Kristallstrukturen von Octacyanomolybdaten(IV). V. Quadratisch-antiprismatische [Mo(CN)8]-Koordination in den cyanoverbrückten Kupfer- und Cadmium-Amminkomplexen Cu2(NH3)8[Mo(CN)8] und Cd2(NH3)6[Mo(CN)8]·H2O/Crystal Structures of Octacyanomolybdates(IV). V. Square Antiprismatic [Mo(CN)8]-Coordination of the Cyano-Bridged Copper and Cadmium Ammine Complexes Cu2(NH3)8[Mo(CN)8] and Cd2(NH3)6[Mo(CN)8]·H2O

Abstract

At single crystals of the cyano complexes Cu2(NH3)8[Mo(CN)8] (a = 934.1(4), b = 1595.9(3), c = 1391.9(4) pm, β = 90.57(2)°, monoclinic space group Cc, Z = 4) and Cd2(NH3)6[Mo(CN)8]·H2O (a = 1708.7(12), b = 1307.8(4), c = 942.9(3) pm, orthorhombic space group Pna21, Z = 4) X-ray structure determinations were performed at temperatures of about 175 K. Both compounds, prepared at about 275 K in aqueous ammonia solutions and easily decomposing, exhibit distorted square antiprismatic [Mo(CN)8]4- coordination of closely resembling dimensions (mean distances Mo-C: 215.7 and 215.3 pm, resp.). The anions are bridged by ammine cations to form chains in the copper and a three-dimensional framework in the cadmium compound. Some of the cyano bridges are strongly bent (C-N-MII as small as 124° and 130°, resp.). The distorted M coordination is square pyramidal and elongated octahedral in the case of the two copper atoms (Cu-N ranging from 197 to 257 pm, three and five ligands, respectively, being NH3). In the case of cadmium both metal atoms are octahedrally coordinated, one exhibiting mer-, the other fac-arrangement of three NH3 and three NC-ligands (Cd-N ranging from 229 to 247 pm, mean 235 pm for either cadmium atom). The findings are compared with related compounds and further details are discussed.