Hydrogen bonds database analyses

As for carboxylate-hydrogen bond donor interactions, carboxylate-metal ion interactions are expected to be most favorable with syn stereochemistry. In a survey of the Cambridge Structural Database, Carrell et al. (1988) presented a stereochemical analysis of carboxylate—metal ion interactions which supports this expectation (Scheme 1). These investigators found that the syn-oriented lone electron pair of the carboxylate... 

Analysis of Hydrogen Bonding Using the Cambridge Structural Database... 

If the statistical quality of the parameters V, E, S, A, B from Table 15.1 are now inspected, it is clear that they are not equally relevant. For instance, parameter A must be rejected from the statistical standpoint its coefficient presents a small Fpartiai, sine qua non condition to rejection, and a largep value for some databases. This is also expected from the physicochemical standpoint the coefficient of parameter A (solute hydrogen bond acidity) reflects the minor differences in hydrogen bond basicity of hydrated sulfate head groups of SDS micelle and the water molecule in the aqueous bulk. Other parameters should be inspected bearing the same statistical criteria in mind. Therefore, the analysis of Table 15.1 reveals that only parameters V and B are statistically significant, with the coefficient of V the most prominent in magnitude and statistical relevance. 

Figure 5. H -O frequency distributions in crystals for hydrogen bonds from C=C-H donors to (top) C=0 acceptors, n = 33, and (bottom) C-OH acceptors, n = 31. Database analysis perform for this article [CSD, June 1997 update with 167797 entries, ordered and error-free crystal structures with R < 0.10, normalized H-atom position based on a linear C=C-H group, and a C-H bond distance of 1.08 A neither donor nor acceptor group directly bonded to a metal atom, H -O < 2.95 A for three-center hydrogen bonds, only the short component is considered).

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