocalyxin J. The crystal structure displays intermolecular O—H...O hydrogen bonds.


2014 ◽  
Vol 70 (10) ◽  
pp. o1133-o1134
Author(s):  
Julian Linshoeft ◽  
Christian Näther ◽  
Anne Staubitz

In the crystal structure of the title compound, C28H36I2S3, a terthiophene monomer, the central thiophene unit is arrangedanti-coplanar to the two outer thiophene rings. There are two crystallographically independent molecules in the asymmetric unit, which show different conformations. In one molecule, the dihedral angles between the inner and the two outer thiophene rings are 15.7 (3) and 3.47 (3)°, whereas these values are 4.2 (3) and 11.3 (3)° for the second molecule. Differences are also found in the arrangement of the hexyl chains: in one of the two molecules, both chains are nearly in plane to the central moiety, whereas in the second molecule, only one chain is in plane and the other one is nearly perpendicular to the central moiety. Some of the C atoms are disordered and were refined using a split model with occupancy ratios of 0.65:0.35 and 0.70:0.30 in the two molecules.


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