A theoretical study of bonding and structure in tricoordinate amido complexes with different d(n) electron configurations is presented. The relative stability of the high- and low-spin states of [Co(NH2)(3)] is discussed, and the preferred orientation of the amido ligands relative to the coordination plane is analyzed for the high-spin state of the [M(NR2)(3)] compounds, where M = V(IV), Cr(III), Mn(III), Fe(III), Co(III), or Ni(II) and R = H or SiH3. Comparison of the computational results with experimental data provides information on the influence of electronic and steric effects. The existence of metal-ligand pi bonding is discussed in the context of the electron configurations, calculated bond distances, and spin-density distributions.