Structurally defined ring-opening and insertion of pinacolborane into aluminium-nitrogen bonds of sterically demanding dialkylaluminium amides

Victoria A. Pollard; Alan R. Kennedy; Ross McLellan; Duncan Ross; Tell Tuttle; Robert E. Mulvey

doi:10.1002/ejic.202000919

Structurally defined ring-opening and insertion of pinacolborane into aluminium-nitrogen bonds of sterically demanding dialkylaluminium amides

Victoria A. Pollard, Alan R. Kennedy, Ross McLellan, Duncan Ross, Tell Tuttle, Robert E. Mulvey

Pure And Applied Chemistry

Research output: Contribution to journal › Article › peer-review

4 Citations (Scopus)

25 Downloads (Pure)

Abstract

Dialkylaluminium amides iBu ₂Al(TMP) and iBu ₂Al(HMDS) can perform catalytic hydroboration of ketones with pinacolborane to form the expected boronic esters. However, repeating the same reactions stoichiometrically without a ketone leads unexpectedly to ring-opening of pinacolborane and insertion of its open chain into the Al−N(amido) bond. To date there has been limited knowledge on decomposition pathways of HBpin despite its prominent role in hydroboration chemistry. X-ray crystallography shows these mixed Al−B products [iBu ₂Al{OC(Me) ₂C(Me) ₂O}B(H)(NR ₂)] ₂ (NR ₂=TMP or HMDS) form dimers with an (AlO) ₂ core and terminal B−N bonds. Since the bond retention (B−H) and bond breaking (B−O) in these transformations seemed surprising, DFT calculations run using M11/6-31G(d,p) gave an energy profile consistent with a σ-bond metathesis mechanism where London dispersion interactions between iBu and (amide) Me groups play an important stabilising role in the final outcome.

Original language	English
Pages (from-to)	50-53
Number of pages	4
Journal	European Journal of Inorganic Chemistry
Volume	2021
Issue number	1
Early online date	30 Oct 2020
DOIs	https://doi.org/10.1002/ejic.202000919
Publication status	Published - 8 Jan 2021

Keywords

aluminium
DFT caluclations
homogeneous catalysis
hydrocarbons

Access to Document

10.1002/ejic.202000919Licence: CC BY 4.0

Pollard-etal-EJIC-2020-Structurally-defined-ring-opening-and-insertion-of-pinacolborane-intoFinal published version, 597 KBLicence: CC BY 4.0

Cite this

@article{6babfb151198400d8d7d2971d8d76d00,

title = "Structurally defined ring-opening and insertion of pinacolborane into aluminium-nitrogen bonds of sterically demanding dialkylaluminium amides",

abstract = "Dialkylaluminium amides iBu 2Al(TMP) and iBu 2Al(HMDS) can perform catalytic hydroboration of ketones with pinacolborane to form the expected boronic esters. However, repeating the same reactions stoichiometrically without a ketone leads unexpectedly to ring-opening of pinacolborane and insertion of its open chain into the Al−N(amido) bond. To date there has been limited knowledge on decomposition pathways of HBpin despite its prominent role in hydroboration chemistry. X-ray crystallography shows these mixed Al−B products [iBu 2Al{OC(Me) 2C(Me) 2O}B(H)(NR 2)] 2 (NR 2=TMP or HMDS) form dimers with an (AlO) 2 core and terminal B−N bonds. Since the bond retention (B−H) and bond breaking (B−O) in these transformations seemed surprising, DFT calculations run using M11/6-31G(d,p) gave an energy profile consistent with a σ-bond metathesis mechanism where London dispersion interactions between iBu and (amide) Me groups play an important stabilising role in the final outcome. ",

keywords = "aluminium, DFT caluclations, homogeneous catalysis, hydrocarbons",

author = "Pollard, {Victoria A.} and Kennedy, {Alan R.} and Ross McLellan and Duncan Ross and Tell Tuttle and Mulvey, {Robert E.}",

year = "2021",

month = jan,

day = "8",

doi = "10.1002/ejic.202000919",

language = "English",

volume = "2021",

pages = "50--53",

journal = "European Journal of Inorganic Chemistry",

issn = "1434-1948",

number = "1",

}

TY - JOUR

T1 - Structurally defined ring-opening and insertion of pinacolborane into aluminium-nitrogen bonds of sterically demanding dialkylaluminium amides

AU - Pollard, Victoria A.

