The substitution of PPh3 for a carbonyl group at the {Fe(CO)(3)} moiety in [Fe-2(CO)(4)(kappa(2)-phen)(mu-pdt)] results in the formation of the trisubstituted complex [Fe-2(CO)(3)(PPh3)(kappa(2)-phen)(mu-pdt)] (2). Unlike its tetracarbonyl precursor, the protonation of 2 at low temperature does not afford any apparent transient terminal hydride species. Hydride formation for [Fe-2(CO)(3)(L)(kappa(2)-phen)(mu-pdt)] (L = PPh3, CO) species is also studied by density functional theory calculations, which show that activation barriers to give terminal and bridging hydrides can be remarkably close for this class of organometallic compounds.