Iminoborane: Difference between revisions

Iminoborane
	; Iminoborane (parent compound)
Names
	Other names Boraneimine
Identifiers
CAS Number	R,R'=H: 15119-97-8 (HB=NH) ;
3D model (JSmol)	R,R'=H: Interactive image;
PubChem CID	R,R'=H: 102382766;
	InChI R,R'=H: InChI=1S/BH2N/c1-2/h1-2H Key: LNLSXDSWJBUPHM-UHFFFAOYSA-N;
	SMILES R,R'=H: B=N;
Properties
Chemical formula	BH2N
Molar mass	26.83 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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Iminoboranes comprise a group of organoboron compounds with the formula RB=NR'. They are electronically related to acetylenes but are usually more reactive due to the polarity.^[2]^[3]

Structure and bonding

The parent iminoborane, HB=NH, is produced by the photolysis of H₃BNH₃.^[4]^[5]^[6] Bonding in iminoboranes can be described by two resonance structures:^[7]

{\ce {R-{\overset {\ominus }{B}}{\equiv }{\overset {\oplus }{N}}-R<->R-B={\ddot {N}}-R}}

The stability is dramatically affected by bulky substituents. One isolable iminoborane is (CH₃)₃C−B⁻≡N⁺−C(CH₃)₃.^[1]

Comparison of bond lengths in simple boron-nitrogen hydrides
Molecule	Ammonia borane^[8]	Aminoborane^[9]	Iminoborane^[10]
Formula	BNH₆	BNH₄	BNH₂
Class	amine-borane	aminoborane	iminoborane
Analogous hydrocarbon	ethane	ethylene	acetylene
Analogous hydrocarbon class	alkane	alkene	alkyne
Structure
Ball-and-stick model
Hybridisation of boron and nitrogen	sp³	sp²	sp
B-N bond length	1.658 Å	1.391 Å	1.238 Å
Proportion of B-N single bond	100%	84%	75%
B-H bond length	1.216 Å	1.195 Å
N-H bond length	1.014 Å	1.004 Å
Structure determination method	microwave spectroscopy	microwave spectroscopy	infrared spectroscopy

Synthesis

Elimination of fluoro- or chlorosilanes provides a well-tested route. Bulky substituents such as (Me₃Si)₃Si stabilize the iminoborane with respect to oligomerization:^[11]

(Me₃Si)₃SiB(F)-N(SiMe₃)₂ → (Me₃Si)₃Si-B=N-SiMe₃ + F-SiMe₃

Thermal decomposition of azidoboranes induces migration of R from boron to the nascent nitrene gives iminoboranes:^[12]

R₂B-N₃ → RB=NR + N₂

Reactivity

Oligomerization

Iminoboranes tend to oligomerize, often forming cyclic derivatives. Preventing this reaction is the purpose of bulky substituents. Five types of oligomerization product are produced: cyclodimers (1,3-diaza-2,4-diboretidines,^[1] Di^[13]), cyclotrimers (borazines, Tr), bicyclotrimers (Dewar borazines, Tr′^[14]), cyclotetramers (octahydro-1,3,5,7-tetraza-2,4,6,8-tetraborocines, Te^[15]), and polymers (polyiminoboranes, Po); which are shown below.^[16] Which product is dominant depends on the structures of reactants and the reaction conditions. Some of the products can be interconverted.^[17]

Addition reactions

The addition of protic agents is fast and quantitive.^[18] Boration reaction of iminoboranes is the addition of B-X single bond to B≡N, where -X can be -Cl (chloro-boration), -N₃ (azido-boration), -SR (thio-boration), -NR2 (amino-boration) and R (alkyl-boration). One of these reactions are illustrated here.

Some electron-rich iminoboranes form adducts with Lewis acids.^[19]

Cycloaddition

The typical [2+3]-cycloaddition is the addition of B≡N and RN₃ to give a BN₄ ring.^[1] One of the widely investigated [2+2]-cycloadditions is the reaction of aldehydes and ketones.

Coordination to transition metals

Like alkynes, iminoboranes bind transition metals.

