Transfer hydrogenation of carbon dioxide: Via bicarbonate promoted by bifunctional C-N chelating Cp?Ir complexes

Article abstract of DOI:10.1039/d0cc04379f

Metal-ligand cooperative Cp?Ir(iii) complexes derived from primary benzylic amines effectively promote transfer hydrogenation of atmospheric CO2 using 2-propanol at 80 °C. Isotope-labelling experiments strengthen that active Ir species can preferentially reduce bicarbonate congeners formed from CO2. The powerful transfer hydrogenation catalyst exhibits remarkable activity for the conversion of bicarbonates into formate salts with a turnover number up to 3200, even without H2 and CO2.

Full text of DOI:10.1039/d0cc04379f

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and T. Ikariya, Chem. Commun., 2020, DOI: 10.1039/D0CC04379F.
Volume 54
Number
January 2018
Pages 1-112
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COMMUNICATION
S. J. Connon, M. O. Senge et al.
Conformational control of nonplanar free base porphyrins:
towards bifunctional catalysts of tunable basicity
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Page 1 of 5
Pleaseꢀd oC ꢀhn eomt ꢀ Ca od mj u ms tꢀmarginsꢀ
View Article Online
DOI: 10.1039/D0CC04379F
JournalꢀNameꢀ
COMMUNICATIONꢀ
ꢀ
TransferꢀhydrogenationꢀofꢀCarbonꢀDioxideꢀviaꢀBicarbonateꢀ
PromotedꢀbyꢀBifunctionalꢀC–NꢀChelatingꢀCp*IrꢀComplexes†ꢀ
Receivedꢀ00thꢀJanuaryꢀ20xx,ꢀ
Acceptedꢀ00thꢀJanuaryꢀ20xxꢀ
a,b
aꢀ
a
YasuhiroꢀSato, ꢀYoshihitoꢀKayaki* ꢀandꢀTakaoꢀIkariya
DOI:ꢀ10.1039/x0xx00000xꢀ
www.rsc.org/ꢀ
Metal-ligandꢀ cooperativeꢀ Cp*Ir(III) complexesꢀ derivedꢀ fromꢀ aboveꢀ200ꢀ°C.ꢀRecently,ꢀformationꢀofꢀformateꢀandꢀlactateꢀviaꢀ
primaryꢀ benzylicꢀ aminesꢀ effectivelyꢀ promoteꢀ transferꢀ reductionꢀ ofꢀ pressurisedꢀ CO ꢀ fromꢀ glycerolꢀ usingꢀ anꢀ NHC-Ruꢀ
hydrogenationꢀ ofꢀ atmosphericꢀ CO ꢀ usingꢀ 2-propanolꢀ atꢀ 80ꢀ °C.ꢀ catalystꢀ atꢀ 150–225ꢀ °Cꢀ wasꢀ demonstratedꢀ byꢀ Voutchkova-
Isotope-labellingꢀexperimentsꢀstrengthenꢀthatꢀactiveꢀIrꢀspeciesꢀcanꢀ Kostal. ꢀ Choudhuryꢀ reportedꢀ activeꢀ abnormalꢀ NHC-ligatedꢀ Irꢀ
preferentiallyꢀ reduceꢀ bicarbonateꢀ congenersꢀ formedꢀ fromꢀ CO .ꢀ catalystsꢀtoꢀpromoteꢀtransferꢀhydrogenationꢀofꢀCO ꢀatꢀambientꢀ
Theꢀpowerfulꢀtransferꢀhydrogenationꢀcatalystꢀexhibitsꢀremarkableꢀ pressureꢀinꢀglycerolꢀorꢀ2-propanolꢀatꢀ110–150ꢀ°C. ꢀ
activityꢀforꢀtheꢀconversionꢀofꢀbicarbonatesꢀintoꢀformateꢀsaltsꢀwithꢀ SinceꢀaꢀstringꢀofꢀRuꢀcatalystsꢀwithꢀ1,2-diamineꢀscaffoldsꢀwasꢀ
aꢀturnoverꢀnumberꢀupꢀtoꢀ3200,ꢀevenꢀwithoutꢀH ꢀandꢀCO .ꢀ
2
2
6c
2
2
6d
ꢀ
2
2
establishedꢀ forꢀ asymmetricꢀ H -hydrogenationꢀ orꢀ transferꢀ
2
7
hydrogenationꢀofꢀacetophenoneꢀderivativesꢀinꢀtheꢀmidꢀ1990s, ꢀ
theꢀ utilityꢀ ofꢀ metal/NHꢀ cooperationꢀ hasꢀ beenꢀ highlightedꢀ
