The Susceptibility to Deformation of Metal-Metal and Metal-Halide Bonds. I. Pascual, A. F. T. Yokochi, L. F. Chen, F. A. Cotton, Department of Chemistry and Laboratory for Molecular Structure and Bonding, Texas A&M University, College Station, TX 77843

The apparent flexibility of chemical entities has usually been studied from the statistical analysis of large structural databases. While this approach yields general trends, it lacks the specificity which would be obtained if only one compound was studied. However, a study in which only one molecule is examined is limited by the fact that only a few measurements are usually available. The recent structural characterization by this laboratory of several different forms of [Zr₆Cl₆(m-Cl)₁₂H₅]Q₃ (Q = PPh₄, NEt₄), in crystal systems which range from triclinic to cubic, offers an opportunity for such a study since it is a molecule with high chemical symmetry and therefore yields many observations per variable of interest.

A cursory examination of the terminal Zr-Cl bonds reveals that, while chemically identical, the length of these bonds shows a remarkably wide distribution. For this reason a statistical analysis of pertinent bond lengths and angles, as well as a rigid body analysis, was performed. The results obtained will be presented and discussed in the context of the susceptibility to deformation due to packing forces displayed by this molecule.