Abstract: Compositions which comprise a complex of:(a) a titanium-containing material having the formula ##STR1## in which X.sub.1 is cyclopentadienyl, chlorine, bromine or C.sub.1 -C.sub.6 alkoxy, X.sub.2 and X.sub.3 are chlorine, bromine, or C.sub.1 -C.sub.6 alkoxy; Y.sub.1 and Y.sub.2 are chlorine or bromine; and z is hydrogen (preferably) or C.sub.1 -C.sub.10 hydrocarbyl are novel reagents for methylenation or analogous reactions with a carbonyl group; and(b) a complexing agent selected from the group consisting of:(i) ethers having the formula R.sub.1 OR.sub.2 in which R.sub.1 and R.sub.2 are C.sub.1 -C.sub.4 alkyl;(ii) cyclic ethers having the formula ##STR2## in which n is an integer from 4 to 7; and (iii) tertiary amines.