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High resolution spectroscopy of a homologous series of small organic molecules probes the role of low frequency, large amplitude motion in vibrational mode coupling. From the structural variation in a series of substituted ethanes, aspects of structure can be linked to the propensity for vibrational mode coupling. The molecules presented include gauche-2-fluoroethanol (2FE), gauche-1,2-difluoroethane (DFE), and gauche-and trans-1-chloro-2-fluoroethane (CFE). The magnitude of the vibrational mode coupling in this series of molecules allows us to speculate about the relationship between intramolecular attractive interactions and vibrational mode coupling. The relative density of states alone is insufficient to explain the trends in mode coupling. The extent of the vibrational mode coupling correlates with the magnitude of the intramolecular attractive interactions. Increased mode coupling occurs in molecules with stronger intramolecular attractive interactions. The degree of intramolecular attractive interactions in this series of molecules ranges from strong bond-dipole/bond-dipole interactions in 2FE to insignificant interactions in trans CFE.