throughꢀ advancesꢀ inꢀ redoxꢀ transformationsꢀ ofꢀ carbonylꢀ orꢀ
8
alcoholicꢀ compounds. ꢀ Theꢀ scopeꢀ ofꢀ substratesꢀ hasꢀ beenꢀ
2
Theꢀ reductiveꢀ transformationꢀ ofꢀ CO ꢀ intoꢀ formicꢀ acidꢀ andꢀ itsꢀ
derivativesꢀhasꢀattractedꢀconsiderableꢀattentionꢀinꢀtheꢀcontextꢀ
ofꢀnondepletableꢀchemicalꢀfeedstocksꢀandꢀaꢀportableꢀhydrogenꢀ
1
storageꢀ application. ꢀ Homogeneousꢀ CO
2
-hydrogenationꢀ hasꢀ
successfullyꢀ broadenedꢀ toꢀ aꢀ rangeꢀ ofꢀ polarisedꢀ moleculesꢀ
9
includingꢀ hardlyꢀ reducibleꢀ molecules. ꢀ Theꢀ relatedꢀ C–Nꢀ
2
beenꢀextensivelyꢀstudiedꢀasꢀtheꢀprimalꢀprocess, ꢀalongꢀwithꢀtheꢀ
3
reductionꢀbyꢀphotochemicalꢀandꢀelectrochemicalꢀapproaches. ꢀ
chelatingꢀ iridiumꢀ complexesꢀ derivedꢀ fromꢀ primaryꢀ benzylicꢀ
aminesꢀ haveꢀ beenꢀ developedꢀ asꢀ highlyꢀ effectiveꢀ hydrogenꢀ
Meanwhile,ꢀtransferꢀhydrogenationꢀusingꢀalcoholsꢀasꢀhydrogenꢀ
donorsꢀisꢀaꢀreliableꢀmethodꢀtoꢀavoidꢀhazardousꢀproceduresꢀandꢀ
4
isꢀcharacterisedꢀbyꢀitsꢀeasyꢀoperationalꢀsetup. ꢀWithꢀregardꢀtoꢀ
10
transferꢀcatalysts. ꢀTheꢀrapidꢀhydrogenꢀtransferꢀfromꢀalcoholsꢀ
toꢀ theꢀ amidoiridiumꢀ andꢀ fromꢀ theꢀ hydrido(amine)iridiumꢀ toꢀ
hydrogenꢀ acceptorsꢀ isꢀ inducedꢀ byꢀ highꢀ basicityꢀ ofꢀ theꢀ amidoꢀ
complexesꢀ asꢀ wellꢀ asꢀ strongꢀ nucleophilicityꢀ ofꢀ theꢀ hydridoꢀ
ligandꢀattributableꢀtoꢀaꢀstrongꢀσ-donorꢀnatureꢀofꢀtheꢀchelatingꢀ
carbonꢀ atom.ꢀ Givenꢀ theꢀ characteristicꢀ cooperativeꢀ effectꢀ
sustainableꢀchemicalꢀprocessesꢀutilisingꢀrenewableꢀresources,ꢀ
CO
heterogeneousꢀ catalyticꢀ systems, ꢀ whilstꢀ homogeneousꢀ
catalystsꢀhaveꢀbeenꢀlimitedlyꢀutilisedꢀforꢀtheꢀH -freeꢀsynthesisꢀ
. ꢀ Perisꢀ andꢀ coworkersꢀ
2
ꢀreductionꢀusingꢀbioderivedꢀalcoholsꢀhasꢀbeenꢀstudiedꢀforꢀ
5
2
6
ofꢀ formicꢀ acidꢀ derivativesꢀ fromꢀ CO
demonstratedꢀthatꢀaꢀhydrogenꢀtransferꢀprocessꢀinꢀaqueousꢀ2-
propanolꢀunderꢀ50ꢀatmꢀofꢀCO ꢀproducedꢀformateꢀanionꢀinꢀtheꢀ
presenceꢀ ofꢀ water-solubleꢀ Irꢀ andꢀ Ruꢀ complexesꢀ withꢀ N-
2
originatingꢀfromꢀtheꢀC–Nꢀchelates,ꢀtheꢀC–OꢀdoubleꢀbondꢀinꢀCO
wouldꢀ beꢀ reducedꢀ underꢀ mildꢀ transferꢀ hydrogenationꢀ
conditionsꢀ(Schemeꢀ1)
Weꢀ commencedꢀ ourꢀ studyꢀ ofꢀ CO
2
ꢀ
2
.
ꢀ
2
ꢀ reductionꢀ usingꢀ
6a,b
heterocyclicꢀ carbeneꢀ (NHC)ꢀ orꢀ mesoionicꢀ carbeneꢀ ligands.
ꢀ
bifunctionalꢀIr,ꢀRhꢀandꢀRuꢀcomplexesꢀbearingꢀaꢀC–Nꢀchelatingꢀ
ligandꢀ (Tableꢀ 1).ꢀ Theꢀ reactionsꢀ wereꢀ carriedꢀ outꢀ inꢀ theꢀ
Theꢀ turnoverꢀ numberꢀ (TON)ꢀ ꢀ wasꢀ asꢀ highꢀ asꢀ 2700,ꢀ whichꢀ
correspondsꢀtoꢀaꢀ0.97%ꢀyieldꢀwithꢀrespectꢀtoꢀtheꢀaddedꢀKOH,ꢀ
andꢀ thusꢀ theꢀ amountꢀ ofꢀ producedꢀ formateꢀ saltꢀ wasꢀ muchꢀ
lowerꢀ thanꢀ thatꢀ ofꢀ theꢀ base.ꢀ Theseꢀ heterogeneousꢀ andꢀ
homogeneousꢀ catalyticꢀ systemsꢀ requiredꢀ harshꢀ conditionsꢀ
t
presenceꢀofꢀKO BuꢀwithꢀaꢀKO Bu/catalystꢀratioꢀofꢀ10000ꢀunderꢀꢀ
t
OH
O
H
Ir
Ir
R
R
N
H
N
H H
H
R
R
HCOO-
CO2
R = C H , CH
base·H+
6
5
3
