X‑ray Crystal Structure of Au<sub>38–<i>x</i></sub>Ag<sub><i>x</i></sub>(SCH<sub>2</sub>CH<sub>2</sub>Ph)<sub>24</sub> Alloy Nanomolecules
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Abstract
Herein, we report the X-ray crystallographic
structure of a 38-metal
atom Au–Ag alloy nanomolecule. The structure of monometallic
Au<sub>38</sub>(SR)<sub>24</sub> consists of 2 central Au atoms and
21 Au atoms forming a bi-icosahedral core protected by 6 dimeric and
3 monomeric units. In Au<sub>38–<i>x</i></sub>Ag<sub><i>x</i></sub>(SR)<sub>24</sub>,where <i>x</i> ranges from 1 to 5, the silver atoms are selectively incorporated
into the Au<sub>21</sub> bi-icosahedral core. Within the Au<sub>21</sub> core, the silver atoms preferentially occupy nine selected locations:
(a) the two vertex edges, three atoms on each edge and six atoms total,
and (b) the middle face-shared three-atom ring, adding to a total
of nine locations. X-ray crystallography yielded a composition of
Au<sub>34.04</sub>Ag<sub>3.96</sub>(SCH<sub>2</sub>CH<sub>2</sub>Ph)<sub>24</sub>. The crystal structure of the alloy nanomolecule can be
described in terms of shells as Au<sub>2</sub>@Au<sub>17.04</sub>Ag<sub>3.96</sub>@ 6×[−SR–Au–SR–Au–SR]
3×[−SR–Au–SR−]
