A Silicon Anvil Crushes Hydrogens!

The two hydrogens on the central axis of this C3-symmetric in,in-bis(hydrosilane) are are crushed together to an unprecendented degree. A combination of crystallographic and computational data indicate that the hydrogen-hydrogen non-bonded contact distance is approximately 1.56 Angstroms, the closest such contact in any crystallographically characterized compound. Nor is there any escape: computational studies show that distortion to less symmetric conformations actually shortens the contact distance! For a brief communication describing both computational and experimental studies of this in,in-bis(hydrosilane), see Zong, J., J. T. Mague, and R. A. Pascal, Jr., J. Am. Chem. Soc. 2013, 135, 13235-13237.