1 research outputs found
[M<sub>16</sub>Ni<sub>24</sub>(CO)<sub>40</sub>]<sup>4–</sup>: Coinage Metal Tetrahedral Superatoms as Useful Building Blocks Related to Pyramidal Au<sub>20</sub> Clusters (M = Cu, Ag, Au). Electronic and Bonding Properties from Relativistic DFT Calculations
Characterization
of the tetrahedral Au<sub>20</sub> structure in
the gas phase remains a major landmark in gold cluster chemistry,
where further efforts to stabilize this bare 20-electron superatom
in solution to extend and understand its chemistry have failed so
far. Here, we account for the structural, electronic, and bonding
properties of [M<sub>16</sub>Ni<sub>24</sub>(CO)<sub>40</sub>]<sup>4–</sup> (M = Cu, Ag, Au) observed in solution for gold and
silver. Our results show a direct electronic relationship with Au<sub>20</sub>, owing that such species share a common tetrahedral [M<sub>16</sub>]<sup>4–</sup> central core with a 1S<sup>2</sup>1P<sup>6</sup>1D<sup>10</sup>2S<sup>2</sup> jellium configuration. In the
case of Au<sub>20</sub>, the [Au<sub>16</sub>]<sup>4–</sup> core is capped by four Au<sup>+</sup> ions, whereas in [M<sub>16</sub>Ni<sub>24</sub>(CO)<sub>40</sub>]<sup>4–</sup> it is capped
by four Ni<sub>6</sub>(CO)<sub>10</sub> units. In both cases, the
capping entities are a full part of the superatom entity, where it
appears that the free (uncapped) [M<sub>16</sub>]<sup>4–</sup> species must be capped for further stabilization. It follows that
the Ni<sub>6</sub>(CO)<sub>10</sub> units in [M<sub>16</sub>Ni<sub>24</sub>(CO)<sub>40</sub>]<sup>4–</sup> should not be considered
as external ligands as their bonding with the [M<sub>16</sub>]<sup>4–</sup> core is mainly associated with a delocalization of
the 20 jellium electrons onto the Ni atoms. Thus, the [M<sub>16</sub>Ni<sub>24</sub>(CO)<sub>40</sub>]<sup>4–</sup> species can
be seen as the solution version of tetrahedral M<sub>20</sub> clusters,
encouraging experimental efforts to further develop the chemistry
of such complexes as M(111) finite surface section structures, with
M = Ag and Au and, particularly promising, with M = Cu. Furthermore,
optical properties were simulated to assist future experimental characterization