C-H/tt interactions

Centrosynmietric dimers in the structures of bis(2,6-di-r-butylphenolato-0)tin(II) (15), with two-coordinated tin atoms within O2 donor sets, are linked into loosely associated pairs via comparatively strong Sn... jr interactions, Table 3.9.1. These are connected with four other dimeric pairs via C-H. ..tt interactions so as to generate a two-dimensional array, as shown in Figure 3.9.10. 

Besides the C H- O interactions, the most relevant C-H- X interactions are the C H- N, C H- S and C-H- TT interactions (see Table 8 for a complete set of results). The trends for the C H- -N contacts found in crystals were first analyzed by Taylor and Kennard [72] in their seminal paper, where they also concluded that there was enough evidence to consider them as hydrogen bonds. These authors also attributed a hydrogen bond nature to the C H- -N and C H- -S contacts. 

The relevance of C-H- - -tt interactions in many supramolecular systems has made them the subject of specific monographies [6]. In these interactions the acceptor is constituted by the region where the ir-electrons are located (double, triple bonds, or aromatic ir-rings). The best known ir-acceptors are phenyl rings, double and triple C-C bonds, cyano groups, and pyridyl rings. The hydrogen bonded nature of the C(sp)-H- n interactions in the acetylene acetylene [102] and HCN-acetylene [103] complexes has been established by a combination of experimental techniques (gas-phase rotational spectroscopy... 

P. Munshi and T. N. Guru Row, Exploring the lower limit in hydrogen bonds analysis of weak C-H- O and C-H- tt interactions in substituted coumarins from charge density analysis,... 

Such C-H... Tt interactions play an important role in the complex formation between the aromatic compounds with hydrogen donor groups and surfactant molecules. Figure 4.30 shows the molecular structures in the CTAB-o-iodophenol complex, V, where the strong hydrogen bond formed between the hydroxyl group and the... 

In a systematic analysis of C-H- -tt interactions occurring between metal acetylacetonate complexes and phenyl rings, it was demonstrated that the acetylacetonate chelate... 

Fig. 38.2 Inclusion complex of /wra-tert-butylcalix[4]arene with toluene (a) molecular formula (b) molecular structure, week C-H - tt interaction stabilizing the inclusion complex shown in green (only one of the two independent complexes in the unit cell is shown) [6]...

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