Anion control of tautomeric equilibria

Fe-H: vs. N-H influenced by NH⋯F hydrogen bonding

Geoffrey M. Chambers, Samantha I. Johnson, Simone Raugei, R Morris Bullock

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Counterions can play an active role in chemical reactivity, modulating reaction pathways, energetics and selectivity. We investigated the tautomeric equilibrium resulting from protonation of Fe(PEtNMePEt)(CO)3 (PEtNMePEt = (Et2PCH2)2NMe) at Fe or N. Protonation of Fe(PEtNMePEt)(CO)3 by [(Et2O)2H]+[B(C6F5)4]- occurs at the metal to give the iron hydride [Fe(PEtNMePEt)(CO)3H]+[B(C6F5)4]-. In contrast, treatment with HBF4·OEt2 gives protonation at the iron and at the pendant amine. Both the FeH and NH tautomers were characterized by single crystal X-ray diffraction. Addition of excess BF4 - to the equilibrium mixture leads to the NH tautomer being exclusively observed, due to NH⋯F hydrogen bonding. A quantum chemical analysis of the bonding properties of these systems provided a quantification of hydrogen bonding of the NH to BF4 - and to OTf-. Treatment of Fe(PEtNMePEt)(CO)3 with excess HOTf gives a dicationic complex where both the iron and nitrogen are protonated. Isomerization of the dicationic complex was studied by NOESY NMR spectroscopy.

Original languageEnglish
Pages (from-to)1410-1418
Number of pages9
JournalChemical Science
Volume10
Issue number5
DOIs
Publication statusPublished - Jan 1 2019

Fingerprint

Carbon Monoxide
Anions
Protonation
Hydrogen bonds
Iron
Chemical reactivity
Catalyst selectivity
Isomerization
Hydrides
Nuclear magnetic resonance spectroscopy
Amines
Nitrogen
Metals
Single crystals
X ray diffraction
Chemical analysis

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Anion control of tautomeric equilibria : Fe-H: vs. N-H influenced by NH⋯F hydrogen bonding. / Chambers, Geoffrey M.; Johnson, Samantha I.; Raugei, Simone; Bullock, R Morris.

In: Chemical Science, Vol. 10, No. 5, 01.01.2019, p. 1410-1418.

Research output: Contribution to journalArticle

@article{b269bf2b75a441a692c7672fb161ead8,
title = "Anion control of tautomeric equilibria: Fe-H: vs. N-H influenced by NH⋯F hydrogen bonding",
abstract = "Counterions can play an active role in chemical reactivity, modulating reaction pathways, energetics and selectivity. We investigated the tautomeric equilibrium resulting from protonation of Fe(PEtNMePEt)(CO)3 (PEtNMePEt = (Et2PCH2)2NMe) at Fe or N. Protonation of Fe(PEtNMePEt)(CO)3 by [(Et2O)2H]+[B(C6F5)4]- occurs at the metal to give the iron hydride [Fe(PEtNMePEt)(CO)3H]+[B(C6F5)4]-. In contrast, treatment with HBF4·OEt2 gives protonation at the iron and at the pendant amine. Both the FeH and NH tautomers were characterized by single crystal X-ray diffraction. Addition of excess BF4 - to the equilibrium mixture leads to the NH tautomer being exclusively observed, due to NH⋯F hydrogen bonding. A quantum chemical analysis of the bonding properties of these systems provided a quantification of hydrogen bonding of the NH to BF4 - and to OTf-. Treatment of Fe(PEtNMePEt)(CO)3 with excess HOTf gives a dicationic complex where both the iron and nitrogen are protonated. Isomerization of the dicationic complex was studied by NOESY NMR spectroscopy.",
author = "Chambers, {Geoffrey M.} and Johnson, {Samantha I.} and Simone Raugei and Bullock, {R Morris}",
year = "2019",
month = "1",
day = "1",
doi = "10.1039/c8sc04239j",
language = "English",
volume = "10",
pages = "1410--1418",
journal = "Chemical Science",
issn = "2041-6520",
publisher = "Royal Society of Chemistry",
number = "5",

}

TY - JOUR

T1 - Anion control of tautomeric equilibria

T2 - Fe-H: vs. N-H influenced by NH⋯F hydrogen bonding

AU - Chambers, Geoffrey M.

AU - Johnson, Samantha I.

AU - Raugei, Simone

AU - Bullock, R Morris

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Counterions can play an active role in chemical reactivity, modulating reaction pathways, energetics and selectivity. We investigated the tautomeric equilibrium resulting from protonation of Fe(PEtNMePEt)(CO)3 (PEtNMePEt = (Et2PCH2)2NMe) at Fe or N. Protonation of Fe(PEtNMePEt)(CO)3 by [(Et2O)2H]+[B(C6F5)4]- occurs at the metal to give the iron hydride [Fe(PEtNMePEt)(CO)3H]+[B(C6F5)4]-. In contrast, treatment with HBF4·OEt2 gives protonation at the iron and at the pendant amine. Both the FeH and NH tautomers were characterized by single crystal X-ray diffraction. Addition of excess BF4 - to the equilibrium mixture leads to the NH tautomer being exclusively observed, due to NH⋯F hydrogen bonding. A quantum chemical analysis of the bonding properties of these systems provided a quantification of hydrogen bonding of the NH to BF4 - and to OTf-. Treatment of Fe(PEtNMePEt)(CO)3 with excess HOTf gives a dicationic complex where both the iron and nitrogen are protonated. Isomerization of the dicationic complex was studied by NOESY NMR spectroscopy.

AB - Counterions can play an active role in chemical reactivity, modulating reaction pathways, energetics and selectivity. We investigated the tautomeric equilibrium resulting from protonation of Fe(PEtNMePEt)(CO)3 (PEtNMePEt = (Et2PCH2)2NMe) at Fe or N. Protonation of Fe(PEtNMePEt)(CO)3 by [(Et2O)2H]+[B(C6F5)4]- occurs at the metal to give the iron hydride [Fe(PEtNMePEt)(CO)3H]+[B(C6F5)4]-. In contrast, treatment with HBF4·OEt2 gives protonation at the iron and at the pendant amine. Both the FeH and NH tautomers were characterized by single crystal X-ray diffraction. Addition of excess BF4 - to the equilibrium mixture leads to the NH tautomer being exclusively observed, due to NH⋯F hydrogen bonding. A quantum chemical analysis of the bonding properties of these systems provided a quantification of hydrogen bonding of the NH to BF4 - and to OTf-. Treatment of Fe(PEtNMePEt)(CO)3 with excess HOTf gives a dicationic complex where both the iron and nitrogen are protonated. Isomerization of the dicationic complex was studied by NOESY NMR spectroscopy.

UR - http://www.scopus.com/inward/record.url?scp=85060894247&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85060894247&partnerID=8YFLogxK

U2 - 10.1039/c8sc04239j

DO - 10.1039/c8sc04239j

M3 - Article

VL - 10

SP - 1410

EP - 1418

JO - Chemical Science

JF - Chemical Science

SN - 2041-6520

IS - 5

ER -