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ARTICLE
This jou nal is © The Royal Socie y o Chemis y 20xx J. Name., 2013, 00, 1-3 | 1
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a.
Ins i u o de In es igaciones Químicas (IIQ), Depa amen o de Química Ino gánica
and Cen o de Inno ación en Química A anzada (ORFEO-CINQA).
CSIC and
Uni e sidad de Se illa. A da. Amé ico Vespucio 49, 41092, Se illa (Spain). E-mails
:
nu [email protected]; and es.sua [email protected]
† Dedica ed o P o . E nes o Ca mona on occasion o his 70
h
anni e sa y.
Elec onic Supplemen a y In o ma ion (ESI) a ailable: [NMR and ESI-MS
spec a o
selec ed de i a i es and ca aly ic eac ions, and X- ay c ys allog aphy da a o
CCDC
1856145]. See DOI: 10.1039/x0xx00000x
Recei ed 00 h Janua y 20xx,
Accep ed 00 h Janua y 20xx
DOI: 10.1039/x0xx00000x
www. sc.o g/
Hyd obo a ion o ca bon dioxide wi h ca echol- and
pinacolbo ane using an I -CNP* pince complex. Wa e in luence
on he ca aly ic ac i i y
P áxedes Sánchez, Ma ín He nández-Juá ez, Nu ia Rendón,* Joaquín López-Se ano, Eleu e io
Ál a ez, Ma ga i a Paneque, and And és Suá ez*
I idium complexes based on dep o ona ed lu idine-de i ed CNP* pince s 2a/2b selec i ely ca alyze he hyd obo a ion o
CO2 unde mild condi ions (1-2 ba CO2, 30 oC) o me hoxybo ane using HBca (TOF up o 56 h-1) and o he o ma e le el
wi h HBpin (TOF up o 1245 h-1). In e es ingly, an in iguing, posi i e wa e e ec on he eac ion a es has been obse ed.
NMR spec oscopy and ESI-MS analysis o he hyd obo a ion eac ions ha e shown he o ma ion o ligand-p o ona ed
[I (CNP)(CO)(BR2)H][B(R2)2] (R2 = ca echola e, pinacola e) de i a i es unde ca aly ic condi ions. Con ol expe imen s,
howe e , ha e demons a ed ha hese de i a i es a e no ca aly ically compe en species in he hyd obo a ion o CO2.
In oduc ion
Ca bon dioxide is he C1 ca bon sou ce pa excellence o
chemicals and uels p oduc ion due o i s abundan , enewable
and non- oxic na u e.
1
Howe e , he chemical ans o ma ion
o CO
2
is signi ican ly hampe ed by i s high he modynamic and
kine ic s abili y. While con e sion o CO
2
by non- edox
p ocesses such as he p oduc ion o ca bona es, ca bama es
and u e hanes a e ela i ely well-es ablished p ocesses,
1
he
educ ion o CO
2
o syn he ically and ene ge ically ele an
p oduc s such as o mic acid de i a i es and me hanol s ill
ep esen s an impo an challenge.
2
Among po en ial
educ an s, dihyd ogen p o ides he mos a om-economical
al e na i e, and consequen ly i is no su p ising ha
hyd ogena ion o CO
2
o o ma es
and, o a lesse ex en , o
MeOH
has been p o usely s udied.
2
Since hyd ogena ion o
CO
2
usually in ol es he use o high empe a u es and
p essu es, o he educing agen s such as hyd osilanes
3
o
hyd obo anes
4
ha e also ecei ed a signi ican a en ion due
o he milde eac ion condi ions ha can be employed wi h
hese species. Fu he mo e, hei eac i i y can be adjus ed by
a ying he silane o bo ane subs i uen s acili a ing access o
di e en C1 p oduc s including CO, CH
2
O, MeOH and CH
4
.
3,4
In
his ein, pa icula ly appealing o syn he ic pu poses is he
educ ion o CO
2
o o ma e and ace al de i a i es ha se e
o he de elopmen o educ i e unc ionaliza ions o CO
2
.
5
Reduc ion o ca bon dioxide can be accomplished in he
absence o a ca alys wi h
me al bo ohyd ides.
6
On he
con a y, he hyd obo a ion o CO
2
wi h e en e y eac i e BH
3
adduc s should be ca ied ou in he p esence o a ca alys .
7,8
Since he seminal wo k o Guan e al. epo ing he educ ion
o CO
2
wi h HBca (ca echolbo ane) o me hanol media ed by
pince nickel complexes,
9
he e has been an in ense impe us
o he de elopmen o non-me al,
8,10
main g oup me al,
11
and
ansi ion me al ca alys s o CO
2
hyd obo a ion.
12-21
Among
hese ca aly ic sys ems, hiola e nickel
12
and palladium
13
pince complexes ha e p o ided he highes TOFs, in he ange
o 1780 o 2400 h
-1
, o he educ ion o CO
2
o
me hoxybo ane using HBca as educ an . Also, while
hyd obo a ion o CO
2
wi h BH
3
and HBca p oceeds o he
me hoxide le el, he educ ion p ocess can be con olled o
some ex en by he use o less eac i e bo anes such as HBpin
(pinacolbo ane).
Thus, selec i e educ ion o CO
2
o
o moxybo ane, which has been p o en o se e as a o ma e
sou ce o syn he ic pu poses,
14
has been achie ed wi h HBpin
and a me al ca alys .
11c,14-17
I is also wo h men ioning
a emp s o gene a e ace al de i a i es ha can be employed
as me hylene ans e eagen s.
18-20
I is in e es ing o no e ha al hough ca alys s o he
hyd obo a ion o CO
2
based on di e en me als, including
mos o g oups 8-11 elemen s, ha e been epo ed, i is
su p ising ha i idium complexes, which ha e been equen ly
employed in hyd obo a ion eac ions,
22-24
ha e no been
in es iga ed in he educ ion o CO
2
by hyd obo anes. While
being less a ac i e in e ms o cos and en i onmen al
aspec s, noble me al ca alys s should no be igno ed since
highe ca aly ic e iciencies and s abili ies may compensa e o
ARTICLE Jou nal Name
2 | J. Name., 2012, 00, 1-3 This jou nal is © The Royal Socie y o Chemis y 20xx
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hei inc ease p ice and be use ul o small scale applica ions.
He ein, we epo an I ca alys p ecu so based on a
dep o ona ed lu idine-de i ed N-he e ocyclic
ca bene/phosphine CNP* pince ha selec i ely ca alyzes he
hyd obo a ion o CO
2
o me hoxy- o o moxybo ane
depending on he employed hyd obo ane (HBca o HBpin).
In e es ingly, an unexpec ed posi i e in luence o he p esence
o small amoun s o wa e in he eac ion a es has been
obse ed. Finally, i idium species o med unde ca aly ic
condi ions ha e been in es iga ed and hei pa icipa ion in
he ca aly ic cycle has been e alua ed.
Resul s and discussion
Syn hesis o he ca alys p ecu so
Reac ion o he ca bonyl i idium complex
1(Cl)
25
wi h KO
Bu in
THF yielded he o ma ion o a mix u e o he dep o ona ed
“ au ome ic” species
2a
and
2b
(Scheme 1).
The a io, as
de e mined by
1
H NMR spec oscopy, be ween hese species
depends on he sol en . In he
1
H NMR spec um egis e ed in
THF-d
8
,
2a
and
2b
appea in a 9:1 a io, whe eas a
2a
/
2b
a io
o 4 was obse ed in C
6
D
6
. In he o me sol en , he CH
2
N
b idge o he pince o
2a
p oduces in he
1
H NMR spec um a
single signal a 4.72 ppm (2H) and he me hyne CHP a m gi es
ise o a double esonance a 3.84 ppm (
2
J
HP
= 1.9 Hz, 1H),
meanwhile
2b
exhibi s a single peak a 6.17 ppm (1H) o he
CHN pince a m and a double signal a 3.51 ppm (
2
J
HP
= 11.4
Hz, 2H) o he hyd ogens o he me hylene CH
2
P moie y. Fo
bo h complexes, he esonances co esponding o he py idine
de i ed agmen s appea signi ican ly shi ed up ield (6.30-
5.37 ppm) in compa ison o
1(Cl)
, in ag eemen wi h he
p esence o dea oma ized cen al ings. In he
13
C{
1
H} NMR
spec um, de i a i e
2a
exhibi s he esonance p oduced by
he ca benic ca bon a om as a double a 182.8 ppm (J
CP
= 92
Hz) and ha o he CO ligand a 182.0 ppm (d, J
CP
= 10 Hz).
Fu he suppo o he in e ed s uc u e o
2a
was ob ained
by a X- ay di ac ion s udy o a single c ys al o he complex
(Fig. 1).
26
Dep o ona ion o he me hylene P-a m is e lec ed
in sho C(19)-P(1) and C(19)-C(18) bond leng hs o 1.743 and
1.370 Å, espec i ely. Fu he mo e, al e na ing C-C dis ances in
he py idine moie y e idence ing dea oma iza ion as shown
by he elonga ed C(18)-C(17) and C(16)-C(15) dis ances o
1.460 and 1.396 Å, and sho en C(17)-C(16) and C(15)-C(14)
bond leng hs o 1.343 and 1.378 Å, espec i ely (a e age C-C
bond in he py idine molecule: 1.38 Å).
As in e ed om he di e en
2a
/
2b
a ios obse ed in
dis inc sol en s, complexes
2a
and
2b
a e in equilib ium in
solu ion. This obse a ion is u he mani es ed in he
1
H,
1
H-
exchange spec oscopy (EXSY) spec um (mixing ime = 0.8 s)
o he
2a
/
2b
mix u e in we THF-d
8
egis e ed a 25
o
C, whe e
in ense exchange c oss-peaks a e obse ed be ween: i) signals
co esponding o he me hyne and me hylene b idges o
2a
, ii)
esonances caused by he CHP and CH
2
N moie ies o
2a
wi h
hose o he CH
2
P and CHN b idges o
2b
, espec i ely, and iii)
he signals o he me hyne and me hylene agmen s o
2a
and
2b
wi h hose o wa e (Fig. S1). These obse a ions suppo
ha he iden a e ligand b idges can ge in ol ed in e e sible
p o ona ion/dep o ona ion media ed by wa e molecules
ac ing as p o on ans e assis an s.
27
Scheme 1
Syn hesis o complexes
2a
and
2b
.
Fig. 1 ORTEP d awing a 30% ellipsoid p obabili y o complex 2a. Mos hyd ogen a oms
and sol en molecule (THF) ha e been omi ed o cla i y. Selec ed bond leng hs [Å]
and angles [o]: I (1)-C(1) 2.034(8), I (1)-N(3) 2.127(5), I (1)-P(1) 2.285(2), I (1)-C(32)
1.818(8), C(1)-I (1)-P(1) 168.3(2), C(1)-I (1)-C(32) 97.2(3), C(32)-I (1)-N(3) 172.9(3), C(1)-
I (1)-N(3) 89.7(2), P(1)-I (1)-N(3) 82.64(16).
Ca aly ic hyd obo a ion o CO2
Hyd obo a ion o CO
2
ca alyzed by he mix u e o complexes
2a
/
2b
was in es iga ed. Ini ial eac ions we e ca ied ou wi h
HBca in THF-d
8
(2 ba CO
2
, 30
o
C) using 1.0 mol% o
2a
/
2b
.
Selec i e CO
2
educ ion o he co esponding me hoxybo ane
(CH
3
OBca ) was es ablished by
1
H NMR spec oscopy a e he
obse a ion o a single esonance a 3.81 ppm, and he
appea ance o a b oad signal in he
11
B NMR spec um a 22.5
ppm. Also, he expec ed concomi an o ma ion o dibo oxane
(ca BOBca ) was con i med by he appea ance o a whi e
p ecipi a e a e emo al o THF-d
8
unde acuum and addi ion
o C
6
H
6
(

H
(THF-d
8
) = 6.83, 6.93 ppm;

B
(THF-d
8
) = 16.5
ppm).
28
Al hough signi ican ca e was exe cised in he se -up o
he ca aly ic expe imen s, hese eac ions we e ini ially ound
di icul o ep oduce. Howe e , a e sc upulous con ol o he
eac ion pa ame e s, a ma ked in luence o he p esence o
wa e in he hyd obo a ion eac ion was no iced.
29
The e o e,
ca aly ic eac ions we e pe o med in he p esence o a iable
amoun s o wa e (Table 1). Reac ions we e ollowed up by
1
H{
11
B} NMR spec oscopy, and o a meaning ul compa ison o
he ca aly ic ac i i y, TON alues we e de e mined a e 1.5 h
Jou nal Name ARTICLE
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al hough upon ex ended eac ion imes all he eac ions
p oceeded o comple ion. Thus, when he ca aly ic eac ion
was pe o med in he p esence o 1 mol% o wa e , o ma ion
o 18% o me hoxybo ane was obse ed (TON = 54; TOF = 36 h
-
1
) (en y 1). By inc easing he wa e con en , as e
ans o ma ion o CO
2
o me hoxybo ane was e idenced,
p o iding up o 28% con e sion o me hoxybo ane in he
p esence o 5 mol% o wa e (TON = 84; TOF = 56 h
-1
) (en ies
2 and 3). I should be no ed ha o he la e eac ion he
maximum yield is 30% a e conside ing he amoun o bo ane
ha is hyd olyzed o ca BOBca . Fu he inc ease in he wa e
con en o he eac ion o 6 mol% somewha dec eased he
ca aly ic ac i i y (TOF = 50 h
-1
) (en y 4). In e es ingly, complex
1(Cl)
was ound a poo e ca alys han
2a
/
2b
p o iding 78
u no e s a e 16 h (TOF = 4.9 h
-1
) (en y 5). Con ol
expe imen s showed ha
2a
/
2b
ca alyzes he hyd olysis o
HBca o yield ca BOBca as he sole p oduc .
Table 1 Ca aly ic hyd obo a ion o CO2 wi h HBca
En y Ca alys H
2
O (mol%) Yield (%) TON
1 2a/2b 1 18 54
2 3 24 72
3 5 28 84
4 6 25 75
5a 1(Cl) 3 26 78
Reac ion condi ions: 1.0 mol% [I ], 2 ba CO2, 30 oC, THF-d8, [HBca ] = 0.5 M.
Reac ion ime: 1.5 h, unless o he wise no ed. Yields we e de e mined by 1H{11B}
NMR spec oscopy using hexame hylbenzene as in e nal s anda d. TON alues
based on moles o B-H bonds eac ed pe mole ca alys : (mmol me hoxybo ane x
3)/(mmol ca ). a Reac ion ime: 16 h.
Nex , he ca aly ic pe o mance o
2a
/
2b
in he
hyd obo a ion o CO
2
wi h HBpin was examined unde 1 ba o
CO
2
a 30
o
C (Table 2). These eac ions we e ca ied ou wi h
low ca alys loadings o 0.2 mol%. While p e ious epo s ha e
shown ha educ ion o CO
2
wi h pinacolbo ane may yield
o ma e (HCO
2
Bpin), ace al (H
2
C(OBpin)
2
) and me hoxy
(CH
3
OBpin) de i a i es, o mix u es he eo , eac ions wi h
2a
/
2b
ga e solely o moxybo ane. Mo eo e , as in he case o
he eac ions wi h HBca , he p esence o small amoun s o
wa e signi ican ly inc eases he eac ion a e. All eac ions
p oceeded o con e sions o HBpin highe han 90%, al hough
TON alues we e compa ed a e a eac ion ime o 20 min.
Fo example, eac ion in he p esence o 1 mol% o wa e
p o ided he o moxybo ane de i a i e in 30% yield (TOF =
450 h
-1
, en y 1), whe eas upon addi ion o inc easing amoun s
o wa e up o 7 mol% a ca. h ee- old ise o he ca aly ic
ac i i y (TOF = 1245 h
-1
)
was obse ed (en ies 2-5). Mo eo e ,
when he ca alys loading was u he educed o 0.1 mol%,
o moxybo ane was ob ained in 74% yield a e 1 h, wha
ep esen s a no able TOF o 740 h
-1
. Among he ew ca alys s
ha selec i ely p oduces o moxybo ane,
11c,14-17
only he
palladium pince complex epo ed by Haza i e al. p o ides
as e eac ion a es wi h low ca alys loadings (TOF = 8500 h
-1
,
0.01 mol% ca alys ).
15
Table 2 Ca aly ic hyd obo a ion o CO2 wi h HBpin
En y H2O (mol%) Yield (%) TON
1 1 30 150
2 2 72 360
3 3 79 395
4 6 80 400
5 7 83 415
6a 3 74 740
Reac ion condi ions, unless o he wise no ed: 0.2 mol% 2a/2b, 1 ba CO2, 30 oC,
THF-d8, [HBpin] = 0.4 M. Reac ion ime: 20 min. Yields we e de e mined by
1H{11B} NMR spec oscopy using hexame hylbenzene as in e nal s anda d. TON
alues as de e mined by (mmol o moxybo ane)/(mmol ca ). a 0.1 mol% 2a/2b.
Reac ion ime: 1.0 h.
S udy o me al species o med unde ca aly ic condi ions
To shed ligh on he me al species o med unde ca aly ic
condi ions, he hyd obo a ion o CO
2
(2 ba ) wi h HBca was
ca ied ou using 20 mol% o
2a
/
2b
in THF-d
8
. Upon eac ion
comple ion only a single signal is obse ed in he
31
P{
1
H} NMR
spec um a 16.9 ppm ha co esponds o a dihyd ide species,
as deduced by he appea ance o wo double s o double s
signals appea ing a 17.5 (
2
J
HP
= 12 Hz,
2
J
HH
= 2 Hz) and 8.3
ppm (
2
J
HP
= 22 Hz,
2
J
HH
= 2 Hz) in he
1
H NMR spec oscopy
expe imen . The e o e, we hypo hesized whe he he species
obse ed a e eac ion comple ion was a dihyd ide I complex
based on a p o ona ed CNP (
3
+
, Scheme 2) o dep o ona ed
CNP* (
4
, Scheme 3) ligand, and consequen ly an independen
syn hesis o bo h complexes was pu sued. Fo he s udy o
complex
3(Cl)
, a CD
2
Cl
2
solu ion o
1(Cl)
was exposed o 1 ba
o H
2
(Scheme 2). The
1
H NMR spec um o he newly o med
species showed a double o double s a 17.45 ppm (
