3 POLYMORPHS OF (RAC-1-CYANOETHYL)(PYRROLIDINE)COBALOXIME

Three crystal forms were found for (rac-1-cyanoethyl)bis(2,3-butanedio ne dioximato)(pyrrolidine)-cobalt(III). Two forms, (1) and (11), were grown from solutions of aqueous methanol and benzene-chloroform, respe ctively, and the third, (III), was obtained by crystalline-state racem ization [Takenaka, Ohashi, Tamura, Uchida, Sasada, Ohgo & Baba (1993). Acta Cryst. B49, 272-277]. The structures of (I) and (11) have been d etermined. (1): [CO(C3H4N)(C4H9N)(C4H7N2O2)2], triclinic, P1, Z = 4, a = 11.723 (2), b = 15.658(3), c = 11.118(2 angstrom, alpha = 98.71 (2) , beta = 90.17 (4), gamma = 98.52 (3)-degrees, V = 1994.2 (8) angstrom 3 , R = 0.065, wR = 0.079, M(r) = 414.4, D(m) = 1.39, D(x) = 1.38 Mg M -3, mu(Mo Kalpha) = 0.887 mm-1, F(000) = 872, T = 296 K. (II): [(Co(C3 H4N)(C4H9N)(C4H7N2O2)2].3/2C6H6, monoclinic, P2(1)/a, Z = 4, a = 16.62 1 (2), b = 18.803 (2), c = 9.155 (1) angstrom, beta = 105.03 (2)-degre es, V = 2763.4 (7) angstrom3, R = 0.085, wR = 0.105, M(r) = 531.6, D(x ) = 1.28 Mg m-3, (Mo Kalpha) = 0.655 mm-1, F(000) = 1124, T = 296 K. A lthough the crystal structures are very different from each other, the cyanoethyl group conformations are well explained by reaction-cavity differences. The volume of the reaction cavity is indicative of the re activity of the cyanoethyl groups in the crystals.