Dioxomolybdenum(VI) complexes with tri- and tetradentate aminobis(phenolate)s

The reactions of tridentate ligands, bis(2-hydroxy-3,5-dimethylbenzyl)methylamine (H2ONOMe) and bis(2-hydroxy-3-tert-butyl-5-methylbenzyl)methylamine (H2ONO/Bu) with [MoO2(acac)(2)] (1) in methanol lead to the precipitation of monomeric dioxomolybdenum(VI) complexes [MoO2(ONOMe)(MeOH)] . MeOH (2a) and [MoO2(ONO/Bu)(MeOH)] . MeOH (2b), respectively. Identical reactions n acetonitrile provide dimeric complexes [Mo2O2(mu-O)(2)(ONOMe)(2)] (3a) and [Mo2O2(mu-O)(2)(ONO/Bu)(2)] (3b). The reactions of 1 with tetradentate ligands, N,N'-bis(2-hydroxy-3,5-dimethylbenzyl)-N,N'-dimethylethane-1,2-diamine (H2ONNOMe) and N,N'-bis(2-hydroxy-3,5-di-tert-butylbenzyl)-N,N'-dimethylethane-1,2-diamine (H2ONNOtBu) yield monomeric complexes [MoO2(ONNOMe)] (4a) and [MoO2(ONNOtBu)] (4b), respectively. All studied complexes catalyse oxotransfer reactions between DMSO and benzoin or triphenyl phosphine. Complexes can also be activated by Et2AlCl to polymerise norbornene. (C) 2004 Elsevier Ltd. All rights reserved.