Determining the sigma-donor ability of the cyclopropane C-C bond.

The low temperature crystal structures of ester and ether derivatives of varying electron demand, derived from cyclopropylmethanol and dicyclopropylmethanol , have been determined. These structures show a very strong response of the C-OR bond distance to the electron demand of the OR substituent, demonstrating the strong sigma-donor ability of the strained C-C bonds in the cyclopropane ring.