Metal-Determined Explosive Characteristics of M(NO₃)₂(1-AT)_x of Thermal and Laser Ignition (M²⁺ = Cr²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺; x = 2 or 3)

Optical and thermal ignition are two common pathways to initiate the explosion of primary explosives, where laser ignition is a more reliable and safer initiation method. Caused by the current-applied laser igniter with the wavelength of 1064 or 915 nm, the energetic complexes with strong absorption in the near-infrared (NIR) region are possibly applied as laser-ignited explosives. Recently, [Cu(NO₃)₂(1-AT)₃] complex has been synthesized with excellent NIR absorption properties, where 1-amino-5H-tetrazole (1-AT) has been proved to be a promising laser-ignited energetic ligand. To confirm the structure-thermal/optical explosive characteristics, based on the structure of synthesized [Cu(NO₃)₂(1-AT)₃], the commonly used transition-metal cations (M²⁺ = Cr²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) have been selected to construct the series of complexes of M(NO₃)₂(1-AT)_x (x = 2 or 3) theoretically. Car-Parrinello molecular dynamics (CPMD) method has been applied to unveil the role of center metals in the initiation and growth pathways. Time-dependent density functional theory (TD-DFT) method is used to explore their charge-transfer (CT) characteristics. The optical characteristic of the metal complex is mainly determined by the behaviors of the 3d electrons of center metals in excitation, where the activity of β-d electrons is an important factor to affect the NIR characteristic of complexes.