Thursday, June 4, 2009

Delta, Phi, and Gamma Bonds, Oh my!

Sorry for the crazy title, but it makes a little more sense at leats than the last thing I had down...

Anyway, continuing my at-least-2-part series of weird chemistry stuff (more if and when I feel like it), some more incredibly rare bonding stuff. In this case, it's not large groups of single hybridized bonds, but instead multiple bonds.

Sigma bonds, aka single bonds, involve just 2 electrons per bond, for example the H-F bond in hydrofluoric acid. They're named after the s-group electrons that form the simplest sigma bonds (for example the simplest possible molecule, H2, has a single sigma bond between the two hyrdrogen atoms).

Pi bonds, formed from p-group orbitals (hence the Greek lettering name), form the double and triple bonds in compounds like O2 (double) and N2 )triple). Pi-bonds are weaker than sigma bonds, but they can use more electrons from a single atom than sigma bonds, allowing non-halogens to form diatomic molecules.

Now we enter a stranger, oft unexplored land.

Delta bonds form, predictably, from the combining of d-group orbitals. They can form quadruple bonds, involving the inner metallic elements (Re, W, Cr, Mo), quintiple bonds, first discovered in 2005 in dichromium compounds, and sextuple bonds, so far known only in W2 and Mo2.

Theorectically, phi and gamma orbitals, corresponding to overlappping f and g orbitals, are possible, but none have yet been observed.

The next two topics: superacids and carbon in all its forms, including the strange dicarbon molecule.

No comments: