Molecule of the Month
November 2014
Squeezing Molecules

Molecules put under moderate pressure modify their conformations. When higher pressure is applied, soft bonds, like that between two metals, are also substantially affected.
A recent example from the Macchi's group is the "off-axis" Mn-Mn bond in crystalline Mn2(CO)10, investigated by synchrotron X-ray diffraction (at SLS-PSI) and by Raman spectroscopy, up to a pressure of 6 GPa (ca. 60.000 atm).


  • P. Macchi, N. Casati, S. R. Evans, F. Gozzo, P. Simoncic, D. Tiana;
    "An 'Off-axis' Mn-Mn bond in Mn2(CO)10 at high pressure"
    Chem. Commun., 50, 12785, (2014); doi:10.1039/C4CC90402H   &
    Chem. Commun., 50, 12824-12827, (2014); doi:10.1039/C4CC04152F.
  • N. Casati, P. Macchi, A. Sironi;
    "Molecular Crystals Under High Pressure: Theoretical and Experimental Investigations of the Solid-Solid Phase Transitions in [Co2(CO)6(XPh3)2] (X=P, As)"
    Chemistry, Eur. J., 15, 4446-4457, (2009); doi:10.1002/chem.200801528.
  • N. Casati, P. Macchi, A. Sironi;
    "Staggered to Eclipsed Conformational Rearrangement of [Co2(CO)6(PPh3)2] in the Solid State: An X-ray Diffraction Study at High Pressure and Low Temperature"
    Angew. Chem. Int. Ed., 44, 7736-7739, (2005); doi:10.1002/anie.200502241.