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Published on: April 14, 2020
Mapping the formation areas of giant molybdenum blue clusters: a spectroscopic study
Bogdan Botar1, Arkady Ellern, Paul Kögerler
1Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany. b.botar@fz-juelich.de
Abstract:
The self-assembly of soluble molybdenum blue species from simple molybdate solutions has primarily been associated with giant mixed-valent wheel-shaped cluster anions, derived from the {Mo(V/VI)(154/176)} archetypes, and a {Mo(V/VI)(368)} lemon-shaped cluster. The combined use of Raman spectroscopy and kinetic precipitation as self-assembly monitoring techniques and single-crystal X-ray diffraction is key to mapping the realm of molybdenum blue species by establishing spherical {Mo(V/VI)(102)}-type Keplerates as an important giant molybdenum blue-type species. We additionally rationalize the empirical effect of reducing agent concentration on the formation of all three relevant skeletal types: wheel, lemon and spheres. Whereas both wheels and the lemon-shaped {Mo(V/VI)(368)} cluster are obtained from weakly reduced molybdenum blue solutions, considerably higher reduced solutions lead to {Mo(V/VI)(102)}-type Keplerates.
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