Hexakis (propargyl-1H-tetrazole) Iron(II) X2 [X = BF4, ClO4]—Spin Switchable Complexes with Functionalization Potential and the Myth of the Explosive SCO Compound

High-Energy-Density Material with Magnetically Modulated Ignition

Preparation of a redox-frustrated high-energy-density energetic material is achieved by gentle protolysis of Mn[N(SiMe3)2]2 with the perchlorate salt of the tetrazolamide [H2NtBuMeTz]ClO4 (Tz = tetrazole), yielding the Mn6N6 hexagonal prismatic cluster, Mn6(μ3-NTztBuMe)6(ClO4)6. Quantum mechanics-based molecular dynamics simulations of the decomposition of this molecule predict that magnetic ordering of the d5 Mn2+ ions influences the pathway and rates of decomposition, suggesting that the initiation of decomposition of the bulk material might be significantly retarded by an applied magnetic field. We report here experimental tests of the prediction showing that the presence of a 0.5 T magnetic field modulates the ignition onset temperature by +10.4 ± 3.9 °C (from 414 ± 4 °C), demonstrating the first example of a magnetically modulated explosive.

Bifunctional Fe(II) spin crossover-complexes based on ω-(1H-tetrazol-1-yl) carboxylic acids

To increase the supramolecular cooperativity in Fe(ii) spin crossover materials based on N1-substituted tetrazoles, a series of ω-(1H-tetrazol-1-yl) carboxylic acids with chain-lengths of C2-C4 were synthesized. Structural characterization confirmed the formation of a strong hydrogen-bond network, responsible for enhanced cooperativity in the materials and thus largely complete spin-state transitions for the ligands with chain lenghts of C2 and C4. To complement the structural and magnetic investigation, electronic spectroscopy was used to investigate the spin-state transition. An initial attempt to utilize the bifunctional coordination ability of the ω-(1H-tetrazol-1-yl) carboxylic acids for preparation of mixed-metallic 3d-4f coordination polymers resulted in a novel one-dimensional gadolinium-oxo chain system with the ω-(1H-tetrazol-1-yl) carboxylic acid acting as μ2-η2:η1 chelating-bridging ligand.

Cooperativity in spin crossover materials as ligand's responsibility – investigations of the Fe(ii) – 1,3-bis((1H-tetrazol-1-yl)methyl)bicyclo[1.1.1]pentane system

In [Fe(ppditz)₃]X₂, X = BF₄⁻, ClO₄⁻, PF₆⁻ spin crossover complexes the observed cooperativity originates only from the rigidity and internal strain of the ligand.