Synthesis, crystal structure and optical spectra of Yb2[CN 2]3

Abstract

Red-orange, transparent single crystals of Yb2[CN 2]3 [trigonal, R3̄c (no. 167), a = 630.02(3) and c = 2947.4(2) pm, Z = 6] are obtained by the reaction of Yb, Sn, Zn[CN2] and NaN3 in arc-welded Nb ampoules at 1100 K. The title compound exhibits characteristic C-N bond lengths and angles [d(C-N) = 122.7(3) pm and (N-C-N) = 178.4(5)°, respectively] within the [N=C=N]2- unit as well as the expected fundamental frequencies in its optical spectra (Roman: vs = 1338; δ = 643 / 683 / 695 cm-1; IR: v as = 2005 / 2037; δ = 640 / 679 cm-1). Since Yb 2[CN2]3 adopts a corundum-type structure, Yb3+ is octahedrally coordinated by six N atoms of different [CN 2]2- anions [d(Yb-N) = 228.6(3) and 233.4(3) pm, 3× each] and every [CN2]2- group has four Yb3+ as next neighbours which form a distorted tetrahedron. © 2007 Verlag der Zeitschrift für Naturforschung.