K2Li(NH2)3 and K2Na(NH2)3-synthesis and crystal structure of two crystal-chemically isotypic mixed-cationic amides

K2Li(NH2)3 (1) was the only crystalline product obtained from the reaction of potassium with dilithium decahydro-closo-decaborate Li2B10H10 in liquid ammonia at -38oC. The compound crystallizes in the space group P42/m with Z=4, a=6.8720(5)A, c=11.706(1)A and V=552.81(7)A3. The investigated crystal-chemically isotypic sodium compound K2Na(NH2)3 (2) was merohedrally twinned and crystallized from a reaction mixture containing potassium and disodium decahydro-closo-decaborate Na2B10H10 in liquid ammonia with a=7.0044(5)A, c=12.362(1)A and V=606.48(9)A3. The compounds contain pairs of edge sharing tetraamidolithium or tetraamidosodium tetrahedra which are interconnected by potassium ions forming three-dimensional infinite networks