Metal Salts and Complexes as Structural Models and Templates for The Solid State Polymerization of Substituted Acetylenes

Preparation, Structure, and Solid-State Reactivity of Lanthanum Propynoates

“…Solid-State Reactivity of 1 and 2. Upon exposure to 60 Co γ-radiation, solid 1 develops a dark-orange to deep black color, similar to the color change observed for the solid-state polymerization of other metal propynoates. − As the irradiation proceeds, there is a concomitant loss in intensity of the C⋮C stretching modes observed at 2090 and 2105 cm -1 , indicating the likely formation of a polypropynoate. Conversion to product occurs linearly with the dose of 60 Co γ-radiation in the range of approximately 8−65 Mrad.…”

“…The product is isolated after removal of reactant by extraction with water. The product is soluble only in acid solution; in 0.6 M DCl/D 2 O solution, the 1 H and 13 C NMR spectra consist mainly of broad resonances ( 1 H, δ 6−8, 2−4; 13 C, δ 164−170, 125−140) which, in part, are in the expected regions for a polypropynoate or substituted polyacetylene. − , The resonances were too poorly resolved to allow assignment of possible stereochemistry of the product(s). Peaks in the 2−4 ppm region may be indicative of protons located at branch points in the polymer, i.e., groups such as CCCHR 2 and CC CH 2 R. The presence of some residual reactant is indicated by sharp resonances at 71 and 77 ppm; this may arise from incomplete extraction or encapsulation of monomer in the product.…”

“…Sets of short C α −C β ‘ contacts for 1 (partial) and 2 (complete) are shown in Figures and ; a complete set for 1 is available as supporting information. To understand the influence of these arrangements on the reactivity of the material, we need apply only the distance criterion (≲4.2 Å) and the requirement that any given set, simple or complex, must be repeated infinitely by a crystallographic unit cell translation. − Figure shows the sets of nearly parallel contacts in 1 which repeat infinitely for acetylenes I (C(11)−C(12)−C(13)) and III (C(31)−C(32)−C(33)). A 3.95 Å contact between acetylenes II, C(22)···C(23 [ x, 1 / 2 − y, z − 1 / 2 ]), is also part of an infinite chain not shown here.…”

“…Irradiation of solid metal propynoates with 60 Co γ-rays produces the corresponding metal polypropynoates . The factors that influence this unusual solid-state reactivity include the relative distance between the reactive acetylenic centers (including the required presence of infinite chains of short acetylene−acetylene contacts), crystal lattice energy, and the absorption cross section of the material for γ-rays. − Salts of the heavier metals show greater sensitivity to ionizing radiation, apparently a consequence of both lattice energy and absorption effects. ,,, Irradiation of solid “all-organic” acetylenes with apparent ideal alignment of reactive groups produces no significant product. − As part of a program to discover new radiation-sensitive heavy-metal carboxylates, we prepared a rare-earth propynoate of stoichiometry [La(O 2 CC⋮CH) 3 (OH 2 ) 3 ] 2 ( 1 ) and observed that a solid-state reaction occurred when 1 was exposed to 60 Co γ-rays. A possible strategy for the production of structurally related reactive solids containing the same metal involves the replacement of aqua ligands.…”

Thermal Solid State Polymerization ofp-Ethynylbenzoic Acid

“…While the criteria for topochemical reactivity has been established for a wide variety of diacetylenes and transcinnamic acids, the structural criteria, if any, for reactivity of crystalline terminal alkyne compounds has not been fully examined. The majority of information regarding both structure-reactivity relationships for terminal alkynes is available from 60 Co γ irradiation studies of various metal propynoates (MPs) [15][16][17][18][19][20][21] and 1,4-diethynylbenzene (DEB) 26 and UV and thermal polymerization studies of 1,4-diethynylnaphthalene (DEN). [23][24][25] The solid-state polymerization of crystalline EBA, DEN, DEB, and (reactive) MPs results in amorphous polyene materials.…”