Inorganic Chemistry, Vol.52, No.23, 13584-13593, 2013
Dispersion Force Stabilized Two-Coordinate Transition Metal-Amido Complexes of the -N(SiMe3)Dipp (Dipp = C6H3-2,6-Pr-2(i)) Ligand: Structural, Spectroscopic, Magnetic, and Computational Studies
A series of high spin, two-coordinate first row transition metal amido complexes, M{N(SiMe3)Dipp}(2) {M = Fe (1), Co (2), or Ni (3); Dipp = C6H3-2,6-Pr-2(i)} and a tetranuclear C-H activated chromium amide, [Cr{N(SiMe2CH2)-Dipp}(2)Cr](2)(THF) (4), were synthesized by reaction of their respective metal dihalides with 2 equiv of the lithium amide salt. They were characterized by X-ray crystallography, electronic and infrared spectroscopy, SQUID magnetic measurements, and computational methods. Contrary to steric considerations, the structures of 1-3 display planar eclipsed M{NSiC(ipso)}(2) arrays and short M-N distances. DFT calculations, corrected for dispersion effects, show that dispersion interactions involving C-H-H-C moieties likely stabilize the structures by 21.1-29.4 kcal mol(-1), depending on the level of the calculations employed. SQUID measurements confirm high spin electron configurations for all the complexes and substantial orbital contributions for 1 and 2.