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

Complexes [Cr(NR)(2)Cl-2] react with Li(fmes) to yield [Cr(NR)(2)(fmes)(2)], where fmes = 2,4,6-(CF3)(3)C6H2. 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 (CrF)-F-... interactions with ortho-CF, groups of the fmes ligands. The reaction of [Mo(NC6H3' Pr-2-2,6)(2)Cl-2(dme)] with Li(fines) gave a dimeric complex [Mo(NC6H3' Pr-2-2,6)(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 mu (2)-bridging between Mo and Li, and two others mu (3)-bridging between one Mo and two Li atoms. (C) 2001 Elsevier Science B.V. All rights reserved.