SOLID-STATE POLYMERIZATION OF AQUABIS(3-BUTENOATO)CALCIUM

Aquabis(3-butenoato)calcium, Ca(C4H5O2)(2)(H2O) (1), the monomeric pre cursor for a new solid-state polymerization reaction, was synthesized from 3-butenoic acid and calcium carbonate. Irradiation of solid 1 wit h Co-60 gamma-rays (305 kGy dose) leads to high molecular weight calci um poly(3-butenoate), (M) over bar(w)= 400 000, in 97% yield. Prior to this report, solid-state reactivity was unknown for metal salts of be ta, gamma-unsaturated. carboxylic acids. An X-ray structure determinat ion of 1 shows it to be a two-dimensional coordination polymer. The mo st outstanding feature of the crystal packing is a bilayer arrangement , leading to nearly parallel, reactive vinyl groups, with short -C=C-. ..-C=C- contacts of 3.73 and 3.90 Angstrom along the crystallographic b direction. Crystal data for 1: monoclinic, space group P2(1)/n, a = 5.9083(13), b = 6.7877(18), c = 27.927(10) Angstrom; beta = 92.42(2)de grees; V= 1119.0(5) Angstrom(3); Z = 4; R = 0.091, R-w = 0.103 for 464 data for which I > 1.96 sigma(I).