The synthesis and characterization of a series of first-row aryl transition metal derivatives of the simplest dialkylamido ligand NMe2 are reported. The complexes Cr{Ar'Cr(mu-NMe2)(2)}(2) (1) and {Ar'M(mu-NMe2)}(2) (M = Mn (2), Fe (3); Ar' = C6H3-2,6-(C6H3-2,6-'Pr-2)(2)) were obtained by reaction of the aryl metal halides {Ar'M(mu-X)}(2) (M = Cr, X = Cl; M = Fe, X = Br) or {Li(THF)Ar'Mnl(2)}(2) with LiNMe2 in a 1:2 ratio. A similar reaction of {(ArCo)-Co-#(mu-l)}(2) (Ar-# = C6H3-2,6-(C6H2-2,4,6-Me-3)(2)) and LiNMe2 in hexanes gave the unusual complex {(ArCo)-Co-#(mu-l)(eta(1)-CH2=NCH3)}(2) (4), in which the NMe2 ligand is dehydrogenated to afford a complexed imine. Complexes 1-4 were characterized by X-ray crystallography, UV-vis spectroscopy, and magnetic measurements. In the unique trinuclear complex 1, the central chromium(II) ion is bound to four NMe2 groups in a square planar fashion The NMe2 groups also bridge to the two outer chromium(II) ions, which are bound to a terminal A group to yield a rare example of three-coordinate T-shaped geometry at these atoms. In the dimers 2 and 3, each metal center is coordinated to a terminal terphenyl ligand and two bridging NMe2 groups to give a distorted trigonal planar geometry. In contrast, the reaction of LiNMe2 with {(ArCo)-Co-#(mu-1)}(2) in a 2:1 ratio did not yield an amido product; instead, the NMe2 ligand underwent hydrogen elimination. As a result, in the dimeric structure of 4, each cobalt ion is coordinated to a terphenyl ligand, two bridging iodides, and a neutral methylimine ligand, CH2=NCH3, to yield a very distorted tetrahedral cobalt(II) coordination environment. The magnetic properties of 1-4 revealed antiferromagnetic exchange coupling between the metal ions with J = -47(1) cm(-1) and J(13) = -25(1) cm(-1) for 1, J = -38(1) cm(-1) for 2, J = -75(3) cm(-1) for 3, and J = -32(4) cm(-1) for 4; the latter compound exhibited an unusually large temperature independent contribution to its molar magnetic susceptibility.