Abstract
The structure of acetatodimethylthallium 2 has been used as a model in an attempt to predict and ‘engineer’ a phase of dimethyl(propynoato)thallium 3 which would be reactive in the solid state. Upon irradiation with X-rays or 60Co γ-rays, 3 is indeed converted to the corresponding deep-brown polypropynoate. The crystal structure of 3 contains, as expected, an infinite set of short contacts (3.454 Å) between acetylene moieties; the presence of such a chain is a requirement for a propynoate material to be sensitive to ionizing radiation. However, the crystal structures of 2 and 3 are quite different owing to subtle changes in CH⋯O hydrogen bonding, Crystals of 3, (CH3)2Rl(O2CC≡CH), belong to the orthorhombic system, space group . Full-matrix least-squares refinement of positional and displacement parameters for all nonhydrogen atoms, using 338 data for which |Fo| > 3.92σ(|Fo|), led to R = 0.059 and Rw = 0.068.