References

^ ^a ^b ^c ^d Paetzold, Peter; Plotho, Christoph Von; Schmid, Günter; Boese, Roland; Schrader, Bernhard; Bougeard, Daniel; Pfeiffer, Uwe; Gleiter, Rolf; Schüfer, Wolfgang (1984). "Darstellung, Reaktionen und Struktur vontert-Butyl(tert-butylimino)boran". Chemische Berichte. 117 (3): 1089–1102. doi:10.1002/cber.19841170324.
^ Inorganic ring systems : 7th International symposium : Papers. Chivers, Tristram. Gordon and Breach Science Publishers. 1994. ISBN 978-2-88449-168-6. OCLC 81135356.{{cite book}}: CS1 maint: others (link)
^ Paetzold, Peter (1987). Iminoboranes. Advances in Inorganic Chemistry. Vol. 31. pp. 123–170. doi:10.1016/s0898-8838(08)60223-8. ISBN 978-0-12-023631-2.
^ Lory, Earl R.; Porter, Richard F. (1973-03-01). "Infrared studies of matrix isolated species in the hydrogen-boron-nitrogen system". Journal of the American Chemical Society. 95 (6): 1766–1770. doi:10.1021/ja00787a012. ISSN 0002-7863.
^ Paetzold, Peter; Richter, Anette; Thijssen, Theo; Würtenberg, Stefan (1979-12-01). "Bildung, Struktur und Reaktivität von (Pentafluorphenyl)bor-tert-butylimid und seinem Cyclodimeren". Chemische Berichte. 112 (12): 3811–3827. doi:10.1002/cber.19791121207. ISSN 1099-0682.
^ Paetzold, Peter; von Plotho, Christoph (1982-08-01). "Über weitere monomere Borimide und ihre Reaktionen". Chemische Berichte. 115 (8): 2819–2825. doi:10.1002/cber.19821150813. ISSN 1099-0682.
^ Mó, Otilia; Yáñez, Manuel; Pendás, Angel Martín; Bene, Janet E. Del; Alkorta, Ibon; Elguero, José (2007-07-23). "Unusual substituent effects on the bonding of iminoboranes". Phys. Chem. Chem. Phys. 9 (30): 3970–3977. Bibcode:2007PCCP....9.3970M. doi:10.1039/b702480k. hdl:10261/72489. ISSN 1463-9084. PMID 17646885.
^ Thorne, L. R.; Suenram, R. D.; Lovas, F. J. (1983). "Microwave spectrum, torsional barrier, and structure of BH₃NH₃". J. Chem. Phys. 78 (1): 167–171. Bibcode:1983JChPh..78..167T. doi:10.1063/1.444528.
^ Sugie, Masaaki; Takeo, Harutoshi; Matsumura, Chi (1987). "Microwave spectrum and molecular structure of aminoborane, BH₂NH₂". J. Mol. Spectrosc. 123 (2): 286–292. Bibcode:1987JMoSp.123..286S. doi:10.1016/0022-2852(87)90279-7.
^ Kawashima, Yoshiyuki (1987). "Detection of HBNH by infrared diode laser spectroscopy". J. Chem. Phys. 87 (11): 6331–6333. Bibcode:1987JChPh..87.6331K. doi:10.1063/1.453462.
^ Haase, Martin; Klingebiel, Uwe (1985-04-01). "Simple Synthesis of Stable Iminoboranes". Angewandte Chemie International Edition in English. 24 (4): 324. doi:10.1002/anie.198503241. ISSN 1521-3773.
^ Paetzold, Peter; Eleftheriadis, Eleftherios; Minkwitz, Rolf; Wölfel, Volker; Gleiter, Rolf; Bischof, Peter; Friedrich, Gert (1988-01-01). "Bildung, Struktur und Reaktionen von Methyl(methylimino)boran". Chemische Berichte. 121 (1): 61–66. doi:10.1002/cber.19881210110. ISSN 1099-0682.
^ Hess, H. (1969-11-15). "Strukturbestimmungen an Bor–Stickstoff-Verbindungen. IV. Die Kristall- und Molekularstruktur von Hexakis(trimethylsilyl)-2,4-diamino-1,3,2,4-diazadiboretidin" (PDF). Acta Crystallographica Section B (in German). 25 (11): 2342–2349. doi:10.1107/s056774086900567x. ISSN 0567-7408.
^ Steuer, Holger-A.; Meller, Anton; Elter, Gernot (1985). "B-t-butyl-borazine und -diazadiboretidine". Journal of Organometallic Chemistry (in German). 295 (1): 1–6. doi:10.1016/0022-328x(85)88065-7.
^ Turner H. S. and Warne R. J. 1962 Proc. Chem. Soc. 69.
^ Advances in inorganic chemistry. Volume 31. Emeléus, H. J. (Harry Julius), Sharpe, A. G. New York: Academic Press. 1987. ISBN 978-0-12-023631-2. OCLC 277086713.{{cite book}}: CS1 maint: others (link)
^ Maier.G. (1978). "Tetra-tert-butyltetrahedrane". Angew. Chem. Int. Ed. Engl. 17 (7): 520–521. doi:10.1002/anie.197805201.
^ Nöth, Heinrich; Weber, Siegfried (1985-05-01). "Beiträge zur Chemie des Bors, 154. Addition von Trimethylsily-Verbindungen und von anderen Elektrophilen an (tert-Butylimino) (tetramethylpiperidino)boran". Chemische Berichte. 118 (5): 2144–2146. doi:10.1002/cber.19851180536. ISSN 1099-0682.
^ Nöth, Heinrich; Weber, Siegfried (1985-06-01). "Beiträge zur Chemie des Bors, 158. Addukte von Aluminium- und Galliumhalogeniden an ein Aminoiminoboran". Chemische Berichte. 118 (6): 2554–2556. doi:10.1002/cber.19851180631. ISSN 1099-0682.

[PPaetz-1] Paetzold, Peter; Plotho, Christoph Von; Schmid, Günter; Boese, Roland; Schrader, Bernhard; Bougeard, Daniel; Pfeiffer, Uwe; Gleiter, Rolf; Schüfer, Wolfgang (1984). "Darstellung, Reaktionen und Struktur vontert-Butyl(tert-butylimino)boran". Chemische Berichte. 117 (3): 1089–1102. doi:10.1002/cber.19841170324.

