The role of H-bonds in controlling the binding mode of epoxides, namely propylene oxide (3) and cis-2,3-epoxybutane (4), to the vanadyl salen-type complexes, N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamino-vanadium (IV) oxide, [VO(1)], and VO(3,5-Bu-t(2)-salophen), [VO(2)], have been examined using cw-EPR, cw-ENDOR and HYSCORE spectroscopy. One of the methine protons from the cyclohexyl backbone in [VO(1)] has previously been shown to form a weak H-bond with the epoxide oxygen atom. The absence of this methine proton in the salophen derivative [VO(2)] removes this H-bonding ability of the complex and in turn weakens the epoxide interaction. (C) 2009 Elsevier B.V. All rights reserved.