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19 citations found for Maverick, E.F.

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The crystal structure of a highly discriminating chiral host, in its complex with a chiral cationic guest, shows the influence of C-H...O and C-H...[pi] interactions on the unanticipated orientation of the guest in the host cavity. These interactions are very similar, but not identical, in the two independent complexes in the asymmetric unit.

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Low-temperature crystal studies of five strained aromatic hydrocarbons yield anisotropic displacement parameters that vary widely in magnitude and precision. The rigidity of tert-butyl substituents is tested; thermal motion analysis indicates that crowded ortho tert-butyls do not `move' with respect to the aromatic core, while rigid-body models for meta and para tert-butyls suggest low rotation barriers (4–10 kJ mol−1), in some cases with additional motion of a tert-butyl methyl group.


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The structure of (11,12,24,25-tetra­hydro-28,34-di­methoxy-3,6,16,19,31,37-hexa­methyl-1,21[1',3']:8,14[1'',3'']-di­benzeno-10H,23H-tetrabenzo­[f,h,o,z][1,5,10,14]­tetraoxa­cyclo­octa­decane)­lithium chloride monohydrate, anti-[Li(C50H48O6)]Cl·H2O, at 100 K reveals that the host is less strained than that of the syn-bridged isomer. There are two independent complex cations, each lying on a center of symmetry. Four short [1.944 (2)-1.998 (2) Å] and two long [2.381 (2) and 2.455 (2) Å] Li+...O distances provide six-coordination in a distorted octahedral environment.

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Weakly diffracting crystals of benz[cd]indol-2(1H)-one (naphtho­lactam), C11H7NO, were unsuitable for data collection by early photographic methods. However, a diffrac­tom­eter data set collected at room temperature in 1989 was solved and refined. The peak scans were broad, and the results indicated disorder or a satellite crystal. Recent data collection (on another crystal from the same sample) with an area detector at 100 K revealed the same disorder, and made it possible to refine two different, more complete, disorder models. Both models assume an occasional 180° rotation of the nearly planar centrosymmetric cis-lactam dimer. The refinements differ, especially in the anisotropic displacement parameters for the -C(=O)-NH- portion of the mol­ecule. Both models at 100 K give a C-N (`amide') bond distance of 1.38 Å, about 0.04 Å longer than the average distance in saturated [gamma]-lactams in the Cambridge Structural Database. Cohesive packing inter­actions between mol­ecules include opposing-dipole dimers; the packing may explain the 10:1 ratio favoring the major-occupancy mol­ecule.

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The potassium complex of the [2.1]cryptahemispherand 33,34,35-trimethoxy-5,10,15-trimethyl-22,25,30-trioxa-1,19-diazapentacyclo[17.8.5. 13,7.18,12.113,17]pentatriaconta-3,5,7(33),8,10,12 (34),13, 15,17 (35)-nonaene, crystallizes from ethyl acetate with a thiocyanate counterion {[K(C36H48N2O6)]SCN}. The space group is Pnma. The longer cryptand-like bridge is disordered, departing from mirror symmetry because it is constrained to fold unsymmetrically by the geometry of the rest of the host. Five of the O atoms and the two N atoms of the host, as well as the N of the SCN- ion, are coordinated by the K+ ion. The sixth O atom of the host is at 3.211 (3) Å from the K+ ion, about 0.5 Å farther than the closest O atoms.





