Ce-4[Si4O4N6]O - A hyperbolically layered oxonitridosilicate oxide with anordered distribution of oxygen and nitrogen

The yellow-orange oxonitridosilicate oxide Ce-4[Si4O4N6]O was obtained by t he reaction of cerium metal with Si(NH)(2) and SiO2 in a radiofrequency fur nace at 1560 degrees C, The crystal structure was determined by single-crys tal X-ray diffraction (a = 1033.67(6) pm, P2(1)3, Z = 4. R1 = 0.0412, wR2 = 0.0678) and powder neutron diffraction, In the solid there are complex cat ions [Ce4O](10+) that are enveloped by a hyperbolical layer structure [Si4O 4N6](10-). The layer is built up by corner-sharing SiON3 tetrahedra of Q(3) type The oxygen atoms of the SiON3 tetrahedra are terminally bound to Si, while all nitrogen atoms bridge two neighboring Si centres, The crystallogr aphic differentiation of O and N was unequivocally possible by a careful ev aluation of the single-crystal X-ray diffraction data combined with lattice -energy calculations by using the MAPLE concept (Madelung part of lattice e nergy). Furthermore the results were confirmed by the chemical analyses. Su bsequently, the determined N/O distribution and their crystallographic orde ring was proved by neutron powder diffraction, In accordance with the molar ratio Si:(O,N) = 2:5 the [Si4O4N6](10-) network may be classified as a lay er silicate. In this specific case a hyperbolically corrugated topology of the layers is observed; this is correlated to periodic nodal surface (PNS) representatives.