base
ꢀ
Schemeꢀ 1ꢀ Transferꢀ hydrogenationꢀ ofꢀ CO
2
ꢀ inꢀ 2-propanolꢀ basedꢀ onꢀ theꢀ metal/NHꢀ
bifunctionality.ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ1ꢀꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

Pleaseꢀd oC ꢀhn eomt ꢀ Ca od mj u ms tꢀmarginsꢀ
Page 2 of 5
COMMUNICATIONꢀ
JournalꢀNameꢀ
2
Tableꢀ 1.ꢀ Reductionꢀ ofꢀ CO ꢀ inꢀ alcoholicꢀ solventsꢀ usingꢀ bifunctionalꢀ
hydrogenꢀtransferꢀcatalystsꢀ
ꢀ
View Article Online
DOI: 10.1039/D0CC04379F
OH
H
catalyst
O
KOH
1 M
KOH/catalyst = 10000
+
CO
2
+
HCOOK
2
+ +
H O
OH
catalyst
R' solvent
0 °C, 5 h
O
KOC(CH
3
3
)
3
3
+
CO
1 atm
/catalyst = 10000
2
+
H
HCOOK
+
(CH
3
)
3
COH
+
1 atm
2-propanol/H
80 °C, 5 h
2
O (1/1)
R
R
R'
1
M
8
KOC(CH
)
Ir
Ir
Ir
C
6
H
C
5
6 5
C H
C H
6 5
Ir
Ir
Rh
Rh
C
6
H
C
5
CH
CH
3
C
6
H
C
5
CH
CH
3
N
H
N
H
N
H
H
5
N
Cl
N
Cl
N
H
Cl
N
H
Cl
6
6
H
5
3
6
H
5
3
H
H
CH
3 3
CH
H
H
H
H
H
H
5
a TON = 655
6a TON = 699
7 TON = 4
1
a
1b
2a
2b
CH
3
PMs
CH3
CH3
C
6
H
H
5
N
Ir
Ir
Ir
CH
CH
3
CH
CH
3
Ru
Ru
CH3
CH3
N
N
H H
H
C
6
H
C
5
CH
CH
3
N
H
Cl
N
H
Cl
C
6
5
N
H
Cl
3
3
O
S
O
6
H
5
3
H
H
H
H
3
a
3b
4
PMs
5b TON = 287
6b TON = 409
ꢀinꢀaqueousꢀ2-propanol.ꢀꢀ
ꢀ
ꢀ
a
b
Schemeꢀ2ꢀTransferꢀHydrogenationꢀofꢀCO
2
Entry ꢀ
Catalystꢀ
1aꢀ
Solventꢀ
TON ꢀ
343ꢀ
282ꢀ
257ꢀ
24ꢀ
1
2
3
4
5
6
7
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
(CH
(CH
(CH
(CH
(CH
(CH
(CH
(CH
3
3
3
3
3
3
3
3
)
)
)
)
)
)
)
)
2
2
2
2
2
2
2
2
CHOHꢀ
CHOHꢀ
CHOHꢀ
CHOHꢀ
CHOHꢀ
CHOHꢀ
CHOHꢀ
CHOHꢀ
1bꢀ
ꢀ
ChangingꢀtheꢀalkoxideꢀbaseꢀtoꢀKOHꢀinꢀanꢀaqueousꢀsystemꢀ
2aꢀ
increasedꢀtheꢀyieldꢀofꢀpotassiumꢀformateꢀ(Schemeꢀ2).ꢀTheꢀTONꢀ
valueꢀ exceededꢀ 600ꢀ withꢀ aꢀ structurallyꢀ well-definedꢀ
amidoiridiumꢀ complexꢀ (5a)ꢀ derivedꢀ fromꢀ 1a.ꢀ Theꢀ reductionꢀ
underꢀpressurisedꢀCO2ꢀdeterioratedꢀtheꢀcatalyst,ꢀpossiblyꢀdueꢀ
toꢀdecompositionꢀofꢀtheꢀamidoiridiumꢀspeciesꢀorꢀtheꢀloweringꢀ
2bꢀ
3aꢀ
55ꢀ
3bꢀ
5ꢀ
4ꢀ
2ꢀ
c
5
8
ꢀ
[(η -C
5
Me
5
)IrCl
2
]
2
ꢀ
0ꢀ
ofꢀ pHꢀ disfavouredꢀ theꢀ CO
Information).ꢀ Aꢀ slightꢀ enhancementꢀ ofꢀ theꢀ catalyticꢀ activitiesꢀ
upꢀtoꢀaꢀTONꢀofꢀca.ꢀ700)ꢀwasꢀobservedꢀbyꢀusingꢀhydrido(amine)ꢀ
2
ꢀ fixationꢀ (seeꢀ theꢀ Supportingꢀ
9
ꢀ
1aꢀ
1aꢀ
1aꢀ
1aꢀ
CH
3
OHꢀ
135ꢀ
13ꢀ
1
1
1
0ꢀ
1ꢀ
2ꢀ
CH
3
CH
2
OHꢀ
(
(CH
3
)
3
COHꢀ
0ꢀ
complexesꢀ (6aꢀ andꢀ 6b),ꢀ whichꢀ areꢀ theꢀ realꢀ catalyticꢀ
intermediatesꢀ inꢀ theꢀ hydrogenꢀ transferꢀ fromꢀ alcohols.ꢀ
Contrastingly,ꢀ aꢀ hydridoiridiumꢀ complexꢀ (7)ꢀ withꢀ aꢀ nonproticꢀ
dimethylaminoꢀ chelateꢀ madeꢀ littleꢀ contributionꢀ toꢀ theꢀ
(CH
3
)
2
CHOH/H
2
Oꢀ(1:1)ꢀ
433ꢀ
a
t
ꢀ
Reactionꢀconditions:ꢀKO Buꢀ(5.0ꢀmmol),ꢀcatalystꢀ(0.50ꢀµmol),ꢀ2-propanolꢀ
b
1
(
5.0ꢀmL),ꢀ80ꢀ°Cꢀ(bathꢀtemp),ꢀ5ꢀh.ꢀ ꢀDeterminedꢀbyꢀ HꢀNMRꢀspectraꢀusingꢀ
NaOAcꢀ asꢀ anꢀ internalꢀ standard.ꢀ Theꢀ repeatabilityꢀ errorꢀ wasꢀ withinꢀ 5%.ꢀꢀꢀꢀ
c
t
reductionꢀ ofꢀ CO
theꢀmetal/NHꢀmoietyꢀisꢀvitalꢀforꢀtransferꢀhydrogenation.ꢀ
2
ꢀatmꢀofꢀCO ꢀinꢀ2-propanolꢀatꢀ80ꢀ°C.ꢀKO Buꢀwasꢀhandledꢀasꢀtheꢀ
ꢀ Inꢀ lightꢀ ofꢀ spontaneousꢀ saltꢀ formationꢀ inꢀ anꢀ aqueousꢀ
2
,ꢀ corroboratingꢀ thatꢀ cooperativeꢀ functionꢀ ofꢀ
ꢀ
KO Bu/catalystꢀ=ꢀ2000.ꢀ
t
1
substrateꢀinꢀthisꢀcatalyticꢀsystem,ꢀbecauseꢀtheꢀproductivityꢀofꢀ alkalineꢀ solutionꢀ underꢀ CO ,ꢀ bicarbonatesꢀ canꢀ alsoꢀ actꢀ asꢀ
2
formateꢀsaltꢀisꢀunlikelyꢀtoꢀexceedꢀtheꢀamountꢀofꢀbase.ꢀAsꢀlistedꢀ feasibleꢀ baseꢀ substratesꢀ insteadꢀ ofꢀ KOHꢀ inꢀ wetꢀ 2-propanolꢀ
inꢀ Tableꢀ 1,ꢀ theꢀ Irꢀ complexesꢀ (1aꢀ andꢀ 1b)ꢀ derivedꢀ fromꢀ usingꢀtheꢀcatalystꢀ5a.ꢀAsꢀshownꢀinꢀentriesꢀ1ꢀandꢀ2ꢀinꢀTableꢀ2,ꢀ
tritylamineꢀorꢀcumylamineꢀproducedꢀformateꢀsaltꢀwithꢀTONsꢀofꢀ bothꢀKHCO ꢀandꢀK CO ꢀwereꢀconvertibleꢀintoꢀtheꢀformateꢀsaltꢀ
3
2
3
3
43ꢀ andꢀ 282ꢀ afterꢀ 5ꢀ hꢀ (Tableꢀ 1,ꢀ entriesꢀ 1ꢀ andꢀ 2).ꢀ Theꢀ Irꢀ withꢀTONsꢀofꢀ673ꢀandꢀ613,ꢀrespectively.ꢀItꢀisꢀworthꢀnotingꢀthatꢀ
complexesꢀhadꢀaꢀgreaterꢀcatalyticꢀactivityꢀthanꢀtheꢀRhꢀandꢀRuꢀ KHCO ꢀwasꢀreducedꢀtoꢀHCOOKꢀwithꢀaꢀratherꢀfavourableꢀTONꢀofꢀ
3
analoguesꢀ (2ꢀ andꢀ 3;ꢀ entriesꢀ 3-6).ꢀ Inꢀ eachꢀ case,ꢀ theꢀ phenylꢀ 760ꢀ evenꢀ inꢀ theꢀ absenceꢀ ofꢀ CO ꢀ underꢀ otherwiseꢀ identicalꢀ
2
substituentsꢀ adjacentꢀ toꢀ theꢀ coordinatedꢀ aminoꢀ groupꢀ conditions,ꢀwhilstꢀK CO ꢀhadꢀscantꢀreactivityꢀ(entriesꢀ3ꢀandꢀ4).ꢀ
2
3
providedꢀ superiorꢀ TONsꢀ toꢀ theꢀ methylꢀ substituents.ꢀ Aꢀ Theseꢀ distinguishableꢀ resultsꢀ suggestꢀ thatꢀ bicarbonateꢀ saltꢀ isꢀ
1
2
congenericꢀ N–Nꢀ chelatingꢀ complex,ꢀ Cp*IrCl(PMsdpen)ꢀ (4;ꢀ primarilyꢀsusceptibleꢀtoꢀtheꢀhydrogenꢀtransferꢀcatalysts ꢀandꢀ
PMsdpenꢀ =ꢀ N-(2,3,4,5,6-pentamethylphenylsulfonyl)-1,2- CO ꢀ engagesꢀ theꢀ reductiveꢀ transformationꢀ ofꢀ carbonateꢀ
2
diphenylethylenediamine),ꢀ provedꢀ toꢀ beꢀ muchꢀ lessꢀ reactive,ꢀ dianionꢀbyꢀwayꢀofꢀbicarbonateꢀinꢀanꢀaqueousꢀreactionꢀmedium.ꢀ
andꢀ [Cp*IrCl
2
]
2
ꢀ showedꢀ noꢀ catalyticꢀ activityꢀ forꢀ theꢀ formateꢀ
ꢀ
Toꢀ elucidateꢀ theꢀ reactionꢀ processesꢀ enꢀ routeꢀ toꢀ formate,ꢀ
13
11
13
formationꢀ (entriesꢀ 7ꢀ andꢀ 8).ꢀ Theꢀ employmentꢀ ofꢀ methanol ꢀ isotope-labellingꢀ experimentsꢀ usingꢀ CO ꢀ orꢀ KH CO ꢀ wereꢀ
andꢀethanolꢀasꢀtheꢀsolventꢀandꢀhydrogenꢀsourceꢀinꢀplaceꢀofꢀ2- executed.ꢀ Theꢀ productꢀ ratiosꢀ ofꢀ HCOOKꢀ andꢀ H COOKꢀ wereꢀ
propanolꢀ ledꢀ toꢀ aꢀ decreaseꢀ inꢀ theꢀ yieldꢀ (entriesꢀ 9ꢀ andꢀ 10),ꢀ determinedꢀbyꢀtheꢀpeakꢀintensitiesꢀinꢀ HꢀNMRꢀspectraꢀ(Figureꢀ
2
3
13
1
becauseꢀ aldehydesꢀ generatedꢀ byꢀ dehydrogenationꢀ ofꢀ theꢀ 1).ꢀWhenꢀtheꢀtransferꢀhydrogenationꢀusingꢀKHCO ꢀinꢀaqueousꢀ
3
primaryꢀalcoholsꢀmayꢀimpedeꢀtheꢀhydrogenꢀdeliveryꢀbyꢀtheꢀIrꢀ 2-propanolꢀ wasꢀ conductedꢀ withꢀ 5aꢀ (bicarbonate/catalystꢀ =ꢀ
13
catalyst.ꢀ Formateꢀ saltꢀ wasꢀ notꢀ producedꢀ atꢀ allꢀ inꢀ tert-butylꢀ 20000/1)ꢀunderꢀatmosphericꢀ CO ꢀatꢀ80ꢀ°C,ꢀaꢀTONꢀofꢀ1600ꢀwasꢀ
2
1
alcoholꢀ lackingꢀ anꢀ availableꢀ hydrideꢀ (entryꢀ 11).ꢀ Notably,ꢀ attainedꢀwithinꢀ1ꢀhꢀ(Schemeꢀ3a).ꢀAsꢀshownꢀinꢀFig.ꢀ1a,ꢀ HꢀNMRꢀ
greaterꢀ accelerationꢀ wasꢀ realisedꢀ inꢀ theꢀ presenceꢀ ofꢀ waterꢀ spectrumꢀofꢀtheꢀproductꢀdisplayedꢀaꢀsingletꢀpeakꢀassignedꢀtoꢀ
13
ratherꢀthanꢀreductionꢀinꢀdehydratedꢀ2-propanol,ꢀleadingꢀtoꢀaꢀ theꢀformylꢀgroupꢀofꢀHCOOKꢀatꢀ8.3ꢀppmꢀaccompaniedꢀbyꢀtheꢀ Cꢀꢀ
TONꢀofꢀ433ꢀ(entryꢀ12).ꢀ
2
ꢀ|ꢀJ.ꢀName.,ꢀ2012,ꢀ00,ꢀ1-3ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
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Pleaseꢀd oC ꢀhn eomt ꢀ Ca od mj u ms tꢀmarginsꢀ
JournalꢀNameꢀ
ꢀCOMMUNICATIONꢀ
Tableꢀ2.ꢀControlꢀexperimentsꢀofꢀtheꢀcatalyticꢀformateꢀsynthesisꢀviaꢀ (a)
transferꢀhydrogenationꢀ
(b)
View Article Online
DOI: 10.1039/D0CC04379F
OH
H
catalyst 5a
O
KX
KX] = 0.5 M
KX/catalyst 5a = 10000
+
CO2
+
+ +
HCOOK HX
2
-propanol/H2O (1/1)
0 °C, 5 h
[
8
ꢀ
c
Entryꢀ
KXꢀ
CO
2
/atmꢀ
1ꢀ
TON ꢀ
673ꢀ
613ꢀ
760ꢀ
4ꢀ
a
1
2
3
4
ꢀ
3
KHCO ꢀ
b
ꢀ
ꢀ
1/2ꢀK
KHCO
1/2ꢀK CO
2
CO
3
3
ꢀ
ꢀ
1ꢀ
a
3
ꢀ
0ꢀ
b
ꢀ
2
0ꢀ
a
1
13
13
ꢀ
Reactionsꢀ performedꢀ onꢀ aꢀ 5.0ꢀ mmolꢀ scaleꢀ usingꢀ 5aꢀ (0.50ꢀ µmol)ꢀ inꢀ 2-
2 3
Fig.ꢀ1ꢀAꢀsectionꢀofꢀ HꢀNMRꢀspectraꢀofꢀtheꢀproductꢀfromꢀ(a)ꢀ CO ꢀorꢀ(b)ꢀKH CO .ꢀ
b
propanolꢀ(5.0ꢀmL)ꢀandꢀH
2
Oꢀ(5.0ꢀmL)ꢀatꢀ80ꢀ°Cꢀforꢀ5ꢀh.ꢀ ꢀReactionsꢀperformedꢀ
Oꢀ
4.1ꢀmL)ꢀatꢀ80ꢀ°Cꢀforꢀ5ꢀh.ꢀ ꢀDeterminedꢀbyꢀ HꢀNMRꢀspectraꢀusingꢀNaOAcꢀasꢀ
anꢀinternalꢀstandard.ꢀ
onꢀaꢀ2.0ꢀmmolꢀscaleꢀusingꢀ5aꢀ(0.41ꢀµmol)ꢀinꢀ2-propanolꢀ(4.1ꢀmL)ꢀandꢀH
2
2
absenceꢀ ofꢀ CO .ꢀ Asꢀ summarisedꢀ inꢀ Tableꢀ 3,ꢀ theꢀ associatedꢀ
c
1
(
cationꢀofꢀbicarbonateꢀsaltsꢀclearlyꢀaffectedꢀtheꢀcatalyticꢀactivity.ꢀ
Theꢀ reductionꢀ usingꢀ relativelyꢀ basicꢀ cesiumꢀ bicarbonateꢀ
13
satellitesꢀ ofꢀ H COOK.ꢀ Theꢀ intensityꢀ ratioꢀ ofꢀ theseꢀ signalsꢀ showedꢀtheꢀhighestꢀactivityꢀ(TONꢀ=ꢀ842)ꢀamongꢀtheꢀcongenersꢀ
indicatedꢀthatꢀ12%ꢀofꢀtheꢀ C-labelledꢀformateꢀwasꢀformed,andꢀ andꢀaꢀbeneficialꢀturnoverꢀfrequencyꢀofꢀ593ꢀh ꢀwithinꢀtheꢀinitialꢀ
thusꢀ bicarbonateꢀ wasꢀ reducedꢀ inꢀ preferenceꢀ toꢀ theꢀ labelledꢀ 1ꢀhꢀ(entriesꢀ1-3).ꢀTheꢀTONꢀcouldꢀbeꢀimprovedꢀtoꢀ1140,ꢀwithꢀanꢀ
CO .ꢀ Theꢀ complementaryꢀ reactionꢀ ofꢀ KH CO ꢀ underꢀ CO ꢀ
2 3 2
increaseꢀ inꢀ theꢀ amountꢀ ofꢀ 2-propanolꢀ toꢀ facilitateꢀ theꢀ
affordedꢀHCOOKꢀconsistently,ꢀwithꢀaꢀ Cꢀcontentꢀofꢀ87%ꢀandꢀaꢀ formationꢀ ofꢀ catalyticallyꢀ activeꢀ hydridoiridiumꢀ speciesꢀ fromꢀ
TONꢀofꢀ1330ꢀ(Schemeꢀ3bꢀandꢀFig.ꢀ1b).ꢀInꢀthisꢀcontext,ꢀBeller'sꢀ theꢀhydrogenꢀdonorꢀ(entriesꢀ3-5).ꢀWhenꢀtheꢀvolumeꢀratioꢀofꢀ2-
13
–1
13
13
groupꢀreportedꢀtheꢀcatalyticꢀsynthesisꢀofꢀHCOOKꢀfromꢀKHCO
andꢀ KOHꢀ inꢀ aꢀ mixtureꢀ ofꢀ methanolꢀ andꢀ H
Oꢀ viaꢀ bicarbonateꢀ (TONꢀ=ꢀ1140).ꢀFurtherꢀincreasesꢀinꢀtheꢀamountꢀofꢀ2-propanolꢀ
3
ꢀ 2
