Provided are phenyl-3-aza-bicyclo[3.1.0]hex-3-yl-methanone derivative compounds of general formula (I), wherein the variables are as described in the specification. Examples of the compounds include [5-Methanesulfonyl-2-(2,2,2-trifluoro-1-methyl-ethoxy)-phenyl]-[1-(5-trifluoromethyl-[1,2,4]oxadiazol-3-yl)-3-aza-bicyclo[3.1.0]hex-3-yl]-methanone and [5-Methanesulfonyl-2-(2,2,2-trifluoro-1-methyl-ethoxy) phenyl]-{ 1-[5-(3-methyl-oxetan-3-yl)-[1,2,4]oxadiazol-3-yl]-3-aza-bicyclo[3.1.0]hex-3-yl} -methanone. The compounds are glycine transporter-1 (GlyT1) inhibitors. The compounds may be useful in the treatment of the positive and negative symptoms of schizophrenia as well as cognitive impairments associated with schizophrenia, Alzheimer’s disease and other neurological and psychiatric disorders.