Silanide

A silanide is a chemical compound containing an anionic silicon(IV) centre, the parent ion being SiH−3. 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.

Silanide

Names
Other names Trihydridosilanide Trihydridosilicate(1-) Trihydridosilicate(IV)
Identifiers
CAS Number	15807-96-2 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:30561
ChemSpider	19684660
Gmelin Reference	266
PubChem CID	166628
CompTox Dashboard (EPA)	DTXSID801317131
InChI InChI=1S/H3Si/h1H3/q-1 Key: LNVJLOIIRUIQCP-UHFFFAOYSA-N
SMILES [SiH3-]
Properties
Chemical formula	SiH−3
Molar mass	31.109 g·mol−1
Related compounds
Related compounds	Methyl anion, Germyl, Stannyl, Phosphinide, Arsinide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Formation

The simplest trihydridosilanides can be produced from a triphenylsilanide in a reaction with hydrogen or PhSiH₃ 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 K(Me₆TREN)SiPh₃ 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 HMSiH₃ 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 C_3v 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.^[7]

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:

46KSiH₃ → K₈Si₄₆ + 38KH + 50H₂.^[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

name	formula	Crystal system	space group	unit cell	volume	density	comment	references
tetramethyl-1,4,7,10-tetraaminocyclododecane lithium silanide	Li(Me4TACD)SiH3						colourless; unstable	[3]
trisilylamine	N(SiH3)3						mp -105 °C; planar	[12]
tetramethyl-1,4,7,10-tetraaminocyclododecane sodium silanide	Na(Me4TACD)SiH3	tetragonal	P4/n	a=9.77 c=9.45 Z=2	901	1.041	colourless	[3]
	Na8(OC2H4OC2H4OCH3)6(SiH3)2						H is bridge	[13]
trisilylphosphine	P(SiH3)3							[14]
Potassium silanide	KSiH3	cubic		a=7.23	377.9	1.241	pale yellow	[7][15]
	β-KSiH3	orthorhombic	Pnma	a = 8.800, b = 5.416, c = 6.823, Z = 4	325.2			[16]
tetramethyl-1,4,7,10-tetraaminocyclododecane potassium silanide	K(Me4TACD)SiH3•2C6H6	tetragonal	P42/mnm	a=12.3401 c=14.9372 Z=2	2274.6	1.10	colourless	[3]
	[K(18-crown-6)SiH3·THF]							[17]
	[K(18-crown-6)SiH3·HSiPh3]						H is bridge	[17]
	Cp2(Me3P)TiSiH3						purple	[6]
	[(C5H5)2TiSiH2]2	tetragonal	P42/mnm	a = 8.018, c = 16.113, Z = 2			olive green; Ti-SiH2-Ti-SiH2- ring	[18]
	[Cp2Ti(μ-HSiH2)]2						dark blue	[19]
	Cp2Ti(μ-HSiH2)(μ-H)TiCp2						dark yellowish green	[19]
	HCrSiH3							[6]
	[Cp(OC)2Fe]2SiH2	triclinic	P1	a=6.318 b=10.653 c=12.453 α=67.884 β=75.35 γ=72.79 Z=2	732.1	1.742	light yellow	[20]
	[(μ2-CO)Cp2(OC)2Fe2]SiH2						dark red	[20]
	[(μ2-CO)Cp2(OC)2Fe2][Cp(OC)2Fe]SiH						dark red	[20]
	HNiSiH3							[6]
	HZnSiH3							[6]
	[(dtbpCbz)GeSiH3]2•C6H18	monoclinic	P21/n	a 16.144 b 15.0369 c 21.974 β 91.927°				[21]
trisilylarsine	As(SiH3)3							[14]
rubidium silanide	RbSiH3	cubic		a=7.52	425.3	1.824	yellow	[7]
tetramethyl-1,4,7,10-tetraaminocyclododecane rubidium silanide	Rb(Me4TACD)SiH3•2C6H6	tetragonal	P42/mnm	a=12.3934 c=14.9632 Z=2	2298.3	1.223	yellow	[3]
	K0.5Rb0.5SiH3	cubic	P43m	a=12.832	2112.7			[22]
	Mo(CO)(H)(SiH3)(depe)2							[6]
	[Cp(OC)2Ru]2SiH2						beige mp 25	[20]
trisilylstibine	Sb(SiH3)3							[14]
caesium silanide	CsSiH3	cubic		a=7.86	485.6	2.243	yellow	[3][7]
	Cs0.5K0.5SiH3	cubic	P43m	a=13.0965	2246.3			[22]
	Cs0.5Rb0.5SiH3	cubic	P43m	a=13.2982	2351.7			[22]
bis(di-tert-butylphenyl)di-tert-butylcanozalide	[(dtbpCbz)BaSiH3]8		P4/nnc	a=38.7375 c=44.8635				[21]
	[Cp2SmSiH3]3						orange	[6]
	(C5Me5)Sm(SiH3)(THF)(C5Me5)K(THF)						dark red	[23]
	(C5Me5)Eu(SiH3)(THF)(C5Me5)K(THF)	orthorhombic	Pna21	a=19.320 b=16.742 c=10.027 Z=4	3240.0	1.406	orange-red	[23]
	(C5Me5)Yb(SiH3)(THF)(C5Me5)K(THF)	orthorhombic	Pna21	a=19.321 b=16.496 c=9.926 Z=4	3163.7		dark red	[23]
	Cp(iPr3P)Os(H)(Br)SiH3						yellow	[6]
	trans-(Cy3P)2HPtSiH3							[6]

Related

Under high hydrogen pressure, pentacoordinated and hexacoordinated silicon hydride ions are stabilised including SiH−5 and SiH2−6.^[24]

More complex derivatives include silanimine -NHSiH₃,^[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 ^∞
₁[(SiH)⁻] can be formed.^[26]

General organic compounds are termed silylium ions.