propanol/H Oꢀ wasꢀ 4/1,ꢀ aꢀ superiorꢀ efficiencyꢀ wasꢀ obtainedꢀ
2
hydrogenationꢀ concomitantlyꢀ withꢀ successiveꢀ methanolꢀ impairedꢀ theꢀ catalyticꢀ efficiency,ꢀ possiblyꢀ dueꢀ toꢀ aꢀ loweredꢀ
dehydrogenationꢀ aidedꢀ byꢀ aꢀ PNP-pincerꢀ Ruꢀ complexꢀ (Ru- solubilityꢀ ofꢀ theꢀ baseꢀ substrateꢀ inꢀ theꢀ liquidꢀ reactionꢀ phaseꢀ
1
3
MACHO). ꢀ Distinctꢀ fromꢀ thisꢀ sequentialꢀ dehydrogenation- (entryꢀ6).ꢀUnderꢀtheꢀoptimisedꢀconditionsꢀusingꢀCsHCO
3
ꢀandꢀaꢀ
hydrogenationꢀprotocol,ꢀtransferꢀhydrogenationꢀwithꢀtheꢀC–Nꢀ 4:1ꢀ mixtureꢀ ofꢀ 2-propanolꢀ andꢀ H O,ꢀ reducingꢀ theꢀ catalystꢀ
2
chelatingꢀ Irꢀ catalystsꢀ proceededꢀ atꢀ aꢀ comparativelyꢀ mildꢀ loadingꢀtoꢀaꢀbase/catalystꢀmolarꢀratioꢀofꢀ50000ꢀgaveꢀriseꢀtoꢀaꢀ
temperatureꢀ withoutꢀ theꢀ evolutionꢀ ofꢀ hydrogenꢀ gas.ꢀ Inꢀ fact,ꢀ maximumꢀ TONꢀ ofꢀ 3200ꢀ (entryꢀ 7).ꢀ Moreover,ꢀ anꢀ additionalꢀ
theꢀreactionꢀofꢀKHCO
3
ꢀusingꢀ5aꢀunderꢀCO
2
ꢀinꢀaꢀ1:1ꢀmixtureꢀofꢀ positiveꢀ effectꢀ onꢀ theꢀ catalyticꢀ efficiencyꢀ wasꢀ foundꢀ byꢀ
Oꢀ atꢀ 80ꢀ °Cꢀ resultedꢀ inꢀ theꢀ nonsignificantꢀ complexationꢀofꢀtheꢀpotassiumꢀandꢀcesiumꢀcationsꢀwithꢀ18-ꢀ
13
3 2
CH OHꢀ andꢀ H
13
incorporationꢀ ofꢀ Cꢀ intoꢀ theꢀ productꢀ formate,ꢀ ensuringꢀ thatꢀ
theꢀ Irꢀ catalystꢀ hasꢀ nothingꢀ toꢀ doꢀ withꢀ theꢀ acceptorlessꢀ
dehydrogenativeꢀ conversionꢀ fromꢀ methanolꢀ toꢀ formateꢀ viaꢀ
ꢀ
Tableꢀ 3.ꢀ Transferꢀ hydrogenationꢀ ofꢀ bicarbonatesꢀ inꢀ aqueousꢀ 2-
propanolꢀ
1
4ꢀ
methanediol.
ꢀ
15
catalyst 5a
Onꢀparꢀwithꢀbicarbonate,ꢀaꢀhalf-esterꢀsaltꢀofꢀcarbonicꢀacid ꢀ
t
KOCO Bu),ꢀwhichꢀwasꢀformedꢀfromꢀKO BuꢀandꢀCO ꢀinꢀaꢀsolidꢀ
2 2
t
OH
additive 1 equiv
O
(
MHCO3
+
H
HCOOM + H O
+
2
stateꢀ(seeꢀtheꢀESI),ꢀwasꢀalsoꢀconvertedꢀintoꢀHCOOKꢀsuccessfullyꢀ
byꢀ usingꢀ 5aꢀ inꢀ anhydrousꢀ 2-propanolꢀ withoutꢀ CO ꢀ underꢀ
otherwiseꢀ identicalꢀ conditionsꢀ toꢀ thoseꢀ describedꢀ inꢀ Tableꢀ 1ꢀ [MHCO
2-propanol/H O
2
80 °C, 5 h
2
] in H O = 1 M
2
3
MHCO /catalyst 5a = 10000
(TONꢀ =ꢀ 262).ꢀ Thisꢀ resultꢀ verifiesꢀ thatꢀ theꢀ transferꢀ
hydrogenationꢀofꢀCO
3
ꢀ
t
ꢀinꢀtheꢀpresenceꢀofꢀKO Buꢀinꢀ2-propanolꢀ
a
b
Entry ꢀ Substrateꢀ
Additiveꢀ
2-Propanol/H
2
Oꢀ TON ꢀ
651ꢀ
2
couldꢀ proceedꢀ viaꢀ formationꢀ ofꢀ theꢀ bicarbonateꢀ equivalentꢀ
evenꢀwithoutꢀwater.ꢀ
1ꢀ
NaHCO
KHCO
3
ꢀ
ꢀ
1ꢀmL/1ꢀmLꢀ
1ꢀmL/1ꢀmLꢀ
1ꢀmL/1ꢀmLꢀ
2ꢀmL/1ꢀmLꢀ
4ꢀmL/1ꢀmLꢀ
8ꢀmL/1ꢀmLꢀ
4ꢀmL/1ꢀmLꢀ
4ꢀmL/1ꢀmLꢀ
4ꢀmL/1ꢀmLꢀ
4ꢀmL/1ꢀmLꢀ
4ꢀmL/1ꢀmLꢀ
2
3
4
ꢀ
ꢀ
ꢀ
3
ꢀ
ꢀ
760ꢀ
CsHCO
CsHCO
CsHCO
CsHCO
CsHCO
3
ꢀ
ꢀ
842ꢀ
ꢀ
transferꢀ hydrogenationꢀ ofꢀ bicarbonatesꢀ asꢀ substituteꢀ forꢀ theꢀ
TheꢀcompetentꢀutilityꢀofꢀtheꢀC–NꢀchelatingꢀIrꢀcatalystꢀinꢀtheꢀ
3
3
3
3
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
877ꢀ
16
5ꢀ
ꢀ
1140ꢀ
521ꢀ
2
H -hydrogenation ꢀwasꢀdeterminedꢀbyꢀtheꢀreactionꢀinꢀtheꢀꢀ
6
ꢀ
ꢀ
c
7
ꢀ
ꢀ
3200ꢀ
1110ꢀ
1200ꢀ
1400ꢀ
1650ꢀ
OH
H
catalyst 5a
O
O
(
a)
KHCO3 + 13CO2