[2] Inorganic ring systems : 7th International symposium : Papers. Chivers, Tristram. Gordon and Breach Science Publishers. 1994. ISBN 978-2-88449-168-6. OCLC 81135356.{{cite book}}: CS1 maint: others (link)

[3] Paetzold, Peter (1987). Iminoboranes. Advances in Inorganic Chemistry. Vol. 31. pp. 123–170. doi:10.1016/s0898-8838(08)60223-8. ISBN 978-0-12-023631-2.

[4] Lory, Earl R.; Porter, Richard F. (1973-03-01). "Infrared studies of matrix isolated species in the hydrogen-boron-nitrogen system". Journal of the American Chemical Society. 95 (6): 1766–1770. doi:10.1021/ja00787a012. ISSN 0002-7863.

[5] Paetzold, Peter; Richter, Anette; Thijssen, Theo; Würtenberg, Stefan (1979-12-01). "Bildung, Struktur und Reaktivität von (Pentafluorphenyl)bor-tert-butylimid und seinem Cyclodimeren". Chemische Berichte. 112 (12): 3811–3827. doi:10.1002/cber.19791121207. ISSN 1099-0682.

[6] Paetzold, Peter; von Plotho, Christoph (1982-08-01). "Über weitere monomere Borimide und ihre Reaktionen". Chemische Berichte. 115 (8): 2819–2825. doi:10.1002/cber.19821150813. ISSN 1099-0682.

[7] Mó, Otilia; Yáñez, Manuel; Pendás, Angel Martín; Bene, Janet E. Del; Alkorta, Ibon; Elguero, José (2007-07-23). "Unusual substituent effects on the bonding of iminoboranes". Phys. Chem. Chem. Phys. 9 (30): 3970–3977. Bibcode:2007PCCP....9.3970M. doi:10.1039/b702480k. hdl:10261/72489. ISSN 1463-9084. PMID 17646885.

[8] Thorne, L. R.; Suenram, R. D.; Lovas, F. J. (1983). "Microwave spectrum, torsional barrier, and structure of BH₃NH₃". J. Chem. Phys. 78 (1): 167–171. Bibcode:1983JChPh..78..167T. doi:10.1063/1.444528.

[9] Sugie, Masaaki; Takeo, Harutoshi; Matsumura, Chi (1987). "Microwave spectrum and molecular structure of aminoborane, BH₂NH₂". J. Mol. Spectrosc. 123 (2): 286–292. Bibcode:1987JMoSp.123..286S. doi:10.1016/0022-2852(87)90279-7.

[10] Kawashima, Yoshiyuki (1987). "Detection of HBNH by infrared diode laser spectroscopy". J. Chem. Phys. 87 (11): 6331–6333. Bibcode:1987JChPh..87.6331K. doi:10.1063/1.453462.

[11] Haase, Martin; Klingebiel, Uwe (1985-04-01). "Simple Synthesis of Stable Iminoboranes". Angewandte Chemie International Edition in English. 24 (4): 324. doi:10.1002/anie.198503241. ISSN 1521-3773.

[12] Paetzold, Peter; Eleftheriadis, Eleftherios; Minkwitz, Rolf; Wölfel, Volker; Gleiter, Rolf; Bischof, Peter; Friedrich, Gert (1988-01-01). "Bildung, Struktur und Reaktionen von Methyl(methylimino)boran". Chemische Berichte. 121 (1): 61–66. doi:10.1002/cber.19881210110. ISSN 1099-0682.

[13] Hess, H. (1969-11-15). "Strukturbestimmungen an Bor–Stickstoff-Verbindungen. IV. Die Kristall- und Molekularstruktur von Hexakis(trimethylsilyl)-2,4-diamino-1,3,2,4-diazadiboretidin" (PDF). Acta Crystallographica Section B (in German). 25 (11): 2342–2349. doi:10.1107/s056774086900567x. ISSN 0567-7408.

[14] Steuer, Holger-A.; Meller, Anton; Elter, Gernot (1985). "B-t-butyl-borazine und -diazadiboretidine". Journal of Organometallic Chemistry (in German). 295 (1): 1–6. doi:10.1016/0022-328x(85)88065-7.

[15] Turner H. S. and Warne R. J. 1962 Proc. Chem. Soc. 69.

[16] Advances in inorganic chemistry. Volume 31. Emeléus, H. J. (Harry Julius), Sharpe, A. G. New York: Academic Press. 1987. ISBN 978-0-12-023631-2. OCLC 277086713.{{cite book}}: CS1 maint: others (link)

[17] Maier.G. (1978). "Tetra-tert-butyltetrahedrane". Angew. Chem. Int. Ed. Engl. 17 (7): 520–521. doi:10.1002/anie.197805201.

[18] Nöth, Heinrich; Weber, Siegfried (1985-05-01). "Beiträge zur Chemie des Bors, 154. Addition von Trimethylsily-Verbindungen und von anderen Elektrophilen an (tert-Butylimino) (tetramethylpiperidino)boran". Chemische Berichte. 118 (5): 2144–2146. doi:10.1002/cber.19851180536. ISSN 1099-0682.

[19] Nöth, Heinrich; Weber, Siegfried (1985-06-01). "Beiträge zur Chemie des Bors, 158. Addukte von Aluminium- und Galliumhalogeniden an ein Aminoiminoboran". Chemische Berichte. 118 (6): 2554–2556. doi:10.1002/cber.19851180631. ISSN 1099-0682.

