Closing the Gap: Synthesis of Three Isomeric N,N-Ditetrazolymethane Ligands and Their Coordination Proficiency in Adaptable Laser Responsive Copper(II) and Sensitive Silver(I) Complexes.

Abstract

N,N-Substituted ditetrazolylalkanes are widely used molecules in the field of coordination chemistry and are known with different alkyl chain lengths. The missing fragment within this row is presented by the elementary methylene-bridged ditetrazoles. The three different isomers (di(tetrazol-1-yl)methane (1,1-dtm, 1), (tetrazol-1-yl)(tetrazol-2-yl)methane (1,2-dtm, 2), and di(tetrazol-2-yl)methane (2,2-dtm, 3)) were synthesized in a convenient one-step reaction. All of them were successfully incorporated as neutral ligands in 15 new energetic coordination compounds (ECC) based on Cu2+ and Ag+ as well as different anions (nitrate, picrate (PA), styphnate (TNR), trinitrophloroglucinate (TNPG), and perchlorate) revealing an extraordinary coordination behavior of the ligands compared to other 5H-ditetrazolylalkanes. All compounds were extensively characterized using single-crystal X-ray diffraction experiments, infrared spectroscopy (IR), elemental analysis (EA), and differential thermal analysis (DTA). Furthermore, the sensitivities were determined using standard techniques, and Hirshfeld surface calculations of the ligands were applied to explain their significant divergences to external stimuli. The ECC possess very good exothermic decomposition temperatures up to 242 °C. The ignition of all colored complexes was tested in laser experiments, and two copper(II) perchlorate compounds showed promising results in classic initiation capability tests using pentaerythritol tetranitrate (PETN).