Silanide
{{Short description|Anionic molecule derived from silane}}
{{Chembox
|ImageFile=SiH3 -.svg
| OtherNames = Trihydridosilanide
Trihydridosilicate(1-)
Trihydridosilicate(IV)
|Section1={{Chembox Identifiers
| CASNo = 15807-96-2
| CASNo_Ref = {{Cascite|correct|CAS}}
| ChEBI = 30561
| ChemSpiderID = 19684660
| Gmelin = 266
| PubChem = 166628
| StdInChI=1S/H3Si/h1H3/q-1
| StdInChIKey = LNVJLOIIRUIQCP-UHFFFAOYSA-N
| SMILES = [SiH3-]
}}
|Section2={{Chembox Properties
| Formula = {{chem2|SiH3−}}
| Si=1|H=3
}}
|Section8={{Chembox Related
| OtherCompounds = Methyl anion, Germyl, Stannyl, Phosphinide, Arsinide
}}
}}
A silanide is a chemical compound containing an anionic silicon(IV) centre, the parent ion being {{chem2|SiH3−}}. The hydrogen atoms can also be substituted to produce more complex derivative anions such as tris(trimethylsilyl)silanide (hypersilyl),{{Cite journal|last=Klinkhammer|first=Karl W.|date=September 1997|title=Tris(trimethylsilyl)silanides of the Heavier Alkali Metals—A Structural Study|url=http://doi.wiley.com/10.1002/chem.19970030908|journal=Chemistry - A European Journal|language=de|volume=3|issue=9|pages=1418–1431|doi=10.1002/chem.19970030908}} tris(tert-butyl)silanide, tris(pentafluoroethyl)silanide, or triphenylsilanide.{{Cite journal|last1=Lickiss|first1=Paul D.|last2=Smith|first2=Colin M.|date=November 1995|title=Silicon derivatives of the metals of groups 1 and 2|url=https://linkinghub.elsevier.com/retrieve/pii/001085459590218X|journal=Coordination Chemistry Reviews|language=en|volume=145|pages=75–124|doi=10.1016/0010-8545(95)90218-X}} 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 {{chem2|PhSiH3}} at standard conditions. The triphenylsilanide can be made in a reaction of Ph3SiSiMe3 with the metal tert-butoxy compound.{{cite journal |last1=Schuhknecht |first1=Danny |last2=Leich |first2=Valeri |last3=Spaniol |first3=Thomas P. |last4=Douair |first4=Iskander |last5=Maron |first5=Laurent |last6=Okuda |first6=Jun |title=Alkali Metal Triphenyl- and Trihydridosilanides Stabilized by a Macrocyclic Polyamine Ligand |journal=Chemistry – A European Journal |date=2 March 2020 |volume=26 |issue=13 |pages=2821–2825 |doi=10.1002/chem.202000187|pmid=31943432 |pmc=7079104 }}
Reacting hydrogen with potassium triphenylsilyl {{chem2|K(Me6TREN)SiPh3}} can yield potassium silanide.{{cite journal |last1=Leich |first1=V. |last2=Spaniol |first2=T. P. |last3=Okuda |first3=J. |title=Formation of α-[KSiH 3 ] by hydrogenolysis of potassium triphenylsilyl |journal=Chemical Communications |date=2015 |volume=51 |issue=79 |pages=14772–14774 |doi=10.1039/C5CC06187C|pmid=26299566 }}
Other method to form silanides are to heat a heavy metal silicide with hydrogen,{{cite journal |last1=Tang |first1=Wan Si |last2=Chotard |first2=Jean-Noël |last3=Raybaud |first3=Pascal |last4=Janot |first4=Raphaël |title=Hydrogenation properties of KSi and NaSi Zintl phases |journal=Physical Chemistry Chemical Physics |date=2012 |volume=14 |issue=38 |pages=13319–13324 |doi=10.1039/C2CP41589E|pmid=22930067 |bibcode=2012PCCP...1413319T }} or react the dissolved metal with silane.
Atomic metals can react directly with silane to yield unstable molecules with {{chem2|HMSiH3}} formulae. These can be condensed into a noble gas matrix. With titanium this also yields molecules with hydrogen bridging between silicon and titanium.{{Cite journal|last=Corey|first=Joyce Y.|date=2011-02-09|title=Reactions of Hydrosilanes with Transition Metal Complexes and Characterization of the Products|url=https://pubs.acs.org/doi/10.1021/cr900359c|journal=Chemical Reviews|language=en|volume=111|issue=2|pages=863–1071|doi=10.1021/cr900359c|pmid=21250634|issn=0009-2665}}
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.{{Cite journal|last1=Weiss|first1=Erwin|last2=Hencken|first2=Günther|last3=Kühr|first3=Heinrich|date=September 1970|title=Kristallstrukturen und kernmagnetische Breitlinienresonanz der Alkalisilyle SiH3M (M = K, Rb, Cs)|url=https://onlinelibrary.wiley.com/doi/10.1002/cber.19701030924|journal=Chemische Berichte|language=de|volume=103|issue=9|pages=2868–2872|doi=10.1002/cber.19701030924}} 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.{{cite journal |last1=Kranak |first1=Verina F. |last2=Lin |first2=Yuan-Chih |last3=Karlsson |first3=Maths |last4=Mink |first4=Janos |last5=Norberg |first5=Stefan T. |last6=Häussermann |first6=Ulrich |title=Structural and Vibrational Properties of Silyl (SiH 3 – ) Anions in KSiH 3 and RbSiH 3 : New Insight into Si–H Interactions |journal=Inorganic Chemistry |date=2 March 2015 |volume=54 |issue=5 |pages=2300–2309 |doi=10.1021/ic502931e|pmid=25668724 }}
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. 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.