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The [1.1] cryptahemispherand host 30,31,32-trimethoxy-5,10,15- trimethyl-22,27-dioxa-1,19-diazapentacyclo[17.5.5.13,7.18,12.113,17] dotriaconta-3,5,7(30),8,10,12 (31),13,15,17 (32)-nonaene forms a crystalline complex, (I), with sodium tetraphenylborate, [Na(C34H44N2O5)] (C24H20B), and also forms a coordination complex, (II), with two molecules of BH3, [mu]-{30,31,32-trimethoxy-5,10,15- trimethyl-22,27-dioxa-1,19-diazapentacyclo[17.5.5.13,7.18,12.113,17]dotriaconta-3,5,7(30),8,10,12 (31),13,15,17 (32)-nonaene}-N1:N19- bis(trihydroboron), C34H50B2N2O5, which crystallizes as a CH2Cl2 hemisolvate. The host of (I) complexes Na+ more strongly than it does any other alkali metal ion, consistent with the nearly ideal coordination of Na+ reported here. The N atoms, which are only about 2.6 Å from the Na+ ion, are unusually close to each other in (I), being separated by about 4.63 Å. The solvent in the structure of (I) is disordered and unidentifiable. The structure of (II) was determined at 115 K. It contains two independent molecules in the asymmetric unit, each with site symmetry m; they have very similar conformations. The BH3 groups attached to the N atoms are directed outward from the cavity of each molecule, giving the molecules the uncommon exo-exo conformation. The N atoms in (II) are about 1.3 Å farther apart than those in (I). Because the N atoms are tetrasubstituted, (II) is a poor complexer. One -CH2CH2OCH2CH2- bridge in each cryptand moiety in (II) adopts a 'crown' conformation, while the other bridge has trans -CH2CH2- torsion angles. The cavity of the host in (II) is filled, and the conformation is stabilized by typical C-H...O interactions.

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Acta Cryst. (1996). A52, C278
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The isomers 3,3'-(1,2-ethynediyl)­bis­(2-pyridone), (I), and 6,6'-(1,2-ethyne­diyl)­bis­(2-pyridone), (II), were designed to form a hydrogen-bonded pair through alignment of their complementary cyclic lactam moieties. Instead, an equimolar mixture of (I) and (II) dissolved in methanol produced crystals of 3,3'-(1,2-ethynediyl)­bis(2-pyridone)-6,6'-(1,2-ethynediyl)­bis(2-py­ri­done)-methanol (1/2/2), 0.5C12H8N2O2·C12H8N2O2·CH4O, in which one mol­ecule of (I), situated at a center of symmetry, is hydrogen bonded to two mol­ecules of (II) and to two mol­ecules of methanol.

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The macrocyclic host 36,37,38-trimethoxy-5,10,15-trimethyl-22,25,30,33-tetraoxa-1,19-diazapentacyclo [17.8.8.13,7.18,12.113,17]octatriaconta-3,5,7(38),8,10,12(37),13,15, 17(36)-nonaene contains a somewhat flexible cavity lined with seven O atoms and two N atoms. The structures of three of its complexes are reported here: that with sodium thiocyanate, (I) {[Na(C38H52N2O7)] SCN}, at 296 K, and those with potassium thiocyanate, (II) {[K(C38H52N2O7)]SCN.H2O}, and caesium perchlorate, (III) {[Cs(C38H52N2O7)]ClO4·H2O}, at 156 K. The host adapts well to Cs+, with effective ninefold coordination; it adapts nearly as well to K+, but is not sufficiently flexible to be a good complexer for the much smaller Na+ ion. In structure (II) and in structure (III), a water molecule forms hydrogen bonds between an O atom of the host and an atom of the anion [N of SCN- in (II), O of ClO4- in (III)].


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The geometrical isomers of 33,34,35-trimethoxy-5,10,15-trimethyl-22,25,30-trioxa-1,19- diazapentacyclo [17.8.5.13,7,18,12.113,17] pentatriaconta-3,5,7(35),8,10,12 (34),13,15,17 (33)-nonaene-2,18-dione, C36H44N2O8, are intermediates in the synthesis of reduced cryptahemispherands. Their amide groups are characteristically coplanar with their attached atoms. Consequently, the N atoms in these structures are neither exo nor endo, unlike the N atoms in most other cryptands and cryptahemispherands. In the isomer formed in smaller amount, (II), the N atoms are about 1 Å closer to each other than they are in the other structure, (I), because the five-atom bridge between these N atoms is so constrained as to draw them together. Structure (I) is more dense than structure (II) by about 9%.

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