In this paper we explore several issues surrounding the catalytic reduction of dinitrogen by molybdenum compounds that contain the [(HIPTNCH2CH2)(3)N](3-) ligand (where HIPT = 3,5-(2,4,6-i-Pr3C6H2)(2)C6H3). Four additional plausible intermediates in the catalytic dinitrogen reduction have now been crystallographically characterized; they are MoN= NH (Mo = [(HIPTNCH2CH2)(3)N]Mo), [Mo=NNH2][BAr'(4)] (Ar' = 3,5-(CF3)(2)C6H3)[Mo=NH][BAr'4], and Mo(NH3). We also have crystallographically characterized a 2,6-lutidine complex, Mo(2,6-Lut)(+), which is formed upon treatment of MoH with [2,6-LutH][B(C6F5)(4)]- We focus on the synthesis of compounds that have not yet been isolated, which include Mo=NNH2, Mo=NH, and Mo(NH2). Mo=NNH2, formed by reduction of [Mo=NNH2](+), has not been observed. It decomposes to give mixtures that contain two or more of the following: MoN=NH, Mo=-N, Mo(NH3)(+), Mo(NH3), and ammonia. Mo=NH, which can be prepared by reduction of [Mo=NH](+), is stable for long periods in the presence of a small amount of CrCP2*, but in the absence of CrCP2*, and in the presence of Mo=NH+ as a catalyst, Mo=NH is slowly converted into a mixture of Mo=-N and Mo(NH2). Mo(NH2) can be produced independently by deprotonation of Mo(NH3)(+) with LiN(SiMe3)(2) in THF, but it decomposes to Mo=N upon attempted isolation. Although catalytic reduction of dinitrogen could involve up to 14 intermediates in a "linear" sequence that involves addition of "external" protons and/or electrons, it seems likely now that several of these intermediates, along with ammonia and/or dihydrogen, can be produced in several reactions between intermediates that themselves behave as proton and/or electron sources.