Synthesis and Structure Determination of a New Au20 Nanocluster Protected by Tripodal Tetraphosphine Ligands

We report the synthesis and structure determination of a new Au20 nanocluster coordinated by four tripodal tetraphosphine (PP3) ligands {PP3 = tris­[2-(diphenylphosphino)­ethyl]­phosphine}. Single-crystal X-ray crystallography and electrospray ionization mass spectrometry show that the cluster assembly can be formulated as [Au20(PP3)4]­Cl4. The Au20 cluster consists of an icosahedral Au13 core and a seven-Au-atom partial outer shell arranged in a local C3 symmetry. One PP3 ligand coordinates to four Au atoms in the outer shell, while the other three PP3 ligands coordinate to one Au atom from the outer shell and three Au atoms from the surface of the Au13 core, giving rise to an overall chiral 16-electron Au cluster core with C3 symmetry.