We report IRAM 30-m observations of DCN and DCO
+ towards the galactic center molecular clouds
Sgr B2 and
Sgr A. We compare our results with simultaneous measurements of H
13CN and HC
18O
+ in order to derive estimates of the [DCN]/[HCN] and [DCO
+]/[HCO
+] abundance ratios. We mapped Sgr B2 in DCN(2-1) and DCN(3-2) and we compared HC
15N with DCN for one position of our maps. The uncertainties in such measurements turn out to be large, due to optical depth effects, in the case of H
13CN, and, in the case of
Sgr B2, due to the strong foreground absorption in H
13CN, HC
15N and HC
18O
+. Taking these effects into account, we conclude that [DCN]/[HCN] towards the molecular ridge in
Sgr B2 is 1.3x10
–4 (uncertain by a factor 2) and towards the
Sgr A molecular cloud is <6x10
–4. Towards
Sgr B2, we also estimate [DCO
+]/[HCO
+] to be 2x10
–4 again with a factor of 2 uncertainty. We have carried out model calculations to estimate the amount of deuterium enhancement in these species in these clouds. We find, for temperatures between 40 and 120K, that one expects D to be enhanced in DCN in the galactic center by a factor between 12 and 140 over the actual ratio of [D/H]. The corresponding enhancement for DCO
+ would be between 23 and 460. Based on these results, we conclude that the ratio of [D/H] in the
Sgr B2 cloud is 5x10
–6 with a factor of 10 uncertainty. This result, while it has large uncertainty, suggests that deuterium is roughly one order of magnitude less abundant in the galactic center than in the solar neighbourhood. We briefly discuss possible consequences of this for the stellar initial mass function in the galactic center.