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@@ Line 1: / Line 1: @@
 {{short description|Class of chemical compounds}}
+{{Chembox
-{{Primary sources|date=February 2018}}
+| OtherNames = Boraneimine
-'''Iminoboranes''' comprise a group of [[inorganic compound]]s with the generic formula containing triple bonds XB≡NY, where X, Y can be H, F, RO, R<sub>2</sub>N, R<sub>3</sub>C, ''etc'', among which the simplest form is HB≡NH. They are electronically related to  [[acetylenes]] but are usually more reactive due to the polarity.<ref>{{Cite book|title=Inorganic ring systems : 7th International symposium : Papers.|date=1994|publisher=Gordon and Breach Science Publishers|others=Chivers, Tristram|isbn=978-2-88449-168-6|oclc=81135356}}</ref><ref>{{Cite book|title=Advances in inorganic chemistry. Volume 31|date=1987|publisher=Academic Press|others=Emeléus, H. J. (Harry Julius), Sharpe, A. G.|isbn=978-0-12-023631-2|location=New York|oclc=277086713|url-access=registration|url=https://archive.org/details/trent_0116400835595_31}}</ref><ref>{{Cite book|title=Iminoboranes|volume=31|last=Paetzold|first=Peter|pages=[https://archive.org/details/trent_0116400835595_31/page/123 123–170]|language=en|doi=10.1016/s0898-8838(08)60223-8|series=Advances in Inorganic Chemistry|year=1987|isbn=978-0-12-023631-2|url=https://archive.org/details/trent_0116400835595_31/page/123}}</ref>
+| ImageFile = Iminoborane-dimensions-IR-1987-2D.png
+| ImageCaption = Iminoborane (parent compound)
+|Section1={{Chembox Identifiers
+| index_label = R,R'=H
+| CASNo = 15119-97-8
+| CASNo_Ref = {{cascite|correct|CAS}}
+| CASNo_Comment = (HB=NH)
+| PubChem = 102382766
+| InChI=1S/BH2N/c1-2/h1-2H
+| InChIKey = LNLSXDSWJBUPHM-UHFFFAOYSA-N
+| SMILES = B=N
+ }}
+|Section2={{Chembox Properties
+| N=1|B=1|H=2
+ }}
+|Section8={{Chembox Related
+ }}
+}}
+[[File:TBuN=B-tBu (CETSUP).png|thumb|right|Structure of tBuN=B-tBu (tBu = [[tert-butyl]]). The B-N bond distance is 126 pm.<ref name=PPaetz/>]]
-== Structure and Bonding ==
+'''Iminoboranes''' comprise a group of [[organoboron compound]]s with the formula RB=NR'. They are electronically related to [[acetylenes]] but are usually more reactive due to the polarity.<ref>{{Cite book|title=Inorganic ring systems : 7th International symposium : Papers.|date=1994|publisher=Gordon and Breach Science Publishers|others=Chivers, Tristram|isbn=978-2-88449-168-6|oclc=81135356}}</ref><ref>{{Cite book|title=Iminoboranes|volume=31|last=Paetzold|first=Peter|pages=[https://archive.org/details/trent_0116400835595_31/page/123 123–170]|language=en|doi=10.1016/s0898-8838(08)60223-8|series=Advances in Inorganic Chemistry|year=1987|isbn=978-0-12-023631-2|url=https://archive.org/details/trent_0116400835595_31/page/123}}</ref>
-[[File:Figure-1- lewis structure of HBNH.png|thumb|[[Lewis structure|Lewis]] Resonance Structure of HBNH.]]
-The parent iminoborane, HB=NH, is produced by the photolysis of H<sub>3</sub>BNH<sub>3</sub>.<ref>{{Cite journal|last=Lory|first=Earl R.|last2=Porter|first2=Richard F.|date=1973-03-01|title=Infrared studies of matrix isolated species in the hydrogen-boron-nitrogen system|journal=Journal of the American Chemical Society|volume=95|issue=6|pages=1766–1770|doi=10.1021/ja00787a012|issn=0002-7863}}</ref><ref>{{Cite journal|last=Paetzold|first=Peter|last2=Richter|first2=Anette|last3=Thijssen|first3=Theo|last4=Würtenberg|first4=Stefan|date=1979-12-01|title=Bildung, Struktur und Reaktivität von (Pentafluorphenyl)bor-tert-butylimid und seinem Cyclodimeren|journal=Chemische Berichte|language=en|volume=112|issue=12|pages=3811–3827|doi=10.1002/cber.19791121207|issn=1099-0682}}</ref><ref>{{Cite journal|last=Paetzold|first=Peter|last2=von Plotho|first2=Christoph|date=1982-08-01|title=Über weitere monomere Borimide und ihre Reaktionen|journal=Chemische Berichte|language=en|volume=115|issue=8|pages=2819–2825|doi=10.1002/cber.19821150813|issn=1099-0682}}</ref> Bonding in iminoboranes can be described by two [[Resonance (chemistry)|resonance structures]].<ref>{{Cite journal|last=Mó|first=Otilia|last2=Yáñez|first2=Manuel|last3=Pendás|first3=Angel Martín|last4=Bene|first4=Janet E. Del|last5=Alkorta|first5=Ibon|last6=Elguero|first6=José|date=2007-07-23|title=Unusual substituent effects on the bonding of iminoboranes|url=http://xlink.rsc.org/?DOI=B702480K|journal=Phys. Chem. Chem. Phys.|language=en|volume=9|issue=30|pages=3970–3977|doi=10.1039/b702480k|pmid=17646885|issn=1463-9084|hdl=10261/72489}}</ref>