2
J
HP
=
11.7 Hz,
2
J
HH
= 1.6 Hz) a ibu able o he I H ans o he
py idine moie y, and a double o double s o double s
appea ing a 8.32 ppm (
2
J
HP
= 22.2 Hz,
2
J
HH
= 1.6 Hz,
4
J
HH
= 1.6
Hz) caused by he hyd ide ligand placed cis o he N-dono
agmen ha couples wi h he o he I H hyd ogen and one o
he hyd ogens o he CH
2
P b idge.
30
Meanwhile, he
31
P{
1
H}
NMR spec um displays a single signal a 16.9 ppm. These
da a ag ee well wi h he obse ed signals a he end o he
ca aly ic eac ion and demons a es ha ligand p o ona ion
occu s unde ca alysis. Complex
3(Cl)
could no be isola ed
since i s a emp ed pu i ica ion yielded mix u es o
3(Cl)
and
1(Cl)
, indica ing ha he dihyd ido complex loses H
2
unde
acuum.
ARTICLE Jou nal Name
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Scheme 2 Reac ion wi h H2 o complex 1(Cl).
Scheme 3 Reac ion wi h H2
o complexes
2a
/
2b
.
Addi ionally, o ma ion o a dep o ona ed dihyd ide
complex
4
was uled ou since exposu e o he
2a
/
2b
mix u e
o H
2
(5 ba ) in THF-d
8
p oduced in he
31
P{
1
H} NMR spec um a
single a 8.8 ppm. Fu he mo e, in he
1
H NMR spec um
de i a i e
4
showed wo double o double s appea ing a
8.64 (
2
J
HP
= 20.8 Hz,
2
J
HH
= 1.5 Hz) and 16.59 (
2
J
HP
= 11.3 Hz,
2
J
HH
= 1.5 Hz),
30
whe eas he signals o he dea oma ized
py idine ing a e signi ican ly shi ed o high ield appea ing in
he ange be ween 6.56 and 5.71 ppm. Complex
4
also
eadily
loses H
2
unde acuum leading o he egene a ion o he
2a
/
2b
mix u e.
Fu he mo e, analysis by ESI-MS (posi i e mode) o he
ca aly ic eac ion be ween CO
2
and HBca in he p esence o
20 mol% o
2a
/
2b
p o ided a peak a m/z 698 a ibu able o
he ca ionic agmen [I H
2
(CNP)(CO)]
+
(
3
+
), while in he
nega i e mode a peak a m/z 227 was obse ed ha has been
assigned o he a ylspi obo ona e es e [Bca
2
] .
Deg ada ion
o HBca p omo ed by nucleophiles, including complexes
con aining anionic ligands, ha e been shown o p o ide he
abo e anion along wi h o he bo on species such as B
2
ca
3
and
BH
3
.
23,24,31
Howe e , o ma ion o hese, o o he , bo on
de i a i es could no be unequi ocally de ec ed by MS o NMR
spec oscopy. Mo eo e , al hough HBpin has been shown o
be less p one o deg ada ion han HBca ,
22d,32
ESI-MS analysis
o a ca aly ic eac ion wi h HBpin using 20 mol% o
2a
/
2b
allowed o he de ec ion o he ca ionic agmen
1
+
and he
anion [Bpin
2
]
(m/z 243).
33
We specula e ha o ma ion o
[Bca
2
] and [Bpin
2
]
anions migh ini ially in ol e nucleophilic
a ack o he hyd obo ane by he me hyne ca bon o he
dep o ona ed CNP* ligand,
27
and ligand-assis ed B-H
ac i a ion, as shown by Mils ein e al. o ela ed Ru
complexes.
34
Howe e , di ec e idence o hese p ocesses has
emained elusi e in ou sys em.
Since he hyd obo a ion eac ion is signi ican ly as e
using HBpin han wi h HBca , he la e p ocess was chosen o
ge insigh in o he o ma ion o o he me al species du ing he
ca aly ic eac ion. Hyd obo a ion o CO
2
(2 ba ) wi h HBca
using 10 mol% o
2a
/
2b
in THF-d
8
was moni o ed by
1
H NMR
spec oscopy, showing he o ma ion o a hyd ide complex
ha p oduces a double esonance a 6.9 ppm (
2
J
HP
= 21 Hz),
and which could be he esul o he oxida i e addi ion o
HBca o
1
+
. In o de o unequi ocally de e mine he s uc u e
o his de i a i e, complex
1(Bca
2
)
was eadily isola ed a e
anion exchange o
1(Cl)
wi h Li[Bca
2
]
35
and made eac wi h
HBca (Scheme 4). Addi ion o a sligh excess o HBca (1.5
equi ) o a THF-d
8
solu ion o
1(Bca
2
)
p oduced he decolo ing
o he ini ially yellow solu ion o yield he bo yli idium hyd ide
complex
5(Bca
2
)
.
24,36
This de i a i e was spec oscopically
cha ac e ized since a emp s o isola e
5(Bca
2
)
yielded
mix u es o
1(Bca
2
)
and
3(Bca
2
)
. Diagnos ic signals o
complex
5(Bca
2
)
in he
1
H NMR and
13
C{
1
H} NMR spec a
egis e ed in THF-d
8
include he p esence o a double
esonance a 6.90 ppm (
2
J
HP
= 21.1 Hz) a ibu able o he
hyd ido ligand, and a double a 154.3 ppm (J
CP
= 96 Hz) due o
he ca benic ca bon, espec i ely. The p esence o he
ca bonyl ligand is mani es ed in he
13
C{
1
H} NMR spec um by
a b oad esonance a 176.8 ppm, and in he IR spec um by an
abso p ion a 2005 cm
-1
. Mo eo e , in addi ion o he HBca
and bisca echolbo a e esonances appea ing in he
11
B NMR
spec um a 22.5 (d, J
BH
= 189 Hz) and 15.1 ppm espec i ely, a
b oad signal a 12.9 ppm is also obse ed, which ha e been
assigned o he bo yl ligand. Also, while hese spec oscopic
da a do no allow o a s aigh o wa d di e en ia ion
be ween he wo possible isome s esul ing om he oxida i e
addi ion o HBca o
1(Bca
2
)
, i.e. ans (
5-I
) o cis (
5-II
)
coo dina ion o he bo yl ligand o he py idine agmen (Fig.
2), compa ison o he chemical shi o he esonance o he
hyd ido ligand wi h hose o complex
3(Cl)
sugges s a cis
coo dina ion o he Bca moie y o he ca bonyl ligand. This
ligand disposi ion p e en s he ans coo dina ion o he wo
po en ially

-accep ing bo yl and ca bonyl ligands.
36b,37
Mo eo e , DFT calcula ions (B3LYP-D3, 6-31g(d,p)/SDD) o
5-I
and
5-II
indica e ha he o me ca ionic species is mo e s able
by 3.2 kcal/mol (Fig. 2). Also o no e, in he
1
H,
1
H-exchange
spec oscopy (EXSY) spec um o he eac ion mix u e o
1(Bca
2
)
and HBca
in THF-d
8
egis e ed a 25
o
C, exchange
c oss peaks a e obse ed be ween he signal o he a oma ic
hyd ogens co esponding o HBca and hose o he [Bca
2
]
anion indica i e o he exis ence o a bo on subs i uen
sc ambling p ocess. Upon egis e ing he same expe imen a
50
o
C, a c oss-peak signal caused by he exchange be ween
ee HBca and he hyd ido ligand is also obse ed poin ing ou
o he e e sibili y o he B-H oxida i e addi ion.
Cl
N
PPh2
NNMes
I CO H2, CD2Cl2
Cl
N
PPh2
NNMes
I H
CO
H
1(Cl) 3(Cl)
acuum
Jou nal Name ARTICLE
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Scheme 4 Syn hesis o 1(Bca 2) and 1(BA F), and eac ions wi h bo anes.
Fig. 2 Rela i e he modynamic s abili y o ca ionic agmen s 5-I and 5-II, and 6-I and 6-
II. Da a in pa en hesis a e G in THF (kcal mol-1).
To es he o ma ion o analogous species o
5(Bca
2
)
wi h
HBpin, complex
1(BA
F
)
, p e iously p epa ed by anion
exchange o
1(Cl)
wi h NaBA
F
, was eac ed wi h an excess o
HBpin (2.4 equi ) (Scheme 4). The newly o med species
6(BA
F
)
p o ided compa able NMR spec a o hose o
5(Bca
2
)
, wi h he logical di e ences o he signals due o he
[BA
F
]
-
anion and he bo yl ligand, e incing he cis a angemen
o he bo yl and CO ligands. Howe e , DFT calcula ions (B3LYP-
D3, 6-31g(d,p)/SDD) shows ha he isome
6-I
is 3.5 kcal/mol
less s able han
6-II
, wha can be asc ibed o he p esence o
non-s abilizing in e ac ions in
6-I
be ween he mo e s e ically
demanding pinacol moie y wi h he subs i uen s o he NHC
and phosphino agmen s (Fig. 2). Also o in e es , exchange
c oss-peaks be ween he esonances o he ee bo ane and
he hyd ido ligand o
6(BA
F
)
a e obse ed in he
1
H,
1
H-EXSY
spec um.
NMR spec a o he eac ion o complexes
5(Bca
2
)
and
6(BA
F
)
wi h CO
2
did no show any no iceable changes, i.e.
inse ion o CO
2
in o he I -H bond o yield a o ma o complex
was no obse ed. The e o e, in o de o de e mine whe he
species
5(Bca
2
)
and
6(BA
F
)
pa icipa e in he educ ion o CO
2
wi h bo anes, complexes
1(Bca
2
)
and
1(BA
F
)
we e employed
as p e-ca alys in lieu o
2a
/
2b
in he hyd obo a ion o CO
2
wi h HBca and HBpin, espec i ely. Unde he eac ion
condi ions o Table 1, en y 5,
1(Bca
2
)
p o ided a signi ican ly
lowe TOF o 6.8 h
-1
(89% con . a e 13 h). Simila ly, complex
1(BA
F
)
was also ound a poo e ca alys p ecu so han
2a
/
2b
in he educ ion o CO
2
since negligible o ma ion o
o moxypinacolbo ane was obse ed (<5% con . a e 21 h).
O e all, hese esul s suppo ha
5(Bca
2
)
and
6(BA
F
)
a e no
signi ican ly in ol ed in he hyd obo a ion o CO
2
using
2a
/
2b
as ca aly ic p ecu so s. Ma de , Bake e al. ha e simila ly
obse ed ha while [I (Cl)(COE)
2
]
2
/PPh
3
mix u es p omo e
HBca deg ada ion and a e ac i e in alkene hyd obo a ions,
isola ed i idium bo yl compounds gene a ed om he eac ion
o his ca aly ic sys em and hyd obo anes p oduce inne ec i e
ca alys s.
24
Simila ly, o hiola e Ni and Pd pince complexes,
which a e e y ac i e ca aly ic p ecu so s in he hyd obo a ion
o CO
2
o CH
3
OBca , i has been shown ha he co esponding
hyd ide species a e p obably no in ol ed in he ca aly ic
p ocess.
12,13
As p e iously epo ed, ca aly ic hyd obo a ion o CO
2
wi h
HBpin can p oceed o he me hoxide le el (CH
3
OBpin),
4
al hough wi h a p ope choice o he ca alys pa ially educed
p oduc s including he co esponding o moxybo ane
de i a i e can be ob ained.
14-20
Guan e al. ha e
compu a ionally s udied he educ ion o CO
2
wi h HBca o
CH
3
OBca media ed by a pince nickel hyd ide complex.
9b
The
delinea ed mechanism is composed o h ee successi e cycles.
The i s cycle in ol es CO
2
inse ion in o he Ni-H bond o
yield a Ni- o ma e in e media e ha upon in e ac ion wi h
HBpin yields HCO
2
Bca . The subsequen educ ion o
o moxybo ane implies he inse ion in o a Ni-H bond o
p oduce o maldehyde, which is inally educed o CH
3
OBca
by a hi d molecule o HBca . Analogous s eps ha e also been
p oposed o he hyd obo a ion o CO
2
wi h HBpin ca alyzed
by a Ru complex.
38
Based on he mechanism p oposed by he
Guan g oup, Haza i e al. ha e assumed ha he high
selec i i y p o ided by a pince Pd complex in he
hyd obo a ion o CO
2
wi h HBpin o he o ma e le el is
de e mined by he la ge size o he pinacol agmen ha
p e en s u he educ ion o HCO
2
Bpin.
15
Fu he mo e,
selec i e educ ion o CO
2
o o moxybo ane wi h HBpin has
only been achie ed wi h me al based ca alys s.
14-17
The e o e,
since a highly selec i e CO
2
hyd obo a ion wi h HBpin o
o moxybo ane akes place using
2a
/
2b
, i can be expec ed
ha me al species should be in ol ed in he ca aly ic
eac ions. Fu he mo e, conside ing he deg ada ion o he
hyd obo anes as well as he obse ed in luence o wa e , i
can be p oposed ha he ca aly ically ac i e species a e
i idium de i a i es o med by eac ion o
2a
/
2b
wi h he
hyd obo anes and wa e . Howe e , since in addi ion o
us a ed Lewis pai s con aining bo on-based moie ies
capable o ca alyzing he hyd obo a ion o CO
2
,
8a,8b,8g
o he
bo on species ha e been shown o ca alyze hyd obo a ion
eac ions, as epo ed o he ca aly ic addi ion o
hyd obo anes o alkenes and alkynes,
39
educ ion o CO
2
media ed by bo on species de i ed om hyd obo ane
deg ada ion p omo ed by
2a
/
2b
, o hei pa icipa ion in
accele a ing an I -ca alyzed eac ion,
40
canno be ully uled
ou .
Conclusions
The i idium complexes suppo ed by dep o ona ed lu idine-
de i ed CNP* pince s
2a
/
2b
ca alyze he hyd obo a ion o CO
2
.
A ma ked in luence o he hyd obo ane is obse ed in he
selec i i y and a e o he eac ions. Mo e in e es ingly,

ARTICLE Jou nal Name
6 | J. Name., 2012, 00, 1-3 This jou nal is © The Royal Socie y o Chemis y 20xx
Please do no adjus ma gins
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signi ican eac ion a e accele a ions ha e been obse ed
a e op imiza ion o he wa e con en o he eac ions,
sugges ing ha wa e is in ol ed in he o ma ion o he
ca aly ically ac i e species. Thus, upon using HBca selec i e
educ ion o CO
2
o he me hanol equi alen is obse ed (TOF
up o 58 h
-1
), whe eas he mos s e ically demanding HBpin
yields he co esponding o moxybo ane as he sole p oduc
wi h no able ca aly ic ac i i ies (TOF up o 1245 h
-1
).
Unde ca aly ic condi ions, i idium species esul ing om
he oxida i e addi ion o he hyd obo ane o ligand-
p o ona ed [I (CNP)(CO)][B(R
2
)
2
] (R
2
= ca echol, pinacol)
complexes has been obse ed. Howe e , con ol expe imen s
indica e ha hese species a e ine icien ca alys s in he
hyd obo a ion o CO
2
. Taking in o accoun he obse ed wa e
e ec , he hyd obo ane deg ada ion leading o he o ma ion
o [B(R
2
)
2
]
-
anions, and he di e en selec i i y obse ed in he
educ ion o CO
2
wi h HBca and HBpin, we eel inclined o
conside ha he hyd obo a ion eac ions a e ca alyzed by I -
con aining species o med a e eac ion o
2a
/
2b
wi h he
hyd obo ane in he p esence o wa e . Un o una ely, we ha e
been unable o de ec such as species by NMR spec oscopy o
MS, sugges ing ha hey a e o med in low concen a ions.
Expe imen al
Gene al p ocedu es
All eac ions and manipula ions we e pe o med unde ni ogen o
a gon, ei he in a B aun Labmas e 100 glo ebox o using s anda d
Schlenk- ype echniques. All sol en s we e dis illed unde ni ogen
wi h he ollowing desiccan s: sodium-benzophenone-ke yl o
die hyl e he (E 2O) and e ahyd o u an (THF); sodium o pen ane
and oluene; CaH2 o dichlo ome hane and ace oni ile (CH2Cl2,
CH3CN); and NaOMe o me hanol (MeOH). Fo he p epa a ion o
we THF-d8 solu ions, comme cial THF-d8 (Eu iso op, <0.05% wa e )
was d ied wi h sodium-benzophenone-ke yl and dis illed unde
a gon, and known amoun s o wa e we e added. Wa e con en in
he hus p epa ed solu ions was con i med by 1H NMR spec oscopy
using hexame hylbenzene as in e nal s anda d. Complex 1(Cl),25
Li[Bca 2]35 and Na[BA F]41 we e syn he ized ollowing p e iously
epo ed me hods. All o he eagen s we e pu chased om
comme cial supplie s and used as ecei ed. NMR spec a we e
ob ained on B uke DPX-300, DRX-400, AVANCEIII/ASCEND 400R o
DRX-500 spec ome e s. 31P{1H} and 11B NMR shi s we e
e e enced o ex e nal 85% H3PO4 and BF3E 2O espec i ely, while
13C{1H} and 1H shi s we e e e enced o he esidual signals o
deu e a ed sol en s. All da a a e epo ed in ppm down ield om
Me4Si. All NMR measu emen s we e ca ied ou a 25 °C, unless
o he wise s a ed. NMR signal assigna ions we e con i med by 2D
NMR spec oscopy (1H-1H COSY, 1H-1H NOESY, 1H-13C HSQC and 1H-
13C HMBC) and 1H{31P} and 1H{11B} NMR expe imen s. HRMS da a
we e ob ained on a JEOL JMS-SX 102A mass spec ome e a he
Ins umen al Se ices o Uni e sidad de Se illa (CITIUS). ESI-MS
expe imen s we e ca ied ou in a B uke 6000 appa a us by he
Mass Spec ome y Se ice o he Ins i u o de In es igaciones
Químicas. Elemen al analyses we e un by he Analy ical Se ice o
he Ins i u o de In es igaciones Químicas in a Leco T ueSpec CHN
elemen al analyze . IR spec a we e acqui ed on a B uke Tenso 27
ins umen .
Syn hesis o complexes
Complexes 2a/2b. To a solu ion o 1(Cl) (0.075 g, 0.10 mmol) in
THF (5 mL) was added a solu ion o KO Bu (0.013 g, 0.11 mmol) in
THF (5 mL) gi ing ise o a ed solu ion. The esul ing solu ion was
s i ed o 2 h, and sol en was e apo a ed unde educed p essu e.
The esidue was ex ac ed wi h oluene (2  10 mL), and ola iles
we e emo ed unde acuum. The solid ob ained was washed wi h
pen ane (2  10 mL) and d ied unde acuum o gi e he mix u e o
complexes 2a and 2b as a ed solid (0.050 g, 70%). C ys als o 2a
sui able o X- ay di ac ion analysis we e g own om a sa u a ed
solu ion o he complexes 2a/2b in THF. Anal. calcd (%) o
C32H29I N3OP: C 55.32, H 4.21, N 6.05; ound: C 55.10, H 4.56, N
6.09. IR (nujol): 1938 (CO) cm-1.
NMR spec oscopy da a o 2a: 1H NMR (500 MHz, THF-d8):

7.57
(m, 4H, 4 H a om PPh), 7.41 (s, 1H, H a om NHC), 7.20 (m, 6H, 6 H
a om PPh), 7.09 (s, 1H, H a om NHC), 6.92 (s, 2H, 2 H a om Mes),
6.30 (m, 2H, Hb + Hc), 5.37 (dd, 3JHH = 3.7 Hz, 3JHH = 3.7 Hz, 1H, Hd),
4.72 (s, 2H, CH2N), 3.84 (d, 2JHP = 1.9 Hz, 1H, Ha), 2.28 (s, 3H, CH3),
2.09 (s, 6H, 2 CH3). 31P{1H} NMR (202 MHz, THF-d8):

28.3. 13C{1H}
NMR (125 MHz, THF-d8):

182.8 (d, JCP = 92 Hz, C-2 NHC), 182.0 (d,
JCP = 10 Hz, CO), 156.3 (d, JCP = 24 Hz, Cq a om), 150.8 (d, JCP = 1 Hz,
Cq a om), 140.6 (d, JCP = 58 Hz, 2 Cq a om), 139.6 (Cq a om), 137.5
(Cq a om), 136.9 (2 Cq a om), 132.9 (d, JCP = 11 Hz, 4 CH a om),
131.9 (d, JCP = 2 Hz, Cc), 129.4 (2 CH a om), 129.3 (d, JCP = 2 Hz, 2 CH
a om), 128.3 (d, JCP = 10 Hz, 4 CH a om), 121.8 (d, JCP = 3 Hz, CH
a om), 121.1 (d, JCP = 3 Hz, CH a om), 117.8 (d, JCP = 19 Hz, Cb), 101.7
(Cd), 69.1 (d, JCP = 69 Hz, Ca), 57.3 (CH2N), 21.2 (CH3), 18.6 (2 CH3).
NMR spec oscopy da a o 2b: 1H NMR (500 MHz, THF-d8):

7.64
(m, 4H, 4 H a om PPh), 7.49 (s, 1H, H a om NHC), 7.32 (m, 6H, 6 H
a om PPh), 7.06 (s, 1H, H a om NHC), 6.91 (s, 2H, 2 H a om Mes),
6.17 (s, 1H, He), 6.17 (d, 3JHH = 8.7 Hz, 3JHH = 6.3 Hz, 1H, Hc), 6.05 (d,
3JHH = 8.9 Hz, 1H, Hd), 5.53 (d, 3JHH = 6.1 Hz, 1H, Hb), 3.51 (d, 2JHP =
11.4 Hz, 1H, CH2P), 2.25 (s, 3H, CH3), 2.12 (s, 6H, 2 CH3). 31P{1H}
NMR (202 MHz, THF-d8):

33.3.
Complex 1(Bca 2). A solu ion o 1(Cl) (0.100 g, 0.14 mmol) and
Li[Bca 2] (0.035 g, 0.15 mmol) in MeCN (8 mL) was s i ed o 1 h.
The esul ing suspension was il e ed, and sol en was emo ed
unde educed p essu e. The esidue was ex ac ed wi h CH2Cl2 (2 
10 mL), and he solu ion was b ough o d yness. The esul ing solid
was washed wi h pen ane (2  8 mL) and d ied unde acuum.
Complex 1(Bca 2) was ob ained as an o ange solid (0.073 g, 58%). IR
(nujol): 1973 cm-1 (CO). 1H NMR (500 MHz, CD2Cl2):

7.79 (dd, 3JHH
= 7.7 Hz, 3JHH = 7.7 Hz, 1H, H a om Py), 7.65 (d, 3JHH = 7.7 Hz, 1H, H
a om Py), 7.59 (m, 6H, 6 H a om), 7.52 (m, 2H, 2 H a om), 7.44 (m,
4H, 4 H a om), 7.04 (s, 2H, 2 H a om Mes), 7.01 (s, 1H, H a om NHC),
6.55 (m, 8H, Bca 2), 5.42 (s, 2H, CH2N), 4.09 (d, 2JHP = 10.1 Hz, 2H,
Jou nal Name ARTICLE
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CH2P), 2.36 (s, 3H, CH3), 2.13 (s, 6H, 2 CH3). 31P{1H} NMR (202 MHz,
CD2Cl2):

45.4. 11B{1H} NMR (96 MHz, CD2Cl2):

14.4. 13C{1H} NMR
(125 MHz, CD2Cl2):

178.6 (d, JCP = 98 Hz, C-2 NHC), 177.1 (d, JCP = 9
Hz, CO), 165.0 (d, JCP = 7 Hz, Cq a om), 155.3 (Cq a om), 152.3 (4 Cq
a om Bca 2), 141.5 (CH a om), 140.3 (Cq a om), 136.3 (2 Cq a om),
135.6 (Cq a om), 133.2 (d, JCP = 12 Hz, 4 CH a om), 132.0 (2 CH
a om), 130.2 (d, JCP = 54 Hz, 2 Cq a om), 129.5 (d, JCP = 11 Hz, 4 CH
a om), 129.3 (2 CH a om), 124.7 (d, JCP = 10 Hz, CH a om), 124.6
(CH a om), 122.8 (CH a om), 122.5 (CH a om), 118.2 (4 CH a om
Bca 2), 108.7 (4 CH a om Bca 2), 55.5 (CH2N), 42.6 (d, JCP = 31 Hz,
CH2P), 21.3 (CH3), 18.5 (2 CH3). HRMS (ESI): m/z 696.1743
[(MBca 2)+] (exac mass calcula ed o C32H30I N3OP: 696.1750).
Complex 1(BA F). A solu ion o 1(Cl) (0.096 g, 0.13 mmol) and
Na[BA F] (0.116 g, 0.13 mmol) in CH2Cl2 (7 mL) was s i ed o 2 h.
The esul ing suspension was il e ed, and sol en was emo ed
unde educed p essu e. The esul ing solid was washed wi h
pen ane (2  10 mL) and d ied unde acuum. Complex 1(BA F) was
isola ed as an o ange solid (0.186 g, 91%). Anal. calcd (%) o
C64H42BF24I N3OP: C 49.31; H 2.72; N 2.70; ound: C 49.20; H 2.92; N
2.78. IR (nujol): 1979 (CO) cm-1. 1H NMR (500 MHz, CD2Cl2):

7.95
(dd, 3JHH = 7.7 Hz, 3JHH = 7.7 Hz, 1H, H a om Py), 7.76 (s, 8H, 8 H a om
BA F), 7.72 (d, 3JHH = 7.8 Hz, 1H, H a om Py), 7.63 (m, 4H, 4 H a om),
7.59 (s, 4H, 4 H a om BA F), 7.51 (m, 7H, 7 H a om), 7.44 (dd, 3JHH =
1.8 Hz, 5JHP = 0.8 Hz, 1H, H a om NHC), 7.17 (d, 3JHH = 1.8 Hz, 1H, H
a om NHC), 7.09 (s, 2H, 2 H a om Mes), 5.39 (s, 2H, CH2N), 4.14 (d,
2JHP = 10.1 Hz, 2H, CH2P), 2.40 (s, 3H, CH3), 2.16 (s, 6H, 2 CH3).
31P{1H} NMR (202 MHz, CD2Cl2):

45.6. 11B{1H} NMR (96 MHz,
CD2Cl2):

6.6. 13C{1H} NMR (125 MHz, CD2Cl2):

179.3 (d, JCP = 99
Hz, C-2 NHC), 176.4 (d, JCP = 10 Hz, CO), 165.9 (d, JCP = 7 Hz, Cq
a om), 162.2 (q, JCB = 50 Hz, 4 BCq a om BA F), 154.9 (Cq a om),
141.5 (CH a om), 140.8 (Cq a om), 136.1 (2 Cq a om), 135.2 (m, 8 CH
a om BA F), 133.2 (d, JCP = 12 Hz, 4 CH a om), 132.3 (2 CH a om),
129.6 (o e lapped, 2 Cq a om), 129.6 (d, JCP = 11 Hz, 4 CH a om),
129.5 (2 CH a om), 129.3 (q, JCF = 32 Hz, 8 Cq a om BA F), 125.0 (q,
JCF = 272 Hz, 8 CF3), 124.9 (d, JCP = 10 Hz, CH a om), 123.9 (CH
a om), 123.3 (CH a om), 121.8 (CH a om), 117.9 (m, 4 CH a om
BA F), 56.3 (CH2N), 43.1 (d, JCP = 31 Hz, CH2P), 21.3 (CH3), 18.5 (2
CH3); signal o one qua e na y a oma ic ca bon could no be
iden i ied.
Complex 3(Cl). In a J.Young- al ed NMR ube, a solu ion o 1(Cl)
(0.050 g, 0.07 mmol) in CD2Cl2 (0.5 mL) was cha ged wi h 1 ba o
H2. The esul ing solu ion was immedia ely analyzed by NMR
spec oscopy indica ing comple e o ma ion o 3(Cl). Complex 3(Cl)
loses hyd ogen upon exposu e o acuum. IR (CD2Cl2): 2338 (I H),
2085 (I H), 1987 (CO) cm-1. 1H NMR (500 MHz, CD2Cl2):

