Diazabicyclo-octane derivatives as 5-HT receptor ligands

A compound of formula I, or a pharmaceutically acceptable salt thereof:

• ##STR24## wherein Z represents imidazole, optionally substituted with C.sub.1-6 alkyl, C.sub.2-6 alkenyl, C.sub.2-6 alkynyl, C.sub.3-7 cycloalkyl, aryl, aryl(C.sub.1-6)alkyl, C.sub.1-6 alkoxy, C.sub.1-6 alkylthio, amino, C.sub.1-6 alkylamino, di(C.sub.1-6)alkylamino, halogen, cyano or trifluoromethyl, wherein aryl represents phenyl or naphthyl;
• E represents a chemical bond or a straight or branched alkylene chain containing from 1 to 4 carbon atoms;
• Q represents a straight or branched alkylene chain containing from 1 to 6 carbon atoms, optionally substituted in any position by one or more substituents selected from fluoro and hydroxy;
• T represents CH;
• U represents C--R.sup.2 ;
• V represents N--R.sup.3 ;
• R.sup.1 represents C.sub.3-6 alkenyl, C.sub.3-6 alkynyl, C.sub.3-7 cycloalkyl(C.sub.1-6)alkyl, or aryl(C.sub.1-6)alkyl, wherein aryl is phenyl or naphthyl, any of which groups may be optionally substituted with one or more substituents selected from halogen, cyano, trifluoromethyl, hydroxy, keto, C.sub.1-6 alkoxy, amino, di(C.sub.1-6)alkylamino, di(C.sub.1-6)alkylaminomethyl, C.sub.2-6 alkylcarbonylamino, C.sub.2-6 alkoxycarbonylamino, N-(C.sub.1-6 )alkyl-N-(C.sub.2-6)alkoxycarbonylamino, C.sub.1-6 alkylsulphonylamino, aminocarbonylamino, aminocarbonyl, C.sub.1-6 alkylaminocarbonyl, di(C.sub.1-6) alkylaminocarbonyl, aminosulphonyl, and C.sub.1-6 alkylaminosulphonylmethyl;
• and
• R.sup.2, R.sup.3, and R.sup.7 independently represent hydrogen or C.sub.1-6 alkyl.