Assembling an isomer grid: the isomorphous 4-, 3- and 2-fluoro-N'-(4-pyridyl)benzamides

The three title isomers, 4-, (I), 3-, (II), and 2-fluoro-N'-(4-pyridyl)benzamide, (III), all C₁₂H₉FN₂O, crystallize in the P21/c space group (No. 14) with similar unit-cell parameters and are isomorphous and isostructural at the primary hydrogen-bonding level. An intramolecular C-H...O=C interaction is present in all three isomers [C...O = 2.8681 (17)-2.884 (2) Å and C-H...O117-118°], with an additional N-H...F [N...F = 2.7544 (15) Å] interaction in (III). Intermolecular amide-pyridine N-H...N hydrogen bonds link molecules into one-dimensional zigzag chains [graph set C(6)] along the [010] direction as the primary hydrogen bond [N...N = 3.022 (2), 3.049 (2) and 3.0213 (17) Å]. These are augmented in (I) by C-H...π(arene) and cyclic C-F...π(arene) contacts about inversion centres, in (II) by C-F...F-C interactions [C...F = 3.037 (2) Å] and weaker C-H...π(arene)/C-H...F contacts, and in (III) by C-H...π(arene) and C=O...O=C interactions, linking the alternating chains into two-dimensional sheets. Typical amide N-H...O=C hydrogen bonds [as C(4) chains] are not present [N...O = 3.438 (2) Å in (I), 3.562 (2) Å in (II) and 3.7854 (16) Å in (III)]; the C=O group is effectively shielded and only participates in weaker interactions/contacts. This series is unusual as the three isomers are isomorphous (having similar unit-cell parameters, packing and alignment), but they differ in their interactions and contacts at the secondary level

2-Ferrocenyl-N-(2-ferrocenylbenzoyl)-N-(4-methyl-2-pyridyl)benzamide

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...[pi] interaction is observed involving a substituted [eta]5-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...[pi](C6) interaction involving substituted benzene rings and two C-H...O=C interactions per molecule

Stratified-drift aquifers in New Hampshire with potential to serve as future, large public water-supplies: Status, circa 2000; projected losses, circa 2025; and data accuracy

Given the growing national water crisis, this research quantified and refined the states of stratified-drift aquifers with potential to yield 75+ gpm (OSDA75) and 150+ gpm (OSDA150) in New Hampshire for 2000 and 2025. Surface waters, cultural features and groundwater hazards from 13 federal/state datasets were buffered according to desired well yields, and then overlain within a geographic information system onto stratified-drift aquifer (OSDA) layer. Non-buffered, highly-transmissive polygons defined the aquifer areas remaining available with potential to meet 75+gpm or 150+ gpm well yields (RSDA75 or RSDA150). Aquifer losses for 2025 were modeled by principal-components regression as function of aquifer area and projected on-aquifer populations. Finally, the source OSDA area and RSDA estimates were reassessed using 1300 verification wells. Results. OSDA encompasses 13.4% of New Hampshire, 41 % of its population and 58.3% of its groundwater hazards. The greatest population and groundwater-hazard densities exist on the most vulnerable aquifer areas, OSDA75 and OSDA150. After overlay analysis, RSDA75 and RSDA150 were estimated as 118.4 mi2 (9.5%) and 47.6 mi2 (3.8%), respectively. Most towns have less than 0.5 mi2 of RSDA75/150, while the majority of RSDA75/150 exists in relatively few towns. Regionally, the highly populated coast has minimal high-yield OSDA, while the more urban South and North each have about 5% and 2% of the state\u27s RSDA75 and RSDA150, respectively. 1990-2000 population growth for Uplands and OSDA was 14% and 7% respectively. Projected OSDA75/150 losses for 2025 were unexpectedly low since historical OSDA population growth was lower than average; losses early in development are high, and the largest aquifers, (those forecast for the greatest population growth), accommodate additional people with lower per capita losses, since buffer overlap increases. Verification wells suggest that 26% of all OSDA is either till, clay or unsaturated. Based on the Mazzafero equation, about 50% of the above RSDA75 and RSDA150 areas lack sufficient saturated thickness to sustain high yields. Existing water-quality issues will likely further reduce these estimates . In summary, high-yield stratified-drift aquifers are far less available, and far more threatened than commonly thought. Given the national situation, these water resources need to be conserved to the greatest degree possible in the present

Methyl 2-[(ferrocenylcarbonyl)amino]thiophene-3-carboxylate

The title compound, [Fe(C₅H₅)(C₁₂H₁₀NO₃S)], was synthesized from ferrocenecarboxylic acid and methyl 2-aminothiophene-3-carboxylate in modest yield. The substituted ring system is essentially planar through the amidothienylcarboxylate moiety, η⁵-(C₅H₄)CONH(C₄H₂S)CO₂Me, with the amido unit at an angle of 3.60 (7)° to the five-atom thienyl group, which is oriented at an angle of 3.17 (7)° to the ester moiety. The primary hydrogen bond is an intramolecular N-H...O=Ccarboxylate interaction [N...O 2.727 (2) Å], and the main intermolecular hydrogen bond involves a thienyl carboxylate and the carboxylate of a symmetry-related molecule [C...O 3.443 (3) Å]

(η5-Cyclopentadienyl)(2-naphthylethynyl)(triphenylphosphine-κP)nickel(II)

The title compound, [Ni(C₅H₅)(C₁₂H₇)(C₁₈H₁₅P)], does not contain strong hydrogen-bond donors or acceptors and the primary interactions are limited to those of the weak C-H...π(arene) type and mainly involving the arene rings