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:
Use
Trihydridosilanides have been investigated as hydrogen storage materials.{{cite journal |last1=Chotard |first1=Jean-Noël |last2=Tang |first2=Wan Si |last3=Raybaud |first3=Pascal |last4=Janot |first4=Raphaël |title=Potassium Silanide (KSiH3): A Reversible Hydrogen Storage Material |journal=Chemistry - A European Journal |date=24 October 2011 |volume=17 |issue=44 |pages=12302–12309 |doi=10.1002/chem.201101865|pmid=21953694 }} Potassium silanide can reversibly gain or lose hydrogen over several hours at 373K. However this does not work for sodium silanide. The rate of hydrogen exchange may be improved by a catalyst. Unwanted reactions may reduce the number of times this process can happen.{{cite journal |last1=Janot |first1=R. |last2=Tang |first2=W. S. |last3=Clémençon |first3=D. |last4=Chotard |first4=J.-N. |title=Catalyzed KSiH 3 as a reversible hydrogen storage material |journal=Journal of Materials Chemistry A |date=2016 |volume=4 |issue=48 |pages=19045–19052 |doi=10.1039/C6TA07563K}}
List
class="wikitable"
!name !formula !Crystal system !space group !unit cell !volume !density !comment !references |
tetramethyl-1,4,7,10-tetraaminocyclododecane lithium silanide
|{{chem2|Li(Me4TACD)SiH3}} | | | | | |colourless; unstable |
trisilylamine
|{{chem2|N(SiH3)3}} | | | | | |mp -105 °C; planar |
tetramethyl-1,4,7,10-tetraaminocyclododecane sodium silanide
|{{chem2|Na(Me4TACD)SiH3}} |tetragonal |P4/n |a=9.77 c=9.45 Z=2 |901 |1.041 |colourless |
|{{chem2|Na8(OC2H4OC2H4OCH3)6(SiH3)2}}
| | | | | |H is bridge |
trisilylphosphine
|{{chem2|P(SiH3)3}} | | | | | | |
Potassium silanide
|{{chem2|KSiH3}} |cubic | |a=7.23 |377.9 |1.241 |pale yellow |{{Cite journal |last1=Vekilova |first1=Olga Yu. |last2=Beyer |first2=Doreen C. |last3=Bhat |first3=Shrikant |last4=Farla |first4=Robert |last5=Baran |first5=Volodymyr |last6=Simak |first6=Sergei I. |last7=Kohlmann |first7=Holger |last8=Häussermann |first8=Ulrich |last9=Spektor |first9=Kristina |date=2023-05-15 |title=Formation and Polymorphism of Semiconducting K 2 SiH 6 and Strategy for Metallization |journal=Inorganic Chemistry |volume=62 |issue=21 |pages=8093–8100 |language=en |doi=10.1021/acs.inorgchem.2c04370 |pmid=37188333 |pmc=10231339 |s2cid=258716226 |issn=0020-1669 }} |
|β-{{chem2|KSiH3}}
|orthorhombic |Pnma |a = 8.800, b = 5.416, c = 6.823, Z = 4 |325.2 | | |
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 |
|[K(18-crown-6)SiH3·THF]
| | | | | | |
|[K(18-crown-6)SiH3·HSiPh3]
| | | | | |H is bridge |
|{{chem2|Cp2(Me3P)TiSiH3}}
| | | | | |purple |
|{{chem2|[(C5H5)2TiSiH2]2}}
|tetragonal |P42/mnm |a = 8.018, c = 16.113, Z = 2 | | |olive green; Ti-SiH2-Ti-SiH2- ring |
|[Cp2Ti(μ-HSiH2)]2
| | | | | |dark blue |
|Cp2Ti(μ-HSiH2)(μ-H)TiCp2
| | | | | |dark yellowish green |
|{{chem2|HCrSiH3}}
| | | | | | |
|{{chem2|[Cp(OC)2Fe]2SiH2}}
|triclinic |P{{overbar|1}} |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 |
|[(μ2-CO)Cp2(OC)2Fe2]SiH2
| | | | | |dark red |
|[(μ2-CO)Cp2(OC)2Fe2][Cp(OC)2Fe]SiH
| | | | | |dark red |
|{{chem2|HNiSiH3}}
| | | | | | |
|{{chem2|HZnSiH3}}
| | | | | | |
|[(dtbpCbz)GeSiH3]2•C6H18
