Independent Control of Optical and Explosive Properties: Pyrazole–Tetrazine Complexes of First Row Transition Metals

Complexes of 3-amino-6-(3,5-dimethylpyrazole)­tetrazine)
(NH2TzDMP, 1) and 3-(3,3′-dinitroazetidine)-6-(3,5-dimethylpyrazole)­tetrazine)
(DNAZTzDMP, 2) with first row transition metal centers
were synthesized. Reactions of FeII(H2O)6(BF4)2 and Fe­(NO3)3·9H2O with 1 and 2 both
led to complexes of the form [(RTzDMP)3Fe]­X2 (X = BF4, R = NH2 (3), DNAZ (4); X = NO3, R = NH2 (5), DNAZ (6)), which showed intense MLCT bands in the
visible region of the spectrum. Ligands 1 and 2 also reacted with CuII(NO3)2·5/2H2O to form [(RTzDMP)2Cu­(NO3)]­[NO3] (R = NH2 (7), DNAZ (8)) in addition to reacting with CuI(CH3CN)4(PF6) to form [(RTzDMP)2Cu]­[PF6] (R = NH2 (9), DNAZ (10)).
Lastly reactions of 1 and 2 with Co­(NO3)2·6H2O and Ni­(NO3)2·6H2O led to [(NH2TzDMP)2Co­(H2O) (NO3)]­[NO3] (11), [(DNAZTzDMP)2Co­(H2O)2]­[NO3]2 (12), [(NH2TzDMP)3Ni]­[NO3]2 (13), and [(DNAZTzDMP)2Ni­(H2O)2]­[NO3]2 (14). The complexes
display rich electrochemical and photophysical properties that are
unaffected by derivation with explosive groups.