SYNTHESIS AND CRYSTAL-STRUCTURE OF A CALCIUM NITRIDE DEUTERIDE CA2ND

Pieces of calcium metal react under definite conditions with nitrogen and deuterium in a stainless steel tube to yield crystals of Ca2ND in the form of black octahedra. The metal is evaporated at 1000 degrees C under p(N-2)= p(D-2) = 25 mbar and the product crystallises at 800 de grees C. Crystals sufficient in size for X-ray structure determination s were obtained: Space group Fd(3) over bar m, Z = 16, a = 10.138(1) A ngstrom, R/R(w)=0.024/0.023 with N(F-0(2)) greater than or equal to 3 sigma (F-0(2)) = 158, N(var) = 8. Ca2ND crystallises in a variant of t he rock salt structure type. Ca atoms are slightly distorted cubic clo se packed with one-half of the octahedral sites occupied by deuterium, the other half by nitride ions in such an ordered way that edge shari ng chains of equally occupied octahedra run through the structure.