Synthesis and Characterization of Magnesium-Hydride Complexes with Alkylene-Bridged Bis(β-diketiminate) Ligands

Abstract

Three magnesium-hydride complexes (3a−c) supported by alkylene-bridged bis(β-diketiminate) ligands have been synthesized by reacting the respective dinuclear magnesium bis(trimethylsilyl)amide complexes 1a−c with phenylsilane; 3a can alternatively be accessed by the same reaction but starting from the dinuclear magnesium n-butyl complex 2a. Single-crystal X-ray diffraction revealed a dimeric structure in the solid state, with inter-and intramolecular μ 2 -hydrides bridging the magnesium centers. The properties of the tetranuclear complexes are strongly impacted by the alkylene bridge. While 3b turned out to be virtually insoluble in common solvents, solutions of 3a and 3c are readily obtained, and NMR spectroscopic data indicate that the dimers persist in solution. 3a readily reacts with phenylacetylene, affording the tetranuclear magnesium complex 4a with bridging phenylacetylide groups.

Cross-coupling of CO and an isocyanide mediated by a tetrameric magnesium hydride cluster

“… 49 Related species have recently been documented from Kretschmer's group. 50 Previously we showed that 1a reacts with two equiv. CO by a deoxygenative pathway leading to the formation of a coordinated acetaldehyde enolate.…”

Low oxidation state and hydrido group 2 complexes: synthesis and applications in the activation of gaseous substrates

“…82 An alternative route to ionic hydride complexes [ 67 ][Al(OC(CF 3 ) 3 ) 4 ] and [ 68 ][Al(OC(CF 3 ) 3 ) 4 ] from [BDI Dipp Mg⋯C 6 D 6 ][Al(OC(CF 3 ) 3 ) 4 ] has also been presented by Hill and co-workers. 83 Joining two β-diketiminate ligands through appropriate alkyl or aryl N , N -linkers has been exploited by the research groups of Harder and Kretschmer to access 69 , 75 70 74 and 74 , 84 and 71–73 , 85 respectively. A fused β-oxo-δ-diiminate ligand was recently used to gain entry to a tetranuclear magnesium( ii ) hydride complex ( 75 ) which contains a rare example of a four-coordinate hydride ligand in a near square planar geometry.…”

Deoxygenative Coupling of CO with a Tetrametallic Magnesium Hydride Complex

“…[14][15][16] The tetrametallic magnesium hydride cluster 1 was originally reported by Harder and co-workers, related species have recently been reported by Kretschmer and coworkers. [17][18][19] Reaction of 1 with CO (1 atm. 60 °C) led to selective formation of 2 (Figure 2a).…”