Two model systems, 3-methylacroleine and 3-(difluoromethyl)acroleine, are investigated computationally with respect to the character of the C-H center dot center dot center dot O interaction in their chelate-type (ZZ) conformers. By selecting the appropriate reference conformers, the C-H center dot center dot center dot O interaction is shown to result in the increase of the C-H stretching frequency (i.e., in the blue shift of the C-H stretching band). This is accompanied by the shortening of the C-H bond distance as compared to its values in reference molecules. Parallel to calculations of the C-H bond distance and stretching frequency, the energy contribution of the C-H center dot center dot center dot O interaction to the total energy (i.e., the energy associated with the C-H center dot center dot center dot O contact) is evaluated by using the methods proposed recently for the estimation of the energies of intramolecular hydrogen bonds. It is found that the C-H center dot center dot center dot O contact in the chelate-type forms of 3-methylacroleine and 3-(difluoromethyl)acroleine corresponds to the negative energy contribution and is repulsive. It is concluded that, despite the stability of the ZZ conformers of the two molecules and their deceptive structural shape, no hydrogen bond in the usual sense is formed between the C-H bond and the lone pair donor. The results are interpreted in terms of the steric compression, which leads to the dominance of the valence repulsion contribution in the C-H center dot center dot center dot O contact. This mechanism suggests that blue-shifting intramolecular interactions should not be that uncommon, although their recognition requires a careful consideration of the reference system.