AU - Kennedy, Alan R.

AU - McLellan, Ross

AU - Ross, Duncan

AU - Tuttle, Tell

AU - Mulvey, Robert E.

PY - 2021/1/8

Y1 - 2021/1/8

N2 - Dialkylaluminium amides iBu 2Al(TMP) and iBu 2Al(HMDS) can perform catalytic hydroboration of ketones with pinacolborane to form the expected boronic esters. However, repeating the same reactions stoichiometrically without a ketone leads unexpectedly to ring-opening of pinacolborane and insertion of its open chain into the Al−N(amido) bond. To date there has been limited knowledge on decomposition pathways of HBpin despite its prominent role in hydroboration chemistry. X-ray crystallography shows these mixed Al−B products [iBu 2Al{OC(Me) 2C(Me) 2O}B(H)(NR 2)] 2 (NR 2=TMP or HMDS) form dimers with an (AlO) 2 core and terminal B−N bonds. Since the bond retention (B−H) and bond breaking (B−O) in these transformations seemed surprising, DFT calculations run using M11/6-31G(d,p) gave an energy profile consistent with a σ-bond metathesis mechanism where London dispersion interactions between iBu and (amide) Me groups play an important stabilising role in the final outcome.

AB - Dialkylaluminium amides iBu 2Al(TMP) and iBu 2Al(HMDS) can perform catalytic hydroboration of ketones with pinacolborane to form the expected boronic esters. However, repeating the same reactions stoichiometrically without a ketone leads unexpectedly to ring-opening of pinacolborane and insertion of its open chain into the Al−N(amido) bond. To date there has been limited knowledge on decomposition pathways of HBpin despite its prominent role in hydroboration chemistry. X-ray crystallography shows these mixed Al−B products [iBu 2Al{OC(Me) 2C(Me) 2O}B(H)(NR 2)] 2 (NR 2=TMP or HMDS) form dimers with an (AlO) 2 core and terminal B−N bonds. Since the bond retention (B−H) and bond breaking (B−O) in these transformations seemed surprising, DFT calculations run using M11/6-31G(d,p) gave an energy profile consistent with a σ-bond metathesis mechanism where London dispersion interactions between iBu and (amide) Me groups play an important stabilising role in the final outcome.

KW - aluminium

KW - DFT caluclations

KW - homogeneous catalysis

KW - hydrocarbons

UR - https://chemistry-europe.onlinelibrary.wiley.com/journal/10990682c

U2 - 10.1002/ejic.202000919

DO - 10.1002/ejic.202000919

M3 - Article

SN - 1434-1948

VL - 2021

SP - 50

EP - 53

JO - European Journal of Inorganic Chemistry

JF - European Journal of Inorganic Chemistry

IS - 1

ER -

Structurally defined ring-opening and insertion of pinacolborane into aluminium-nitrogen bonds of sterically demanding dialkylaluminium amides

Abstract

Keywords

Access to Document

Other files and links

Fingerprint

Doctoral Training Partnership (DTP - University of Strathclyde) | Pollard-Nelson, Victoria

Data for: "Structurally Defined Ring-Opening and Insertion of Pinacolborane into Aluminium-Nitrogen Bonds of Sterically Demanding Dialkylaluminium Amides"

Cite this

Structurally defined ring-opening and insertion of pinacolborane into aluminium-nitrogen bonds of sterically demanding dialkylaluminium amides

Abstract

Keywords

Access to Document

Other files and links

Fingerprint

Projects

Doctoral Training Partnership (DTP - University of Strathclyde) | Pollard-Nelson, Victoria

Datasets

Data for: "Structurally Defined Ring-Opening and Insertion of Pinacolborane into Aluminium-Nitrogen Bonds of Sterically Demanding Dialkylaluminium Amides"

Cite this