supplier for rare heavy metal (mercury) salt

[oxalis at friedel.csb.yale.edu]

Please help me find a supplier (anywhere in the world) for the 
heavy metal salt:

 mercury thallium nitrite    Hg2Tl2(NO2)6

I haven't been able to find ordering information from any of the 
standard U.S. suppliers (e.g., SIGMA or Aldrich).

Thanks for your help.