Tangential ligand-induced strain in icosahedral Au₁₃

A quantitative comparison of first principles calculations with extended X-ray absorption fine structure and transmission electron microscopy measurements provides strong evidence that Au₁₃ nanocrystals are stabilized in a slightly distorted icosahedral structure by on-top phosphine ligands and a combination of on-top and bridging thiol ligands. Importantly, the ligands change the icosahedral strain (i.e., the radial-tangential bond length ratio) significantly, with the tangential bonds within the Au core exhibiting much more disorder than the radial ones.