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Figure 1
(a) Example of inferior methyl group geometries in a CSD structure (which is to remain anonymous; only part of the molecule is shown). The highlighted C—C—H angle is 67.5°. The same methyl group also has a 153.7° C—C—H angle. (b) Distribution of C—C—H angles < 75° (blue bars) and water H—O—H angles > 135° (red bars) in CSD structures as a function of decennium. (c) Typical checkCIF warning for a methyl group with suspicious geometry. In this case one methyl H atom, originally positioned by a SHELXL (Sheldrick, 2015BB11) AFIX 33 command, was manually shifted slightly away from its theoretical position.

ISSN: 2052-5206
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