Digallane: Difference between revisions
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'''Digallane''' (systematically named '''digallane(6)''' and '''di-μ-hydrido-bis(dihydridogallium)''') is an [[inorganic compound]] with the [[chemical formula]] {{Chem|GaH|2|(H)|2|GaH|2}} (also written {{Chem|[{GaH|2|(μ-H)}|2|]}} or {{Chem|[Ga|2|H|6|]}}). It is the [[Dimer (chemistry)|dimer]] of the monomeric compound [[gallane]]. The eventual preparation of the pure compound, reported in 1989,<ref>{{cite journal |
'''Digallane''' (systematically named '''digallane(6)''' and '''di-μ-hydrido-bis(dihydridogallium)''') is an [[inorganic compound]] with the [[chemical formula]] {{Chem|GaH|2|(H)|2|GaH|2}} (also written {{Chem|[{GaH|2|(μ-H)}|2|]}} or {{Chem|[Ga|2|H|6|]}}). It is the [[Dimer (chemistry)|dimer]] of the monomeric compound [[gallane]]. The eventual preparation of the pure compound, reported in 1989,<ref>{{cite journal |
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| title = Gallane at last! |
| title = Gallane at last! |
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| |
|author1=Anthony J. Downs |author2=Michael J. Goode |author3=Colin R. Pulham | journal =Journal of the American Chemical Society |
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| journal =Journal of the American Chemical Society |
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| year = 1989 |
| year = 1989 |
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| volume = 111 |
| volume = 111 |
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}}</ref><ref name = "Pulham">{{cite journal |
}}</ref><ref name = "Pulham">{{cite journal |
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| title = Gallane: Synthesis, Physical and Chemical Properties, and Structure of the Gaseous Molecule Ga<sub>2</sub>H<sub>6</sub> As Determined by Electron Diffraction |
| title = Gallane: Synthesis, Physical and Chemical Properties, and Structure of the Gaseous Molecule Ga<sub>2</sub>H<sub>6</sub> As Determined by Electron Diffraction |
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|author1=Pulham C.R. |author2=Downs A.J. |author3=Goode M.J |author4=Rankin D.W.H. Roberson H.E. | journal =Journal of the American Chemical Society |
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| journal =Journal of the American Chemical Society |
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| year = 1991 |
| year = 1991 |
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| volume = 113 |
| volume = 113 |
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}}</ref> Digallane had been reported as early as 1941 by Wiberg;<ref>{{cite journal |
}}</ref> Digallane had been reported as early as 1941 by Wiberg;<ref>{{cite journal |
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| title = Über einen flüchtigen Galliumwasserstoff der Formel Ga<sub>2</sub>H<sub><sub>6</sub></sub> und sein Tetramethylderivat |
| title = Über einen flüchtigen Galliumwasserstoff der Formel Ga<sub>2</sub>H<sub><sub>6</sub></sub> und sein Tetramethylderivat |
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|author1=Wiberg E. |author2=Johannsen T. | journal =Naturwissenschaften |
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| journal =Naturwissenschaften |
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| year = 1941 |
| year = 1941 |
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| volume = 29 |
| volume = 29 |
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| Line 67: | Line 64: | ||
}}</ref> however, this claim could not be verified by later work by Greenwood and others.<ref>{{cite journal |
}}</ref> however, this claim could not be verified by later work by Greenwood and others.<ref>{{cite journal |
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| title = Some Observations Relative to Digallane |
| title = Some Observations Relative to Digallane |
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| |
