第7回SPring-8先端放射光技術による化学イノベーション研究会−先端放射光分析が拓く持続可能社会実現のための化学イノベーション−
2022. 9. 13

均一系触媒反応機構研究におけるXAFSの活用と高度化

植竹 裕太
大阪大学 大学院工学研究科 応用化学専攻

1

2

Curriculum Vitae
植竹 裕太 (Ph. D.)

専門: 有機化学
O
O
HO

1986年 千葉県に生まれる
2012年‒2015年（大学院）早稲田大学 先進理工学研究科（中田雅久 教授）『天然物の全合成研究、不斉触媒反応』

N
O

O

H

R

R

F

SMe

F

2015年‒2017年（ポスドク）
理化学研究所 CLST（細谷孝充 TL）『遷移金属触媒を用いるホウ素化反応』『生体内分子イメージング用PETプローブの合成』

SEt
18F

OH

OH
CO2H

N

2017年‒（特任助教、助教）
大阪大学 大学院工学研究科（櫻井英博 教授）『金属ナノ粒子を用いた触媒反応開発』『スマネンπ共役分子の化学』『放射光を活用した溶液系の反応機構解析』

O

R

N

N

N

iPr

iPr

O

B

topics

1. 均一系触媒反応研究の実際とXASの活用
2. ルイス酸を用いる鈴木・宮浦クロスカップリング反応
3. 低温 in situ XAS装置の高度化
4. Ni錯体の配位子場構造と価数について3

Homogeneous catalysis

A

分子性触媒
-

溶媒に溶ける分子設計できる
単一に近い組成B

現象の解明、真実の追求（物理科学、分析化学、計算化学）

Novel Prize in Chemistry
1981: K. Fukui (theoretical chemistry)
2001: R. Noyori (asymmetric catalysis)
2010: A. Suzuki, E. Negishi (cross-coupling)<<

ものづくり、実学（合成化学、反応化学）

若干（かなり）ものづくり重視（反応が進行すれば、細かいことは気にしない）

4

Whereas only a trace amount of 3 a was obtained when thethioesters to form 1,4-adducts, 4-methoxycinnamic acidreaction was performed without KOAc, almost quantitative
S-ethyl ester (2 ai) was transformed to alkenylboronic ester
5 [27]
transformation was achieved using 20 mol % of KOAc.
3 ai in high yield under the same conditions. Furthermore,
These results suggested that KOAc contributed to thealthough not fully optimized, the borylative cleavage of3
regeneration of an active species from the deactivateda C(sp )ˇC bond in 2 aj also proceeded to afford alkylboronic
ester 3 aj by the use of cesium fluoride as a base instead ofrhodium complex.[28](Bpin)2 (2.0 eqiv)
The practicality of this method was demonstrated by the
KOAc.[11][Rh(OH)(cod)]2 (5 mol%)
We currently anticipate that O
the borylativeP(n-Bu)
CˇC bond
two-step decarboxylative borylation of carboxylic acid3 (50 mol%)RR
cleavage of thioester 2 proceeds by the decarbonylation
containing drugs suchas probenecid, adapalene, febuxostat,
Bpin
KOAc (20ofmol%)acyl(boryl)rhodium(III) species V, asSEt
we initially envisioned
and repaglinide, which have various functional groups
CPME, 80 °C, 24h 3). After thioesterification of these acids by conven(Scheme 2 A). This mechanism begins with transmetalation(Tabletional methods,[15] thioesters 2 ak–an were smoothly converted to the corresponding
3 ak–anhigh yields.
Angew. Chem.,boronates
Int. Ed. 2017,
56,in2482.
In summary, we have developed an efficient synthetic
method for borylarenes from a wide range of aromatic
carboxylic acids by a simple two-step procedure. The key to
多くの場合、
success
was the use of thioesters and the rhodium catalyst,
which enabled the promotion of the desired decarbonylative
borylation at significantly lower temperature (80 8C) than that(> 150 8特に中間体を単離したり観測
C) required for previously reported nickel-catalyzed
methods using
ester or amide derivatives.[14] In combination
しているわけではないwith versatile and reliable organoboron chemistries, as well as
recent progress on carboxyl group-directed CˇH bond

Motivation

想定される（想像できる）
Table 3: Two-step反応機構を書いている
borylation of carboxylic acid-containing drugs.

[a]Scheme 2. Mechanistic considerations.

「想定反応機構」から脱却し、（可能な限り）正確な反応機構を提示したい。

between a rhodium(I) species III and diboron 4 a to affordborylrhodium(I) IV,[23] which then generates V by oxidative
addition of thioester 2. Subsequent reverse insertion of the
carbonyl group in V gives arylrhodium(III) species VI withthe liberation of carbon monoxide.[24] Finally, reductive

6

What we want to know
R

(Bpin)2 (2.0 eqiv)[Rh(OH)(cod)]2 (5 mol%)ligand (50 mol%)
KOAc (20 mol%)

O
SEt

R

Bpin

CPME, 80 °C, 24 h

Angew. Chem., Int. Ed. 2017, 56, 2482.

