This paper describes the synthesis and characterization of several salts of 4,4',5,5'-tetranitro-2,2'-biimidazolate (N4BIM). Each of the salts were characterized chemically, thermally, morphologically, as well as with respect to destructive stimuli (impact, electrostatic discharge, friction, thermal). These salts show promise as propellant ingredient additives, and in particular, the bis-triaminoguanidinium salt of N4BIM displays excellent burn rate and combustion behavior. Our combustion studies have shown that TAGN4BIM displays a fast burning rate and has the lowest pressure dependence exponent yet measured for a triaminoguanidinium salt.