The present invention is directed to novel compounds represented by structural Formula (I): ##STR00001## or a pharmaceutically acceptable salt thereof, wherein R.sup.1, R.sup.4a, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9,and m, are defined herein. The invention is also concerned with pharmaceutical formulations comprising these novel compounds as active ingredients and the use of the novel compounds and their formulations in the treatment of certain central nervous system disorders. The compounds of this invention are serotonin receptor modulators, in particular 5HT.sub.2C receptor agonists and antagonists, and are useful in the control or prevention of central nervous system disorders including obesity, anorexia, bulemia, depression, anxiety, psychosis, schizophrenia, migraine, addictive behavior, obsessive-compulsive disorder, and sexual disorders.