.5 M 1 atm
HCOOK
H2O
+
+
+
8ꢀ
KHCO
KHCO
3
ꢀ
ꢀ
18-crown-6ꢀ
[2.2.2]cryptandꢀ
[2.2.2]cryptandꢀ
dibenzo-21-crown-7ꢀ
3
2
-propanol/H2O (1/1)
0 °C, 1 h
0
TON = 1600
9
ꢀ
8
2% 13
1
C
KHCO3/catalyst 5a = 20000
10ꢀ
11ꢀ
CsHCO
CsHCO
ꢀ
3
(b)
OH
3
ꢀ
catalyst 5a
KH13CO3 + CO2
.5 M 1 atm
KHCO3/catalyst 5a = 20000
HCOOK
H2O
+
H
+
+
a
2
-propanol/H2O (1/1)
0 °C, 1 h
ꢀ Reactionsꢀ performedꢀ onꢀ aꢀ 1.0ꢀ mmolꢀ scaleꢀ usingꢀ 5aꢀ (0.10ꢀ µmol)ꢀ andꢀ anꢀ
0
TON = 1330
b
1
8
7% 13
appropriateꢀadditiveꢀ(1.0ꢀmmol)ꢀatꢀ80ꢀ°Cꢀforꢀ5ꢀh.ꢀ ꢀDeterminedꢀbyꢀ HꢀNMRꢀ
8
C
ꢀ
c
3
spectraꢀusingꢀNaOAcꢀasꢀanꢀinternalꢀstandard.ꢀ ꢀCsHCO /catalystꢀ=ꢀ50000.ꢀ
1
3
Schemeꢀ3ꢀTransferꢀhydrogenationꢀusingꢀ C-labelledꢀcompounds.ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ3ꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

Pleaseꢀd oC ꢀhn eomt ꢀ Ca od mj u ms tꢀmarginsꢀ
Page 4 of 5
COMMUNICATIONꢀ
JournalꢀNameꢀ
(a)ꢀK.ꢀMuñiz,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.,ꢀ2005,ꢀ44V,ꢀie6w6A2rt2ic;lꢀe(Obn)lꢀinTe.ꢀ
8
9
crown-6ꢀorꢀ[2.2.2]cryptandꢀ(entriesꢀ8-10).ꢀTheꢀhighestꢀyieldꢀofꢀ
1
Ikariya,ꢀBull.ꢀChem.ꢀSoc.ꢀJpn.,ꢀ2011,ꢀ84,ꢀ1;ꢀ(c)ꢀB.ꢀZhao,ꢀZ.ꢀHanꢀ
DOI: 10.1039/D0CC04379F
3
6.5%ꢀ wasꢀ attainedꢀ byꢀ theꢀ combinationꢀ ofꢀ CsHCO ꢀ andꢀ
andꢀK.ꢀDing,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.,ꢀ2013,ꢀ52,ꢀ4744;ꢀ(d)ꢀP.ꢀA.ꢀ
DubꢀandꢀJ.ꢀC.ꢀGordon,ꢀNat.ꢀRev.ꢀChem.,ꢀ2018,ꢀ2,ꢀ396.ꢀ
A.ꢀMatsunamiꢀandꢀY.ꢀKayaki,ꢀTetrahedronꢀLett.,ꢀ2018,ꢀ59,ꢀ504.ꢀ
dibenzo-21-crown-7ꢀ (entryꢀ 11),ꢀ suggestingꢀ thatꢀ enhancedꢀ
basicityꢀbyꢀcapturingꢀtheꢀcationꢀcontributedꢀtoꢀsmoothingꢀtheꢀ
hydrideꢀtransferꢀprocess.ꢀ
10 (a)ꢀJ.-B.ꢀSortais,ꢀN.ꢀPannetier,ꢀA.ꢀHoluigue,ꢀL.ꢀBarloy,ꢀC.ꢀSirlin,ꢀ
M.ꢀ Pfefferꢀ andꢀ N.ꢀ Kyritsakas,ꢀ Organometallics,ꢀ 2007,ꢀ 26,ꢀ
1856;ꢀ (b)ꢀ S.ꢀ Arita,ꢀ T.ꢀ Koike,ꢀ Y.ꢀ Kayakiꢀ andꢀ T.ꢀ Ikariya,ꢀ
Organometallics,ꢀ2008,ꢀ27,ꢀ2795;ꢀ(c)ꢀY.ꢀSato,ꢀY.ꢀKayakiꢀandꢀT.ꢀ
Ikariya,ꢀChem.ꢀCommun.,ꢀ2012,ꢀ48,ꢀ3635;ꢀ(d)ꢀS.ꢀSabater,ꢀM.ꢀ
BayaꢀandꢀJ.ꢀA.ꢀMata,ꢀOrganometallics,ꢀ2014,ꢀ33,ꢀ6830;ꢀ(e)ꢀY.ꢀ
Sato,ꢀY.ꢀKayakiꢀandꢀT.ꢀIkariya,ꢀChem.ꢀAsianꢀJ.,ꢀ2016,ꢀ11,ꢀ2924;ꢀ
ꢀ
Inꢀconclusion,ꢀweꢀhaveꢀdemonstratedꢀthatꢀtheꢀbifunctionalꢀ
IrꢀcomplexesꢀisꢀfeasibleꢀforꢀtheꢀtransferꢀhydrogenationꢀofꢀCO
2
ꢀ
inꢀ theꢀ presenceꢀ ofꢀ baseꢀ usingꢀ 2-propanolꢀ asꢀ theꢀ hydrogenꢀ
donor.ꢀTheꢀsmoothꢀreductionꢀprocessꢀisꢀadvantageousꢀinꢀtermsꢀ
ofꢀ theꢀ mildꢀ reactionꢀ conditions,ꢀ includingꢀ aꢀ lowꢀ temperatureꢀ
andꢀ ambientꢀ pressureꢀ ofꢀ CO
reportedꢀ homogeneousꢀ andꢀ heterogeneousꢀ catalystꢀ systems.ꢀ
2
,ꢀ comparedꢀ toꢀ thoseꢀ ofꢀ otherꢀ
(
f)ꢀA.ꢀMatsunami,ꢀS.ꢀKuwataꢀandꢀY.ꢀKayaki,ꢀACSꢀCatal.,ꢀ2016,ꢀ
,ꢀ5181.ꢀ
1 A.ꢀH.ꢀAboo,ꢀE.ꢀL.ꢀBennett,ꢀM.ꢀDeeprose,ꢀC.ꢀM.ꢀRobertson,ꢀJ.ꢀA.ꢀ
6
13
Theꢀ controlꢀ experimentsꢀ andꢀ theꢀ reactionꢀ usingꢀ C-labelledꢀ