+== Structure and bonding ==
-===Substituent effects===
-Bonding and hence reactiviity is dramatically affected by substitution.<ref>{{Cite journal|last=Mó|first=Otilia|last2=Yáñez|first2=Manuel|last3=Pendás|first3=Angel Martín|last4=Bene|first4=Janet E. Del|last5=Alkorta|first5=Ibon|last6=Elguero|first6=José|date=2007-07-23|title=Unusual substituent effects on the bonding of iminoboranes|url=http://xlink.rsc.org/?DOI=B702480K|journal=Phys. Chem. Chem. Phys.|language=en|volume=9|issue=30|pages=3970–3977|doi=10.1039/b702480k|pmid=17646885|issn=1463-9084|hdl=10261/72489}}</ref> Strong shielding effect of bulky substitutions can make the iminoboranes more stable and more resistant to oligomerization, which allows for the storage at room temperature.<ref>{{Cite journal|last=Haase|first=Martin|last2=Klingebiel|first2=Uwe|date=1985-04-01|title=Simple Synthesis of Stable Iminoboranes|journal=Angewandte Chemie International Edition in English|language=en|volume=24|issue=4|pages=324|doi=10.1002/anie.198503241|issn=1521-3773}}</ref> Thermal decomposition of azidoboranes and trimethyl-silyl(trimethylsilyloxy)aminoboranes can be used to access symmetric iminoboranes, especially those with bulky R groups.<ref>{{Cite journal|last=Weiß|first=Robert|last2=Wagner|first2=Klaus-Georg|date=1984-05-01|title=Notizen. Die Erzeugung von Nitrosylsalzen in wasserfreien organischen Medien|journal=Chemische Berichte|language=en|volume=117|issue=5|pages=1973–1976|doi=10.1002/cber.19841170526|issn=1099-0682}}</ref>
+The parent iminoborane, HB=NH, is produced by the [[photodissociation|photolysis]] of H<sub>3</sub>BNH<sub>3</sub>.<ref>{{Cite journal|last1=Lory|first1=Earl R.|last2=Porter|first2=Richard F.|date=1973-03-01|title=Infrared studies of matrix isolated species in the hydrogen-boron-nitrogen system|journal=Journal of the American Chemical Society|volume=95|issue=6|pages=1766–1770|doi=10.1021/ja00787a012|issn=0002-7863}}</ref><ref>{{Cite journal|last1=Paetzold|first1=Peter|last2=Richter|first2=Anette|last3=Thijssen|first3=Theo|last4=Würtenberg|first4=Stefan|date=1979-12-01|title=Bildung, Struktur und Reaktivität von (Pentafluorphenyl)bor-tert-butylimid und seinem Cyclodimeren|journal=Chemische Berichte|language=en|volume=112|issue=12|pages=3811–3827|doi=10.1002/cber.19791121207|issn=1099-0682}}</ref><ref>{{Cite journal|last1=Paetzold|first1=Peter|last2=von Plotho|first2=Christoph|date=1982-08-01|title=Über weitere monomere Borimide und ihre Reaktionen|journal=Chemische Berichte|language=en|volume=115|issue=8|pages=2819–2825|doi=10.1002/cber.19821150813|issn=1099-0682}}</ref> Bonding in iminoboranes can be described by two [[Resonance (chemistry)|resonance structures]]:<ref>{{Cite journal|last1=Mó|first1=Otilia|last2=Yáñez|first2=Manuel|last3=Pendás|first3=Angel Martín|last4=Bene|first4=Janet E. Del|last5=Alkorta|first5=Ibon|last6=Elguero|first6=José|date=2007-07-23|title=Unusual substituent effects on the bonding of iminoboranes|url=http://xlink.rsc.org/?DOI=B702480K|journal=Phys. Chem. Chem. Phys.|language=en|volume=9|issue=30|pages=3970–3977|doi=10.1039/b702480k|pmid=17646885|bibcode=2007PCCP....9.3970M|issn=1463-9084|hdl=10261/72489}}</ref>
+:<chem>R-\overset{\ominus}{B}{\equiv}\overset{\oplus}{N}-R <-> R-B=\ddot{N}-R</chem>
+The stability is dramatically affected by bulky substituents. One isolable iminoborane is {{chem2|(CH3)3C\sB−\tN+\sC(CH3)3}}.<ref name=PPaetz>{{Cite journal|doi=10.1002/cber.19841170324|title=Darstellung, Reaktionen und Struktur vontert-Butyl(tert-butylimino)boran|year=1984|last1=Paetzold|first1=Peter|last2=Plotho|first2=Christoph Von|last3=Schmid|first3=Günter|last4=Boese|first4=Roland|last5=Schrader|first5=Bernhard|last6=Bougeard|first6=Daniel|last7=Pfeiffer|first7=Uwe|last8=Gleiter|first8=Rolf|last9=Schüfer|first9=Wolfgang|journal=Chemische Berichte|volume=117|issue=3|pages=1089–1102}}</ref>