|author1=Shriver, D. F. |author2=Parry, R. W. |author3=Greenwood, N. N. |author4=Storr, A, |author5=Wallbridge, M. G. H. | journal =Inorg. Chem. |
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| journal =Inorg. Chem. |
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| year = 1963 |
| year = 1963 |
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| volume = 2 |
| volume = 2 |
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==Preparation== |
==Preparation== |
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A two-stage approach proved to be the key to successful synthesis of pure digallane. Firstly the dimeric [[monochlorogallane]], (H<sub>2</sub>GaCl)<sub>2</sub> (containing [[Bridging ligand|bridging]] chlorine atoms and thus formulated as (H<sub>2</sub>Ga(μ-Cl))<sub>2</sub>) was prepared via the hydrogenation of [[gallium trichloride]], GaCl<sub>3</sub>, with [[Methyl group|Me]]<sub>3</sub>SiH. This step was followed by a further reduction with LiGaH<sub>4</sub>, solvent free, at −23 |
A two-stage approach proved to be the key to successful synthesis of pure digallane. Firstly the dimeric [[monochlorogallane]], (H<sub>2</sub>GaCl)<sub>2</sub> (containing [[Bridging ligand|bridging]] chlorine atoms and thus formulated as (H<sub>2</sub>Ga(μ-Cl))<sub>2</sub>) was prepared via the hydrogenation of [[gallium trichloride]], GaCl<sub>3</sub>, with [[Methyl group|Me]]<sub>3</sub>SiH. This step was followed by a further reduction with LiGaH<sub>4</sub>, solvent free, at −23 °C, to produce digallane, Ga<sub>2</sub>H<sub>6</sub> in low yield. |
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:Ga<sub>2</sub>Cl<sub>6</sub> + 4 Me<sub>3</sub>SiH → (H<sub>2</sub>GaCl)<sub>2</sub> + 4 Me<sub>3</sub>SiCl |
:Ga<sub>2</sub>Cl<sub>6</sub> + 4 Me<sub>3</sub>SiH → (H<sub>2</sub>GaCl)<sub>2</sub> + 4 Me<sub>3</sub>SiCl |
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:1/2 (H<sub>2</sub>GaCl)<sub>2</sub> + LiGaH<sub>4</sub> → Ga<sub>2</sub>H<sub>6</sub> + LiCl |
:1/2 (H<sub>2</sub>GaCl)<sub>2</sub> + LiGaH<sub>4</sub> → Ga<sub>2</sub>H<sub>6</sub> + LiCl |
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Digallane is volatile and condenses at −50 |
Digallane is volatile and condenses at −50 °C into a white solid. |
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==Structure and bonding== |
==Structure and bonding== |
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Electron diffraction measurements of the vapour at 255 K established that digallane is structurally similar to [[diborane]] with 2 bridging hydrogen atoms<ref name="Pulham"/> (so-called [[three-center two-electron bond]]s). The terminal Ga—H bond length is 152 pm, the Ga—H bridging is 171 pm and the Ga—H—Ga angle is 98°. The Ga—Ga distance is 258 pm. The <sup>1</sup>H [[Nuclear magnetic resonance|NMR]] spectrum of a solution of digallane in [[toluene]] shows two peaks attributable to terminal and bridging hydrogen atoms.<ref name = "Pulham"/> |
Electron diffraction measurements of the vapour at 255 K established that digallane is structurally similar to [[diborane]] with 2 bridging hydrogen atoms<ref name="Pulham"/> (so-called [[three-center two-electron bond]]s). The terminal Ga—H bond length is 152 pm, the Ga—H bridging is 171 pm and the Ga—H—Ga angle is 98°. The Ga—Ga distance is 258 pm. The <sup>1</sup>H [[Nuclear magnetic resonance|NMR]] spectrum of a solution of digallane in [[toluene]] shows two peaks attributable to terminal and bridging hydrogen atoms.<ref name = "Pulham"/> |
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In the solid state, digallane appears to adopt a polymeric or oligomeric structure. The vibrational spectrum is consistent with tetramer (i.e. (GaH<sub>3</sub>)<sub>4</sub>).<ref name = "Pulham"/> The vibrational data indicate the presence of terminal hydride ligands. In contrast, the hydrogen atoms are all bridging in [[aluminium hydride|α-alane]], a high-melting, relatively stable polymeric form of [[aluminium hydride]] wherein the aluminium centers are 6-coordinated. Digallane decomposes at ambient temperatures: |
