Red-orange crystals of the tris(imido) anion of molybdenum, [Mo(NAr)(3)Cl](-) (3, Ar = 2,6-C6H3-i-Pr-2) are isolated as the [Li(THF)4](+) salt from the rapid workup of the reaction between Mo(NAr)(2)Cl-2(THF)(2) (1) and 2 equiv of LiNHAr (in THF). [Li(THF)(4)][Mo(NAr)(3)Cl] (3) constitutes the kinetic product of this reaction since it readily reacts with byproduct H2NAr to afford stable Mo(NAr)(2)(NHAr)(2) (4). Complex 3 undergoes nucIeophilic attack by PMe(3), MeLi, Me(3)CCH(2)Li, or Br- to form Mo(NAr)(3)(PMe(3)) (5), [Li(THF)(4)][Mo(NAr)(3)Me] (6), [Li(THF)(4)][Mo(NAr)(3)(CH(2)CMe(3))] (7), and [n-Bu(4)N][Mo(NAr)(3)Br] (8), respectively. The imido ligands in these tris(imido) complexes are also subject to electrophilic attack by a range of electrophiles to afford four- or five-coordinate bis(imido) complexes of Mo(VI), Thus, Mo(NAr)(2)(OCMe(3))(2) (9) is prepared from Mo(NAr)(3)(PMe(3)) (5) and Me(3)COH, while metallacyclic Mo[NArC(O)NPh](NAr)(2)(PMe(3)) (10) arises from Mo(NAr)(3)(PMe(3)) (5) and PhNCO. [Li(THF)(4)][Mo(NAr)(3)Cl] (3) is readily protonated by cyclopentadiene C5H6 to provide CpMo(NAr)(2)(NHAr) (11, Cp = [eta(5)-C5H5](-)) The reaction of [HNMe(3)]BPh(4) with [Li(THF)(4)][Mo(NAr)(3)(CH(2)CMe(3))] (7) protonates an imido ligand rather than the alkyl to give Mo(NAr)(2)(NHAr)(CH(2)CMe(3)) (12). The electronic structure of the d(0) Mo(=NR)(3) functional group is described in terms of related M(sigma+2 pi)(3) complexes with 3-fold symmetry.