Molecules: You'd better learn to live with them.
Like cubane, windowpane (also named "[4.4.4.4]fenestrane" for the Latin for window) is another of those compounds people like because it looks like something anthropomorphic, with clean right angles (in contrast to the bulk of molecules, which assume their bond angles with little regard for what looks nice on paper). This introduces a great deal of strain, since quantum mechanics would rather we avoid bond angles very far from ~110 degrees in these sorts of compounds. See this entry on cubane from the old site for more information on why right and 180 degree angles are so tricky here.
In fact, planar carbon is so hard to come by, we've had much more luck talking about it than making it. I'm not sure what we've managed to make and what we haven't.
I think (and someone who knows, tell me if I'm wrong) the closest we've got are the higher fenestranes (like 5.5.5.6), which are a little less unhappy existing, and "broken" 4.4.4.4 fenestrane (yes, they call it "broken windowpane.").
![[5.5.5.6]fenestrane: InChI=1/C14H22/c1-2-10-4-6-12-8-9-13-7-5-11(3-1)14(10,12)13/h10-13H,1-9H2](/moleculeoftheday/images/5.5.5.6.fenestrane.gif)
