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Search Results: 1 - 10 of 174906 matches for " John F. Gallagher "
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2-Ferrocenyl-N-(6-methyl-2-pyridyl)benzamide
John F. Gallagher,Steven Alley,Alan J. Lough
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810008342
Abstract: The title compound, [Fe(C5H5)(C18H15N2O)], a product of the reaction of 2-ferrocenylbenzoic acid and 2-amino-6-methylpyridine, crystallizes with two dissimilar molecules in the asymmetric unit. In one molecule, the picoline amide group is directed away from the 2-ferrocenylbenzene moiety (anti) whereas in the other, these are proximate (syn). In the crystal structure, molecules aggregate into dimers via cyclic, asymmetric N—H...N interactions with graph set R22(8), and are further augmented via intramolecular C—H...O=C and interdimer C—H...π(arene) interactions. Dimers are linked into chains along the [102] direction via weak C—H...O hydrogen bonds.
2-Ferrocenyl-N-(2-ferrocenylbenzoyl)-N-(4-methyl-2-pyridyl)benzamide
John F. Gallagher,Steven Alley,Alan J. Lough
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809006278
Abstract: The title compound, [Fe2(C5H5)2(C30H22N2O2)], a 2:1 product of the reaction of 2-ferrocenylbenzoic acid and 2-amino-4-methylpyridine, forms a twisted molecular structure in the solid state due to steric effects from the two benzene rings ortho-substituted with ferrocenyl and carbonyl-derived groups. A short intramolecular C—H...π interaction is observed involving a substituted η5-C5H4 ring and an ortho H atom of the benzene ring on the opposite side of the molecule. In the crystal structure, there are no classical hydrogen bonds: interactions comprise a short C6—H...π(C6) interaction involving substituted benzene rings and two C—H...O=C interactions per molecule.
3-Fluoro-N-(3-fluorobenzoyl)-N-(2-pyridyl)benzamide
John F. Gallagher,Katie Donnelly,Alan J. Lough
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536808041093
Abstract: The title compound, C19H12F2N2O2, a 2:1 product of the reaction of 3-fluorobenzoylchloride and 2-aminopyridine crystallizes with a disordered 3-fluorobenzene ring adopting two conformations [ratio of occupancies 0.959 (4):0.041 (4)]. In the crystal structure, there are no classical hydrogen bonds and interactions comprise C—H...O in the form 2(C—H)...O=C [with motif R21(5)]; C—H...π(arene) interactions are also present.
2-Fluoro-N-(2-fluorobenzoyl)-N-(2-pyridyl)benzamide
John F. Gallagher,Katie Donnelly,Alan J. Lough
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809002189
Abstract: The title compound, C19H12F2N2O2, a 2:1 product of the reaction of 2-fluorobenzoyl chloride and 2-aminopyridine, crystallizes with a disordered 2-fluorobenzene ring adopting two conformations [ratio of occupancies = 0.930 (4):0.070 (4)] in one of the two independent molecules (differing slightly in conformation) comprising the asymmetric unit. In the crystal structure, C—H...O and C—H...π(arene) interactions are present.
(η5-Cyclopentadienyl){[3-(2,2-dicyanoethenyl)bicyclo[2.2.1]hepta-2,5-dien-2-yl]ethynyl}(triphenylphosphine)nickel(II)
John F. Gallagher,Peter Butler,A. R. Manning
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808002328
Abstract: The title compound, [Ni(C5H5)(C13H7N2)(C18H15P)] or (η5-C5H5)(PPh3)Ni—C[triple-bond]C—C7H6—C(H)=C(CN)2, contains an unusual disubstituted norbornadienyl (NBD) ligand containing ethynyl (–C[triple-bond]C–) and dicyanovinyl [–C(H)=C(CN)2] groups. Disorder is present in the NBD group with site occupancies of 0.636 (10) and 0.364 (10) for two distinct orientations. There are no strong hydrogen bonds and the primary interactions are weak C—H...π(arene) interactions.
