It can be, but a more typical one I use is \ce{Cu_{1-x}Pd_{x}} and that has to be wrapped in @@latex:...@@.

John

-----------------------------------
Professor John Kitchin 
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803

On Tue, Nov 24, 2015 at 4:00 AM, Eric S Fraga <e.fraga@ucl.ac.uk> wrote:
On Monday, 23 Nov 2015 at 14:42, John Kitchin wrote:
> True enough! I wasn't thinking very large when I had the question in
> mind! I end up with a lot of chemical formulas like this
> @@latex:\ce{H_{2}O}@@  in my writing because the {} inside the {} makes

OT but just wondering: shouldn't this be @@latex:\ce{H2O}@@?  And this
would work just fine without the @@ directive for LaTeX export at least.

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: Eric S Fraga (0xFFFCF67D), Emacs 24.5.1, Org release_8.3.2-215-gb4af3f