Melem 4e was synthesized by heating cyanamide 5 (Fluka, ≥98%) or ammonium dicyanamide 6 (for preparation, see ref 24) or dicyandiamide 7 (Avocado, 99%) or melamine 1a (Fluka, purum, ≥99% (NT)). The commercial products were used as purchased: 80 mg of starting material (1.90 mmol of 5, 0.95 mmol of 6, 0.95 mmol of 7, or 0.63 mmol of 1a, respectively) was filled into a glass ampule (outer diameter, 16 mm; inner diameter, 12 mm). The ampule was sealed at a length of 120 mm and heated to 450 °C (heating rate: 1 °C min-1). After about 5 h at this temperature, the ampule was slowly (2 °C min-1) cooled to room temperature. After the ampule was opened, the typical smell of ammonia was detected. At the top of the ampule, colorless crystals were found which were identified by X-ray powder diffractometry as sublimated melamine. At the bottom, a white-beige powder containing melem was isolated. Melem C6N7(NH2)3. yield 60%. Anal. calcd for melem: H, 2.75; C, 33.03; N, 64.22. Found: H, 2.98; C, 32.62; N, 62.04.
