Chromium(III) Bis(diketiminate) Complexes

Reaction of two equivalents of the lithium salt of N,N′-dibenzyl-2-amino-4-iminopent-2-ene, nacnacBnLi(THF), 1, with CrCl3(THF)3 or CrCl3 yielded nacnacBn2CrCl as a putative intermediate, which could be trapped by addition of 2,6-xylyl isocyanide to give the isocyanide-coordinated, octahedral complex nacnacBn2CrCl(CNC6Me2H3), 5. In the absence of isocyanide, ligand redistribution to the homoleptic tris(diketiminate) complex nacnacBn3Cr, 3, occurred upon concentration, standing, or workup with apolar solvents. Workup with diethyl ether afforded the bimetallic-bridged complex nacnacBn2Cr(μ-Cl)2Li(THF)2, 6. Reaction of CrCl3(THF)3 with one equivalent of 1 afforded the monodiketiminate complexes {nacnacBnCrCl(THF)(μ-Cl)}2 or {nacnacBnCrCl(μ-Cl)}2, depending on reaction conditions. Reaction of CrCl2(THF)x with two equivalents of 1 gave rise to nacnacBn2Cr, 4. Complexes 3−6 were characterized by X-ray diffraction studies. All octahedral complexes display a cis geometry with two nacnac ligands in a distorted, boat-like conformation.