Alkaline and alkaline earth salts of 5-ferrocenyl-1H-tetrazole. Synthesis, characterization and catalytic effects on thermal decomposition of energetic compounds

5-Ferrocenyl-1H-tetrazole (HFcTz) was deprotonated using alkali hydroxides or carbonates, yielding the corresponding metal salts [Li-4(H2O)(8)(FcTz)(4)]center dot 2CH(3)CN (1), NaFcTz (2), KFcTz (3), RbFcTz center dot H2O (4) and [Cs-2(H2O)](FcTz)(2) (5). Ca(FcTz)(2)center dot 4H(2)O (6) was prepared by deprotonation of HFcTz with CaO under reflux. Sr(FcTz)2 center dot 4H(2)O (7) and [Ba(H2O)6](FcTz)2 center dot H2O (8) were synthesized using HFcTz with Sr(OH)(2)center dot 8H(2)O and Ba(OH)(2)center dot 8H(2)O, respectively. All salts were characterized by FT-IR, UV Vis and elementary analysis. The crystal structures of HFcTz, 1, 2, 5, 8 and [Ba-2(H2O)(8)](FcTz)(4)center dot 5H(2)O (8') were additionally characterized by single crystal X-ray diffraction. TG and DSC analyses revealed that the new compounds have high thermal stability. Cyclic voltammetry investigations suggested that the compounds except 8 exhibit redox waves for the ferrocenyl groups and are considered as quasi-reversible/irreversible redox systems. Their catalytic effects on the thermal degradation of ammonium perchlorate (AP), 1,3,5-trinitro-1,3,5-triazacyclo-hexane (RDX) and 1,2,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) were evaluated by DSC technique. All the new compounds exhibit high catalytic activity for the thermal decomposition of AP and their catalytic activity is higher than that of HFcTz. Most of the new compounds can also accelerate the thermal degradation of RDX. (C) 2015 Elsevier Ltd. All rights reserved.