Abstract
Upon irradiation with X-rays or 60Co γ-rays, diaquabis(propynoato)magnesium (5) is converted to the corresponding deep brown polypropynoate. The crystal structure of 5 contains an infinite set of short contacts (3.698 Å) between nearly parallel acetylene moieties; the presence of such a chain is a requirement for a propynoate material to be sensitive to ionizing radiation. Crystals of 5, Mg(O2CCCH)2(OH2)2, belong to the orthorhombic system, space group Pbca, a=6.901(2), b=16.134(3), c=7.391(2) Å, Z=4. Full-matrix least-squares refinement of positional and displacement parameters for all atoms, using 888 data for which |Fo|⩽3.92σ|Fo| led to R=0.035; Rw=0.049.