Ligand eﬀect

Steric eﬀect

P
P

95%

1%

P

P

P Rh

Electric
state

P

48%

0%

配位子構造のわずかな違いによって反応性が劇的に変わる

電子状態、溶液中の構造7

Methodology
溶液中でも測定可能な手法

NMR

UV-visIR, Raman

・とりあえずNMR！
・理論計算もやってみよう！
（他の方法知らんし...）- 適切にメソッドを選択しているわけではない- NMRに偏重（原理的に議論可能？）

8

XAS in homogenous catalysis
XANES(内殻軌道 → 空軌道)

(光電子波の干渉)

0.8

Intensity (a.u.)

X-ray

・
・
・
・
・

EXAFS

1.0

X-ray

0.6

0.4

0.2

放出光電子波0.0

9000

価数、配位子場構造、対称性

9200

energy (eV)9400

散乱光電子波9600

近接元素の種類、原子間距離高い元素選択性、溶液OK、高真空を必要としない、などなど

XASは溶液系においても非常に都合が良いProblems in XAS experiment using organic solvent
Q1. 放射光ってどうしたら使えるの？
Q2. 有機溶媒が使えるセルがない
Q3. 有機溶媒系を扱っている研究者が少ない
Q4. 放射光にグローブボックスがない
Q5. スペクトルのシミュレーションはどうするか？

Sumanene Chemistry

Metal Nanocluster

Molecular Crystal

Laser Abla7on Chemistry9

Problems in XAS experiment using organic solvent

10

Q1. 放射光ってどうしたら使えるの？
Q2. 有機溶媒が使えるセルがない
Q3. 有機溶媒系を扱っている研究者が少ない
Q4. 放射光にグローブボックスがない
Q5. スペクトルのシミュレーションはどうするか？
Assisted by Prof. H. Takaya
Glass Cell

PEEK Cell

Pinchcock

PTFE window (50 μm)

Silicon rubber

PTFE O-ring

For details, see supporting information in
Nature Catal. 2021, 4, 1080.
J. Am. Chem. Soc. 2022, 144, 8818.

Rh-P
Rh-C

2.26
2.28

Rh-0

Rh(diPAMP)/

Rh-Pd

2.01

2.31

(diPHOS)

Rh-Od 1.99
Rh(AcAc)/
c
Rh-Pb
2.30
Rh(DIOP)NBD+
Rh-C
2.22
Rh-Pb
Cationic
Rh intermediate 2.35
Rh(CAMP)2COD+e
Rh-C
2.20
Rh (ds-ethylene)Rh-Pb
2.26
CODte
Rh-C
2.26

2.30

2.29

11

2.03
2.29
2.19
2.32
2.10
2.27
2.26

2.07
2.34
2.36
2.34
2.30

Rh K-edge@SSRL

Seminal works
2.34
2.30 NHAc

PSee refP9 for ligand abbreviations. b Two unique atom fit.
dFour
fit.P 6 X-ray crystalloCO2H
P
Rhunique atom fit. H2 One unique atom
^ For
ref
results:
this
work.
See
X-ray crystallographic
10a,b. Rh
J. K.;Parker,
E. B.Acta
H
graphic results, see: Morrow,MeOHOO H Crystallogr.,
Sect. B 1973, B29, 1145. AcAc is the acetylacetonate anion.
B For
M. C.; Kilboum,
X-ray crystallographic results, see:Me
Hall, MeB. T.; Taylor, K. A. J. Chem. Soc. A 1970, 2540. h See ref 14.
Ac is a-(acylamino)cinnamic acid.
°

c

O
P

P

Figure P2. SolidP curves: Fourier-filtered EXAFS spectrum for RhOinTwo unique atom fits
O to the solid(CAMP)2+ methanol. Triangles:Rh
curves. All fits include contributions from two phosphorus atoms plus
O atom, (b) two oxygen atoms, (c) three oxygen atoms,in (a) one oxygen
fourfive oxygen atoms.
(d)oxygen atoms, and (e)CAMP
diPAMPP

solution EXAFS is given in Table I. The distances from thesolid-state EXAFS studies are in good agreement with crystalprepared in situ under simulated reaction conditions.
lographic results. The accuracy of the Rh-X distances are in the
Rhodium K-edge absorption data were recorded at the Stanford
range ±0.02 Á. Single crystals of the compound Rh(diPAMP)Ac+
RadiationboththesolidsandDatafor
P attempts
P
Laboratory.
Synchrotron
to grow them.
were not P
obtained
P in spite of repeatedthe solutions were recorded in the transmission mode by using
EXAFS
However, onRhthe basis of the solid-stateRh
H results, the costandard procedures. The solution EXAFS data were obtainedfor Rh(diPHOS)Ac+
and Rh(diordination environmentO
O H
by using a special glass cell having a 5-cm path length between
areviewedasthesame.
PAMP)Ac+
being
essentially
Generally
C
HO2C
Me
HO2C
NHAc
NHAc
Mylar windows. The cell was designed to allow either H2 or N2
obtainedsolid-state
andsolutionwasbetweenthegood agreement
NHAc
O
to be bubbled through the solution while it was being magnetically
EXAFS data. The accuracy of the bond distances from thestirred. At the appropriate time (step II in Figure 1), solutions
solution data is of the order ±0.07 Á. The lower accuracy of thesecontaining the substrate were added by syringe injection throughthevalues arises in part fromP
P lack of data in the high k region,a septum stopper. Solvents were degassed prior to addition ofa probable consequence of vibrational dampening. In solution
Rhthe catalyst, and an oxygen-free atmosphere was maintained
very little data is obtained above k = 14 A"1, whereas in the solid
throughout the reaction cycle. The data were processed using
18 A-1. A general increasestate the data extends beyondNk = COH
2H
The values of theHOCprocedures outlined by Sandstrom.ub'13
in the Rh-P and 2Rh-C bond distances
is seen on going from solids
Ac
NHAc
structural parameters reported in Table I for the first shell ento their corresponding solutions. This might reflect relaxation
vironments were obtained by least-squares fitting of the backof the crystal packing forces or a failure of our fitting parameters
usedFourier-filtered
The
data.
transformed,
input parameters(which were derived from solid-state data) to adequately describe
in the least-squares fitting were obtained from analysis of model
the solution EXAFS data or a combination of both effects.
B. R. Stults,(Wilkinson’s
R. M. Friedman,
W. Knowles,The
F. W. Lytle, etfocus
al. J.ofAm.
Chem. Soc. 1981, 103, 3235.
catalyst),
crystalline compounds: Rh[P(C6H5)3]3Cl
our work by using EXAFS was to deprimaryRh(cís-ethylene)COD+BF4~, and Rh203. The various amplitude
termine the structural parameters for the catalyst intermediates
1

AFS
XAFSspectrum
spectrumassignableassignabletotoeach
eachspecies.
species.

■

spectrum
spectrumwhile
whilej jrefers
referstotoa aparticularparticulartime
timepoint.
point.The
TheSVD
SVD
sikslikkmlkm
vmjvmj, whereallows, wheresiksikis isallowsdecomposition
decompositionofofthis
thismatrix
matrixasasmm
ij =
ij =
ananabsorption
absorptioncoeﬃcient
coeﬃcientforforthe
thecomponent
componentnumber
numberk,k,lkmlkmare
are12
the
theelements
elementsofofthe
thediagonal
diagonalmatrix
matrixwith
withthethediagonal
diagonalelements
elements
vmjvmjis isthesortedtheconcentration
concentration
sortedinindecreased
decreasedorder,order,and
andwkjwkj= =lkmlkm
dependence
dependenceforforthe
thecomponent
componentk.k.IEIEfunction
functionand
andIND
IND
functionfunctionare
areexpressed
expressedasas

Seminal works

EXPERIMENTAL
EXPERIMENTALSECTIONSECTION
NiNiK-Edge
K-EdgeX-ray
X-rayAbsorption
AbsorptionSpectroscopy.
Spectroscopy.NiNiK-edge
K-edgeXAFS
nsitu
situtime-resolved
time-resolved
XAFSdata
datawere
wererecordedinintransmission
transmission
Ni intermediates
inrecorded
Yamamoto
coupling
2121
dndquickquickscan
scanmode
modeatatSPring-8
SPring-8BL01B1
BL01B1 (8(8GeV,
GeV,100
100mA).
mA).
N
with
Aﬁxed
ﬁxedexit
exitSi(111)
Si(111)double-crystal
double-crystalmonochromator
monochromator
withanan
Ni
c c
c c
AreV
Ar
2 2
2 2
ergy
was
Rh-coated mirror
Br wasnergyresolution
resolutionofof∼1.3∼1.3eV
wasused.
used.AA
mirrorwas
N Rh-coated Ar
∑
n n∑∑
l
l
∑
l
jj
jj
jj
j =jn=+n1+ 1 l jj
j =jn=+n1+ 1
ed atata aglancing
usedglancingangle
angleofof3.5
3.5mradmradininthe
thepreliminary
preliminarytest
testatatIE(n)n)==
IND(n)n)==
IE(
IND(
rcrc
(c(c−−n)n)r(rc(c−−n)n5)5
ound
round9 9keV
keVtotocut
cutthethehigh-energy
high-energyX-ray
X-rayharmonics
harmonicsoﬀ.
oﬀ.ForFor
llspectra,
spectra,a ametallic
metallicCu
Cureference
referencefoil
foilwaswasusedusedtotoprovide
providean
DMF anN
Ar
N
Ar
Not detected
ergy
forforthe
nergycalibration
calibration
themonochromator.
monochromator.
where
wherer ris isthethenumbernumberofofrows
rowsofofthe
thedatadatamatrix,
matrix,c cis isthe
the
Ni
Ni
Ar
N
First,BrFirst,100100mM
mMbpy/DMF
bpy/DMF0.7
0.7mL
mLwas
wasinjected
injectedinto
intoaN acustomcustomnumber
ofofcolumns
numbercolumnsofofthe
thedatadatamatrix,
matrix,and
andn nis isthethenumbernumberofof
XANESの因子分析と速度論解析からilt XAFS(20mg,
mg,0.073
0.073mmol)
mmol)
built
XAFScellcellcontaining
containing[Ni(cod)[Ni(cod)2]2](20components.
The
components.
Theminimum
minimumofofIEIEand
andIND
INDasasa afunction
functionofofn n
EXAFSを分割、３つの中間体を同定
cated
in
the
high-temperature
controller
equippedcryostatocated in the high-temperature controller equipped cryostat
corresponds
correspondstotothe
thecorrect
correctnumber
numberofofcomponents
componentspresent.
present.
DMF
Nth a amicrosyringe
septum
under
NN
,
and
with
microsyringethroughthroughtherubber
rubberseptum
under
dimer
Brthe
2, 2andThus,
Thus,these
thesecriteria
criteriaallow
allowdetermination
determinationofofthe
thenumbernumberofof
intermediateNiehesolution
immediately.
ThesolutionwasheatedBrsolutionwas
wasshaken
shakenimmediately.
ThesolutionwasheatedH.
Asakura,T.
Shishido,
T.
Tanaka,
J.
Phys.
Chem.
A
2012,
116,be4029.
Nobserved
observedintermediates.
intermediates.The
Theminimum
minimumwill
willnot
notclearlyclearlybe
Not detected
DMF
o323
323KKforfor3030min
mintotoform
formthethe[Ni(cod)(bpy)]/DMF[Ni(cod)(bpy)]/DMF
deﬁneddeﬁnedif ifthetheerrors
errorsarearenotnottruly
trulyrandom,
random,that
thatis,is,thethesystematic
systematic
ecatalyst solution.
Afterformation,
precatalyst
solution.
Afterthetheprecatalyst
precatalyst
formation,bromobromoFe
intermediates
in Kumada–Tamao–Corriu
coupling
error
errordoes
doesnot
notexist.
exist.Such
Suchcontributions
contributionscan
canleadleadtotoappearance
appearance
nzene (2(2equiv,
benzeneequiv,0.14
0.14mmol)mmol)waswasinjected
injectedinto
intothethesolution.
solution.
ofofthethenonchemical
nonchemicalcomponents.
components.InInthis
thisstudy,
study,IEIEand
andIND
IND
AFS
acquiredper
1.5
h hduringthe
XAFSdata
datawerewereacquired
scans
per
1.5
duringtheAr =Mes forfor3030scans
MgX2
ArMgX
functionsfunctionsare
arecalculated
calculatedwith
withthethePCA
PCAfunction
functionimplemented
implementedinintalytic
atalyticreaction
reaction(3(3min/spectrum)min/spectrum)atat323
323K.K.
thethecommercial
commercialsoftware,
software,Igor
IgorProProversion
version6.22.
6.22.
Data
DataReduction.
Reduction.XAFS
XAFSdata
datareduction
reductionwas
wasperformed
performedwith
with
On
Onthe
thebasis
basisofofthe
thenumbernumberofofthe
theobserved
observedcomponents
componentsinin
EX2000
REX2000version
version2.5.9
2.5.9(Rigaku(RigakuCo.,
Co.,Japan).
Japan).Backscattering
Backscatteringthekinetic
analysis
thereaction
reactionmixture,
mixture,kinetic
analysis(global(globalﬁtting
ﬁttinganalysis)
analysis)
tor andforfora acurve
actor
andphasephaseshift
shiftparametersparameterscurveﬁtting
ﬁttinganalysis
analysis
２つの中間体の存在を観測
P Ar PPP
waswasperformed
performedononthe
theseries
seriesofofspectra
spectrawith
withSpecﬁt
Specﬁtversion
version2.12
2.12
re calculated
8.4 code2222using
usingthetheHedin−Hedin−
were
calculatedwith
withthetheFEFF
FEFF
Fe 8.4 code
Fe
価数変化なしforforMS-DOS.
MS-DOS.The
Theﬁttingﬁttingscheme
schemeis isdescribed
describedininthe
theResults
Resultsand
andndqvist exchange
EXAFS spectra were smoothed
Lundqvist
exchangepotential.
potential.
Ar
X EXAFS spectra were smoothed Ar
th theDiscussion
with
theSavitzky−Golay
Savitzky−Golayalgorithm.
algorithm.
Discussionsection.
section.

