Stable Radical Cation and Dication of an N‐Heterocyclic Carbene Stabilized Digallene: Synthesis, Characterization and Reactivity

Abstract

One‐ and two‐electron oxidation of a digallene stabilized by an N‐heterocyclic carbene afforded the first stable gallium‐based radical cation and dication salts, respectively. Structural analysis and theoretical calculations reveal that the oxidation occurs at the Ga=Ga double bond, leading to removal of π electrons of the double bond and a decrease of the bond order. The spin density of the radical cation mainly locates at the two gallium centers as demonstrated by EPR spectroscopy and theoretical calculations. Moreover, the reactivity of the radical cation salt toward nBu3SnH and cyclo‐S8 was studied; a digallium–hydride cation salt containing a Ga−Ga single bond and a gallium sulfide cluster bearing an unprecedented ladder‐like Ga4S4 core structure were obtained, respectively.

Bis‐NHC Aluminium and Gallium Dihydride Cations [(NHC)2EH2]+ (E = Al, Ga)

“…Infrared spectra were recorded on a Bruker alpha spectrometer as solids using an ATR unit. 1 H, 27 Al, and 13 [22] (Me 2 Im Me )•AlH 2 I (7): Elemental solid iodine (370 mg, 1.46 mmol) was added at room temperature to a solution of (Me 2 Im Me )•AlH 3 (450 mg, 2.92 mmol) 1 dissolved in 15 mL of toluene and the resulting solution was stirred for 45 minutes. The solvent was evaporated to dryness which gave 7 as colourless powder.…”

“…[7] Stephan et al presented [8] Jones and Stasch et al 4, Al1-H2 1.66(4), Al1-I1 2.586 (8); H1-Al1-H2 109.4 (18), H1-Al1-I1 108.7 (12), H2-Al1-I1 106.5 (14), C1-Al1-H1 114.3 (14), C1-Al1-H2 106.5 (14), C1-Al1-I1 105.88(7); 9: C1-Al1 2.039(3), Al1-H1 1.58 (5), Al1-H2 1.60(4), Al1-I1 2.5960 (10); H1-Al1-H2 104(2), H1-Al1-I1 110.5 (17), H2-Al1-I1 111.1 (14), C1-Al1-H1 106.7 (18), C1-Al1-H2 120.2 (14), C1-Al1-I1 103.77(9); 10: Ga-C1 2.036(4), Ga-H1 1.52 (6), Ga-H2 1.44 (7), Ga-I 2.6415 (6). C1-Ga-H1 109(2), C1-Ga-H2 108(2), C1-Ga-I 100.07 (13), H1-Ga-H2 122(3), H1-Ga-I 110(2), H2-Ga-I 105(2).…”

“…[7,11,12] Thermally stable examples such as (Dipp 2 Im)•MH 3 (M = Al, Ga, In) have been prepared particularly for sterically demanding NHCs. Moreover, the syntheses of some low-valent, NHC-stabilized dinuclear hydrodialane and hydrodigallene compounds were presented, [13] for example the dialane [(Dipp 2 Im)•AlH 2 ] 2 which was reported by Jones et al [12,14] However, the formation of cationic aluminium and gallium dihydrides is rare and stabilization of [EH 2 ] + with two strong σ-donating NHC-ligands should lead to accessible hydroalane and hydrogallane cations. Herein we present the forma-tion of such cationic bis-NHC aluminium and gallium hydrides from the reaction of (NHC)•AlH 2 I and (NHC)•GaH 2 I with additional NHC for the carbenes Me 2 Im Me , iPr 2 Im, iPr 2 Im Me , and Dipp 2 Im.…”

Taming the Antiferromagnetic Beast: Computational Design of Ultrashort Mn−Mn Bonds Stabilized by N‐Heterocyclic Carbenes

“…Another remarkable property of NHCs is their ability to stabilize unusual and reactive main group [27] and transition metal species. Consequently, completely new structures have been isolated and characterized, such as the boron dimer featuring double and triple bonds, [28] molecular silicon oxides, [29] doubly bonded Si 2 , [30] Ge 2 , [31] Sn 2 , [32] Al 2 , [33] and Ga 2 , [34] phosphorus clusters, [35] low-valent Be, [36] B, [37] C, [38] and Al [39] species, coinage metal atoms, [40] and many others. Moreover, NHCs have also been systematically incorporated in periodic systems [41] and extended networks, [42] and their ability to stabilize main group dimers into these structures is currently under investigation.…”

The Coordination Chemistry and Clustering of Subvalent Ga+ and In+ upon Addition of σ‐Donor Ligands

“…[97] Moreover, a similar dicationic digallane was repoted recently by Wang. [98] Lessons Learned on the Formation of the Triangular Clusters: To investigate the differences in cluster formation between indium and gallium, the interacting [M(bipy) 2 ] + fragments were analyzed in more detail. In Figure 15 possible underlying reasons for indium cluster formation but gallium disproportionation are described.…”