A Linear Two-Coordinate Cr(II) Complex: Synthesis, Characterization, and Reactivity.

The synthesis and characterization of a linear two-coordinate Cr(II) amido complex, Cr{N( Bu)Dipp} (Dipp=2,6-diisopropylphenyl), from the reaction of 1 molar equivalent (equiv) of CrCl and 2 equiv. of LiN( Bu)Dipp is reported. Single-crystal X-ray diffractometry (SC-XRD) analysis revealed that it has a short Cr-N bond distance of 1.8878(9) Å, which could be attributed to the relatively less bulky nature of the amido ligand compared with reported systems. Furthermore, the oxidation reaction of the two-coordinate Cr(II) complex was explored. The oxidation reaction of Cr{N( Bu)Dipp} with the one-electron oxidants AgOTf and [FeCp ][BAr ] (BAr =[B{C H -3,5-(CF ) } ] ) afforded the trigonal planar three- and bent two-coordinate Cr(III) complexes Cr{N( Bu)Dipp} (OTf) and [Cr{N( Bu)Dipp} ][BAr ], respectively. The reaction of Cr{N( Bu)Dipp} with 1 equiv. of the organic azides AdN (Ad=1-adamantyl) and PhN afforded the three-coordinate Cr(IV) imido complexes Cr{N( Bu)Dipp} (NAd) and Cr{N( Bu)Dipp} (NPh), respectively. The reaction of Cr{N( Bu)Dipp} and two equiv. of Me NO afforded the Cr(VI) dioxo complex Cr{N( Bu)Dipp} (O) . The reaction of Cr{N( Bu)Dipp} with 1 equiv. of CyN=C=NCy resulted in the insertion of the carbodiimide into the Cr-N bond, with the formation of a three-coordinate Cr(II) complex. Finally, density functional theory (DFT) calculations were used to elucidate the electronic structure of these complexes.