Carbon oxygen bond anomeric. shortening

Another anomeric effect is that acetal C-0 bonds, and to a lesser extent, the bonds between acetal carbons and ether oxygens, are shortened or elongated as a function of their associated torsional angles. Jeffrey and Taylor modified MMl to account for these anomeric effects (17) and similar additions were put in the standard 1985 version of MM2 (11). The parameterization of MM3 for anomeric effects is preliminary, with recent (18-20) results being monitored. 

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