Hybridization in highly strained small ring hydrocarbons. V. Methylene and isopropylene substituted spiropentanes

Using the method of maximum overlap, the hybrids, the bond overlaps and the deviation angles as well as the interhybrid angles have been calculated for several methylene and isopropylene substituted spiropentanes. Considerably different hybrids are found for the spiro carbon when the two C₃ rings have a different number of substituants. They deviate appreciably from the usually assumed sp³ type, being as different as sp^2.70 and sp^3.34. A brief discussion and comparison of some experimental molecular properties and the corresponding calculated parameters is presented. A discussion of factors which influence the hybridization in small rings has been given with some critical remarks on the reliability of predictions of molecular geometry (bond lengths) and molecular shapes (bond angles) by the maximum overlap method.