The invention relates to pyrazolopyrimidine derivatives of formula (I) wherein Y.sup.1, Y.sup.2 and Y.sup.3 independently are e.g. CR.sup.10, NH, S or O, whereby at least one of Y.sup.1, Y.sup.2 and Y.sup.3 represents CR.sup.10; R.sup.1 represents chloro or bromo; R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 represent e.g. hydrogen or C.sub.1-C.sub.6-alkyl, and R.sup.10 represents e.g. hydrogen, halogen or phenyl; which are potent mGluR5 modulators and are e.g. useful for the treatment of various neurological disorders.