Fe(II)(tetrahedral)

4030
4030

R Ar

Fe(II)
R X(square planer)dx.doi.org/10.1021/jp211627v| J. | Phys.
Chem.
A 2012,116,4029−4034
dx.doi.org/10.1021/jp211627v
J. Phys.
Chem.
A 2012,116,4029−4034

H. Takaya, M. Murakami, et al. Bull. Chem. Soc. Jpn. 2015, 88, 410.

topics

2. ルイス酸を用いる鈴木・宮浦クロスカップリング反応

13

“The base problem” in Suzuki–Miyaura Cross-CouplingWith external baseWithout external basecat. Pd
R1

R1

cat. Pd
base

R1

X
B

cat. Pd
–CO

R2

B

R2

+

B

R2

acyl ﬂuoride
R1

this work

Protodeborylation

Cl

+

F

R2

B(OH)2

R2

O
R1

R2

Cl

+

triolborate

Lewis acid
H

X

RO
RO B–
RO

X

F
F

F

F

B(OH)2

N

N
S

B(OH)2

NMe

B(OH)2

N

B(OH)2F

Electron deﬁcient aromaTc and heteroaromaTc compounds
Review: Miyaura, N. Suzuki, A. Chem. Rev. 1995, 95, 2457; Buskes, M. J.; Blanco, M.-J., Molecules 2020, 25, 3493
Organotriolborate: Cammidge, A. N. et al. Org. Lett. 2006, 8, 4071; Yamamoto, Y.; Miyaura, N. et al. Angew. Chem. Int.
Ed. 2008, 47, 928. Acyl fluoride: Sanford, M. S. et al. Nature 2018, 563, 100.

14

15

How to facilitate the transmetalation without base?
Aryldiazonium salt

F

F
F

F

Pd2(dba)3 (0.55 mol%)
PAd3 (1 mol%)(HO)2BF

THF, rt, 1 h

N2+BF4–+
Et2N

F(1.5 equiv)

No external base

F

F
F
F

Et2N
82%

Genet, J.-P. et al. Tetrahedron Lett. 1996, 37, 3857

Cationic Pd(II) intermediate (stoichiometric)
L

L

Pd
Cl
F
L = PAd3AgX

Pd+

C6F5B(OH)2(10 equiv)

CH2Cl2 / THF-d8–78 °C to –25 °C

X–

CH2Cl2 / THF-d8–25 °C, 1.5 h(X = BF4, SbF6)

F

Ca5onic Pd(II)C6F5F
X = BF4 88%
SbF6 93%

Carrow, B. P. J. Am. Chem. Soc. 2017, 139, 12418- Transmetala=on ac=ve to unac=vated boronic acid
- Thermal instability (stable at –25 C for several hours)

Controlled generation of cationic Pd intermediate
R1

+

X

Oregano halideoxidative
addition
R1

Pd : Pd cat.
R1

R2

B

dehalogenation agent

Organo borane

product

Pd

– Pd

X

R1

Pd

dehalogena/on

Lewis acid（dehalogena/on agent）–MX“Protected”
Cationic Pd(II)Thermally stable

X
R1

II+

Pd

n

– –MXn+1

B

R2

R2

Reductive
elimination
Pd

R2

transmetala/on
Cationic Pd(II)

R1

PdII+

High reactivity
Thermally instable

Lewis acid having moderate dehalogena/on ac/vity is required

16

17

Lewis acid-mediated SMCC
R1

R2

Br

PdCl2(amphos)2(2 mol%)[Zn]3 (0.72 equiv/Zn)

+

R1

TfO

N
H

N

THF, 80 °C

KF3B(1 equiv)

R2

O
Zn

N

(1.1 equiv)

N
Zn
O

O

OTf

H

P tBu

N

Zn
N

H
OTf

F
F

amphos
EtO2C

F

F

OTs

AcHN
S

F
Ph
80%

Ph

F
79%

O

Et2N
82%

OH

TMD-512 56%

pinB
H
N

Me

PEERRE VIE W ED

O

O PEN
ACCES SNNO

M U LT I D I S C I P L I N A RY

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ORIGINAL
R ES E A RCH

Nature Catal. 2021, 4, 1080.

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www.nature.com/natcatal / December 2021 Vol. 4 No. 12

OMeO

Vol.4 | No.12 | December 2021 pp 987–1090

MeN

ONLINEnature catalysis

MeO2C
O

Dr. Takashi Niwa
(TMDU, RIKEN BDR)

Me2N

[Zn]3

CO2H

F

tBu

Linking with acids

18

What kind of intermediate was formed?
tBu

F
L

Pd

Br
Br

Pd

L

metal salt

(PhBO)3 (12 equiv)

THF/THF-d8–78 °C, 10 min–30 °C

Me2N

F(1 equiv as Pd)

F

P tBu

L = amphos

Time course plot (reac;vity)

F

ArPdBF4

VT-NMR@–30 C

80

yield(%)
yieldof 3 (%)

Thermal stability
L

[Zn]3

60

Pd

Br
Br

Pd

L

F

AgBF4 or AgOTf

40

[Zn]3

ArPdOTfF

20

key intermediate

L
Pd
X

0
0

2

4

6

8

time (min)

10

12

14

(X = OTf or BF4)

Decompose at room temp.

Stable at room temp.
(>39 hours)

The key intermediate shows both high reactivity and thermal stability

19

Low temperature NMR experiments
TfO

F
L

F

Pd

Br
Br

N
H

N

O
Zn

N

Pd

L

N
Zn
O

O

H

N

Zn

H

OTf

H

N

P
Pd

Me2N

OTf

O
O

O
S
CF3

PdOTf?
F+ [Zn]3 (23 C)+ [Zn]3 (–30 C)+ AgBF4 (–30 C)+ AgOTf (–30 C)
ArPdBr (–30 C)[LPdArBr]2 + AgOTf≠[LPdArBr]2 + [Zn]3Single crystals were diﬃcult to prepare.

Solution XAS

20Result of Solu+on XAS experiments
TfO
F

H

N

O
Zn

N
Br
Pd
L

@SPring-8 BL14B2

N

L

N
Zn
O

O

H

OTf
N

Zn

Br

N

H

P

OTf

Pd

O

Br
F

S
O

THF
(0.32 mmol as Zn)

P

O

Pd

Me2N

Pd

Me2N

N

O
O

CF3

S
O

CF3

OTf
F

F

(0.08 mmol as Pd)

Palladium triflate(Inconsistent with NMR)Br K-edge

Triflate-bridged
Pd/Zn binuclear complex

Pd K-edge

Zn K-edge

5

7[Pd]2 + [Zn]3[Pd]2 + [Zn]36

CN = 2

[Pd]2

[Pd]2
4

Br–Pd

Pd–P

(tmeda)ZnBr2

CN = 1

3

4[Zn]3[Zn]3 + [Pd]2

5

FT (k3χ(k))

N
Zn

Pd–Br/P
Br–Zn

3

Pd–(O)–S

2

Br–Br

Zn–Br

2

1
1

0

0
0

1

2

3

R (Å)

4

5

0

1

2

3

R (Å)

4

5

R (Å)

Global structure reconstruction by DFT calculation
B3PW91-D3/Def2-SVP/gas phaseBr

2.073 Å

N
Zn

P
O

S
O

O

S

3.238 Å

N

O
Pd

Me2N

21

CF3

OTf

P
F

Pd

Triﬂate-bridged
Pd/Zn binuclear complex

Br

Zn

Exp.
Fit.

Pd K-edge

3.626 Å
2

ΔE0 (eV)σ2 (10–3 Å2)

ΔR (Å)

C

–2.39

6.28

2.53

1.30

+0.034

0.013

O

–2.39

6.28

2.53

1.30

+0.007

0.027

P

2.78

5.95

6.60

2.54

+0.035

0.032

S

–3.09

6.64

6.75

1.70

–0.196

0.038

FT (k3χ(k))

element

R-factor: 1.28%
reduced χ2 = 117.40
fitting range: 1.2 < r < 3.0

1

0
0

1

2

3

R (Å)

4

5

22

Noncovalent interaction analysis
B3PW91-D3/aug-cc-pVDZ,LanL2DZ/IEF-PCM(THF)//B3PW91-D3/def2-SVP/gas phaseBr

weak interaction(Pd–Br)

N
Zn

P

Br

Pd

Me2N

N

O
O

S
O

CF3

OTf

Zn

F

Triflate-bridged
Pd/Zn binuclear complex
5a (1.0 equiv) + 4b (4.0 equiv)P

THF
rt, 30 min

weak interaction

S

Pd

O
CF3

S

O

tBu

OTf

Pd
van
der
Walls
interaction
O Br
P Bu
t

N

O

Zn

strongN attractive interaction

HF

agostic interaction(C–H/Pd)

NMe2

Hydrogen bonding, halogen bonding, etc.
7

Strong C–H/Pd interaction (agostic interaction)
Weak interaction between Pd and Br located at an apical site

Kinetic and thermodynamic stabilization by apical Br
BCPPd–Br

E. R. Johnson, S. Keinan, P. Mori-Sánches,
J. Contreras-García, A. J. Cohen, W. Yang, J. Am. Chem. Soc. 2010, 132, 6498.
Br
Zn

23

Possible reac?on mechanism
F

B3PW91-D3/def2-TZVP/IEF-PCM(THF)//
B3PW91-D3/def2-SVP/gas phase, 298.15 K

F

PdCl2(amphos)2Br
Pd0(amphos)
A

Reductive
elimination
ΔG‡ = +4.3
ΔG = –28.5

F
Pd
E

L

Oxidative
addition
ΔG‡ = +5.2

F
Br
TfO

Pd

H

B

L

Transmetalation
ΔG‡ = +20.7
ΔG = +9.6

BF3K

Dehalogenation
ΔG = –13.7

+

Me2N
H

Zinc removal
ΔG = +5.8

F

Pd+

X–

P

F 3C O
S

O
Zn

NMe2

O
NMe2 H Me2N
OTf+Zn NMe
2
Br

O

X–

F

H Pd

D (X– = BF3(OH))

OTf

H

Zn
Zn

Me2N

Zn OH
OTf
C (with BF3)

Me2N

O
tBu

N

NMe2

O

[Zn]3
N

BF3, KBF3(OH)

Me2N

H

=

X
R1

–MX
n

II+

Pd

P
Me2N
Br

Zn NMe2BrG

one more
cycle

Me2N
TfO

Zn NMe
2
Br
F

tBu

NMe2

key intermediate(X– = BF3(OH))

Proposed by XAS and NMR

Precursor of
the cationic Pd(II)topics

3. 低温 in situ XAS装置の高度化

24

25

Catalytic borylation using borylmetal complex

Rh B
R

SMe

(Bpin)2 (2.0 eqiv)[Rh(OH)(cod)]2 (2 mol%)
PCy3 (12 mol%)

Cu B
R

Bpin

R

F
F

n-hexane, 80 °C, 12 h

R

O
SEt

R

F

TsO
F

Angew. Chem., Int. Ed. 2017, 56, 2482.

