Syntheses, crystal structures, and vibrational spectroscopic properties of MgCN2, SrCN2, and BaCN2

Abstract

The alkaline-earth metal cyanamides MgCN* SrCN* and BaCN 2 were prepared by the reaction of melamine with the metal nitrides (M&N2, Sr-jN, Ba 3 N 2 ) at temperatures between 740 e C and 850 °C. MgCN 2 was structurally characterized by X-ray analysis using powder methods (R3m, Ζ -3, a=327.34(1) pm, c-1412.82 (5)

Ammonia Nitridation Synthesis and Structural Change of Strontium Cyanamide Polymorphs

“…11 Other methods were the reaction between metal nitride and melanine C 3 N 3 NH 2 3 for AECN 2 AE Ca, Sr, Ba , 12 and between EuN, carbon and NaN 3 for EuCN 2 .…”

Ammonothermal Synthesis of Alkali‐Alkaline Earth Metal and Alkali‐Rare Earth Metal Carbodiimides: K5–xMx(CN2)2+x(HCN2)1–x(M= Sr, Eu) and Na4.32Sr0.68(CN2)2.68(HCN2)0.32

“…The new carbodiimides K 4 2 ) 0.32 were synthesized by the ammonothermal method, starting from alkali metal azides, dicyandiamide, and alkaline earth metals or rare earth metal amides. Crystals with sizes up to several hundred μm were formed during the reaction of the potassium carbodiimides, whereas Na 4.32 Sr 0.68 (CN 2 ) 2.68 (HCN 2 ) 0.32 was preferentially formed as microcrystalline powder.…”

“…The carbodiimide ions (C-N distances around 1.22 Å, see Table 3) are very similar to those in alkaline earth metal carbodiimides and to those in K 5 H(CN 2 ) 3 , which is homeotypic with the title compounds. [4,27] (9) and 2.8723(13) Å (see Table 3). Due to the partial exchange of K + by smaller cations like Sr 2+ or Eu 2+ , the distances are shorter than in K 5 H(CN 2 ) 3 and in good agreement with pure potassium, strontium, or europium carbodiimides.…”

“…We were able to synthesize Na 4 [24][25][26] During further heating to 823 K the intermediates react with carbon containing species (e.g. dicyandiamide or during the reaction formed carbodiimides like K 2 CN 2 ) under formation of single crystals of the products.…”

“…The other alkaline earth metal carbodiimides (MgCN 2 , SrCN 2 , and BaCN 2 ) were synthesized by reactions of the corresponding metal nitrides with melamine. [4] Li 2 CN 2 a = 7.8304(5) Å, Z = 2, R 1 = 0.024, wR 2 = 0.052; K 4.40 Eu 0.60 (CN 2 ) 2.60 (HCN 2 ) 0.40 : space group Im3m (no. 229), a = 7.8502(6) Å, Z = 2, R 1 = 0.022, wR 2 = 0.049].…”