-[[File:Figure 9- preparation of iminoboranes.png|center|frameless|282x282px]]
+{| class="wikitable" style="text-align:center;"
-[[File:Figure 10- preparation of iminoboranes.png|center|frameless]]
+|+Comparison of bond lengths in simple boron-nitrogen hydrides
+|-
+! Molecule
+| '''[[Ammonia borane]]'''<ref>{{ cite journal | first1 = L. R. | last1 = Thorne | first2 = R. D. | last2 = Suenram | first3 = F. J. | last3 = Lovas | title = Microwave spectrum, torsional barrier, and structure of BH<sub>3</sub>NH<sub>3</sub> | journal = [[The Journal of Chemical Physics|J. Chem. Phys.]] | volume = 78 | issue = 1 | year = 1983 | pages = 167–171 | doi = 10.1063/1.444528 | bibcode = 1983JChPh..78..167T }}</ref>
+| '''[[Aminoborane]]'''<ref>{{ cite journal | first1 = Masaaki | last1 = Sugie | first2 = Harutoshi | last2 = Takeo | first3 = Chi | last3 = Matsumura | title = Microwave spectrum and molecular structure of aminoborane, BH<sub>2</sub>NH<sub>2</sub> | journal = [[Journal of Molecular Spectroscopy|J. Mol. Spectrosc.]] | volume = 123 | issue = 2 | year = 1987 | pages = 286–292 | doi = 10.1016/0022-2852(87)90279-7 | bibcode = 1987JMoSp.123..286S }}</ref>
+| '''Iminoborane'''<ref>{{ cite journal | first1 = Yoshiyuki | last1 = Kawashima | title = Detection of HBNH by infrared diode laser spectroscopy | journal = [[The Journal of Chemical Physics|J. Chem. Phys.]] | year = 1987 | volume = 87 | issue = 11 | pages = 6331–6333 | doi = 10.1063/1.453462 | bibcode = 1987JChPh..87.6331K }}</ref>
+|-
+! Formula
+| BNH<sub>6</sub>
+| BNH<sub>4</sub>
+| BNH<sub>2</sub>
+|-
+! Class
+| [[amine-borane]]
+| [[aminoborane]]
+| iminoborane
+|-
+! Analogous hydrocarbon
+| [[ethane]]
+| [[ethylene]]
+| [[acetylene]]
+|-
+! Analogous hydrocarbon class
+| [[alkane]]
+| [[alkene]]
+| [[alkyne]]
+|-
+! Structure
+| [[File:Ammonia-borane-dimensions-MW-1983-2D.png|100px]]
+| [[File:Aminoborane-dimensions-MW-1987-2D.png |100px]]
+| [[File:Iminoborane-dimensions-IR-1987-2D.png|120px]]
+|-
+! [[Ball-and-stick model]]
+| [[File:Ammonia-borane-from-xtal-3D-balls.png|100px]]
+| [[File:Aminoborane-from-MW-1987-double-3D-balls.png|100px]]
+| [[File:Iminoborane-from-IR-1987-triple-3D-balls.png|120px]]
+|-
+! Hybridisation of boron and nitrogen
+| sp<sup>3</sup>
+| sp<sup>2</sup>
+| sp
+|-
+! B-N bond length
+| '''1.658 Å'''
+| '''1.391 Å'''
+| '''1.238 Å'''
+|-
+! Proportion of B-N single bond
+| 100%
+| 84%
+| 75%
+|-
+! B-H bond length
+| 1.216 Å
+| 1.195&nbsp;Å
+|
+|-
+! N-H bond length
+| 1.014 Å
+| 1.004 Å
+|
+|-
+! Structure determination method
+| [[rotational spectroscopy|microwave spectroscopy]]
+| microwave spectroscopy
+| [[infrared spectroscopy]]
+|}
+==Synthesis==
+Elimination of fluoro- or chlorosilanes provides a well-tested route. Bulky substituents such as [[tris(trimethylsilyl)silane|(Me<sub>3</sub>Si)<sub>3</sub>Si]] stabilize the iminoborane with respect to oligomerization:<ref>{{Cite journal|last1=Haase|first1=Martin|last2=Klingebiel|first2=Uwe|date=1985-04-01|title=Simple Synthesis of Stable Iminoboranes|journal=Angewandte Chemie International Edition in English|language=en|volume=24|issue=4|pages=324|doi=10.1002/anie.198503241|issn=1521-3773}}</ref>
+:(Me<sub>3</sub>Si)<sub>3</sub>SiB(F)-N(SiMe<sub>3</sub>)<sub>2</sub>  <big>→</big>  (Me<sub>3</sub>Si)<sub>3</sub>Si-B=N-SiMe<sub>3</sub> +  F-SiMe<sub>3</sub>
+Thermal decomposition of azidoboranes induces migration of R from boron to the nascent nitrene gives iminoboranes:<ref>{{Cite journal|last1=Paetzold|first1=Peter|last2=Eleftheriadis|first2=Eleftherios|last3=Minkwitz|first3=Rolf|last4=Wölfel|first4=Volker|last5=Gleiter|first5=Rolf|last6=Bischof|first6=Peter|last7=Friedrich|first7=Gert|date=1988-01-01|title=Bildung, Struktur und Reaktionen von Methyl(methylimino)boran|journal=Chemische Berichte|language=en|volume=121|issue=1|pages=61–66|doi=10.1002/cber.19881210110|issn=1099-0682}}</ref>
+:R<sub>2</sub>B-N<sub>3</sub>  <big>→</big>   RB=NR  + N<sub>2</sub>
 == Reactivity ==
 === Oligomerization ===
