Abstract
A pyridine-alkoxide ligand (pyalk = 2-(2-pyridinyl)-2-propanolate) promotes high oxidation states, water-oxidation catalysis and is resistant to oxidation under catalytic conditions. However, several minor byproducts of pyalk are formed during syntheses of Ir(III) and (IV) complexes. We have now characterized three of these, which, although only formed as minor products, have given unexpected results. Under the reaction conditions studied, we find that pyalkH can undergo various modifications: conversion to the N-oxide, degradation of the geminal methyl groups to give picolinate, oxidation of the arene ring CH group adjacent to nitrogen, and coupling to give a dimeric pincer ligand. One of these products has a Ir2(µ-O)(µ-OOCH) core that provides a plausible structural analogue for our elusive ‘blue solution’ oxidation catalyst, formed from our Cp∗Ir(pyalk)Cl precursor under oxidative conditions. In another case, a mononuclear Ir(III) product contains a novel NCCN pincer having a metal-bound aliphatic alkene as the central unit. Alkene complexes of Ir(III) are rare but here the binding is constrained by the pincer.
| Original language | English |
|---|---|
| Pages (from-to) | 75-78 |
| Number of pages | 4 |
| Journal | Inorganica Chimica Acta |
| Volume | 484 |
| DOIs | |
| Publication status | Published - Jan 1 2019 |
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Keywords
- Coordination chemistry
- Iridium
- Ligand oxidation
- Water-oxidation catalysis
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry
Cite this
Modification of a pyridine-alkoxide ligand during the synthesis of coordination compounds. / Shopov, Dimitar Y.; Sharninghausen, Liam S.; Sinha, Shashi Bhushan; Mercado, Brandon Q.; Brudvig, Gary W; Crabtree, Robert H.
In: Inorganica Chimica Acta, Vol. 484, 01.01.2019, p. 75-78.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Modification of a pyridine-alkoxide ligand during the synthesis of coordination compounds
AU - Shopov, Dimitar Y.
AU - Sharninghausen, Liam S.
AU - Sinha, Shashi Bhushan
AU - Mercado, Brandon Q.
AU - Brudvig, Gary W
AU - Crabtree, Robert H.
PY - 2019/1/1
Y1 - 2019/1/1
N2 - A pyridine-alkoxide ligand (pyalk = 2-(2-pyridinyl)-2-propanolate) promotes high oxidation states, water-oxidation catalysis and is resistant to oxidation under catalytic conditions. However, several minor byproducts of pyalk are formed during syntheses of Ir(III) and (IV) complexes. We have now characterized three of these, which, although only formed as minor products, have given unexpected results. Under the reaction conditions studied, we find that pyalkH can undergo various modifications: conversion to the N-oxide, degradation of the geminal methyl groups to give picolinate, oxidation of the arene ring CH group adjacent to nitrogen, and coupling to give a dimeric pincer ligand. One of these products has a Ir2(µ-O)(µ-OOCH) core that provides a plausible structural analogue for our elusive ‘blue solution’ oxidation catalyst, formed from our Cp∗Ir(pyalk)Cl precursor under oxidative conditions. In another case, a mononuclear Ir(III) product contains a novel NCCN pincer having a metal-bound aliphatic alkene as the central unit. Alkene complexes of Ir(III) are rare but here the binding is constrained by the pincer.
AB - A pyridine-alkoxide ligand (pyalk = 2-(2-pyridinyl)-2-propanolate) promotes high oxidation states, water-oxidation catalysis and is resistant to oxidation under catalytic conditions. However, several minor byproducts of pyalk are formed during syntheses of Ir(III) and (IV) complexes. We have now characterized three of these, which, although only formed as minor products, have given unexpected results. Under the reaction conditions studied, we find that pyalkH can undergo various modifications: conversion to the N-oxide, degradation of the geminal methyl groups to give picolinate, oxidation of the arene ring CH group adjacent to nitrogen, and coupling to give a dimeric pincer ligand. One of these products has a Ir2(µ-O)(µ-OOCH) core that provides a plausible structural analogue for our elusive ‘blue solution’ oxidation catalyst, formed from our Cp∗Ir(pyalk)Cl precursor under oxidative conditions. In another case, a mononuclear Ir(III) product contains a novel NCCN pincer having a metal-bound aliphatic alkene as the central unit. Alkene complexes of Ir(III) are rare but here the binding is constrained by the pincer.
KW - Coordination chemistry
KW - Iridium
KW - Ligand oxidation
KW - Water-oxidation catalysis
UR - http://www.scopus.com/inward/record.url?scp=85053308380&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85053308380&partnerID=8YFLogxK
U2 - 10.1016/j.ica.2018.09.020
DO - 10.1016/j.ica.2018.09.020
M3 - Article
AN - SCOPUS:85053308380
VL - 484
SP - 75
EP - 78
JO - Inorganica Chimica Acta
JF - Inorganica Chimica Acta
SN - 0020-1693
ER -