The H2S 22,0 - 21,1 line emission is observed to be strongly localized toward Sgr B2(M), and emissions from other positions in the more extended SgrB2 region are almost negligible. H2S is thought to form effectively by the passage of the C-type shocks but to be quickly transformed to SO2 or other sulfur species (Pineau des Forets et al. 1993). Such a shock may have enhanced the H2S abundance in Sgr B2(M), where massive star formation is taking place. But the negligible emission of H2S from other observed positions may indicate that these positions have not been affected by shocks enough to produce H2S, or if they have experienced shocks, H2S may have transformed already to other sulfur-containing species. The SO2 222,20 - 221,21 line was also observed to be detectable only toward the (M) position. The line intensity ratios of these two molecules appear to be very similar at Sgr B2(M) and IRAS 16239-2422, where the latter is a region of low-mass star formation. This may suggest that the shock environment in these two star-forming regions is similar and that the shock chemistry also proceeds in a similar fashion in these two different regions, if we accept shock formation of these two species.

We have mapped the C 3 H 2 2 12 − 1 01 transition line toward the Sgr A molecular cloud on a 1' grid spacing and derived C 3 H 2 column densities of 3 \~ 7 × 10 14 c m − 2 for molecular clouds of Sgr A. The fractional abundances of C 3 H 2 relative to H 2 are obtained to be 3 \~ 6 × 10 − 9 , which are slightly lower than that for the cold dark cloud TMC-1 but are enhanced by factors of 5-60 compared to those for Sgr B2 and the Orion extended ridge. We also estimate from the C 3 H 2 column densities total masses of \~ 10 6 M ⨀ for two clouds (M - 0.13 - 0.08 and M - 0.02 - 0.07), which are thought to be close to the virial equilibrium. We suggest that the large abundance of C 3 H 2 in Sgr A may be partly due to the activities of the Galactic center.