compoundsꢀillustrateꢀthatꢀtheꢀIrꢀcatalystꢀreducesꢀbicarbonateꢀ
1
Iggo,ꢀandꢀJ.ꢀXiao,ꢀChem.ꢀCommun.,ꢀ2018,ꢀ54,ꢀ11805.ꢀ
inꢀpriorityꢀtoꢀCO
andꢀhydrido(amine)ꢀcomplexes.ꢀAccordingly,ꢀtheꢀbifunctionalꢀIrꢀ
2
ꢀthroughꢀtheꢀinterconversionꢀbetweenꢀamidoꢀ 12 (a)ꢀB.ꢀWu,ꢀY.ꢀGao,ꢀF.ꢀJin,ꢀJ.ꢀCao,ꢀY.ꢀDuꢀandꢀY.ꢀZhang,ꢀCatal.ꢀ
Today,ꢀ2009,ꢀ148,ꢀ405;ꢀ(b)ꢀJ.ꢀSu,ꢀL.ꢀYang,ꢀX.ꢀYang,ꢀM.ꢀLu,ꢀB.ꢀ
LuoꢀandꢀH.ꢀLin,ꢀACSꢀSustainableꢀChem.ꢀEng.,ꢀ2015,ꢀ3,ꢀ195;ꢀ(c)ꢀ
G.ꢀ Ding,ꢀ J.ꢀ Su,ꢀ C.ꢀ Zhang,ꢀ K.ꢀ Tang,ꢀ L.ꢀ Yangꢀ andꢀ H.ꢀ Lin,ꢀ
ChemSusChem,ꢀ2018,ꢀ11,ꢀ2029.ꢀ
2
catalystꢀ couldꢀ alsoꢀ beꢀ utilisedꢀ forꢀ theꢀ H -freeꢀ reductionꢀ ofꢀ
bicarbonateꢀandꢀleadꢀtoꢀanꢀenhancedꢀyieldꢀofꢀformateꢀrelativeꢀ
toꢀtheꢀaddedꢀbase.ꢀLow-energyꢀtransferꢀhydrogenation,ꢀasꢀanꢀ 13 (a)ꢀQ.ꢀLiu,ꢀL.ꢀWu,ꢀS.ꢀGülak,ꢀN.ꢀRockstroh,ꢀR.ꢀJackstellꢀandꢀM.ꢀ
alternativeꢀ toꢀ CO
proactiveꢀuseꢀofꢀbicarbonateꢀasꢀCO
Thisꢀ workꢀ wasꢀ financiallyꢀ supportedꢀ byꢀ theꢀ Japanꢀ Societyꢀ
forꢀ theꢀ Promotionꢀ ofꢀ Scienceꢀ (JSPS)ꢀ KAKENHIꢀ Grantꢀ no.ꢀ
6621043.ꢀ
2
ꢀ hydrogenation,ꢀ hasꢀ theꢀ potentialꢀ toꢀ allowꢀ
Beller,ꢀ Angew.ꢀ Chem.,ꢀ Int.ꢀ Ed.,ꢀ 2014,ꢀ 53,ꢀ 7085;ꢀ (b)ꢀ F.ꢀ Joó,ꢀ
ChemCatChem,ꢀ2014,ꢀ6,ꢀ3306.ꢀ
4 (a)ꢀ M.ꢀ Nielsen,ꢀ E.ꢀ Alberico,ꢀ W.ꢀ Baumann,ꢀ H.-J.ꢀ Drexler,ꢀ H.ꢀ
Junge,ꢀS.ꢀGladialiꢀandꢀM.ꢀBeller,ꢀNature,ꢀ2013,ꢀ495,ꢀ85;ꢀ(b)ꢀR.ꢀ
E.ꢀ Rodríguez-Lugo,ꢀ M.ꢀ Trincado,ꢀ M.ꢀ Vogt,ꢀ F.ꢀ Tewes,ꢀ G.ꢀ
Santiso-QuinonesꢀandꢀH.ꢀGrützmacher,ꢀNat.ꢀChem.,ꢀ2013,ꢀ5,ꢀ
2
ꢀinterimꢀstorage.ꢀ
1
ꢀ
2
3
42;ꢀ(c)ꢀP.ꢀHu,ꢀY.ꢀDiskin-Posner,ꢀY.ꢀBen-DavidꢀandꢀD.ꢀMilstein,ꢀ
ACSꢀCatal.,ꢀ2014,ꢀ4,ꢀ2649;ꢀ(d)ꢀJ.ꢀCampos,ꢀL.ꢀS.ꢀSharninghausen,ꢀ
M.ꢀ G.ꢀ Manasꢀ andꢀ R.ꢀ H.ꢀ Crabtree,ꢀ Inorg.ꢀ Chem.,ꢀ 2015,ꢀ 54,ꢀ
Conflictsꢀofꢀinterestꢀ
Thereꢀareꢀnoꢀconflictsꢀtoꢀdeclare.ꢀ
5
079;ꢀ (e)ꢀ K.-i.ꢀ Fujita,ꢀ R.ꢀ Kawahara,ꢀ T.ꢀ Aikawaꢀ andꢀ R.ꢀ
Yamaguchi,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.,ꢀ2015,ꢀ54,ꢀ9057.ꢀ
5 Utilisationꢀ ofꢀ aꢀ CO -inducedꢀ ROCO Na/ROCO Hꢀ bufferꢀ
1
2
2
2
solutionꢀforꢀcyclicꢀcarbonateꢀsynthesisꢀwasꢀrecentlyꢀreported:ꢀ
S.ꢀYan,ꢀR.ꢀZhou,ꢀF.ꢀHan,ꢀM.ꢀFeng,ꢀC.ꢀMiao,ꢀS.ꢀZhangꢀandꢀS.ꢀAi,ꢀ
Catal.ꢀSci.ꢀTechnol.,ꢀ2020,ꢀ10,ꢀ736.ꢀ
Notesꢀandꢀreferencesꢀ
1
(a)ꢀ M.ꢀ Aresta,ꢀ A.ꢀ Dibebedettoꢀ andꢀ A.ꢀ Angelini,ꢀ Chem.ꢀ Rev.,ꢀ 16 (a)ꢀ Y.ꢀ Himeda,ꢀ N.ꢀ Onozawa-Komatsuzaki,ꢀ H.ꢀ Sugihara,ꢀ H.ꢀ
2
014,ꢀ114,ꢀ1709;ꢀ(b)ꢀK.ꢀSordakis,ꢀC.ꢀTang,ꢀL.ꢀK.ꢀVogt,ꢀH.ꢀJunge,ꢀ
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ChemComm
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DOI: 10.1039/D0CC04379F
A table of contents entry
Metal-NH cooperative Ir complexes derived from primary benzylic amines
effectively promoted reduction of bicarbonate and half-carbonate salts
formed from formed from CO in 2-propanol under mild conditions to
2
produce formate salts with a maximum turnover number of 3200.