|monoclinic |P21/n |a 16.144 b 15.0369 c 21.974 β 91.927° | | | |
trisilylarsine
|{{chem2|As(SiH3)3}} | | | | | | |
rubidium silanide
|{{chem2|RbSiH3}} |cubic | |a=7.52 |425.3 |1.824 |yellow |
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 |
|{{chem2|K0.5Rb0.5SiH3}}
|cubic |P{{overbar|4}}3m |a=12.832 |2112.7 | | |
|{{chem2|Mo(CO)(H)(SiH3)(depe)2}}
| | | | | | |
|{{chem2|[Cp(OC)2Ru]2SiH2}}
| | | | | |beige mp 25 |
trisilylstibine
|{{chem2|Sb(SiH3)3}} | | | | | | |
caesium silanide
|{{chem2|CsSiH3}} |cubic | |a=7.86 |485.6 |2.243 |yellow |
|{{chem2|Cs0.5K0.5SiH3}}
|cubic |P{{overbar|4}}3m |a=13.0965 |2246.3 | | |
|{{chem2|Cs0.5Rb0.5SiH3}}
|cubic |P{{overbar|4}}3m |a=13.2982 |2351.7 | | |
bis(di-tert-butylphenyl)di-tert-butylcanozalide
|[(dtbpCbz)BaSiH3]8 | |P4/nnc |a=38.7375 c=44.8635 | | | |
|{{chem2|[Cp2SmSiH3]3}}
| | | | | |orange |
|{{chem2|(C5Me5)Sm(SiH3)(THF)(C5Me5)K(THF)}}
| | | | | | dark red |
|{{chem2|(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 |
|{{chem2|(C5Me5)Yb(SiH3)(THF)(C5Me5)K(THF)}}
|orthorhombic |Pna21 |a=19.321 b=16.496 c=9.926 Z=4 |3163.7 | | dark red |
|Cp(iPr3P)Os(H)(Br)SiH3
| | | | | |yellow |
|trans-{{chem2|(Cy3P)2HPtSiH3}}
| | | | | | |
Related
Under high hydrogen pressure, pentacoordinated and hexacoordinated silicon hydride ions are stabilised including {{chem2|SiH5(−)}} and {{chem2|SiH6(2−)}}.{{Cite journal|last1=Liang|first1=Tianxiao|last2=Zhang|first2=Zihan|last3=Feng|first3=Xiaolei|last4=Jia|first4=Haojun|last5=Pickard|first5=Chris J.|last6=Redfern|first6=Simon A. T.|last7=Duan|first7=Defang|date=2020-11-18|title=Ternary hypervalent silicon hydrides via lithium at high pressure|url=https://link.aps.org/doi/10.1103/PhysRevMaterials.4.113607|journal=Physical Review Materials|language=en|volume=4|issue=11|pages=113607|doi=10.1103/PhysRevMaterials.4.113607|arxiv=2010.01469|bibcode=2020PhRvM...4k3607L|hdl=10356/146521 |s2cid=222134096|issn=2475-9953}}
More complex derivatives include silanimine -{{chem2|NHSiH3}},{{Cite journal|last1=Chen|first1=Yang|last2=Song|first2=Haibin|last3=Cui|first3=Chunming|date=2010-11-15|title=Dehydrosilylation of ArNHSiH3 with Ytterbium(II) Amide: Formation of a Dimeric Ytterbium(II) Silanimine Complex|url=https://onlinelibrary.wiley.com/doi/10.1002/ange.201004856|journal=Angewandte Chemie|language=en|volume=122|issue=47|pages=9142–9145|doi=10.1002/ange.201004856|bibcode=2010AngCh.122.9142C}}
With a double bond between silicon and the metal {{chem2|=SiH2}} 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 {{su|p=∞|b=1}}[(SiH)−] can be formed.{{cite journal |last1=Auer |first1=Henry |last2=Guehne |first2=Robin |last3=Bertmer |first3=Marko |last4=Weber |first4=Sebastian |last5=Wenderoth |first5=Patrick |last6=Hansen |first6=Thomas Christian |last7=Haase |first7=Jürgen |last8=Kohlmann |first8=Holger |title=Hydrides of Alkaline Earth–Tetrel (AeTt) Zintl Phases: Covalent Tt–H Bonds from Silicon to Tin |journal=Inorganic Chemistry |date=6 February 2017 |volume=56 |issue=3 |pages=1061–1071 |doi=10.1021/acs.inorgchem.6b01944|pmid=28098994 |url=http://ul.qucosa.de/id/qucosa%3A33406 }}
General organic compounds are termed silylium ions.