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).