This application relates to compounds of the formula (I) ##STR00001## in which R.sup.1 is chlorine, cyano, trifluoromethyl or methoxy and R.sup.2 is hydrogen or flurorine; or R.sup.1 and R.sup.2 are both fluorine; and to pharmaceutically acceptable salts of these materials. Pharmaceutical compositions containing these materials, and methods of using them in treatment of hypertension and sexual dysfunction are also disclosed and claimed.