The extent to which deuterium can act as a protecting group to prevent unwanted 1,5-hydrogen atom transfer to aryl and vinyl radical intermediates was examined in the context of the generation of α-aminoalkyl radicals in a pyrrolidine ring. Intra- and intermolecular radical trapping following hydrogen atom transfer provides an illustration of the use of the primary kinetic isotope effect in dir...

The ir-spectra in the N-H stretching region of Piv-Pro-NHMe and Boc-Pro-NHMe have been studied in carbon tetrachloride and chloroform solutions over a wide range of concentrations. Based on the concentration dependence of the N-H stretching bands, i t has been shown that the characteristic N-H stretching band due to the C7 intramolecular hydrogen bond is around 3335 cm-'. Intermolecular hydroge...

1-Benzoylthioureas contain both carbonyl and thiocarbonyl functional groups and are of interest for their biological activity, metal coordination ability and involvement in hydrogen-bond formation. Two novel 1-benzoylthiourea derivatives, namely 1-benzoyl-3-(3,4-dimethoxyphenyl)thiourea, C16H16N2O3S, (I), and 1-benzoyl-3-(2-hydroxypropyl)thiourea, C11H14N2O2S, (II), have been synthesized and ch...

hydrogen bonds between C-3 OH and the carboxyl. It seems difficult to invoke an intermolecular hydrogen bond without having some sort of added hydrophobic contribution in aqueous solution. This kind of effect has been observed in aliphatic carboxylic acids-larger aliphatic chains leading to stronger dimerization effects in aqueous solution.32 To describe the 13C NMR shifts as due to intermolecu...

In this paper, the hydrogen bonding (HB) effects on the NMR chemical shifts of selected atoms in serineand serine-nH2O complexes (from one to ten water molecules) have been investigated with quantummechanical calculations of the 15N and 13C tensors. Interaction with water molecules causes importantchanges in geometry and electronic structure of serine.For the compound studied, the most importan...

An analysis of hydrogen bonds involving ester Osp3 atoms as acceptors has been performed based on the data extracted from the Cambridge Structural Database [Allen (2002). Acta Cryst. B58, 380-388; version 5.25, November 2003], using the ConQuest package to evaluate the stereochemical and electronic properties of the acceptors. Evidence for the existence of this particular type of hydrogen bond ...

The nature of the intermolecular forces between water molecules is the same in small hydrogen-bonded clusters as in the bulk. The rotational spectra of the clusters therefore give insight into the intermolecular forces present in liquid water and ice. The water hexamer is the smallest water cluster to support low-energy structures with branched three-dimensional hydrogen-bond networks, rather t...

Vibration–rotation–tunneling ~VRT! spectroscopy has been extended to the 4 THz spectral region through the observation of a second intermolecular vibration of (D2O)4 . Analysis of the precisely measured perpendicular transition confirms the previously reported cyclic homodromic structure and reveals a dramatically increased ~303! hydrogen bond rearrangement rate in the excited state. © 1999 Ame...

In the title compound, C(17)H(10)Br(2)O(5), the chromene ring is almost planar with minimal puckering [total puckering amplitude = 0.067 (4) Å]. The dihedral angle between chromeme ring system and phenyl ring is 3.7 (2)°. The crystal structure is stabilized by intermolecular C-H⋯O inter-actions and an intramolecular O-H⋯O hydrogen bond also occurs.

We present a first principles theoretical study of vibrational spectral diffusion and hydrogen bond dynamics in liquid methanol at room temperature. The dynamics of spectral diffusion of OD modes of deuterated methanol reveals two times scales: a short time scale of about 120 fs and a longer time scale of about 3.2 ps. A damped oscillation is also found at around 120–180 fs. Calculations of pow...