No abstract

at 286 K. 349 and 635 unique reflections refined to R(F) = 0.023 and 0.019 at 139 and 286 K, respectively. The structure consists of infinite chains along c, built from corner sharing Se03E tetrahedra, with E representing the Se lone pair. Observed bonding distances are Se-O(l) (*2) 1.7926(4) [1.795(1)] and Se-O(2) 1.6226(9) [1.624(2)] A at 286 [139] K. The shortest inter-chain distances, Se-O(2) 2.758(1) [2.743(2)] and (*2) 2.857(1) [2.843(1)] A at 286 [139] K, indicate considerable electrostatic interactions between chains. Including these next nearest oxygens the Se-0 coordination can be described as distorted octahedral in a novel type of net. The final difference electron density map showed residual density in the predicted Se lone pair region.

The crystal structure of potassium uranyl oxalate K6[(UO2)2(C204)5]. 10H20 has been established by X-ray diffraction on two crystals at room temperature. The compound crystallizes in space group PT. Lattice constants are a= 10

Slow evaporation of an aqueous solution of 3,3-bis(2-imidazolyl)propionic acid monohydrate, C,~HIc~N402.-H20, yields crystals of the hemihydrate, C~H~N_~O_~.-0.5H20. In both hydrates the molecules of 3,3-bis(2-imidazolyl)propionic acid are in a zwitterionic form containing-COO-and-(imidazole)H ÷ residues, i.e. 3-(2-imidazolyl)-3-(2-imidazolio)propionate. The crystal structure of the hemihydrate contains two crystallographically independent zwitterions and one water molecule linked by hydrogen bonds. In the two molecules of the hemihydrate, as well as in the monohydrate, the dihedral angles between the planes of the imidazole rings and the carboxylate group show remarkable differences, indicating that 3,3-bis(2-imidazolyl)propionic acid can be used as a flexible ligand. Comment

Structural characterization and electrical conductivity studies of the donor‐acceptor compounds (I), obtained as needles from the slow interdiffusion of solutions of (TTF)3(BF4)2 and Bu4N[ML2], are described.