-Iminoboranes tend to oligomerize. Five types of oligomerization product are mainly produced: cyclodimers (1,3,2,4-diazadiboretidines, '''Di'''<ref>{{Cite journal|last=Paetzold|first=Peter|last2=Eleftheriadis|first2=Eleftherios|last3=Minkwitz|first3=Rolf|last4=Wölfel|first4=Volker|last5=Gleiter|first5=Rolf|last6=Bischof|first6=Peter|last7=Friedrich|first7=Gert|date=1988-01-01|title=Bildung, Struktur und Reaktionen von Methyl(methylimino)boran|journal=Chemische Berichte|language=en|volume=121|issue=1|pages=61–66|doi=10.1002/cber.19881210110|issn=1099-0682}}</ref><ref>{{Cite journal|last=Hess|first=H.|date=1969-11-15|title=Strukturbestimmungen an Bor–Stickstoff-Verbindungen. IV. Die Kristall- und Molekularstruktur von Hexakis(trimethylsilyl)-2,4-diamino-1,3,2,4-diazadiboretidin|journal=Acta Crystallographica Section B|language=de|volume=25|issue=11|pages=2342–2349|doi=10.1107/s056774086900567x|issn=0567-7408|url=http://journals.iucr.org/b/issues/1969/11/00/a06979/a06979.pdf}}</ref>), cyclotrimers ([[borazines]], '''Tr'''), bicyclotrimers ([[James Dewar|Dewar]] borazines, '''Tr’'''<ref>{{Cite journal|last=Steuer|first=Holger-A.|last2=Meller|first2=Anton|last3=Elter|first3=Gernot|title=B-t-butyl-borazine und -diazadiboretidine|journal=Journal of Organometallic Chemistry|language=en|volume=295|issue=1|pages=1–6|doi=10.1016/0022-328x(85)88065-7|year=1985}}</ref>), cyclotetramers (octahydro-1,3,5,7-tetraza-2,4,6,8-tetraborocines, '''Te'''<ref>{{Cite book|title=Turner H. S. and Warne R. J. 1962 Proc. Chem. Soc. 69|last=|first=|publisher=|year=|isbn=|location=|pages=}}</ref>), and polymers (polyiminoboranes, '''Po'''); which are shown below.<ref>{{Cite book|title=Advances in inorganic chemistry. Volume 31|date=1987|publisher=Academic Press|others=Emeléus, H. J. (Harry Julius), Sharpe, A. G.|isbn=978-0-12-023631-2|location=New York|oclc=277086713|url-access=registration|url=https://archive.org/details/trent_0116400835595_31}}</ref> Which product is dominant depends on the structures of reactants and the reaction conditions. Some of the products can be interconverted.<ref>{{Cite journal|last=Maier.G.|date=1978|title=Tetra-tert-butyltetrahedrane|url=|journal=Angew. Chem. Int. Ed. Engl.|volume=17|pages=520|via=|doi=10.1002/anie.197805201}}</ref>
+Iminoboranes tend to oligomerize, often forming cyclic derivatives.  Preventing this reaction is the purpose of bulky substituents. Five types of oligomerization product are produced: cyclodimers ({{chem name|1,3-diaza-2,4-diboretidine}}s,<ref name=PPaetz/> '''Di'''<ref>{{Cite journal|last=Hess|first=H.|date=1969-11-15|title=Strukturbestimmungen an Bor–Stickstoff-Verbindungen. IV. Die Kristall- und Molekularstruktur von Hexakis(trimethylsilyl)-2,4-diamino-1,3,2,4-diazadiboretidin|journal=Acta Crystallographica Section B|language=de|volume=25|issue=11|pages=2342–2349|doi=10.1107/s056774086900567x|issn=0567-7408|url=http://journals.iucr.org/b/issues/1969/11/00/a06979/a06979.pdf}}</ref>), cyclotrimers ([[Borazine|borazines]], '''Tr'''), bicyclotrimers ([[Dewar benzene|Dewar]] borazines, '''{{prime|Tr}}'''<ref>{{Cite journal|last1=Steuer|first1=Holger-A.|last2=Meller|first2=Anton|last3=Elter|first3=Gernot|title=B-t-butyl-borazine und -diazadiboretidine|journal=Journal of Organometallic Chemistry|language=de|volume=295|issue=1|pages=1–6|doi=10.1016/0022-328x(85)88065-7|year=1985}}</ref>), cyclotetramers ({{chem name|octahydro-1,3,5,7-tetraza-2,4,6,8-tetraborocine}}s, '''Te'''<ref>{{Cite book|title=Turner H. S. and Warne R. J. 1962 Proc. Chem. Soc. 69}}</ref>), and polymers (polyiminoboranes, '''Po'''); which are shown below.<ref>{{Cite book|title=Advances in inorganic chemistry. Volume 31|date=1987|publisher=Academic Press|others=Emeléus, H. J. (Harry Julius), Sharpe, A. G.|isbn=978-0-12-023631-2|location=New York|oclc=277086713|url-access=registration|url=https://archive.org/details/trent_0116400835595_31}}</ref> Which product is dominant depends on the structures of reactants and the reaction conditions. Some of the products can be interconverted.<ref>{{Cite journal|last=Maier.G.|date=1978|title=Tetra-tert-butyltetrahedrane|journal=Angew. Chem. Int. Ed. Engl.|volume=17|issue=7|pages=520–521|doi=10.1002/anie.197805201}}</ref>
