Stabilizing Magnesium Hydride Complexes with Neutral Ligands

Abstract

The reaction of Mg[N(SiMe 3 ) 2 ] 2 with PhSiH 3 in benzene at room temperature gave a white precipitate of approximate constitution MgH 1.5 N′′ 0.5 . This undefined hydride rich Mg salt can be dissolved by addition of well-known neutral donors, such as PMDTA, DABCO or the N-heterocyclic carbene I Me iPr (N,N′-diisopropyl-2,3-dimethylimidazol-2-ylidine). This allowed for crystallization and structural characterization of five new magnesium hydride complexes: Mg 2 (μ-H) 2 N′′ 2 ·(PMDTA) (1), Mg 4 (μ-H) 6 N′′ 2 ·(PMDTA) 2 (2), Mg 5 (μ-H) 7 N′′ 3 ·(PMDTA) 2 (3), Mg 2 -(μ-H) 2 N′′ 2 ·(DABCO) 2 (4) and Mg 2 (μ-H) 2 N′′ 2 ·(I Me iPr) 2 (5). The PMDTA complexes 1-3 were only isolated as mixtures that could not be separated but complexes 4 and 5 have been fully [a]

Molecular Main Group Metal Hydrides

“…As part of the same study that resulted in the isolation of compound 108 , Harder and coworkers reported that reaction of Mg­[N­(SiMe 3 ) 2 ] 2 with PhSiH 3 in benzene at room temperature gave a white precipitate of approximate constitution MgH 1.5 {N­(SiMe 3 ) 2 } 0.5 , and which could be dissolved by addition of the neutral N -donors N , N , N ′, N ′′, N ′′-pentamethyl­diethylenetriamine (PMDTA) and 1,4-diazabicyclo­[2.2.2]­octane (DABCO) (Scheme ). This procedure enabled the structural characterization of four magnesium hydride complexes, [Mg 2 (μ-H) 2 {N­(SiMe 3 ) 2 } 2 ·(PMDTA)] ( 109 ), [Mg 4 (μ-H) 6 {N­(SiMe 3 ) 2 } 2 ·(PMDTA) 2 ( 110 ), [Mg 5 (μ-H) 7 {N­(SiMe 3 ) 2 } 3 ·(PMDTA) 2 ] ( 111 ), and [Mg 2 (μ-H) 2 {N­(SiMe 3 ) 2 } 2 ·(DABCO) 2 ] ( 112 ) (Scheme ). The PMDTA complexes 109 – 111 were only isolated as inseparable mixtures, whereas compound 112 was isolated in pure form and fully characterized.…”

“…In 2019, effectively contemporaneous reports by the groups of Gilliard and Harder demonstrated that the magnesium–hydride complexes, [(ImMe 2 i Pr 2 )­Mg­{N­(SiMe 3 ) 2 }­(μ-H)] 2 ( 107 , ImMe 2 i Pr 2 = (MeCN i Pr) 2 C:) and [(ImMe 2 i Pr 2 )­Mg­(μ-H)­(ASCP)] 2 ( 108 , ASCP = 2,2,5,5-tetramethyl-2,5-disila-1-azacyclopent-1-yl), were accessible by an analogous route to that employed in the synthesis of [(IPr) 2 Mg 4 H 6 {N­(SiMe 3 ) 2 } 2 ] ( 106 , Scheme b). , Both compounds 107 and 108 were shown to exist in the solid state as centrosymmetric dimers with [Mg 2 (μ-H) 2 ] 2+ cores and provided sharp Mg–H singlet resonances at 4.28 and 4.29 ppm in their respective 1 H NMR spectra in C 6 D 6 .…”

Magnesium hydrides bearing sterically demanding amidinate ligands: synthesis, reactivity and catalytic application

“…S2 †). 4,[7][8][9][13][14][15][16][17][18][19][20][21][22] Compound 3b can also be made using a more facile synthetic route, reacting LH 2 Scheme 1 Synthetic procedure for the formation of compounds 1a, 1b and 2b.…”

Heterometallic Mg−Ba Hydride Clusters in Hydrogenation Catalysis

“…The NPA charges for Mg in 1*-3* compare well to those in recently reported Mg hydride dimer complexes stabilized by the (Me 3 Si) 2 N À anion and neutral Lewis bases: Mg + 1.63/ + 1.67. [65] Charges on the hydrides in the latter Mg hydride dimer (H -0.79) are at the lower end of those in 1*-3*. The NPA charges for Ba in 1*-3* compare well to those in the related (HBaN") 7 cluster (F in Scheme 1) which vary from + 1.68 to + 1.77.…”