In the solid state, digallane appears to adopt a polymeric or oligomeric structure. The vibrational spectrum is consistent with tetramer (i.e. (GaH<sub>3</sub>)<sub>4</sub>).<ref name = "Pulham"/> The vibrational data indicate the presence of terminal hydride ligands. In contrast, the hydrogen atoms are all bridging in [[aluminium hydride|α-alane]], a high-melting, relatively stable polymeric form of [[aluminium hydride]] wherein the aluminium centers are 6-coordinated. Digallane decomposes at ambient temperatures: |
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Revision as of 19:29, 29 May 2016
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| Names | |
|---|---|
| IUPAC name
digallane(6)
| |
| Other names
Di-μ-hydrido-tetrahydridodigallium
Gallane dimer | |
| Identifiers | |
| Properties | |
| Ga2H6 | |
| Molar mass | 145.494 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Digallane (systematically named digallane(6) and di-μ-hydrido-bis(dihydridogallium)) is an inorganic compound with the chemical formula GaH
2(H)
2GaH
2 (also written [{GaH
2(μ-H)}
2] or [Ga
2H
6]). It is the dimer of the monomeric compound gallane. The eventual preparation of the pure compound, reported in 1989,[1][2]
was hailed as a "tour de force."[3] Digallane had been reported as early as 1941 by Wiberg;[4] however, this claim could not be verified by later work by Greenwood and others.[5]
Preparation
A two-stage approach proved to be the key to successful synthesis of pure digallane. Firstly the dimeric monochlorogallane, (H2GaCl)2 (containing bridging chlorine atoms and thus formulated as (H2Ga(μ-Cl))2) was prepared via the hydrogenation of gallium trichloride, GaCl3, with Me3SiH. This step was followed by a further reduction with LiGaH4, solvent free, at −23 °C, to produce digallane, Ga2H6 in low yield.
- Ga2Cl6 + 4 Me3SiH → (H2GaCl)2 + 4 Me3SiCl
- 1/2 (H2GaCl)2 + LiGaH4 → Ga2H6 + LiCl
Digallane is volatile and condenses at −50 °C into a white solid.
Structure and bonding
Electron diffraction measurements of the vapour at 255 K established that digallane is structurally similar to diborane with 2 bridging hydrogen atoms[2] (so-called three-center two-electron bonds). The terminal Ga—H bond length is 152 pm, the Ga—H bridging is 171 pm and the Ga—H—Ga angle is 98°. The Ga—Ga distance is 258 pm. The 1H NMR spectrum of a solution of digallane in toluene shows two peaks attributable to terminal and bridging hydrogen atoms.[2]
In the solid state, digallane appears to adopt a polymeric or oligomeric structure. The vibrational spectrum is consistent with tetramer (i.e. (GaH3)4).[2] The vibrational data indicate the presence of terminal hydride ligands. In contrast, the hydrogen atoms are all bridging in α-alane, a high-melting, relatively stable polymeric form of aluminium hydride wherein the aluminium centers are 6-coordinated. Digallane decomposes at ambient temperatures:
- Ga2H6 → 2 Ga + 3 H2
References
- ^ Anthony J. Downs; Michael J. Goode; Colin R. Pulham (1989). "Gallane at last!". Journal of the American Chemical Society. 111 (5): 1936–1937. doi:10.1021/ja00187a090.
- ^ a b c d Pulham C.R.; Downs A.J.; Goode M.J; Rankin D.W.H. Roberson H.E. (1991). "Gallane: Synthesis, Physical and Chemical Properties, and Structure of the Gaseous Molecule Ga2H6 As Determined by Electron Diffraction". Journal of the American Chemical Society. 113 (14): 5149–5162. doi:10.1021/ja00014a003.
- ^ N.N. Greenwood (2001). "Main group element chemistry at the millennium". J. Chem. Soc., Dalton Trans. (14): 2055–2066. doi:10.1039/b103917m.
- ^ Wiberg E.; Johannsen T. (1941). "Über einen flüchtigen Galliumwasserstoff der Formel Ga2H6 und sein Tetramethylderivat". Naturwissenschaften. 29 (21): 320. doi:10.1007/BF01479551.
- ^ Shriver, D. F.; Parry, R. W.; Greenwood, N. N.; Storr, A,; Wallbridge, M. G. H. (1963). "Some Observations Relative to Digallane". Inorg. Chem. 2 (4): 867–868. doi:10.1021/ic50008a053.
{{cite journal}}: CS1 maint: extra punctuation (link) CS1 maint: multiple names: authors list (link)