Silanide Explained

A silanide is a chemical compound containing an anionic silicon(IV) centre, the parent ion being . The hydrogen atoms can also be substituted to produce more complex derivative anions such as tris(trimethylsilyl)silanide (hypersilyl),[1] tris(tert-butyl)silanide, tris(pentafluoroethyl)silanide, or triphenylsilanide.[2] The simple silanide ion can also be called trihydridosilanide or silyl hydride.

Formation

The simplest trihydridosilanides can be produced from a triphenylsilanide in a reaction with hydrogen or at standard conditions. The triphenylsilanide can be made in a reaction of Ph3SiSiMe3 with the metal tert-butoxy compound.[3]

Reacting hydrogen with potassium triphenylsilyl can yield potassium silanide.[4]

Other method to form silanides are to heat a heavy metal silicide with hydrogen,[5] or react the dissolved metal with silane.[3]

Atomic metals can react directly with silane to yield unstable molecules with formulae. These can be condensed into a noble gas matrix. With titanium this also yields molecules with hydrogen bridging between silicon and titanium.[6]

Properties

The silanide ion has an effective ionic radius of 2.26 Å. In salts at room temperature the ion's orientation is not stable, and it rotates. But at lower temperatures (under 200K) silanide becomes fixed in orientation.[7] The ordered structure forms the β- phase, whereas the higher temperature and more symmetrical disordered structure is called α- phase. The β- phase is about 15% more compact than the α-phase.[8]

The silanide ion has C3v symmetry. The silicon to hydrogen bond length is 1.52 Å and the H-Si-H bond angle is 92.2°, not far off a right angle.[8] In a range of compounds, the stretching force constant for the Si-H bond is 1.9 to 2.05 N cm–1, which is much softer than that of silane's 2.77 N cm–1.[8]

Silanide salts are very easily damaged by air or water.

Heating to under 414K results in the release of hydrogen and the formation of a Zintl-phase MSi. If an alkali silande is rapidly heated to 500K another irreversible reaction occurs:

.[9]

Use

Trihydridosilanides have been investigated as hydrogen storage materials.[10] Potassium silanide can reversibly gain or lose hydrogen over several hours at 373K. However this does not work for sodium silanide.[5] The rate of hydrogen exchange may be improved by a catalyst. Unwanted reactions may reduce the number of times this process can happen.[11]

List

nameformulaCrystal systemspace groupunit cellvolumedensitycommentreferences
tetramethyl-1,4,7,10-tetraaminocyclododecane lithium silanidecolourless; unstable
trisilylaminemp -105 °C; planar[12]
tetramethyl-1,4,7,10-tetraaminocyclododecane sodium silanidetetragonalP4/na=9.77 c=9.45 Z=29011.041colourless
H is bridge[13]
trisilylphosphine[14]
Potassium silanidecubica=7.23377.91.241pale yellow[15]
β-orthorhombicPnmaa = 8.800, b = 5.416, c = 6.823, Z = 4325.2[16]
tetramethyl-1,4,7,10-tetraaminocyclododecane potassium silanideK(Me4TACD)SiH3•2C6H6tetragonalP42/mnma=12.3401 c=14.9372 Z=22274.61.10colourless
[K(18-crown-6)SiH<sub>3</sub>·THF][17]
[K(18-crown-6)SiH<sub>3</sub>·HSiPh<sub>3</sub>]H is bridge
purple
tetragonalP42/mnma = 8.018, c = 16.113, Z = 2olive green; Ti-SiH2-Ti-SiH2- ring[18]
[Cp<sub>2</sub>Ti(μ-HSiH<sub>2</sub>)]2dark blue[19]
Cp2Ti(μ-HSiH2)(μ-H)TiCp2dark yellowish green
triclinicPa=6.318 b=10.653 c=12.453 α=67.884 β=75.35 γ=72.79 Z=2732.11.742light yellow[20]
[(μ<sub>2</sub>-CO)Cp<sub>2</sub>(OC)<sub>2</sub>Fe<sub>2</sub>]SiH2dark red
[(μ<sub>2</sub>-CO)Cp<sub>2</sub>(OC)<sub>2</sub>Fe<sub>2</sub>][Cp(OC)<sub>2</sub>Fe]SiHdark red
[(<sup>dtbp</sup>Cbz)GeSiH<sub>3</sub>]2•C6H18monoclinicP21/na 16.144 b 15.0369 c 21.974 β 91.927°[21]
trisilylarsine
rubidium silanidecubica=7.52425.31.824yellow
tetramethyl-1,4,7,10-tetraaminocyclododecane rubidium silanideRb(Me4TACD)SiH3•2C6H6tetragonalP42/mnma=12.3934 c=14.9632 Z=22298.31.223yellow
cubicP3ma=12.8322112.7[22]
beige mp 25
trisilylstibine
caesium silanidecubica=7.86485.62.243yellow
cubicP3ma=13.09652246.3
cubicP3ma=13.29822351.7
bis(di-tert-butylphenyl)di-tert-butylcanozalide[(<sup>dtbp</sup>Cbz)BaSiH<sub>3</sub>]8P4/nnca=38.7375 c=44.8635
orange
dark red[23]
orthorhombicPna21a=19.320 b=16.742 c=10.027 Z=43240.01.406orange-red
orthorhombicPna21a=19.321 b=16.496 c=9.926 Z=43163.7dark red
Cp(iPr3P)Os(H)(Br)SiH3yellow
trans-

