Digallane: Difference between revisions

Digallane
Names
	IUPAC name digallane(6)
	Other names Di-μ-hydrido-tetrahydridodigallium; Gallane dimer
Identifiers
CAS Number	12140-58-8 ;
3D model (JSmol)	Interactive image;
ChemSpider	24769416;
	InChI InChI=1S/2Ga.6H Key: GFQCQFDOQMRGIQ-UHFFFAOYSA-N;
	SMILES [GaH2]1[H] [GaH2] [H]1;
Properties
Chemical formula	Ga2H6
Molar mass	145.494 g/mol
Appearance	White solid or colorless gas
Melting point	−50 °C (−58 °F; 223 K) (sublimes)
Boiling point	0 °C (32 °F; 273 K) (decomposes)
Solubility in water	Reacts to form gallium(III) hydroxide
Related compounds
Related compounds	Diborane; Aluminium hydride; Indium trihydride; Thallium hydride;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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Digallane (systematically named digallane(6)) is an inorganic compound with the chemical formula GaH₂(H)₂GaH₂ (also written [{GaH₂(μ-H)}₂] or [Ga₂H₆]). 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] This compound is a colorless gas that decomposes above 0 °C.

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 trimethylsilane, Me₃SiH. This step was followed by a further reduction with Li[GaH₄] (lithium tetrahydrogallate), solvent free, at −23 °C, to produce digallane, Ga₂H₆ in low yield.

Ga₂Cl₆ + 4 Me₃SiH → (H₂GaCl)₂ + 4 Me₃SiCl

(H₂GaCl)₂ + 2 Li[GaH₄] → 2 Ga₂H₆ + 2 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. Bibcode:1941NW.....29..320W. doi:10.1007/BF01479551. S2CID 44840674.
^ 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.

[1] 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.

[Pulham-2] 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.

[3] N.N. Greenwood (2001). "Main group element chemistry at the millennium". J. Chem. Soc., Dalton Trans. (14): 2055–2066. doi:10.1039/b103917m.

[4] Wiberg E.; Johannsen T. (1941). "Über einen flüchtigen Galliumwasserstoff der Formel Ga₂H₆ und sein Tetramethylderivat". Naturwissenschaften. 29 (21): 320. Bibcode:1941NW.....29..320W. doi:10.1007/BF01479551. S2CID 44840674.

[5] 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.

[1]

[2]

[3]

[4]

[5]