 [[File:Figure product of iminboboranes oligomerization-1.png|453x453px|center|frameless]]
 ===Addition reactions===
-Some electron-rich iminoboranes form adducts with Lewis acids.<ref>{{Cite journal|last=Nöth|first=Heinrich|last2=Weber|first2=Siegfried|date=1985-06-01|title=Beiträge zur Chemie des Bors, 158. Addukte von Aluminium- und Galliumhalogeniden an ein Aminoiminoboran|journal=Chemische Berichte|language=en|volume=118|issue=6|pages=2554–2556|doi=10.1002/cber.19851180631|issn=1099-0682}}</ref>
+The addition of protic agents is fast and quantitive.<ref>{{Cite journal|last1=Nöth|first1=Heinrich|last2=Weber|first2=Siegfried|date=1985-05-01|title=Beiträge zur Chemie des Bors, 154. Addition von Trimethylsily-Verbindungen und von anderen Elektrophilen an (tert-Butylimino) (tetramethylpiperidino)boran|journal=Chemische Berichte|language=en|volume=118|issue=5|pages=2144–2146|doi=10.1002/cber.19851180536|issn=1099-0682}}</ref> Boration reaction of iminoboranes is the addition of B-X single bond to B≡N, where -X can be -Cl (chloro-boration), -N<sub>3</sub> (azido-boration), -SR (thio-boration), -NR2 (amino-boration) and R (alkyl-boration). One of these reactions are illustrated here. [[File:Chloro-boration of iminoborane.png|415x415px|center|frameless]]
+Some electron-rich iminoboranes form adducts with Lewis acids.<ref>{{Cite journal|last1=Nöth|first1=Heinrich|last2=Weber|first2=Siegfried|date=1985-06-01|title=Beiträge zur Chemie des Bors, 158. Addukte von Aluminium- und Galliumhalogeniden an ein Aminoiminoboran|journal=Chemische Berichte|language=en|volume=118|issue=6|pages=2554–2556|doi=10.1002/cber.19851180631|issn=1099-0682}}</ref>
 [[File:Lewis_acid_addition_of_iminoboranes.png|center|frameless|401x401px]]
+===Cycloaddition===
-The addition of protic agents is a fast quantitive reaction.<ref>{{Cite journal|last=Nöth|first=Heinrich|last2=Weber|first2=Siegfried|date=1985-05-01|title=Beiträge zur Chemie des Bors, 154. Addition von Trimethylsily-Verbindungen und von anderen Elektrophilen an (tert-Butylimino) (tetramethylpiperidino)boran|journal=Chemische Berichte|language=en|volume=118|issue=5|pages=2144–2146|doi=10.1002/cber.19851180536|issn=1099-0682}}</ref>
+The typical [2+3]-cycloaddition is the addition of B≡N and RN<sub>3</sub> to give a BN<sub>4</sub> ring.<ref name=PPaetz/> One of the widely investigated [2+2]-cycloadditions is the reaction of aldehydes and ketones.
-Boration reaction of iminoboranes is the addition of B-X single bond to B≡N, where -X can be -Cl (chloro-boration), -N<sub>3</sub> (azido-boration), -SR (thio-boration), -NR2 (amino-boration) and R (alkyl-boration). One of these reactions are illustrated here. [[File:Chloro-boration of iminoborane.png|415x415px|center|frameless]]
-Cycloaddition is the addition of π bond to B≡N, and can be categorized into [2+2]-cycloadditions, [2+3]-cycloadditions, [2+4]-cycloadditions ''etc''.
-One of the widely investigated [2+2]-cycloadditions is the reaction of aldehydes and ketones with iminoboranes, which has two possible pathways. Usually, the relatively stable iminoboranes which are less likely to undergo the total opening of  B≡N,  and the ketones containing enolic protons, prefer to undergo path b.<ref>{{Cite journal|last=von Kutepow|first=Nikolaus|date=1972-04-01|title=Chemistry of acetylenes. Von H. G. Viehe. Marcel Dekker Inc., New York 1969. 1. Aufl., XV, 1298 S., zahlr. Tab. u. Formeln, geb. $ 59.50|journal=Angewandte Chemie|language=en|volume=84|issue=8|pages=367|doi=10.1002/ange.19720840843|issn=1521-3757}}</ref>
-The typical [2+3]-cycloaddition is the addition of B≡N and RN<sub>3</sub>,and the typical [2+4]-cycloaddition is the addition of B≡N and cyclopentadiene.[[File:Figure 2- cycloaddition of iminoboranes.png|380x380px|center|frameless]]
 === Coordination to transition metals ===
-Like acetylenes, iminoboranes can also coordinate with transition metals.
+Like alkynes, iminoboranes bind transition metals.
 [[File:Coordination of iminoboranes to metals.png|440x440px|center|frameless]]
@@ Line 44: / Line 131: @@
 [[Category:Boranes]]
 [[Category:Amines]]
+[[Category:Boron–nitrogen compounds]]