Related

Under high hydrogen pressure, pentacoordinated and hexacoordinated silicon hydride ions are stabilised including and .[24]

More complex derivatives include silanimine -,[25]

With a double bond between silicon and the metal a silylene complex is formed. With a triple bond, M≡SiH forms with metals such as molybdenum and tungsten.

With less hydrogen, a polyanionic hydride [(SiH)<sup>−</sup>] can be formed.[26]

General organic compounds are termed silylium ions.

Notes and References

  1. Klinkhammer. Karl W.. September 1997. Tris(trimethylsilyl)silanides of the Heavier Alkali Metals—A Structural Study. Chemistry - A European Journal. de. 3. 9. 1418–1431. 10.1002/chem.19970030908.
  2. Lickiss. Paul D.. Smith. Colin M.. November 1995. Silicon derivatives of the metals of groups 1 and 2. Coordination Chemistry Reviews. en. 145. 75–124. 10.1016/0010-8545(95)90218-X.
  3. Schuhknecht . Danny . Leich . Valeri . Spaniol . Thomas P. . Douair . Iskander . Maron . Laurent . Okuda . Jun . Alkali Metal Triphenyl- and Trihydridosilanides Stabilized by a Macrocyclic Polyamine Ligand . Chemistry – A European Journal . 2 March 2020 . 26 . 13 . 2821–2825 . 10.1002/chem.202000187. 31943432 . 7079104 .
  4. Leich . V. . Spaniol . T. P. . Okuda . J. . Formation of α-[KSiH <sub>3</sub> ] by hydrogenolysis of potassium triphenylsilyl . Chemical Communications . 2015 . 51 . 79 . 14772–14774 . 10.1039/C5CC06187C. 26299566 .
  5. Tang . Wan Si . Chotard . Jean-Noël . Raybaud . Pascal . Janot . Raphaël . Hydrogenation properties of KSi and NaSi Zintl phases . Physical Chemistry Chemical Physics . 2012 . 14 . 38 . 13319–13324 . 10.1039/C2CP41589E. 22930067 . 2012PCCP...1413319T .
  6. Corey. Joyce Y.. 2011-02-09. Reactions of Hydrosilanes with Transition Metal Complexes and Characterization of the Products. Chemical Reviews. en. 111. 2. 863–1071. 10.1021/cr900359c. 21250634. 0009-2665.
  7. Weiss. Erwin. Hencken. Günther. Kühr. Heinrich. September 1970. Kristallstrukturen und kernmagnetische Breitlinienresonanz der Alkalisilyle SiH3M (M = K, Rb, Cs). Chemische Berichte. de. 103. 9. 2868–2872. 10.1002/cber.19701030924.
  8. Kranak . Verina F. . Lin . Yuan-Chih . Karlsson . Maths . Mink . Janos . Norberg . Stefan T. . Häussermann . Ulrich . Structural and Vibrational Properties of Silyl (SiH 3 –) Anions in KSiH 3 and RbSiH 3 : New Insight into Si–H Interactions . Inorganic Chemistry . 2 March 2015 . 54 . 5 . 2300–2309 . 10.1021/ic502931e. 25668724 .
