The present invention relates to novel compounds of formula (I) or a pharmaceutically acceptable salt thereof: wherein R1 is hydrogen or C1-4alkyl; R2 is C1-4alkyl; R3 is hydrogen, or a phenyl group, a heterocyclyl group, a 5- or 6-membered heteroaromatic group, or a 8- to 11-membered bicyclic group, any of which groups is optionally substituted by 1, 2, 3 or 4 substituents selected from the group consisting of: halogen, cyano, C1-4alkyl, haloC1-4alkyl, C1-4alkoxy, C1-4alkanoyl and SF5; p is 0, 1, 2, 3 or 4; and R4 is independently selected from a group consisting of: halogen, hydroxy, cyano, C1-4alkyl, haloC1-4alkyl, C1-4alkoxy, haloC1-4alkoxy and C1-4alkanoyl; n is 0 or 1; wherein when R4 is chlorine and p is 1, such R4 is not present in the ortho position with respect to the linking bond to the rest of the molecule; and wherein, if n is 0, R3 comprises at least one SF5 group as a substituent; processes for their preparation, intermediates used in these processes, pharmaceutical compositions containing them and their use in therapy, as modulators of dopamine D3 receptors, e.g. to treat drug dependency, as antipsychotic agents, to treat obsessive compulsive spectrum disorders, premature ejaculation or cognition impairment.