Single-Crystal and Electronic Structure of a 1.3 nm Indium Phosphide Nanocluster

Magic-sized
nanoclusters have been implicated as mechanistically
relevant intermediates in the synthesis of group III-V quantum dots.
Herein we report the single-crystal X-ray diffraction structure of
a carboxylate-ligated indium phosphide magic-sized nanocluster at
0.83 Å resolution. The structure of this cluster, In37P20(O2CR)51, deviates from that
of known crystal phases and possesses a non-stoichiometric, charged
core composed of a series of fused 6-membered rings. The cluster is
completely passivated by bidentate carboxylate ligands exhibiting
predominantly bridging binding modes. The absorption spectrum of the
cluster shows an asymmetric line shape that is broader than what would
be expected from a homogeneous sample. A combination of computational
and experimental evidence suggests that the spectral line width is
a result of multiple, discrete electronic transitions that couple
to vibrations of the nanocrystal lattice. The product of reaction
of this nanocluster with 1 equiv of water has also been structurally
characterized, demonstrating site selectivity without a drastic alteration
of electronic structure.