Collisions between K(np) Rydberg atoms and electron attaching molecules can result in the creation of ion pairs through electron transfer. The mutual Coulomb attraction of these ions can lead to the formation of weakly-bound heavy-Rydberg ion-pair states orbiting at large radii. In this work, ion-pair states are created through collisions with SF6 and CCl4 in a small collision cell. These ion-pair states are allowed to drift into an analysis region where electric-field-induced dissociation allows for the velocity and binding energy distributions of these states to be determined. These distributions are analyzed through comparisons with the results of a Monte Carlo collision code. The data reveal that both CCl4 and SF6 form ion-pair states with long lifetimes and broad binding energy distributions, and their velocity distributions are strongly forward-peaked.