The acidity and the process for deprotonation of (eta(6)-toluene)Fe(H)(2)(SiCl3)2 in acetonitrile were studied with pyridine derivatives. (eta(6)-Toluene)Fe(H)(2)(SiCl3)(2) is a very strong acid and deprotonates in acetonitrile. The formation of hydrogen-bonded complexes M-H ... N prior to deprotonation is observed when pyridine, 2,6-lutidine, and 2,2’-bipyridine are used. With 1 equiv of bipyridine, the hydrogen-bonded species is quite stable, two hydrides are deprotonated, and [bpyH(2)](2+) is formed. The small Fe-57-hydride coupling constant (3.6 Hz) for (eta(6)-toluene)Fe(H)(2)(SiCl3)(2) is consistent with strong acidity of the compound. The 10.8 Hz coupling between Fe-57 and the hydride in [(eta(6)-toluene)Fe(H)(SiCl3)(2)](-) and (eta(6)-toluene)Fe(H)(py)(SiCl3) is similar to those observed in other Fe(II) hydride compounds. The observation of the coupling only between p-H and the hydride in [(eta(6)-toluene)Fe(H)(SiCl3)(2)](-) and (eta(6)-toluene)Fe(H)(py)(SiCl3) indicates that the configuration with the hydride trans to p-H is dominant in solution and the rotation of the toluene is not fast at room temperature.