RR

n-hexane, 80 °C, 6 hOrg. Lett. 2019, 21, 4933.

Bpin
F

THF, 40 °C, 24 h

Bpin

CPME, 80 °C, 24 h

(Bpin)2 (2.0 eqiv)[Rh(OH)(cod)]2 (5 mol%)P(n-Bu)3 (12 mol%)SMe K2CO3 (12 mol%)R

J. Am. Chem. Soc. 2017, 139, 12855.

Org. Le(. 2016, 18, 2758.
(Bpin)2 (2.0 eqiv)[Rh(OH)(cod)]2 (5 mol%)P(n-Bu)3 (50 mol%)
KOAc (20 mol%)(Bpin)2 (1.5 eqiv)
CuCl(PCy3)2 (1 mol%)
KOAc (1.2 equiv)(Bpin)2 (1.5 eqiv)
CuTC (5 mol%)
PPh3 (15 mol%)
KOAc (1.2 equiv)
THF, 40 °C, 72 h

J. Org. Chem. 2021, 86, 1622.

Bpin
Bpin

Bpin

TsO
F

26

Catalytic borylation using boryl–metal complex
PhO

B2pin2 (2.0 equiv)[Cu(MeCN)4]BF4 (5 mol%)ligand (5 mol%)t-BuOK (50 mol%)OOsterically demanding
silyl group(interlocking effect)

Bpin
R

THF
50 °C, 24 hallyl carbonateNallylboronate

NR

DFT calculation

P
R R

O
Cu B
O

ωB97X-D/Def2-TZVP/THF(SMD) (at 50 ℃)

R R O O
R R
B
P
P
Cu
Cu
P
P
B
R R
O O R R

(ΔG = 0.0)
monomerPtBu
Me(R,R)-QuinoxP* (R = H): 12% yield, 79% ee(R,R)-5,8-TMS-QuinoxP* (R = TMS): 92% yield, 93% ee

R R
P

Me
P tBu

Me
P tBu

N
N

P
tBu
Me

SiMe3
N
SiMe3

N

Me
P tBu
P
tBu
Me

QuinoxP*

5,8-TMS-QuinoxP*–8.3 kcal/mol–0.9 kcal/mol

dimer

ダイマー体の不安定化によるボリル銅モノマーの生成が鍵
H. Iwamoto, Y. Ozawa, Y. Takenouchi, T. Imamoto, H. Ito, J. Am. Chem. Soc. 2021, 143, 6413.

Borylcopper complexes are thermally instable
N

N
B

iPr
Cu P iPr
iPrB

iPr
iPr P Cu
iPr
N

N

P(i-Pr)3

Ph Ph O O
Ph Ph
B
P
P
Cu
Cu
P
P
B
Ph Ph
O O Ph Ph

DPPBz

27

結晶状態でダイマーとして存在‒40 ℃以上で徐々に分解
C. Kleeberg, et al. Organometallics 2017, 36, 4687.

冷却して反応を観測したいという需要はそれなりにあるが、ただ冷やせればいいというものでもない- 発生させた瞬間から不安定な場合など- liq. N2で固める？ → 透過法は難しい

やはり溶液 in situでやりたい28

Low-temperature solu/on XAS system
VT-XASシステムの外観
スターリングクーラー

アルミブロック

スターリング
クーラー

断熱材

筐体

XZステージスターラー（矢沢科学 KF-22R）

入射光

カプトン膜（25 μm）

透過光

蛍光X線

✔ 液体窒素などの冷媒の供給が不要✔ 光軸上から装置を退避可能 → 低温反応中に別の測定ができる

29

Low-temperature solution XAS system
セルの分解図クライオスタットの内部構造
試薬ポート

アルミブロック

PTFEパッキン

スターリング
クーラー

断熱材

筐体

Si3N4膜 (1 μm)
ラバーパッキン
入射光

透過光

攪拌子
PTFEスペーサー

カプトン膜（25 μm）

蛍光X線✔ 縦方向に流路が通っており、攪拌効率が良い✔ 低温でも弾性を保持するラバーパッキンにより気密性を保持Low-temperature solu/on XAS system30

結露防止用N2ガス導入口

セルの分解図試薬ポート
PTFEパッキン
Si3N4膜 (1 μm)
ラバーパッキンreagent in攪拌子PTFEスペーサー

gas out

ストップコックバルブ
緩衝スポンジ✔ 試薬を後から追加できる → in situ測定が容易に実施可能

31

How to iden*fy?
Me O OtBu Me
B
P tBu
P
N
Cu
Cu

N
N

N

P

P
N
tBu B
Me
O O Me tBu

Cu
P
tBu
Me

dimer (tetrahedral)
z

Me
P tBu

N

tetrahedral

trigonal planer

Cu

Cu

Simulation (FDMNES)

Intensity (a.u.)

