The Big Wheel
The first publication of the structure of wheel shaped cluster anion, first determined for the nitrosyl derivative by Achim Müller et al. was announced in New Scientist as "Big Wheel rolls back the molecular frontier". Further work by the same group then refined the initial findings and determined the structure of the wheel produced in molybdate solutions as 14−. The Mo154 type cluster was then shown to be the basic structural type of molybdenum blue compounds obtained under slightly different conditions.
The structure of the big wheel is constructed from units containing 11 Mo atoms ({Mo11}-type units), 14 of which are linked together to form the {Mo154}-type cluster that has an external diameter of 3.4 nm. (12 {Mo11}-type units are also involved in the construction of higher symmetrical spherical systems called Keplerates) These units consist of a central MoO7 bipyramid sharing edges with 5 MoO6 octahedra (an illustration of this is on page 155 of the review ). With 5 more linking MoO6 octahedra the repeating {Mo11}-type unit is built up.
Read more about this topic: Molybdenum Blue
Famous quotes containing the words big and/or wheel:
“The true gardener then brushes over the ground with slow and gentle hand, to liberate a space for breath round some favourite; but he is not thinking about destruction except incidentally. It is only the amateur like myself who becomes obsessed and rejoices with a sadistic pleasure in weeds that are big and bad enough to pull, and at last, almost forgetting the flowers altogether, turns into a Reformer.”
—Freya Stark (1893–1993)
“Everything goes, everything comes back; eternally rolls the wheel of being. Everything dies, everything blossoms again; eternally runs the year of being. Everything breaks, everything is joined anew; eternally the same house of being is built. Everything parts, everything greets every other thing again; eternally the ring of being remains faithful to itself. In every Now, being begins; round every Here rolls the sphere There. The center is everywhere. Bent is the path of eternity.”
—Friedrich Nietzsche (1844–1900)