@@ Line 1: / Line 1: @@
 {{redirect2|Gallium trihydride|Gallium(III) hydride|the mononuclear compound|Gallane}}
+{{more citations|date=October 2022}}
 {{chembox
 | verifiedrevid = 429881396
-| ImageFile = Digallane-3D-balls.png
+| Name =
+| ImageFile = Digallane-2D.png
+| ImageFileL1 = Digallane-3D-balls.png
+| ImageFileR1 = Digallane-3D-vdW.png
 | ImageSize = 200 px
 | IUPACName = digallane(6)
-| OtherNames = Di-μ-hydrido-tetrahydridodigallium<br/>Gallane dimer
+| OtherNames = Di-μ-hydrido-tetrahydridodigallium<br />Gallane dimer
+| SystematicName =
-|Section1={{Chembox Identifiers
+| Section1 = {{Chembox Identifiers
 | CASNo_Ref = {{cascite|correct|??}}
 | CASNo = 12140-58-8
+| ChemSpiderID = 24769416
-| PubChem =
-| SMILES = [GaH2]1[H][GaH2][H]1
+| PubChem =
+| SMILES = [GaH2]1[H] [GaH2] [H]1
+| StdInChI=1S/2Ga.6H
+| StdInChIKey=GFQCQFDOQMRGIQ-UHFFFAOYSA-N
  }}
-|Section2={{Chembox Properties
+| Section2 = {{Chembox Properties
-| Formula = Ga<sub>2</sub>H<sub>6</sub>
+| Formula = {{chem2|Ga2H6}}
 | MolarMass = 145.494 g/mol
-| Appearance =
+| Appearance = White solid or colorless gas
 | Density =
-| MeltingPt =
+| MeltingPtC = -50
-| BoilingPt = -50<sup>o</sup>C(sublimes)
+| MeltingPt_notes = (sublimes)
-| Solubility =
+| BoilingPtC = 0
+| BoilingPt_notes = (decomposes)
+| Solubility = Reacts to form [[gallium(III) hydroxide]]
  }}
-|Section3={{Chembox Hazards
+| Section7 = {{Chembox Hazards
 | MainHazards =
 | FlashPt =
 | AutoignitionPt =
  }}
+| Section9 = {{Chembox Related
+| OtherCompounds = {{ubl|[[Diborane]]|[[Aluminium hydride]]|[[Indium trihydride]]|[[Thallium hydride]]}}
+}}
 }}
-'''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)''') is an [[inorganic compound]] with the [[chemical formula]] {{Chem2|GaH2(H)2GaH2}} (also written {{Chem2|[{GaH2(''μ''\-H)}2]}} or {{Chem2|[Ga2H6]}}). It is the [[Dimer (chemistry)|dimer]] of the monomeric compound [[gallane]]. The eventual preparation of the pure compound, reported in 1989,<ref>{{cite journal
 | title = Gallane at last!
 |author1=Anthony J. Downs |author2=Michael J. Goode |author3=Colin R. Pulham | journal =Journal of the American Chemical Society
 | year = 1989
 | volume = 111
 | issue = 5
@@ Line 39: / Line 52: @@
 | 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
 |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
 | year = 1991
 | volume = 113
 | issue = 14
@@ Line 49: / Line 62: @@
 | author = N.N. Greenwood
 | journal =J. Chem. Soc., Dalton Trans.
 | year = 2001
 | volume =
 | issue = 14
 | pages = 2055–2066
 | doi =10.1039/b103917m
 }}</ref> Digallane had been reported as early as 1941 by Wiberg;<ref>{{cite journal
 | title = Über einen flüchtigen Galliumwasserstoff der Formel Ga<sub>2</sub>H<sub>6</sub> und sein Tetramethylderivat
 |author1=Wiberg E. |author2=Johannsen T. | journal =Naturwissenschaften
 | year = 1941
 | volume = 29
 | issue = 21
 | page = 320
 | doi = 10.1007/BF01479551
-|bibcode=1941NW.....29..320W }}</ref> however, this claim could not be verified by later work by Greenwood and others.<ref>{{cite journal
+|bibcode=1941NW.....29..320W |s2cid=44840674 }}</ref> however, this claim could not be verified by later work by Greenwood and others.<ref>{{cite journal
 | title = Some Observations Relative to Digallane
 |author1=Shriver, D. F. |author2=Parry, R. W. |author3=Greenwood, N. N. |author4=Storr, A |author5=Wallbridge, M. G. H. | journal =Inorg. Chem.
 | year = 1963
 | volume = 2
 | issue = 4
 | pages = 867–868
 | doi = 10.1021/ic50008a053
+}}</ref> This compound is a colorless gas that decomposes above 0 °C.
-}}</ref>
+__TOC__
 ==Preparation==
-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&nbsp;°C, to produce digallane, Ga<sub>2</sub>H<sub>6</sub> in low yield.
+A two-stage approach proved to be the key to successful synthesis of pure digallane. Firstly the dimeric [[monochlorogallane]], {{chem2|(H2GaCl)2}} (containing [[Bridging ligand|bridging]] chlorine atoms and thus formulated as ({{chem2|H2Ga(''μ''\-Cl))2}}) was prepared via the hydrogenation of [[gallium trichloride]], {{chem2|GaCl3}}, with [[trimethylsilane]], {{chem2|[[Methyl group|Me]]3SiH}}. This step was followed by a further reduction with {{chem2|Li[GaH4]}} (lithium tetrahydrogallate), solvent free, at −23&nbsp;°C, to produce digallane, {{chem2|Ga2H6}} in low yield.
+:{{chem2|Ga2Cl6 + 4 Me3SiH → (H2GaCl)2 + 4 Me3SiCl}}
-: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
+:{{chem2|(H2GaCl)2 + 2 Li[GaH4] → 2 Ga2H6 + 2 LiCl}}
-:1/2 (H<sub>2</sub>GaCl)<sub>2</sub> + LiGaH<sub>4</sub> → Ga<sub>2</sub>H<sub>6</sub> + LiCl
 Digallane is volatile and condenses at −50&nbsp;°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<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"/>
-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. {{chem2|(GaH3)4}}).<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:
-: Ga<sub>2</sub>H<sub>6</sub> → 2 Ga + 3 H<sub>2</sub>
+:{{chem2|Ga2H6 → 2 Ga + 3 H2}}
 ==References==
 {{reflist}}
+{{Gallium compounds}}
 {{Hydrides by group}}
@@ Line 94: / Line 110: @@
 [[Category:Metal hydrides]]
 [[Category:Reducing agents]]
+[[Category:Substances discovered in the 1980s]]