Understanding the physical mechanism of a solid-state reaction: Polymerization of metal propynoates

INOR 665

J. Prakasha Reddy, prakash@brandeis.edu, Robert B. Sandor, and Bruce M. Foxman, foxman1@brandeis.edu. Department of Chemistry, MS 015, Brandeis University, Waltham, MA 024549110
Our earlier studies on crystalline metal propynoate coordination compounds revealed that, upon 60Co γ-irradiation, most undergo solid-state polymerization to form the analogous polypropynoates. The reactants themselves are superior X- and γ-ray dosimeters. Irradiation of single crystals yields pseudomorphs, with the product as an amorphous phase. In order to understand the physical change that occurs in a reacting single crystal, we have carried out successive determinations of the structure of tetraaquabis(propynoato)cobalt(II) at various stages of conversion. Anisotropic changes in cell constants as the reaction proceeds reflect both the nature of hydrogen bonding in the structure as well as the likely geometric pathway for the reaction. While it has been postulated that ionizing radiation effects changes akin to thermal expansion, that is explicitly NOT the case in this reaction. The structures and behavior of related systems containing nitrogen donors will also be presented.
 

Characterization and Applications of Coordination Compounds
7:00 PM-10:00 PM, Tuesday, August 21, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Inorganic Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007