  We present temporal scattering measurements of single pulses and average
profiles of PSR J1745--2900, a magnetar recently discovered only 3 arcsec away
from Sagittarius A* (Sgr A*), from 1.2 - 18.95 GHz using the Effelsberg 100-m
Radio Telescope, the Nan\c{c}ay Decimetric Radio Telescope, and the Jodrell
Bank Lovell Telescope. Single pulse analysis shows that the integrated pulse
profile above 2 GHz is dominated by pulse jitter, while below 2 GHz the pulse
profile shape is dominated by scattering. The high dispersion measure and
rotation measure of the magnetar suggest that it is close to Sgr A* (within
~0.1 pc). This is the first object in the GC with both pulse broadening and
angular broadening measurements. We measure a pulse broadening spectral index
of alpha = -3.8 +/- 0.2 and a pulse broadening time scale at 1 GHz of tau_GHz =
1.3 +/- 0.2 s, which is several orders of magnitude lower than the scattering
predicted by the NE2001 model (Cordes and Lazio 2002). If this scattering
timescale is representative of the GC as a whole, then previous surveys should
have detected many pulsars. The lack of detections implies either our
understanding of scattering in the GC is incomplete or there are fewer pulsars
in the GC than previously predicted. Given that magnetars are a rare class of
radio pulsar, we believe that there are many canonical and millisecond pulsars
in the GC, and not surprisingly, scattering regions in the GC have complex
spatial structures.
