Bis(pinacolato)diboron

Bis(pinacolato)diboron
Names
	Preferred IUPAC name Octamethyl-2,2′-bi-1,3,2-dioxaborolane
Identifiers
CAS Number	73183-34-3 ;
3D model (JSmol)	Interactive image;
Abbreviations	B2pin2
ChEBI	CHEBI:183312;
ChemSpider	2015334 ;
ECHA InfoCard	100.111.245
PubChem CID	2733548;
UNII	I906W26P4U ;
CompTox Dashboard (EPA)	DTXSID30369935 ;
	InChI InChI=1S/C12H24B2O4/c1-9(2)10(3,4)16-13(15-9)14-17-11(5,6)12(7,8)18-14/h1-8H3 Key: IPWKHHSGDUIRAH-UHFFFAOYSA-N ; InChI=1/C12H24B2O4/c1-9(2)10(3,4)16-13(15-9)14-17-11(5,6)12(7,8)18-14/h1-8H3 Key: IPWKHHSGDUIRAH-UHFFFAOYAV;
	SMILES B1(OC(C(O1)(C)C)(C)C)B2OC(C(O2)(C)C)(C)C;
Properties
Chemical formula	C12H24B2O4
Molar mass	253.94 g·mol−1
Melting point	137 to 140 °C (279 to 284 °F; 410 to 413 K)
	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

Bis(pinacolato)diboron is a covalent compound containing two boron atoms and two pinacolato ligands. It has the formula [(CH₃)₄C₂O₂B]₂; the pinacol groups are sometimes abbreviated as "pin", so the structure is sometimes represented as B₂pin₂. It is a colourless solid that is soluble in organic solvents. It is a commercially available reagent for making pinacol boronic esters for organic synthesis. Unlike some other diboron compounds, B₂pin₂ is not moisture-sensitive and can be handled in air.^[1]

Preparation and structure

This compound may be prepared by treating tetrakis(dimethylamino)diboron with pinacol in acidic conditions.^[1] The B-B bond length is 1.711(6) Å.

Dehydrogenation of pinacolborane provides an alternative route:^[2]

2 (CH₃)₄C₂O₂BH → (CH₃)₄C₂O₂B-BO₂C₂(CH₃)₄ + H₂

Reactions

Pinacolborane is a closely related reagent.

The B-B bond adds across alkenes and alkynes to give the 1,2-diborylated alkanes and alkenes. Using various organorhodium or organoiridium catalysts, it can also be installed onto saturated hydrocarbons:^[3]

CH₃(CH₂)₆CH₃ + [pinB]₂ → pinBH + CH₃(CH₂)₇Bpin

These reactions proceed via boryl complexes. Bis(pinacolato)diboron can also be used as reducing agent for example in transition metal catalyzed hydrogenations of alkenes and alkynes. ^[4]

References

^ ^a ^b Tatsuo Ishiyama; Miki Murata; Taka-aki Ahiko & Norio Miyaura (2004). "Bis(pinacolato)diboron". Organic Syntheses; Collected Volumes, vol. 10, p. 115.
^ Neeve, Emily C.; Geier, Stephen J.; Mkhalid, Ibraheem A. I.; Westcott, Stephen A.; Marder, Todd B. (2016). "Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse". Chemical Reviews. 116 (16): 9091–9161. doi:10.1021/acs.chemrev.6b00193. hdl:1807/78811. PMID 27434758.
^ Xinyu Liu "Bis(pinacolato)diboron" Synlett 2003, pp 2442–2443. doi:10.1055/s-2003-43344
^ "Bis(pinacolato)diboron, B2pin2".

[OS-1] Tatsuo Ishiyama; Miki Murata; Taka-aki Ahiko & Norio Miyaura (2004). "Bis(pinacolato)diboron". Organic Syntheses; Collected Volumes, vol. 10, p. 115.

[2] Neeve, Emily C.; Geier, Stephen J.; Mkhalid, Ibraheem A. I.; Westcott, Stephen A.; Marder, Todd B. (2016). "Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse". Chemical Reviews. 116 (16): 9091–9161. doi:10.1021/acs.chemrev.6b00193. hdl:1807/78811. PMID 27434758.

[3] Xinyu Liu "Bis(pinacolato)diboron" Synlett 2003, pp 2442–2443. doi:10.1055/s-2003-43344

[4] "Bis(pinacolato)diboron, B2pin2".

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