  9. Auer . Henry . Kohlmann . Holger . In situ Investigations on the Formation and Decomposition of KSiH 3 and CsSiH 3: In situ Investigations on the Formation and Decomposition of KSiH 3 and CsSiH 3 . Zeitschrift für anorganische und allgemeine Chemie . 3 August 2017 . 643 . 14 . 945–951 . 10.1002/zaac.201700164.
  10. Chotard . Jean-Noël . Tang . Wan Si . Raybaud . Pascal . Janot . Raphaël . Potassium Silanide (KSiH3): A Reversible Hydrogen Storage Material . Chemistry - A European Journal . 24 October 2011 . 17 . 44 . 12302–12309 . 10.1002/chem.201101865. 21953694 .
  11. Janot . R. . Tang . W. S. . Clémençon . D. . Chotard . J.-N. . Catalyzed KSiH 3 as a reversible hydrogen storage material . Journal of Materials Chemistry A . 2016 . 4 . 48 . 19045–19052 . 10.1039/C6TA07563K.
  12. Hedberg. Kenneth. December 1955. The Molecular Structure of Trisilylamine (SiH 3) 3 N 1,2. Journal of the American Chemical Society. en. 77. 24. 6491–6492. 10.1021/ja01629a015. 0002-7863.
  13. Pritzkow. Hans. Lobreyer. Thomas. Sundermeyer. Wolfgang. van Eikema Hommes. Nicolaas J. R.. von Ragué Schleyer. Paul. 1994-02-01. Inversely Coordinating Silanide Ions in an Oligomeric Sodium Alcoholate. Angewandte Chemie International Edition in English. en. 33. 2. 216–217. 10.1002/anie.199402161. 0570-0833.
  14. Amberger. Eberhard. Boeters. Hans D.. July 1964. Trisilylverbindungen. Chemische Berichte. de. 97. 7. 1999–2004. 10.1002/cber.19640970731.
  15. Vekilova . Olga Yu. . Beyer . Doreen C. . Bhat . Shrikant . Farla . Robert . Baran . Volodymyr . Simak . Sergei I. . Kohlmann . Holger . Häussermann . Ulrich . Spektor . Kristina . 2023-05-15 . Formation and Polymorphism of Semiconducting K 2 SiH 6 and Strategy for Metallization . Inorganic Chemistry . 62 . 21 . 8093–8100 . en . 10.1021/acs.inorgchem.2c04370 . 37188333 . 10231339 . 258716226 . 0020-1669 .
  16. Mundt. Otto. Becker. Gerd. Hartmann. Hans-Martin. Schwarz. Wolfgang. May 1989. Metallderivate von Molekülverbindungen. II. Darstellung und Struktur des beta-Kaliumsilanids. Zeitschrift für anorganische und allgemeine Chemie. de. 572. 1. 75–88. 10.1002/zaac.19895720109. 0044-2313.
  17. Wolstenholme. David J.. Prince. Paul D.. McGrady. G. Sean. Landry. Michael J.. Steed. Jonathan W.. 2011-11-07. Structure and Bonding of KSiH 3 and Its 18-Crown-6 Derivatives: Unusual Ambidentate Behavior of the SiH 3 – Anion. Inorganic Chemistry. en. 50. 21. 11222–11227. 10.1021/ic201774x. 21981304. 0020-1669.
  18. Hencken. Günther. Weiss. Erwin. June 1973. Darstellung und Kristallstruktur des Tetrakis(π-cyclopentadienyl)-di-μ-silyleno-dititans [(C5H5)2TiSiH2]2]. Chemische Berichte. de. 106. 6. 1747–1751. 10.1002/cber.19731060608.