8.45 (s,
1H, H a om NHC), 8.29 (d, 3JHH = 6.4 Hz, 1H, H a om Py), 7.99 (dd,
3JHH = 7.3 Hz, 3JHH = 6.6 Hz, 1H, H a om Py), 7.82 (d, 3JHH = 6.4 Hz, 1H,
H a om Py), 7.60 (dd, 3JHP = 12.8 Hz, 3JHH = 7.7 Hz, 2H, 2 H a om PPh),
7.51 (dd, 3JHH = 7.6 Hz, JHP = 6.3 Hz, 1H, H a om PPh), 7.40 (m, 5H, 5
H a om PPh), 7.27 (m, 2H, 2 H a om PPh), 7.12 (d, 2JHH = 15.4 Hz, 1H,
CHHN), 7.07 (s, 1H, H a om NHC), 7.05 (s, 2H, 2 H a om Xyl), 4.89 (d,
2JHH = 15.3 Hz, 1H, CHHN), 4.82 (dd, 2JHH = 17.1 Hz, 2JHP = 12.5 Hz,
1H, CHHP), 3.63 (dd, 2JHH = 17.1 Hz, 2JHP = 10.2 Hz, 1H, CHHP), 2.42
(s, 3H, CH3), 2.01 (s, 3H, CH3), 1.86 (s, 3H, CH3), 8.32 (ddd, 2JHP =
22.2 Hz, 2JHH = 1.6 Hz, 4JHH = 1.6 Hz, 1H, I H cis o Py), 17.45 (dd,
2JHP = 11.7 Hz, 2JHH = 1.6 Hz, 1H, I H ans o Py). 31P{1H} NMR (202
MHz, CD2Cl2):

16.9. 13C{1H} NMR (125 MHz, CD2Cl2):

175.0 (CO),
163.4 (d, JCP = 3 Hz, Cq a om), 156.9 (d, JCP = 100 Hz, C-2 NHC), 155.8
(Cq a om), 140.3 (CH a om), 139.6 (Cq a om), 136.8 (Cq a om), 135.7
(Cq a om), 135.5 (Cq a om), 134.9 (d, JCP = 12 Hz, 2 CH a om), 134.4
(d, JCP = 49 Hz, Cq a om), 132.3 (d, JCP = 2 Hz, CH a om), 131.3 (d, JCP
= 2 Hz, CH a om), 130.4 (d, JCP = 11 Hz, 2 CH a om), 130.1 (d, JCP = 63
Hz, Cq a om), 129.5 (d, JCP = 10 Hz, 2 CH a om), 129.4 (CH a om),
129.2 (CH a om), 129.1 (d, JCP = 12 Hz, 2 CH a om), 125.7 (CH a om),
124.1 (d, JCP = 3 Hz, CH a om), 123.4 (d, JCP = 10 Hz, CH a om), 121.8
(d, JCP = 3 Hz, CH a om), 58.1 (CH2N), 46.1 (d, JCP = 37 Hz, CH2P), 21.3
(CH3), 18.4 (CH3), 18.2 (CH3). MS (ESI, CH2Cl2/MeCN): m/z (%): 698
(100) [(MCl)+].
Complex 4. In a J.Young- al ed NMR ube, a solu ion o 2a/2b
(0.010 g, 0.014 mmol) in THF-d8 (0.5 mL) was cha ged wi h 5 ba o
H2. The esul ing solu ion was immedia ely analyzed by NMR
spec oscopy showing comple e o ma ion o 4. Complex 4 eadily
loses hyd ogen upon emo al o he H2 a mosphe e.
1
H NMR (500 MHz, THF-d
8
):

7.58 (m, 3H, 3 H a om), 7.41 (dd,
J
HP
= 10.1 Hz,
3
J
HH
= 7.6 Hz, 2H, 2 H a om), 7.19 (m, 7H, 7 H
a om), 7.06 (m, 2H, 2 H a om), 6.56 (dd,
3
J
HH
= 8.8 Hz,
3
J
HH
= 6.2
Hz, 1H, H
c
), 6.43 (d,
3
J
HH
= 8.8 Hz, 1H, H
b
), 5.71 (d,
3
J
HH
= 6.2 Hz,
1H, H
d
), 5.01 (d,
2
J
HH
= 14.1 Hz, 1H, CHHN), 4.70 (d,
2
J
HH
= 14.3
Hz, 1H, CHHN), 3.93 (d,
2
J
HP
= 2.7 Hz, 1H, H
a
), 2.43 (s, 3H, CH
3
),
2.03 (s, 3H, CH
3
), 1.95 (s, 3H, CH
3
), 8.64 (dd,
2
J
HP
= 20.8 Hz,
2
J
HH
= 1.5 Hz, 1H, I H), 16.59 (dd,
2
J
HP
= 11.3 Hz,
2
J
HH
= 1.6 Hz,
1H, I H).
31
P{
1
H} NMR (202 MHz, THF-d
8
):

8.8.
13
C{
1
H} NMR
(125 MHz, THF-d
8
):

176.5 (b m, CO), 174.7 (d, J
CP
= 19 Hz, C
q
a om), 162.7 (d, J
CP
= 92 Hz, C-2 NHC), 150.3 (C
q
a om), 145.0
(d, J
CP
= 50 Hz, C
q
a om), 140.7 (d, J
CP
= 71 Hz, C
q
a om), 139.2
(C
q
a om), 138.4 (C
q
a om), 136.7 (C
q
a om), 136.0 (C
q
a om),
134.7 (d, J
CP
= 11 Hz, 2 CH a om), 132.0 (d, J
CP
= 2 Hz, C
c
), 131.4
(d, J
CP
= 12 Hz, 2 CH a om), 129.5 (CH a om), 129.3 (CH a om),
129.0 (CH a om), 128.6 (CH a om), 128.0 (d, J
CP
= 10 Hz, 2 CH
a om), 127.8 (d, J
CP
= 11 Hz, 2 CH a om), 122.0 (CH a om),
121.8 (d, J
CP
= 3 Hz, CH a om), 115.3 (d, J
CP
= 18 Hz, C
b
), 102.0
(C
d
), 66.6 (d, J
CP
= 78 Hz, C
a
), 60.3 (CH
2
N), 21.2 (CH
3
), 18.7
(CH
3
), 18.4 (CH
3
).
Complex 5(Bca
2
).
In a J.Young- al ed NMR ube, a
solu ion o
1(Bca
2
)
(0.035 g, 0.04 mmol) in THF-d
8
(0.5 mL)
was ea ed wi h HBca (5.0

L, 0.05 mmol). Comple e
con e sion o
1(Bca
2
)
o
5(Bca
2
)
was de e mined by NMR
spec oscopy. IR (CH
2
Cl
2
): 2101 (

I H
), 2005 (

CO
) cm
-1
.
1
H NMR
(500 MHz, THF-d
8
):

