Synthesis of a terminal zinc hydride compound, [TpBut,Me]ZnH, from a hydroxide derivative, [

Michael Rauch

¹

,

Yi Rong

²

,

Wesley Sattler

³

et al.

Abstract

The terminal zinc hydride complex, [Tp Bu t ,Me ]ZnH, can be conveniently obtained from the hydroxide derivative, [Tp Bu t ,Me ]ZnOH, by reaction with H3NBH3. The zinc hydride complex [Tp Bu t ,Me ]ZnH is reactive and the Zn-H bond undergoes (i) insertion of CO2 to produce the formate complex, [Tp Bu t ,Me ]Zn( 1 -O2CH), (ii) protolytic cleavage with Me3SiOH to afford [Tp Bu t ,Me ]ZnOSiMe3, and (iii) metathesis with Me3SnF to form the zinc fluoride derivative, [Tp Bu t ,Me ]ZnF. The fluoride derivative, which may also be formed by the reactions of [Tp Bu t ,Me ]ZnOH with [Me3O][BF4] or Me3SnF, can be converted back to [Tp Bu t ,Me ]ZnH upon treatment with either H3NBH3 or (MeO)3SiH.

Role of Ligand in the Selective Production of Hydrogen from Formic Acid Catalysed by the Mononuclear Cationic Zinc Complexes [(L)Zn(H)]+ (L=tpy, phen, and bpy)

“…For example, the zinc hydride complex [Tptm]ZnH (where Tptm = tris(2-pyridylthio)methyla nion) reacts with formic acid to produce molecular hydrogen and [Tptm]Zn(O 2 CH). [15] [Tptm]Zn(H) also readily reacts with CO 2 to form the formate complex [Tptm]Zn(O 2 CH), [16] which is the reverse reaction of step II in Scheme1Aa nd represents ak ey step in catalytic cycles for the production of formic acid via hydrogenation of CO 2 .H ere we use gas-phase studies to evaluate the efficiency of as eries of zinc-based [(L)Zn(H)] + catalysts with variousN -based ligands L( Scheme 1F)i nd ecomposing gaseous formic into molecular hydrogen andc arbon dioxide as wella si nt he reverse CO 2 reactionw ith hydrides [(L)Zn(H)] + . In order to study the role of denticity,w ec ompare the reactivity of the complexes with the tridentate ligand,2 ,2';6',2"-t erpyridine (tpy, a)t ot hose with the bidentate ligands 2,2'-bipyridyl (bpy, b)a nd 1,10-phenanthroline (phen, c).…”

“…Thus, we were intrigued by recent reports of zinc‐based catalysts by Parkin and co‐workers. For example, the zinc hydride complex [Tptm]ZnH (where Tptm=tris(2‐pyridylthio)methyl anion) reacts with formic acid to produce molecular hydrogen and [Tptm]Zn(O 2 CH) . [Tptm]Zn(H) also readily reacts with CO 2 to form the formate complex [Tptm]Zn(O 2 CH), which is the reverse reaction of step II in Scheme A and represents a key step in catalytic cycles for the production of formic acid via hydrogenation of CO 2 .…”

Cationic Zinc Hydride Catalyzed Carbon Dioxide Reduction to Formate: Deciphering Elementary Reactions, Isolation of Intermediates, and Computational Investigations

“…Molecular zinc compounds have received prominence as reagents for the reduction of unsaturated bonds [1–4] . They are employed in the reduction of olefins, [5–8] imines, [9–11] aldehydes, ketones, [12–18] and carbon dioxide [19–30] . Catalytic reduction of carbon dioxide through catalytic hydrosilylation [31–34] and, to some extent, hydroboration [35, 36] with zinc catalysts has been investigated [37–44] .…”

“…[1][2][3][4] They are employedi nt he reduction of olefins, [5][6][7][8] imines, [9][10][11] aldehydes, ketones, [12][13][14][15][16][17][18] and carbond ioxide. [19][20][21][22][23][24][25][26][27][28][29][30] Catalyticr eductiono f carbon dioxide through catalytic hydrosilylation [31][32][33][34] and, to some extent, hydroboration [35,36] with zinc catalysts has been investigated. [37][38][39][40][41][42][43][44] Zinc acetate is known to hydrosilylateC O 2 to am ixture of reduced products:s ilyl formates, bis(silyl) acetals, methoxysilanes, and methane.…”

Synthesis and Characterization of Tris(oxazolinyl)borato Copper(II) and Copper(I) Complexes

“…In contrast, the neighboring tetrahedral zinc(II) hydride congeners are isolable as scorpionate‐supported species [30–35] and even as an NHC‐supported dihydride [36,37] . Some of these hydride compounds are inert, for example, to O 2 , and others are reactive in catalytic chemistry such as dehydrocoupling of silanes and alcohol [31,38] or hydrosilylation [39,40] .…”