Synthesis and characterization of a novel precursor for BCN compound

A novel precursor for BCN compound, C ₃H ₆N ₆(H ₃BO ₃) ₂, was synthesized with C ₃H ₆N ₆ melamine and H ₃BO ₃ as raw materials in aqueous solution. The precursor was characterized by elementary analysis, XRD, FT-IR, electrospray mass spectrometry and single crystal X-ray diffraction. It revealed that the precursor contained the characteristic groups of C ₃H ₆N ₆ and H ₃BO ₃ such as triazine ring, NH ₂, and B-OH. The precursor crystallized in monoclinic space group P2 ₁/c, with the cell parameters a=0.35970(7) nm, b=2.0105(4) nm, c=1.4112(3) nm, β=92.07(3)°, Z=4. One crystallographically distinct C ₃H ₆N ₆ molecule and two H ₃BO ₃ molecules constituted the asymmetric unit of the precursor. A 3D supramolecular network was constructed by different hydrogen-bonding interactions between C ₃H ₆N ₆ and H ₃BO ₃ molecules. The precursor was further pyrolyzed at 1900°C under flowing N ₂ atmosphere. XRD and XPS analysis were applied for the characterization of the pyrolysis product. The results indicated that a new BCN ternary compound with turbostratic graphite structure was obtained. B-N, B-C, and C-N chemical bonds were established and there was no phase separation between graphite and h-BN, which suggests an atomic-level hybrid of B, C, and N elements in the compound. The BCN compound has lower carbon content and its empirical formula can be expressed as B ₃CN ₃.