The present invention relates to compounds of formula (I) wherein R1 is hydrogen, halogen, cyano, lower alkyl, lower alkyl substituted by halogen, lower alkoxy, lower alkoxy substituted by halogen or C(O)NH2, or is phenyl optionally substituted by halogen, cyano or lower alkoxy substituted by halogen, or is 2,2-difluorobenzo[d][1,3]dioxol-5-yl, or is 6-(trifluoromethyl)pyrazin-2-yl or 5-(trifluoromethyl)pyrazin-2-yl or is 6-(trifluoromethyl)pyrimidin-4-yl, or is 6- (trifluoromethyl)pyridin-3-yl, or is 5-cyanopyrazin-2-yl or is 2- (trifluoromethyl)pyrimidin-4-yl; n is 1 or 2 R2 is halogen, lower alkyl or cyano and R3 is hydrogen, or R2 is hydrogen and R3 is halogen, lower alkyl or cyano; X is a bond, -NR'-, -CH2NH- or -CHR'-; R' is hydrogen or lower alkyl; Z is a bond, -CH2- or -O-; Ar is phenyl or is heteroaryl, selected from the group consisting of 1H-indazole-3yl, pyridine-2-yl, pyridine-3-yl, pyridine-4-yl, pyrimidine-5-yl, lH-pyrazole-3-yl, 1H- pyrazole-4-yl or lH-pyrazole-5-yl; or to a pharmaceutically suitable acid addition salt thereof, which may be used for the treatment of depression, anxiety disorders, bipolar disorder, attention deficit hyperactivity disorder (ADHD), stress-related disorders, psychotic disorders, schizophrenia, neurological diseases, Parkinson's disease, neurodegenerative disorders, Alzheimer's disease, epilepsy, migraine, hypertension, substance abuse, metabolic disorders, eating disorders, diabetes, diabetic complications, obesity, dyslipidemia, disorders of energy consumption and assimilation, disorders and malfunction of body temperature homeostasis, disorders of sleep and circadian rhythm, and cardiovascular disorders.