A structural systematic study of three isomers of difluoro-N-(4-pyridyl)benzamide

The isomers 2,3-, (I), 2,4-, (II), and 2,5-difluoro-N-(4-pyridyl)benzamide, (III), all with formula C₁₂H₈F₂N₂O, all exhibit intramolecular C-H...O=C and N-H...F contacts [both with S(6) motifs]. In (I), intermolecular N-H...O=C interactions form one-dimensional chains along [010] [N...O = 3.0181 (16) Å], with weaker C-H...N interactions linking the chains into sheets parallel to the [001] plane, further linked into pairs via C-H...F contacts about inversion centres; a three-dimensional herring-bone network forms via C-H...π(py) (py is pyridyl) interactions. In (II), weak aromatic C-H...N(py) interactions form one-dimensional zigzag chains along [001]; no other interactions with H...N/O/F < 2.50 Å are present, apart from long N/C-H...O=C and C-H...F contacts. In (III), N-H...N(py) interactions form one-dimensional zigzag chains [as C(6) chains] along [010] augmented by a myriad of weak C-H...π(arene) and O=C...O=C interactions and C-H...O/N/F contacts. Compound (III) is isomorphous with the parent N-(4-pyridyl)benzamide [Noveron, Lah, Del Sesto, Arif, Miller & Stang (2002). J. Am. Chem. Soc. 124, 6613-6625] and the three 2/3/4-fluoro-N-(4-pyridyl)benzamides [Donnelly, Gallagher & Lough (2008). Acta Cryst. C64, o335-o340]. The study expands our series of fluoro(pyridyl)benzamides and augments our understanding of the competition between strong hydrogen-bond formation and weaker influences on crystal packing

A structural systematic study of four isomers of difluoro-N-(3-pyridyl)benzamide

The four isomers 2,4-, (I), 2,5-, (II), 3,4-, (III), and 3,5-difluoro-N-(3-pyridyl)benzamide, (IV), all with formula C12H8F2N2O, display molecular similarity, with interplanar angles between the C6/C5N rings ranging from 2.94 (11)° in (IV) to 4.48 (18)° in (I), although the amide group is twisted from either plane by 18.0 (2)-27.3 (3)°. Compounds (I) and (II) are isostructural but are not isomorphous. Intermolecular N-H...O=C interactions form one-dimensional C(4) chains along [010]. The only other significant interaction is C-H...F. The pyridyl (py) N atom does not participate in hydrogen bonding; the closest H...Npy contact is 2.71 Å in (I) and 2.69 Å in (II). Packing of pairs of one-dimensional chains in a herring-bone fashion occurs via [pi]-stacking interactions. Compounds (III) and (IV) are essentially isomorphous (their a and b unit-cell lengths differ by 9%, due mainly to 3,4-F2 and 3,5-F2 substitution patterns in the arene ring) and are quasi-isostructural. In (III), benzene rotational disorder is present, with the meta F atom occupying both 3- and 5-F positions with site occupancies of 0.809 (4) and 0.191 (4), respectively. The N-H...Npy intermolecular interactions dominate as C(5) chains in tandem with C-H...Npy interactions. C-H...O=C interactions form R22(8) rings about inversion centres, and there are [pi]-[pi] stacks about inversion centres, all combining to form a three-dimensional network. By contrast, (IV) has no strong hydrogen bonds; the N-H...Npy interaction is 0.3 Å longer than in (III). The carbonyl O atom participates only in weak interactions and is surrounded in a square-pyramidal contact geometry with two intramolecular and three intermolecular C-H...O=C interactions. Compounds (III) and (IV) are interesting examples of two isomers with similar unit-cell parameters and gross packing but which display quite different intermolecular interactions at the primary level due to subtle packing differences at the atom/group/ring level arising from differences in the peripheral ring-substitution patterns

Redetermination of para-aminopyridine (fampridine, EL-970) at 150 K

The structure of fampridine (EL-970) or 4-aminopyridine, C₅H₆N₂, has been redetermined at 150 K. The room-temperature structure has been reported previously [Chao & Schempp (1977). Acta Cryst. B33, 1557-1564]. Pyramidalization at the amine N atom occurs in fampridine, with the N atom 0.133 (11) Å from the plane of the three C/H/H atoms to which it is bonded; the interplanar angle between the pyridyl ring and NH2 group is 21 (2)°. Aggregation in the solid state occurs by N-H...N and N-H...[pi](pyridine) interactions with N...N and N...[pi](centroid) distances of 2.9829 (18) and 3.3954 (15) Å, respectively; a C-H...[pi](pyridine) contact completes the intermolecular interactions [C...[pi](centroid) = 3.6360 (16) Å]

Intermolecular interactions in N-(ferrocenylmethyl)anthracene-9-carboxamide

The title compound, [Fe(C₅H₅)(C₂₁H₁₆NO)], was synthesized from the coupling reaction of anthracene-9-carboxylic acid and ferrocenylmethylamine. The ferrocenyl (Fc) group and the anthracene ring system both lie approximately orthogonal to the amide moiety. An amide-amide interaction (along the a axis) is the principal interaction [N...O = 2.910 (2) Å]. A C-H...π(arene) interaction [C...centroid = 3.573 (2) Å] and a C-H...O interaction [C...O = 3.275 (3) Å] complete the hydrogen bonding; two short (Fc)C...C(anthracene) contacts are also present