Cationic magnesium hydride [MgH] stabilized by an NNNN-type macrocycle.

A magnesium hydride cation [(L)MgH] supported by a macrocyclic ligand (L = MeTACD; 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane) has been prepared by partial protonolysis of a mixed amide hydride [(L)MgHMg{N(SiMe)}] and shown to undergo a variety of reactions with unsaturated substrates, including pyridine.

1,4-Dihydropyridyl complexes of magnesium: synthesis by pyridine insertion into the magnesium-silicon bond of triphenylsilyls and catalytic pyridine hydrofunctionalization.

Magnesium bis(triphenylsilyl) [Mg(SiPh3)2(THF)2]·THF (1) reacted with a stoichiometric amount of pyridine to give the magnesium 4-(triphenylsilyl)dihydropyridyl complex [Mg(NC5H5-4-SiPh3)2(THF)3] (2). Using an excess of pyridine, a mixture of magnesium dihydropyridyl [Mg(NC5H6)2(py)4] (3) and 4-(triphenylsilyl)pyridine was formed. Complex 3 underwent exchange with pyridine-d5 at 25 °C to give [Mg(NC5D5H-4)2(py-d5)4] (3-HD).

Donor-influenced Structure-Activity Correlations in Stoichiometric and Catalytic Reactions of Lithium Monoamido-Monohydrido-Dialkylaluminates.

A series of heteroleptic monoamido-monohydrido-dialkylaluminate complexes of general formula [iBu AlTMPHLi⋅donor] were synthesized and characterised in solution and in the solid state. Applying these complexes in catalytic hydroboration reactions with representative aldehydes and ketones reveals that all are competent, however a definite donor substituent effect is discernible. The bifunctional nature of the complexes is also probed by assessing their performance in metallation of a triazole and phenylacetylene and addition across pyrazine.

Silyl-Hydrosilane Exchange at a Magnesium Triphenylsilyl Complex Supported by a Cyclen-Derived NNNN-Type Macrocyclic Ligand.

The magnesium triphenylsilyl complex [(MeTACD)Mg(SiPh)] (2) was synthesized from magnesium bis(triphenylsilyl) [Mg(SiPh)(THF)]·THF (1; THF = tetrahydrofuran) and the NNNN-type macrocyclic amidotriamine proligand (MeTACD)H ((MeTACD)H = Me[12]aneN = 1,4,7-trimethyl-1,4,7,10-tetraazacyclododecane). Treating 2 with AlR (R = Me, Et) gave the magnesium triphenylsilyl complexes with "blocked" amido function [(MeTACD·AlR)Mg(SiPh)] (3a: R = Me; 3b: R = Et). Instead of forming a Mg-H bond upon reaction with dihydrogen or hydrosilanes, 2 and 3a,b underwent rapid silyl-silane exchange with hydrosilanes.