I love heavy atoms because they're fun. Yes, it is in fact often easier to just go for Selenium or Sulfur-SAD but if you like the thrill of the chase you can't beat HA.

My first choices are often ethylmercury phosphate, potassium nitrito platinate (II), lead (II) acetate, and potassium di-cyano aurate (I) followed by suitable salts of Samarium and other fun lanthanoids, as well as metallic Iodine. In the olden days Uranium compounds featured in the 'fun list' but it's hard/impossible to use them now due to (mostly overblown) radiation concerns. I'd say that around 80% of all HA structures I've solved (so, about 80 structures) were solved using the set of derivatives above. The remaining 20% were more esoteric - higher oxidation states of Pt and Au (which often tend to cook the protein), truly esoteric Lanthanoids, aggressive Mercury compounds (also cook the protein), clusters, etc.

Hope this helps!

Artem

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