Synthesis and crystal structures of chromium and molybdenum complexes containing the 2,4,6-tris(trifluoromethyl)phenyl ligand

Complexes [Cr(NR)2Cl2] react with Li(fmes) to yield [Cr(NR)2(fmes)2], where fmes=2,4,6-(CF3)3C6H2. X-ray diffraction studies of the newly synthesised complex with R=adamantyl, and the previously known one with R=tert-butyl, have revealed tetrahedral coordination of the metal, complemented by two secondary Cr⋯F interactions with ortho-CF3 groups of the fmes ligands. The reaction of [Mo(NC6H3iPr2-2,6)2Cl2(dme)] with Li(fmes) gave a dimeric complex [Mo(NC6H3iPr2-2,6)2(fmes)Cl·LiCl(dme)]2. The X-ray structure of the latter (as its pentane solvate) shows a double-ribbon Mo2Li2Cl4 arrangement, with two Cl atoms μ2-bridging between Mo and Li, and two others μ3-bridging between one Mo and two Li atoms.