Graphical abstract Controlled hydrolysis of donor-substituted titanium (IV) salan complexes led to the formation of well-defined dinuclear complexes with cytotoxicities in the low micro-molar region. Highlights ► Donor substituted Ti(IV)salan complexes are cytotoxic in human cancer cell lines. ► Structurally characterized dinuclear complexes form upon fast hydrolysis. ►μ 2-oxo bridged dinuclear complexes show enhanced cytotoxicity. ► First identified cytotoxic intermediates from Ti(IV)salan hydrolysis. ► Partial hydrolysis acts as activating mechanism.