Syntheses, Vibrational Spectroscopy, and Crystal Structure Determination from X-Ray Powder Diffraction Data of Alkaline Earth Dicyanamides M[N(CN)_2]_2 with M = Mg, Ca, Sr, and Ba

摘要

The alkaline earth dicyanamids Mg[N(CN)_2]_2, Ca[N(CN)_2]_2, Sr[N(CN)_2]_2, and Ba[N(CN)_2]_2 were synthesized by ion exchange using Na[N(CN)_2] and the respective nitrates or bromides as starting materials. The crystal structures were determined from X-ray powder diffractmetry: Mg[N(CN)_2]_2, Pnnm, Z = 2, a = 617. 14 (3), b = 716.97(3), and c = 740.35(5) pm; Ca[N(CN)_2]_2 and Sr[N(CN)_2]_2, C2-c, Z = 4; Ca[N9CN)_2]_2, a = 1244.55(3), b = 607.97(1), and c = 789.81(1) pm, #beta# = 98.864(2) deg; Sr[N(CN)_2]_2, a = 1279.63(2), b = 624.756(8), and c = 817.56(1) pm, #beta# = 99.787(1) deg; Ba[N(CN)_2]_2, Pnma, Z = 4, a = 1368.68(7), B = 429.07(7), and c = 1226.26(2) pm. The dicyanamides conist of the respective alkaine earth cations and bent planar [N(CN)_2]~- ions. The structural features were correlated with vibrational spectroscopic data. The thermal behavior was studied by thermoanalytical experiments.