Polyoxometallate sponges turn this color when they are reduced. For 10 points each:
[10e] Usually, what color are inorganic complexes that exhibit strong intervalence charge transfer? 18th century German chemists synthesized a pigment of this color containing iron (III) (“three”) and iron (II) (“two”) cyanides.
ANSWER: blue [accept blue pigments; accept more specific answers like dark blue or bright blue or specific shades of blue; accept heteropoly blues or Prussian blue]
[10m] Additional electrons turn a heteropoly blue into a heteropoly brown, reducing its terminal oxo groups to this ligand. During olation, acidic complexes containing this ligand are deprotonated and polymerize.
ANSWER: aquo ligands [or aqua; accept water or H2O]
[10h] With distinct electron-rich and electron-poor domains, heteropoly browns form this type of anisotropic complex. Pierre de Gennes’ Nobel lecture popularized this term for a nanoparticle or ligand in which different surfaces have different chemical properties.
ANSWER: Janus particle [or Janus complex; or Janus-like complex or Janus-type particle]
<S, Chemistry>