Preparation and characterisation of dimolybdenum complexes containing fluorophenylimide ligands

Abstract

The arylimido complexes [Mo 2 O 2 (µ-NR)(µ-O)(η 5 -C 5 H 4 Me) 2 ] and [{MoO(µ-NR)(η 5 -C 5 H 4 Me)} 2 ] (R = C 6 H 4 F-2 or C 6 H 4 CF 3 -2) were obtained from the reaction between [{Mo(η 5 -C 5 H 4 Me)(CO) 3 } 2 ] and the appropriate nitrobenzene RNO 2 . In contrast, the corresponding reaction between O 2 NC 6 H 3 F 2 -2,6 and [{Mo(η 5 -C 5 H 4 Me)(CO) 3 } 2 ] generated two isomeric bis(imido) complexes [{MoO(µ-NC 6 H 3 F 2 -2,6)(η 5 -C 5 H 4 Me)} 2 ], which were separated by column chromatography. Hydrogen-1 and 19 F NMR spectroscopic studies suggested that [{MoO(µ-NC 6 H 4 CF 3 -2)(η 5 -C 5 H 4 Me)} 2 ] exists in two chemically inseparable isomeric forms. The molecular structures of [Mo 2 O 2 (µ-NC 6 H 4 F-2)(µ-O)( η 5 -C 5 H 4 Me) 2 ], [Mo 2 O 2 (µ-NC 6 H 4 CF 3 -2)(µ-O)(η 5 -C 5 H 4 Me) 2 ] and the centrosymmetric isomer of [{MoO(µ-NC 6 H 4 CF 3 -2)(η 5 -C 5 H 4 Me)} 2 ] have been determined by single-crystal X-ray diffraction. In each structure the central Mo 2 (µ-O)(µ-NR) or Mo 2 (µ-NR) 2 core is planar with a trans configuration of methylcyclopentadienyl ligands and a substantial twist angle between the phenyl rings and the metallacycle planes.