Dwarf Spheroidal Galaxies : Keystones of Galaxy Evolution
John S. Gallagher III,Rosemary F. G. Wyse
Physics , 1994, DOI: 10.1086/133500
Abstract: Dwarf spheroidal galaxies are the most insignificant extragalactic stellar systems in terms of their visibility, but potentially very significant in terms of their role in the formation and evolution of much more luminous galaxies. We discuss the present observational data and their implications for theories of the formation and evolution of both dwarf and giant galaxies. The putative dark matter content of these low-surface-brightness systems is of particular interest, as is their chemical evolution. Surveys for new dwarf spheroidals hidden behind the stars of our Galaxy and those which are not bound to giant galaxies may give new clues as to the origins of this unique class of galaxy.
Dynamics and the Origin of Low-Mass Galaxies in the Virgo Cluster
Christopher J. Conselice,John S. Gallagher,Rosemary F. G. Wyse
Physics , 2001, DOI: 10.1086/322373
Abstract: Early-type dwarfs are the most common galaxy in the local universe, yet their origin and evolution remain a mystery. Various cosmological scenarios predict that dwarf-like galaxies in dense areas are the first to form and hence should be the oldest stellar systems in clusters. By using radial velocities of early-type dwarfs in the Virgo cluster we demonstrate that these galaxies are not an old cluster population but have signatures of production from the infall of field galaxies. Evidence of this includes the combined large dispersions and sub-structure in spatial and kinematic distributions for Virgo early-type dwarfs, and a velocity dispersion ratio with giant ellipticals expected for virialized and accreted populations. We also argue that these galaxies cannot originate from accreted field dwarfs, but must have physically evolved from a precursor population, of different morphology, that fell into Virgo some time in the past.
Populations of Dwarfs in Clusters of Galaxies: Environmental Connections
John S. Gallagher,Christopher J. Conselice,Rosemary F. G. Wyse
Physics , 2001,
Abstract: Despite their apparent fragile appearance, dwarf spheroidals are the most common galaxy type in clusters. In this paper we consider some of the issues associated with two major models for the origin of these dwarfs: primeval galaxies which formed with the cluster and the modification of accreted systems. We argue that the present observational evidence, derived from the Virgo and Perseus clusters, points to infall as the origin of many of these objects.
On the Nature of the NGC 1275 System
Christopher J. Conselice,John S. Gallagher,Rosemary F. G. Wyse
Physics , 2001, DOI: 10.1086/323534
Abstract: Sub-arcsecond images, taken in B, R, and H-Alpha filters, and area spectroscopy obtained with the WIYN 3.5-m telescope provide the basis for an investigation of the unusual structures in the stellar body and ionized gas in and around the Perseus cluster central galaxy, NGC 1275. Our H-Alpha filter is tuned to gas at the velocity of NGC 1275, revealing complex, probably unresolved, small-scale features in the extended ionized gas, located up to 50/h kpc from NGC 1275. The mean H-Alpha surface brightness varies little along the outer filaments; this, together with the complex excitation state demonstrated by spectra, imply that the filaments are likely to be tubes, or ribbons, of gas. The morphology, location and inferred physical parameters of the gas in the filaments are consistent with a model whereby the filaments form through compression of the intracluster gas by relativistic plasma emitted from the active nucleus of NGC 1275. Imaging spectroscopy with the Densepak fiber array on WIYN suggests partial rotational support of the inner component of low velocity ionized gas. We confirm and extend evidence for features in the stellar body of NGC 1275, and identify outer stellar regions containing very blue, probably very young, star clusters. We interpret these as evidence for recent accretion of a gas-rich system, with subsequent star formation. We suggest that two main processes, which may be causally connected, are responsible for the rich phenomenology of the NGC 1275 system -- NGC 1275 experienced a recent merger/interaction with a group of gas-rich galaxies, and recent outflows from its AGN have compressed the intracluster gas, and perhaps the gas in the infalling galaxies, to produce a complex web of filaments. (Abridged)
2,3-Difluoro-N-(2-pyridyl)benzamide
John F. Gallagher,Joyce McMahon,Frankie P. Anderson,Alan J. Lough
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808038269
Abstract: The title compound, C12H8F2N2O, crystallizes with two independent molecules in the asymmetric unit. The independent molecules differ slightly in conformation; the dihedral angles between the benzene and pyridine rings are 51.58 (5) and 49.97 (4)°. In the crystal structure, molecules aggregate via N—H...Npyridine interactions as hydrogen-bonded dimers with the structural motif R22(8), and these dimers are linked via C—H...O interactions to form a supramolecular chain.
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