Reversible Oxidative Addition of Zinc Hydride at a Gallium(I)‐Centre: Labile Mono‐ and Bis(hydridogallyl)zinc Complexes

Abstract

In the presence of TMEDA (N,N,N',N'-tetramethylethylenediamine), partially deaggregated zinc dihydride as hydrocarbon suspensions react with the gallium(I) compound [(BDI)Ga] (I, BDI = {HC(C(CH 3 )N(2,6-iPr 2 -C 6 H 3 )) 2 } À ) by formal oxidative addition of a ZnÀ H bond to the gallium(I) centre. Dissociation of the labile TMEDA ligand in the resulting complex [(BDI)Ga(H)À (H)Zn(tmeda)] (1) facilitates insertion of a second equiv. of I into the remaining ZnÀ H to form a thermally sensitive trinuclear species [{(BDI)Ga(H)} 2 Zn] (2). Compound 1 exchanges with polymeric zinc dideuteride [ZnD 2 ] n in the presence of TMEDA, and with compounds I and 2 via sequential and reversible ligand dissociation and gallium(I) insertion. Spectroscopic and computational studies demonstrate the reversibility of oxidative addition of each ZnÀ H bond to the gallium(I) centres.

Reactions of Zinc Hydride with Silylenes: From Oxidative Addition to Ligand Exchange Reactions

“…Deuterated benzene, toluene, and THF were dried by refluxing with sodium/potassium alloy under Ar. NMR ( 1 H, 13 C, 27 Si and 2D) spectra were recorded on a Bruker Avance II 600 MHz spectrometer. Elemental analyses were performed at the Elementaranalyse Labor of the University of Duisburg-Essen.…”

“…Found: C, 67.4; H, 8.52; N, 7.09. 1 H NMR (600 MHz, toluene-d 8 , 25 °C) δ = 0.61 (s, 18H, tBu), 1.26 (br, 12H, CHMe 2 ), 1.48 (d, 3 J HH = 6.0 Hz, 6H, CHMe 2 ), 1.62 (d, 3 J HH = 12.0 Hz, 6H, CHMe 2 ), 1.71 (s, 6H, CMe), 3.70 (sept, 3 J HH = 6.0 Hz, 2H, CHMe 2 ), 4.02 (sept, 3 J HH = 6.0 Hz, 2H, CHMe 2 ), 4.89 (s, 1H, CH), 5.87 (s, 1H, SiH), 6.76−7.59 (m, 11H, C 6 H 5 and C 6 H 3 ); 13 LH 2 Si(NMe 2 )ZnL (3). LZnH (0.38 mmol, 183 mg) and 115 mg of L 2 SiNMe 2 (0.38 mmol) were dissolved in 2 mL of toluene and the resulting solution was stirred for 40 h at 130 °C in a closed reaction vessel.…”

“…Heterobimetallic hydride complexes with main-group and transition metals may show potentially advantageous synergistic reactivity effects. , While main-group metal hydrides typically exhibit versatile reactivity in organic and inorganic synthesis, transition metal hydrides are often key intermediates in organic catalytic processes such as (de)­hydrogenation and hydroformylation reactions. , Recent progress on heterobimetallic hydride complexes prompted our interest toward Si–Zn hydride complexes. − The oxidative addition of low-valent main group metal complexes to a Zn–H bond may offer a direct pathway to zinc-containing heterobimetallic hydride complexes. Although silylenes have been largely used for the oxidative addition of H–X bonds (X = H, B, N, P, O, etc.…”

“…Furthermore, eight septets at 2.43, 2.62, 2.81, 2.92, 3.11, 3.52, 3.77, and 3.83 ppm of eight magnetically inequivalent isopropyl groups prove an asymmetric geometry of 1 in solution. In the 13 C NMR spectrum, the typical γ-C resonances were observed at 99.0 and 106.4 ppm, while the CH 2 unit exhibits a resonance at 84.7 ppm. In the 1 H NMR spectrum of 2, the singlet at 4.89 ppm corresponds to the γ-H of the ligand backbone, while the singlet at 5.87 ppm is assigned to the Si− H group as was verified by 1 H− 29 Si COSY NMR spectroscopy (Figure S11).…”

Syntheses, characterizations and catalytic properties of three zinc complexes and one lithium compound chelated by β-diketiminate ligands

“…The last 20 years have witnessed a renaissance of studies on the preparation and reactivity of zinc complexes. [1][2][3][4][5][6][7] In addition to the aesthetically pleasing topologies that many zinc complexes display, interest in these compounds also comes from their versatile reactivity, [8][9][10][11][12][13] including but not limited to the hydroboration of alkynes [14][15][16] and various polymerizations. [17][18][19] These compounds can be used in the Barbier reaction [20][21][22] and Strecker reaction.…”