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Substantial Spatial (substantial + spatial)
Selected Abstracts4-Methoxy-1-naphthol: chains formed by O,H...O hydrogen bonds and ,,, stacking interactionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2009Bernard Marciniak The structure of 4-methoxy-1-naphthol, C11H10O2, (I), contains an intermolecular O,H...O hydrogen bond which links the molecules into a simple C(2) chain running parallel to the shortest crystallographic b axis. This chain is reinforced by intermolecular ,,, stacking interactions. Comparisons are drawn between the crystal structure of (I) and those of several of its simple analogues, including 1-naphthol and some monosubstituted derivatives, and that of its isomer 7-methoxy-2-naphthol. This comparison shows a close similarity in the packing of the molecules of its simple analogues that form ,-stacks along the shortest crystallographic axes. A substantial spatial overlap is observed between adjacent molecules in such stacks. In this group of monosubstituted naphthols, the overlap depends mainly on the position of the substituents carried by the naphthalene moiety, and the extent of the overlap depends on the substituent type. By contrast with (I), in the crystal structure of the isomeric 7-methoxy-2-naphthol there are no O,H...O hydrogen bonds or ,,, stacking interactions, and sheets are formed by O,H..., and C,H..., interactions. [source] 5-Amino-1-naphthol: two-dimensional sheets built up from R44(18) rings formed by O,H...N, N,H...O and ,,, interactionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2009Ewa Rozycka-Sokolowska The crystal structure of the title compound, C10H9NO, (I), contains intermolecular O,H...N and N,H...O hydrogen bonds which together form sheets parallel to the (001) plane containing rings with an unusual R44(18) motif. These rings are additionally stabilized by an intermolecular ,,, stacking interaction. The significance of this study lies in the comparison drawn between the molecular structure of (I) and those of related compounds (1,5-diaminonaphthalene, 8-amino-2-naphthol, 3-amino-2-naphthol and aniline), which shows a close similarity in the noncoplanar orientation of the amine group and the aromatic moiety. Comparison of the crystal structures of (I) and several of its simple analogues (1-naphthol, naphthalene-1,4-diol, naphthalene-1,5-diol and 4-chloro-1-naphthol) shows a close similarity in the packing of the molecules, which form ,-stacks along the shortest crystallographic axes with a substantial spatial overlap between adjacent molecules. [source] 4-Chloro-1-naphtholACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Ewa Rozycka-Sokolowska Molecules of the title compound, C10H7ClO, (I), are connected by a single strong O,H...O hydrogen bond into a simple C(2) chain, which runs parallel to the c axis and is additionally stabilized by intermolecular ,,, stacking interactions. The significance of this study lies in the comparison drawn between the crystal structure of (I) and those of several of its simple analogues. This comparison shows a close similarity in the packing of the molecules that form ,-stacks along the shortest crystallographic axes. A substantial spatial overlap is observed between adjacent molecules in such a ,-stack, depending mainly on the kind of substituent. [source] Dispersion-Oriented Soft Interaction in a Frustrated Lewis Pair and the Entropic Encouragement Effect in its FormationCHEMISTRY - A EUROPEAN JOURNAL, Issue 48 2009Woo Kim Abstract The origin of the stability of a frustrated Lewis pair (FLP) tBu3P:B(C6F5)3 is investigated computationally to demonstrate the importance of the dispersion interaction. To this end, the interaction between alkyl-substituted phosphines (Me3P and tBu3P) and hexafluorobenzene (C6F6) is first investigated. Driven by the lone-pair to ,-orbital interaction, the binding energy is found to be even larger than usual ,,, interaction energies between small aromatic compounds. This character, which is inherited to fluorophenyl-substituted B(C6F5)3 in the FLP, induces large flexibility in the FLP over the molecular surface of B(C6F5)3. This soft interaction, in turn, causes an entropic stabilization of the FLP formation in comparison with classical Lewis pairs based on close and tight PB dative bonds. It also suggests a diverse nature of the FLP when it is involved in chemical reactions. Even with the cooperative participation of the perfluorophenyl groups, a detailed inspection of the FLP interaction potential energy surface indicates that the boron atom is still the major interaction site for the pair formation. This non-negligible direct PB interaction, which is related also to the soft nature of the borane frontier orbital, is further supported by substantial spatial overlap between the frontier orbitals on the phosphine/borane fragments and their interaction energy estimations. [source] | ||||||||||