Donor-stabilised molecular Mg/Al-bimetallic hydrides†
Abstract
Treatment of dimethylmagnesium with dimethylaluminum hydride in common ethereal solvents led to the bimetallic monomagnesium addition compounds [(do)xMg{(μ2-H)(AlMe3)}2] (do = thf, x = 4, do = Et2O, x = 3; do = dme, x = 2). Utilization of methyl tert-butyl ether (mtbe) resulted in alkyl/hydrido overexchange and formation of an 8-membered ring structure of composition [(mtbe)2Mg{(μ2-H)(AlMe3)(μ2-H)(μ2-H)(AlMe2)}]2. Salt metathesis of [(thf)4Mg{(μ2-H)(AlMe3)}2] with potassium 1,2,3,4,5-pentamethyl-cyclopentadienide (KCp*) gave [Cp*Mg{(μ2-H)(AlMe3)}(thf)2] featuring a rare isolable magnesium half-sandwich hydride complex. Furthermore, magnesium hydride-inherent reactivity was proven for [(thf)4Mg{(μ2-H)(AlMe3)}2] by the selective reduction of pyridine to 1,4-dihydropyridide (1,4-DHP) at ambient temperature and the hydromagnesiation of 1-hexene in the absence of any transition metal catalyst (low conversion).