Dioxomolybdenum(VI) and -tungsten(VI) complexes with tetradentate aminobis(phenol)s

Aminobis(phenol) ligands (H2Ln) carrying either a dimethylamino, a pyridyl or a methoxy sidearm donor were used in the preparation of new tungsten and molybdenum complexes. Treatment of [W(eg)3] (eg = 1,2-ethanediolate dianion) with H2Ln under hydrolytic conditions in a CHCl3–MeOH mixture gave the cis-dioxotungsten(VI) complexes [WO2(Ln)] in good yields. The corresponding molybdenum complexes [MoO2(Ln)] were prepared from [MoO2(acac)2] and respective ligands. The solid-state structures of two molybdenum and one tungsten compounds were determined by single crystal X-ray diffraction, which revealed that the dianionic aminobis(phenolate) backbones of the ligands have coordinated to the metal centre as [O,N,O] donors, whereas the last coordination sphere has been occupied by a N or O donor atom of the ligand sidearm. All synthesized new complexes can catalyse the oxotransfer reaction between benzoin and dmso at 120 °C.

Graphical abstractAminobis(phenol) ligands (H2Ln) carrying either a dimethylamino, a pyridyl or a methoxy sidearm donor react with [W(eg)3] (eg = 1,2-ethanediolate dianion) or [MoO2(acac)2] to yield mononuclear dioxometal(VI) complexes of type [MO2(Ln)].Figure optionsDownload full-size imageDownload as PowerPoint slide