CU3ER(SEO3)(2)O2CL, THE ERBIUM ANALOG OF FRANCISITE

The title compound, tricopper erbium chloride bis(oxide) bis[trioxosel enate(2-)], consists of an infinite three-dimensional framework of cat ions and O atoms, and contains eight-coordinate Er3+, square-planar Cu 2+ and three-coordinate Se4+ ions, The Cl ions and the Se lone pair of electrons occupy tunnels parallel to [001], The mean bond distances a re: Er-O 2.38(8), Cu1-O (in the square plane) 1.96(7), Cu1-C1 (out of plane) 3.015(2), Cu2-O 1.95(3), Cu2-C1 3.1753 (9) and Se-O 1.696 Angst rom. The shortest Cu ... Cu distance is 3.150 Angstrom and the shortes t O ... O distance is 2.48 Angstrom (O3 ... O3).