  19. Hao. Leijun. Lebuis. Anne-Marie. Harrod. John F.. Hao. Leijun. Samuel. Edmond. 1997. Preparation and characterization of titanocene silyl hydrides [Cp2Ti(μ-HSiH2)]2 and [Cp2Ti(μ-HSiH2)(μ-H)TiCp2]]. Chemical Communications. 22. 2193–2194. 10.1039/a705102f.
  20. Malisch. Wolfgang. Vögler. Matthias. Käb. Harald. Wekel. Hans-Ulrich. July 2002. [(μ 2 -CO)Cp 2 (OC) 2 Fe 2 ][Cp(OC) 2 Fe]SiH: A SiH-Functionalized Tris(metallo)silane. Synthesis from [Cp(OC) 2 Fe] 2 SiH 2 1]. Organometallics. en. 21. 14. 2830–2832. 10.1021/om0201922. 0276-7333.
  21. Sun . Xiaofei . Hinz . Alexander . 2023-06-21 . A Barium Complex of the Silanide SiH 3 – : Hydride Surrogate and Source of Silicon . Inorganic Chemistry . 62 . 26 . 10249–10255 . en . 10.1021/acs.inorgchem.3c01045 . 37341997 . 0020-1669.
  22. Tang. Wan Si. Dimitrievska. Mirjana. Chotard. Jean-Noël. Zhou. Wei. Janot. Raphaël. Skripov. Alexander V.. Udovic. Terrence J.. 2016-09-29. Structural and Dynamical Trends in Alkali-Metal Silanides Characterized by Neutron-Scattering Methods. The Journal of Physical Chemistry C. en. 120. 38. 21218–21227. 10.1021/acs.jpcc.6b06591. 1329467. 1932-7447.
  23. Hou. Zhaomin. Zhang. Yugen. Nishiura. Masayoshi. Wakatsuki. Yasuo. 2003-01-01. (Pentamethylcyclopentadienyl)lanthanide(II) Alkyl and Silyl Complexes: Synthesis, Structures, and Catalysis in Polymerization of Ethylene and Styrene. Organometallics. en. 22. 1. 129–135. 10.1021/om020742w. 0276-7333.
  24. Liang. Tianxiao. Zhang. Zihan. Feng. Xiaolei. Jia. Haojun. Pickard. Chris J.. Redfern. Simon A. T.. Duan. Defang. 2020-11-18. Ternary hypervalent silicon hydrides via lithium at high pressure. Physical Review Materials. en. 4. 11. 113607. 10.1103/PhysRevMaterials.4.113607. 2010.01469. 2020PhRvM...4k3607L. 10356/146521 . 222134096. 2475-9953.
  25. Chen. Yang. Song. Haibin. Cui. Chunming. 2010-11-15. Dehydrosilylation of ArNHSiH3 with Ytterbium(II) Amide: Formation of a Dimeric Ytterbium(II) Silanimine Complex. Angewandte Chemie. en. 122. 47. 9142–9145. 10.1002/ange.201004856. 2010AngCh.122.9142C.
  26. Auer . Henry . Guehne . Robin . Bertmer . Marko . Weber . Sebastian . Wenderoth . Patrick . Hansen . Thomas Christian . Haase . Jürgen . Kohlmann . Holger . Hydrides of Alkaline Earth–Tetrel (AeTt) Zintl Phases: Covalent Tt–H Bonds from Silicon to Tin . Inorganic Chemistry . 6 February 2017 . 56 . 3 . 1061–1071 . 10.1021/acs.inorgchem.6b01944. 28098994 .

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