additions of catecholborane across alkynes. Dimethyltitanocene leads to predominantly anti-Markovnikov regiochemistry with alkyl-substituted olefins, and exclusive anti-Markovnikov regiochemistry with vinylarenes. Two titanium(III) complexes, Cp2Ti(H2Bcat) and Cp2Ti(Bcat2), were isolated from the reaction mixtures. These Ti(III) complexes, as well as [Cp2TiH]2 and [Cp2TiMe]2, catalyze the addition of catecholborane