Unusual reaction pathways of gallium(III) silylamide complexes

Abstract

The synthesis of homoleptic gallium(III) bis(dimethylsilyl)amide Ga[N(SiHMe 2 ) 2 ] 3 was attempted via different pathways. A transsilylamination protocol using Ga[N(SiMe 3 ) 2 ] 3 and HN(SiHMe 2 ) 2 was unsuccessfully applied. An unexpected side product, MeGa[N(SiMe 3 ) SiMe 2 N(SiMe 3 ) 2 ] 2 , could be obtained from the synthesis of homoleptic gallium(III) bis(trimethylsilyl)amide via GaCl 3 and LiN(SiMe 3 ) 2 . Alkane elimination from Me 3 Ga or Et 3 Ga and HN(SiHMe 2 ) 2 did not lead to the isolation of Ga[N(SiHMe 2 ) 2 ] 3 either. When a salt metathesis route was conducted, reacting GaCl 3 with LiN(SiHMe 2 ) 2 , the silylamido-bridged dimeric hydride complex {H 2 Ga[μ-N(SiHMe 2 ) 2 ]} 2 was obtained. Its further reaction with N,N,N′,N′-tetramethylethylendiamine (tmeda) gave the dinuclear, tmeda-bridged {[H 2 GaN(SiHMe 2 ) 2 ] 2 (μ-tmeda)}.

Molecular Main Group Metal Hydrides

“…Amide ligands have long been exploited in the stabilization of gallium hydrides, with oliomeric N-bridged structures typically predominating with simple NR 2 donors. ,− Synthetic access can be achieved via a number of routes including metathesis and protonolysis. Thus, Gladfelter and coworkers synthesized HGa­(NMe 2 ) 2 ( 639 ) via the reaction of Li­[NMe 2 ] with the quinuclidine adduct of dichlororogallane, quin·GaHCl 2 .…”

Silylamide Complexes of Chromium(II), Manganese(II), and Cobalt(II) Bearing the Ligands N(SiHMe2)2 and N(SiPhMe2)2

“…The transsilylamination route offers a straightforward protocol for the synthesis of bis(dimethylsilyl)amide complexes (p K a [N(SiHMe 2 ) 2 ] = 22.8). , Moreover, the ligand is an excellent IR/NMR spectroscopic probe, allowing for an easy monitoring of ligand exchange and surface reactions. Bis(dimethylsilyl)amide complexes have been synthesized for most rare-earth metals − and alkaline-earth metals, , as well as group 13 metals . In contrast, only a few transition metal bis(dimethylsilyl)amide complexes have been described in the literature so far; namely, homoleptic Hf[N(SiHMe 2 ) 2 ] 4 , U[N(SiHMe 2 ) 2 ] 4 , {Fe(II)[N(SiHMe 2 ) 2 ] 2 } 2 , and Zn[N(SiHMe 2 ) 2 ] 2 and heteroleptic Mo 2 (O 2 CR) 2 [N(SiHMe 2 ) 2 ] 2 (PR′ 3 ) 2 (R = Me, t Bu; PR′ 3 = PMe 3 , PMe 2 Ph, PEt 3 ), M[N(SiHMe 2 ) 2 ] 3 (NSiHMe 2 ) (M = Nb, Ta), Zr[N(SiHMe 2 ) 2 ] 2 Cl 2 , Ti[N(SiHMe 2 ) 2 ](NMe 2 ) 3 , and Fe(III)[N(SiHMe 2 ) 2 ] 3 (μ-Cl)Li(thf) 3 are known.…”

Hydride Affinities for Main-Group Hydride Reductants: Assessment of Density Functionals and Trends in Reactivities

“…It is also noteworthy that group 13 hydrides are potentially stronger reducing agents than the corresponding group 14 analogues. In this regard, gallium hydrides may represent candidates for advanced reductants, and we have briefly examined two such existing organogallium species …”

“…In this regard, gallium hydrides may represent candidates for advanced reductants, and we have briefly examined two such existing organogallium species. 66 The calculated hydride affinities for the conjugate cation of the hydrides are shown in Table 3. Before we discuss our results, we note that some of the silane reductants have been applied to numerous synthetic processes, and one can roughly sort their reduction capability in the following ascending order: 64 In comparison, our hydride affinities for the associate cation species are 1076.0 [SiCl + and SiH 2 Ph + are consistent with their mild reactivities.…”