Single‐Source Cyanurate Precursor for Making Manganese Carbodiimide and the Second Harmonic Generation Effect of the Intermediate Manganese Monohydrocyanurate Mn(HC ₃ N ₃ O ₃ )

Two manganese cyanurate compounds, Mn(H 2 C 3 N 3 O 3 ) 2 (H 2 O) 4 and Mn(H 2 C 3 N 3 O 3 ) 2 (H 2 O) 7 were prepared and structurally characterized. The thermal conversion cascade of Mn(H 2 C 3 N 3 O 3 ) 2 (H 2 O) 4 is explored by combined differential thermoanalytic and thermogravimetric studies, revealing this compound as a useful precursor for the formation of pure Mn(CN 2 ). During this process, manganese monohydrocyanurate Mn(HC 3 N 3 O 3 ) (MHCY) appears as a new compound that was refined to crystallize in a noncentrosymmetric space group. The noncentrosymmetric space group and the presence of a cyanurate ring gave rise to the study of the second‐order nonlinear susceptibility of MHCY single crystals, revealing a remarkable second harmonic generation response.