C-H Hydrogen bond

Two early examples of CTV being incorporated into network structures involves CTV acting as a hydrogen bond acceptor when the hydrogen bond donor is the acidic C-H groups of o-carborane [79]. Carboranes form C-H hydrogen bonds of this type in a number of other instances [80], and may also act as spherical guest molecules for CTV [77]. 

Analysis of supramolecular structures in ionic liquids Supramolecular assemblies are the molecular base for some of the unique properties of ILs. Therefore, the knowledge of the nature, type, and strength of these structures [23] is a prerequisite for a deeper understanding of ILs as well as for the tailor-made design of new compounds. The most important noncovalent interactions responsible for the formation of such a structure are C-H hydrogen bonds [25]. Other interactions encompass the formation of clusters by ion pairing, which can be found, for example, in chloroaluminates [12]. 

Amendola, V., Boiocchi, M., Colasson, B., Fabbrizzi, L., Douton, M.-J. R., Ugozzoli, F., A Metal based tris-imidazolium cage that provides six C-H hydrogen bond donor fragments and includes halides and pseudohalides. Angew. Chem. Int. Ed. 2006, 45, 6920-6924. 

In terms of supramolecular chemistry, imidazolium type ionic liquids are interesting because they are excellent C-H hydrogen bond donors. The X-ray crystal structure of bmim Cl shown this property clearly with C-Cl 3.39 A, Figure 13.24. Interestingly, two different polymorphic forms of this material are known depending on whether it is crystallised from the molten ionic liquid for from solution,... 

Gbrbitz, C. H. Hydrogen-bond distances and angles in the structures of amino acids and peptides. Acta Cryst. B45, 390-395 (1989). 

The main purpose of Section III is to establish the position of phenols on the scales of hydrogen-bond acidity, either solute (log X", a" logXa) or solvent (Ej(30)) scales. Here, the ability of phenols to act as hydrogen-bond donors will be compared to that of other O—H (water, alcohols, carboxylic acids), N—H, S—H and C—H hydrogen-bond... 

A survey of structural effects on formation constants in C H hydrogen bonding, J. Org. Chem. 41, 2693-2699. 

From your reading of Section 6.7, guess possible values for the template ratios for the synthesis of 6.98 in NMP in the presence of the following guests. Consider the influence of molecular size and shape, as well as host-guest interactions such as C— H hydrogen bonds, n-n stacking etc. 

Figure 18. Two examples of interconnected C=C-H - C=C-H hydrogen bonds. Top in prop-2-ynylglycine (drawn using published atomic coordinates [53]). Bottom in pent-4-ynoic acid the contact is directed at the C=C midpoint with H -C distances of 2.71 and 2.75 A (drawn using published atomic coordinates [54]).

Figure 21. The intermolecular contact pattern of the ethynyl groups in 3-phenyl-l, 4-diyn-3-ol, representing a chain of interconnected bifurcated C=C-H - C=C-H hydrogen bonds (drawn using published atomic coordinates [67]). There are also C=C-H—O hydrogen bonds formed. The H-atom of the hydroxyl group is twofold disordered both alternative positions are shown.

In contrast to the above described behavior of the basic component of an amphoteric metal oxide catalyst, the electrophilic function interacts with methane in a different manner. Here, the relatively electron rich C-H hydrogen bonds serve as electron donors to the metal center, resulting in a weakening of these bonds and methane activation, leading to formation of ethane or even direct formation of ethylene. 

Figure 8.12 (a) C-H- % hydrogen bonds with indicated distances (A) between 17 and 18 adjacent molecules, (b) Top view of adjacent molecules of 17 and 18. (Reprinted with permission from Ref. [22]. Copyright 2010, The Royal Society of Chemistry.)... 

Fig. 6 Structure of methyl Lewis Le Le and Le Le. The newly-identified C-H hydrogen bond is indicated by the dashed line.

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