Facile Synthesis and Structures of Cyclic Triimidazole and Its Boric Acid Adduct

Cyclic triimidazole, C9H6N6 (1), was prepared by thermolysis of the easily prepared copper imidazolate framework solid, Cu(C3H3N2)(2) (2), Providing a convenient route to this potentially useful tecton for molecular design. Anhydrous 1 and a hydrate, 1.0.5H(2)O, were characterized by single-crystal X-ray diffraction. Hydrate 1.0.5H(2)O contains two crystallographically independent 1 molecules. Supramolecular structures of 1 and 1.0.5H(2)O feature stacking arrangements in which the 1 molecule deviates from idealized geometry. A 3-fold H-bond acceptor 1 forms an adduct with boric acid, 1 . B(OH)(3), which was also structurally characterized. This adduct is composed of hydrogen-bonded sheets of 1 and B(OH)(3) molecules with sheet interplanar separations of 3.175(4) angstrom and B(OH)(3) boron atoms positioned above and below the centroids of 1 in adjacent sheets. Unlike 1 and its hydrate, 1 . B(OH)(3) contains 1 molecules that display crystallographically required D-3/1, symmetry. Anhydrous 1 crystallizes in the triclinic system, space group P (1) over bar, with a = 7.2138(12), b = 8.3667(15), c = 8.8361(13) angstrom, alpha = 99.826(13),beta = 113.825(10), gamma = 110.721(11)degrees, V = 424.55(12) angstrom(3), Z = 2; 1(2) . H2O (or 1.0.5H(2)O), triclinic, P (1) over bar, a = 7.5608(3), b = 7.5669(5), c = 15.8436(8) A, a = 84.504(3), beta = 81.269(3)degrees, gamma = 87.038(3), V = 891.18(8) angstrom(3), Z = 2; 1 . B(OH)(3), trigonal, P (3) over bar a = 10.1186(3), b = 10.1186(3), c = 6.3488(4) angstrom, alpha = 90,beta = 90, gamma = 120 degrees, V = 562.94(4) angstrom(3), Z = 2.