References

1. Klinkhammer, Karl W. (September 1997). "Tris(trimethylsilyl)silanides of the Heavier Alkali Metals—A Structural Study". Chemistry - A European Journal (in German). 3 (9): 1418–1431. doi: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. 145: 75–124. doi:10.1016/0010-8545(95)90218-X.
3. Schuhknecht, Danny; Leich, Valeri; Spaniol, Thomas P.; Douair, Iskander; Maron, Laurent; Okuda, Jun (2 March 2020). "Alkali Metal Triphenyl- and Trihydridosilanides Stabilized by a Macrocyclic Polyamine Ligand". Chemistry – A European Journal. 26 (13): 2821–2825. doi:10.1002/chem.202000187. PMC 7079104. PMID 31943432.
4. Leich, V.; Spaniol, T. P.; Okuda, J. (2015). "Formation of α-[KSiH ₃ ] by hydrogenolysis of potassium triphenylsilyl". Chemical Communications. 51 (79): 14772–14774. doi:10.1039/C5CC06187C. PMID 26299566.
5. Tang, Wan Si; Chotard, Jean-Noël; Raybaud, Pascal; Janot, Raphaël (2012). "Hydrogenation properties of KSi and NaSi Zintl phases". Physical Chemistry Chemical Physics. 14 (38): 13319–13324. Bibcode:2012PCCP...1413319T. doi:10.1039/C2CP41589E. PMID 22930067.
6. Corey, Joyce Y. (2011-02-09). "Reactions of Hydrosilanes with Transition Metal Complexes and Characterization of the Products". Chemical Reviews. 111 (2): 863–1071. doi:10.1021/cr900359c. ISSN 0009-2665. PMID 21250634.
7. Weiss, Erwin; Hencken, Günther; Kühr, Heinrich (September 1970). "Kristallstrukturen und kernmagnetische Breitlinienresonanz der Alkalisilyle SiH3M (M = K, Rb, Cs)". Chemische Berichte (in German). 103 (9): 2868–2872. doi:10.1002/cber.19701030924.
8. Kranak, Verina F.; Lin, Yuan-Chih; Karlsson, Maths; Mink, Janos; Norberg, Stefan T.; Häussermann, Ulrich (2 March 2015). "Structural and Vibrational Properties of Silyl (SiH 3 – ) Anions in KSiH 3 and RbSiH 3 : New Insight into Si–H Interactions". Inorganic Chemistry. 54 (5): 2300–2309. doi:10.1021/ic502931e. PMID 25668724.
9. Auer, Henry; Kohlmann, Holger (3 August 2017). "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. 643 (14): 945–951. doi:10.1002/zaac.201700164.
10. Chotard, Jean-Noël; Tang, Wan Si; Raybaud, Pascal; Janot, Raphaël (24 October 2011). "Potassium Silanide (KSiH3): A Reversible Hydrogen Storage Material". Chemistry - A European Journal. 17 (44): 12302–12309. doi:10.1002/chem.201101865. PMID 21953694.
11. Janot, R.; Tang, W. S.; Clémençon, D.; Chotard, J.-N. (2016). "Catalyzed KSiH 3 as a reversible hydrogen storage material". Journal of Materials Chemistry A. 4 (48): 19045–19052. doi: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. 77 (24): 6491–6492. doi:10.1021/ja01629a015. ISSN 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. 33 (2): 216–217. doi:10.1002/anie.199402161. ISSN 0570-0833.
14. Amberger, Eberhard; Boeters, Hans D. (July 1964). "Trisilylverbindungen". Chemische Berichte (in German). 97 (7): 1999–2004. doi: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. doi:10.1021/acs.inorgchem.2c04370. ISSN 0020-1669. PMC 10231339. PMID 37188333. S2CID 258716226.
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 (in German). 572 (1): 75–88. doi:10.1002/zaac.19895720109. ISSN 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. 50 (21): 11222–11227. doi:10.1021/ic201774x. ISSN 0020-1669. PMID 21981304.
18. Hencken, Günther; Weiss, Erwin (June 1973). "Darstellung und Kristallstruktur des Tetrakis(π-cyclopentadienyl)-di-μ-silyleno-dititans [(C5H5)2TiSiH2]2". Chemische Berichte (in German). 106 (6): 1747–1751. doi: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. doi: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. 21 (14): 2830–2832. doi:10.1021/om0201922. ISSN 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. doi:10.1021/acs.inorgchem.3c01045. ISSN 0020-1669. PMID 37341997.
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. 120 (38): 21218–21227. doi:10.1021/acs.jpcc.6b06591. ISSN 1932-7447. OSTI 1329467.
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. 22 (1): 129–135. doi:10.1021/om020742w. ISSN 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. 4 (11): 113607. arXiv:2010.01469. Bibcode:2020PhRvM...4k3607L. doi:10.1103/PhysRevMaterials.4.113607. hdl:10356/146521. ISSN 2475-9953. S2CID 222134096.
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. 122 (47): 9142–9145. Bibcode:2010AngCh.122.9142C. doi:10.1002/ange.201004856.
26. Auer, Henry; Guehne, Robin; Bertmer, Marko; Weber, Sebastian; Wenderoth, Patrick; Hansen, Thomas Christian; Haase, Jürgen; Kohlmann, Holger (6 February 2017). "Hydrides of Alkaline Earth–Tetrel (AeTt) Zintl Phases: Covalent Tt–H Bonds from Silicon to Tin". Inorganic Chemistry. 56 (3): 1061–1071. doi:10.1021/acs.inorgchem.6b01944. PMID 28098994.