Mirica's metal complex solves half the problem of methane-to-ethane conversion. It takes two methyl groups (CH3) and, in the presence of oxygen and light, binds the carbon atoms to one another to form ethane.
The complex consists of an organic molecule that binds a central palladium atom through four nitrogen atoms, holding it like a ball in a glove.
The organic molecule is key to the metal complex's function, since it stabilizes it in the unusual +3 oxidation state (it has given up three electrons), which is responsible for its unprecedented chemical activity.
Once in the glove, the palladium atom still has two docking spots that can be occupied by chemical species whose reaction it might catalyze.
In the reported work, these sites are occupied by methyl groups, which the palladium atom joins to produce ethane. But, Mirica emphasizes, the sites could easily be occupied by other chemical species. What's more the reactions could be reducing ones (where electrons are donated to reactants) rather than the oxidizing ones (where electrons are removed from reactants) like the methyl-to-ethane conversion.
In short the complex opens up a whole new area of palladium chemistry.
The To-Do list
Mirica's lab is currently to tweak the metal complex so that it can peform the entire methane-to-ethane reaction.
The first part of that reaction is pulling methyl groups off methane molecules. That's a bit tricky, says Mirica, because it is hard to break one C-H bond of the methane molecule, which has four C-H bonds, without breaking all four.
"The reaction wants to run straight down the energy hill all the way to the bottom (CO2)," Mirica says. "Our goal is to design a catalyst that stops the reaction part of the way down the hill (when only one hydrogen has been removed).
His lab is also test
|Contact: Diana Lutz|
Washington University in St. Louis