Energy4px,y4px,y,zOmonomer (trigonal)

x
y

O
B

4pz

[LCuCl]2
dimer
monomer1s

1s

K. O. Hodgson, E. I. Solomon, et al. J. Am. Chem. Soc. 1987, 109, 6433

-10

0

10

20

30

E–E0 (eV)

4p軌道の配位子場分裂のため, もし三配位Cu(I)錯体が生成しているならば縮退が解けた4pz軌道への遷移に対応するピークが強く観測される

40

topics

4. Ni錯体の配位子場構造と価数について32

CO purification using transition metal

33

Coordination/dissociation processes

Fe(II)Cu(II)CO separation from CO/N2−191 ºC, 0.99 atm
CO desorption
27 ºC, in vacuo

脱着に高温が必要
K. Kirchner et al., Angew. Chem. Int. Ed. 2008, 47, 9142.

吸着に低温が必要
S. Kitagawa et al., Science 2014, 343, 167.

34

Low-valent metal complex
Back-donation

Metal valency

Adsorption
efficiency

Desorption
efficiency

High

Weak

Low

High

Low

StrongHigh

Low

Mond Process for purification of Ni

脱着過程を低温化できればいいはず

L. Mond et al., J. Chem. Soc. Trans. 1890, 57, 749.

Pressure-swing absorp0on/desorp0on behavior

35

IL, room temp.
Intermolecular
SN2

IL

Hoshimoto G (Osaka Univ.)☑ Interconversion between Ni(0) complexes at room temperature☑ Reversible, recyclable, and pressure-swing chemisorp0on
J. Am. Chem. Soc. 2022, 144, 8818

36

Ligand effect–CONi K-edge@SPring-8 BL14B2

1.2

Intensity (a.u.)

1.0

0.8

d–p mixing

2a

0.6

2.227 Å
0.4

2b2a (97%)

0.2
8320

8325

>

2.269 Å

2b (9%)

配位子の柔軟性がNi近傍の構造にも影響

8330

0.0
8320

8340

8360

8380

Energy (eV)

8400

8420

8440

配位子のアシストにCO脱着を加速Summary37

1. 均一系触媒反応研究の実際とXASの活用
2. ルイス酸を用いる鈴木・宮浦クロスカップリング反応
3. 低温 in situ XAS装置の高度化
4. Ni錯体の配位子場構造と価数について

Chemists need physicists

Physicists need chemists

多少無理やりでもとにかくcollaboration

Acknowledgments

Lab. members

Collaborators

Prof. Dr. Hidehiro Sakurai
Assoc. Prof. Dr. Yumi Yakiyama
Mr. Naoto Kibayashi
Mr. Takuya Kawamura
Ms. Fuki Shibagaki
Ms. Butsaratip Suwattanan
Mr. Yasutaka Yoshida
Mr. Kazuma Sugimura
Mr. Ramadhani Ihsan

Dr. Yoichi Hoshimoto
Mr. Yasuhiro Yamauchi
Mr. Yutaka Mondori
Dr. Masahiro Miura
Dr. Yuji Nishii
Dr. Michiya Matsusaki
Mr. Tomoyuki Suezawa
Dr. Shuji Akai
Dr. Kyohei Kanomata
Dr. Kengo Kasama
Dr. Yutaka Saga
Dr. Yuma Morimoto
Mr. Ryoichiro Ogumo
Dr. Hayato Tsurugi
Dr. Satoshi Seino
Dr. Takashi Nakagawa

SR facilities
Dr. Tetsuo Homma (JASRI)
Dr. Masanari Nagasaka (IMS)
Dr. Hiroshi Iwayama (IMS)
Dr. Takuya Masuda (NIMS)

38

Mr. Naoki Shinyoshi
Mr. Yuji Tamaki
Dr. Kanta Ono
Dr. Yasuo Takeichi
Dr. Takamitsu Hosoya (TMDU, RIKEN)
Dr. Takashi Niwa (TMDU, RIKEN)
Dr. Hajime Ito (Hokkaido Univ.)
Dr. Koji Kubota (Hokkaido Univ.)
Dr. Yu Ozawa (Hokkaido Univ.)
Mr. Fumitoshi Kumaki (KEK)
Dr. Hiroshi Kondo (Keio Univ.)
Dr. Ryo Toyoshima (Keio Univ.)
Mr. Risei Ichikawa (Keio Univ.)
Dr. Takaya Hikaru (Teikyo Univ. Sci.)
Mr. Kazuki Matsumoto (DFC Co. Ltd.)