Proton potentials for widely varied hydrogen bond lengths in a water dimer

Co-crystallization of N-methyl-substituted ureas with di(organosulfonyl)amines, (RSO2)2NH, leads unpredictably to either molecular co-crystals or, via proton transfer, to uronium salts. As a sequel to former reports, this communication describes the formation and the crystal structures of the new ionic compounds 1,1-dimethyluronium di(4-fluorobenzenesulfonyl)amide (1, monoclinic, space group P21/c, Z´ = 1) and di(1-methylurea)hydrogen(I) di(4-fluorobenzenesulfonyl)amide (2, triclinic, P1̄, Z´ = 1); both salts were obtained from dichloromethane/petroleum ether. In the structure of 2, the urea moieties of the cationic homoconjugate are connected by a very short [O-H· · ·O]+ hydrogen bond [d(O· · ·O) = 244.6(2) pm, θ (O-H· · ·O)≈170°, bridging H atom asymmetrically disordered over two positions]. The O-protonation induces a specific elongation of the C-O bond lengths to 131.2(2) pm in 1 or 129.5(2) and 127.4(2) pm in 2, as compared to literature data of ca. 126 pm for the unprotonated ureas. Both crystal structures are dominated by conventional two- and threecentre hydrogen bonds, which involve the OH and all NH donors and give rise to one-dimensional cation-anion arrays. In particular, the ionic entities of 1 are alternatingly associated into simple chains propagated by glide-plane operations parallel to the c axis, whereas the donor-richer structure of 2 displays inversion symmetric dimers of formula units, which are further hydrogen-bonded into strands propagated by translation parallel to the a axis.

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Nitrogen-hydrogen bond lengths in DNA

Journal of the American Chemical Society ◽

10.1021/ja00370a063 ◽

1982 ◽

Vol 104 (6) ◽

pp. 1761-1762 ◽

Cited By ~ 40

Author(s):

J. A. DiVerdi ◽

S. J. Opella

Keyword(s):

Hydrogen Bond ◽

Bond Lengths ◽

Nitrogen Hydrogen Bond

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Hydrogen-bond thio acceptors in O-methyl 3,4-dimethylpyrrole-2-thiocarboxylate

Acta Crystallographica Section E Structure Reports Online ◽

10.1107/s1600536807047599 ◽

2007 ◽

Vol 63 (11) ◽

pp. o4217-o4217 ◽

Cited By ~ 2

Author(s):

Tobias Kerscher ◽

Peter Klüfers ◽

Wolfgang Kügel

Keyword(s):

Hydrogen Bond ◽

Title Compound ◽

Van Der Waals ◽

Hydrogen Bond Acceptor ◽

Molecular Plane ◽

Bond Lengths ◽

Dimer Structure ◽

Compound C ◽

Oxo Compounds ◽

Centrosymmetric Dimers

Molecules of the title compound, C8H11NOS, are flat and almost C s-symmetric. Bond lengths and angles resemble calculated values at the B3LYP/6-311+G(2 d,p) level of theory. The solid is characterized by van der Waals bonding and π stacking (stacking distance = 3.352 Å) of the basic motif of the structure: planar centrosymmetric dimers that are bonded by pairs of symmetry-equivalent N—H...S bonds. The dimer structure is rationalized by the nature of the hydrogen-bond acceptor orbital, the S(3p) orbital located in the molecular plane. The double-donor–double-acceptor situation in the dimer results in an unusual C=S...H angle of about 127° which is large compared with isolated C=S...H bonds (circa 100°), but small compared with the almost linear acceptor geometry in related oxo compounds.

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Article

Canadian Journal of Chemistry ◽

10.1139/v98-020 ◽

1998 ◽

Vol 76 (3) ◽

pp. 301-306

Author(s):

Sengen Sun ◽

James F Britten ◽

Christopher N Cow ◽

Chérif F Matta ◽

Paul HM Harrison

Keyword(s):

Crystal Structure ◽

Hydrogen Bond ◽

The Other ◽

Methyl Groups ◽

X Ray Diffraction ◽

X Ray ◽

Bond Lengths ◽

Form Part ◽

Two Sides ◽

Opposite Helicity

The crystal structure of 3,4,7,8-tetramethylglycoluril (5) was determined by X-ray diffraction. The structure reveals a hydrogen-bonding motif in the crystal lattice that differs from that present in related glycolurils. The two sides of each molecule form part of two independent, but parallel, infinite helical chains. These chains are formed by the NH donor and C==O acceptor on one side of a glycoluril molecule, forming H-bonds to two different molecules at adjacent positions within the helix. On the other side of the same molecule, a similar motif generates another helix of opposite helicity to the first. The molecule has a crystallographic plane of symmetry through the two bridgehead carbon atoms and the two bridgehead methyl groups, which are syn-periplanar. Thus, 5 is similar to 3,4-dimethylglycoluril (3), but differs from some glycolurils, where there is a significant dihedral angle between the two bridgehead-to-bridgehead substituent bonds. Bond lengths and angles in 5 resemble those reported for 3, but bond lengths around the bridgehead positions are slightly lengthened relative to 3.Key words: glycoluril, 1,2,5,8-tetramethyl-2,6,7,8-tetraazabicyclo[3.3.0]octane-3,7-dione, X-ray diffraction, crystal structure, hydrogen-bond array.

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