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The Doerrer group makes compounds that have the
potential to serve as molecular wires and contribute to the
understanding of electronic conduction through metallic wires that
are one atom wide. The atoms are assembled in a linear fashion via
the synthesis of double-salt compounds with ions containing third
row transition metals such as gold and platinum coordinated in a
square-planar or linear ligand field environment. These cations and
anions with d8 or d10 electron configurations stack under
electrostatic and metallophilic forces. Although not as obviously
strong as coulombic attractions, metallophilic forces are
increasingly recognized as significant and demonstrable force in
chemical bonding. When [Pt(terpy)Cl]Cl is recrystallized from DMSO,
for example, the cations associate as pairs in spite of coulombic
repulsion and these pairs stack infinitely in the crystal structure
to form a chain of platinum atoms. We have prepared several double
salt compounds with polypyridyl-containing cations such as [Pt(terpy)X]+
or [Au(bpy)2X2]+ and anions including [Au(CN)2]- and [AuX4]-.
These compounds often exhibit infinite chains of
metal atoms in the solid state including heteratomic chains with {PtAuPt}..
repeating units. Ultimately such compounds could find a role in
molecular electronics9 as a conducting wires. We are expanding
this family of compounds to other cations and anions with d8 or d10
electron configurations. Manuel¿s project was to make more soluble
derivatives of the Au(III) compounds to facilitate crystallographic
characterization. The reactions below yielded new compounds
including X-ray structural characterization of the product of
reaction (a).
a) KAuCl4 + Me2bpy --> [Au(Me2bpy)Cl2]Cl
b) [Au(Me2bpy)Cl2] + KBr --> [Au(Me2bpy)Br2]Br
c) [Au(Me2bpy)Cl2]Cl + K[Au(CN)2] --> [Au(Me2bpy)Cl2][Au(CN)2]
Accurate elemental analysis data were obtained for the products of
reactions (a) and (b). Though reaction B yielded nice small chunks,
the atoms apparently did not bond as we had predicted. Finally, from
reaction (c), the proposed product was obtained in reasonable
yields, with noticeably less solubility than (a) or (b). Uv-visible
and 1H-NMR data were collected for the (a) and (b) but could not be
obtained for (c) due to low solubility. These experiments show that
different substituent patterns on the bipyridine group successfully
lead to different solubilities and made structural characterization
possible.
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