7.91 (d,
3
J
HH
= 1.1 Hz, 1H, H
a om NHC),
7.86 (d,
3
J
HH
= 7.9 Hz, 1H, H
a om Py), 7.82 (dd,
3
J
HH
= 7.8 Hz,
3
J
HH
= 7.8 Hz, 1H, H
a om Py), 7.74 (d,
3
J
HH
= 7.4 Hz, 1H, H
a om
Py), 7.48 (m, 4H, 4 H a om), 7.36 (m, 4H, 4 H a om), 7.24 (m,
2H, 2 H
a om), 7.11 (b , H a om HBca ), 7.05 (d,
3
J
HH
= 1.1 Hz,
1H, H
a om NHC), 6.97 (b , H a om HBca ), 6.82 (s, 1H, H a om
Mes), 6.76 (m, 2H, 2 H a om I Bca ), 6.70 (m, 2H, 2 H a om
ARTICLE Jou nal Name
8 | J. Name., 2012, 00, 1-3 This jou nal is © The Royal Socie y o Chemis y 20xx
Please do no adjus ma gins
Please do no adjus ma gins
I Bca ), 6.39 (b m, 8H, 8 H a om Bca
2
), 6.00 (d,
2
J
HH
= 15.7 Hz,
1H, NCHH), 5.97 (s, 1H, H a om Mes), 5.01 (dd,
2
J
HH
= 17.3 Hz,
2
J
HP
= 12.5 Hz, 1H, PCHH), 5.00 (d,
2
J
HH
= 15.7 Hz, 1H, NCHH),
4.37 (q,
1
J
HB
= 190 Hz, HBca ), 3.98 (dd,
2
J
HH
= 17.1 Hz,
2
J
HP
=
10.2 Hz, 1H, PCHH), 2.01 (s, 3H, CH
3
), 1.86 (s, 3H, CH
3
), 1.81 (s,
3H, CH
3
), 6.90 (d,
2
J
HP
= 21.1 Hz, 1H, I H).
31
P{
1
H} NMR (202
MHz, THF-d
8
):

15.7.
11
B NMR (96 MHz, THF-d
8
):

22.5 (d, J
BH
= 189 Hz, HBca ), 15.1 (b , Bca
2
), 12.9 (I Bca ).
13
C{
1
H} NMR
(101 MHz, THF-d
8
):

176.8 (b , CO), 162.0 (C
q
a om), 155.1 (C
q
a om), 154.3 (d, J
CP
= 96 Hz, C-2 NHC), 153.3 (4 C
q
a om Bca
2
),
151.0 (2 C
q
a om I Bca ), 149.5 (2 C
q
a om HBca ), 141.3 (CH
a om), 140.1 (C
q
a om), 136.2 (C
q
a om), 135.8 (C
q
a om),
135.2 (C
q
a om), 133.7 (d, J
CP
= 11 Hz, 2 CH a om), 132.4 (d, J
CP
= 11 Hz, 2 CH a om), 132.2 (CH a om), 131.9 (CH a om), 131.8
(d, J
CP
= 50 Hz, C
q
a om), 130.0 (d, J
CP
= 11 Hz, 2 CH a om),
129.9 (CH a om), 129.4 (CH a om), 129.2 (d, J
CP
= 62 Hz, C
q
a om), 129.1 (d, J
CP
= 12 Hz, 2 CH a om), 125.0 (CH a om),
124.9 (CH a om), 124.7 (d, J
CP
= 10 Hz, CH a om), 123.9 (CH
a om), 122.6 (b , 2 CH a om HBca ), 121.4 (2 CH a om I Bca ),
118.0 (4 CH a om Bca
2
), 112.4 (b , 2 CH a om HBca ), 111.3 (2
CH a om I Bca ), 108.7 (4 CH a om Bca
2
), 59.1 (CH
2
N), 46.1 (d,
J
CP
= 39 Hz, CH
2
P), 21.3 (CH
3
), 18.6 (CH
3
), 17.6 (CH
3
).
Complex 6(BA
F
).
In a J.Young- al ed NMR ube, a solu ion
o
1(BA
F
)
(0.023 g, 0.015 mmol) in THF-d
8
(0.5 mL) was
ea ed wi h pinBH (5.3

L, 0.036 mmol). Comple e con e sion
o
1(BA
F
)
o
6(BA
F
)
was de e mined by NMR spec oscopy. IR
(CH
2
Cl
2
): 2089 (

I H
), 1993 (

CO
) cm
-1
.
1
H NMR (400 MHz, THF-
d
8
):

8.03 (dd,
3
J
HH
= 7.7 Hz,
3
J
HH
= 7.7 Hz, 1H, H
a om Py), 7.79
(s, 8H, 8 H a om BA
F
), 7.73 (m, 2H, 2 H a om), 7.68 (d,
3
J
HH
=
7.7 Hz, 1H, H
a om Py), 7.61 (m, 2H, 2 H a om), 7.57 (s, 4H, 4 H
a om BA
F
), 7.45 (m, 8H, 8 H
a om), 7.25 (s, 1H, H a om), 7.06
(s, 1H, H a om), 7.01 (s, 1H, H a om), 5.79 (d,
2
J
HH
= 15.8 Hz,
1H, NCHH), 5.19 (d,
2
J
HH
= 15.8 Hz, 1H, NCHH), 4.86 (dd,
2
J
HH
=
16.9 Hz,
2
J
HP
= 12.5 Hz, 1H, PCHH), 3.83 (dd,
2
J
HH
= 17.1 Hz,
2
J
HP
= 10.4 Hz, 1H, PCHH), 3.75 (q,
1
J
HB
= 172 Hz, HBpin), 2.33 (s, 3H,
CH
3
), 2.12 (s, 3H, CH
3
), 2.05 (s, 3H, CH
3
), 1.22 (s, 4 CH
3
HBpin),
0.74 (s, 6H, 2 CH
3
I Bpin), 0.71 (s, 6H, 2 CH
3
I Bpin), 6.81 (d,
2
J
HP
= 22.1 Hz, 1H, I H).
31
P{
1
H} NMR (162 MHz, THF-d
8
):

18.1.
11
B NMR (128 MHz, THF-d
8
):

30.1 (d, J
BH
= 173 Hz, HBpin),
23.2 (b , I Bpin), 4.6 ppm (BA
F
).
13
C{
1
H} NMR (101 MHz, THF-
d
8
):

178.0 (b , CO), 162.6 (q, J
CB
= 50 Hz, 4 BC
q
a om BA
F
),
162.4 (C
q
a om), 156.8 (d, J
CP
= 102 Hz, C-2 NHC), 155.6 (C
q
a om), 140.8 (CH a om), 139.8 (C
q
a om), 137.2 (C
q
a om),
135.9 (C
q
a om), 135.4 (m, 8 CH a om BA
F
), 133.8 (d, J
CP
= 11
Hz, 2 CH a om), 132.1 (m, 2 CH a om), 132.0 (CH a om), 131.8
(CH a om), 129.8 (m, 4 CH a om + 8 C
q
a om BA
F
), 128.8 (d, J
CP
= 11 Hz, 2 CH a om), 125.2 (q, J
CF
= 272 Hz, 8 CF
3
), 125.0 (CH
a om), 123.6 (CH a om), 123.4 (CH a om), 123.3 (CH a om),
118.0 (m, 4 CH a om BA
F
), 83.6 (2 C
q
HBpin), 82.8 (2 C
q
I Bpin),
59.7 (CH
2
N), 47.3 (d, J
CP
= 37 Hz, CH
2
P), 25.0 (4 CH
3
HBpin),
24.9 (o e lapped wi h sol en signal, 2 CH
3
I Bpin), 24.2 (2 CH
3
I Bpin), 20.9 (CH
3
), 18.9 (CH
3
), 18.8 (CH
3
); signals o h ee
qua e na y a oma ic ca bons could no be de ec ed due o
signi ican spec um complexi y.
Rep esen a i e p ocedu e o CO
2
hyd obo a ion wi h HBca
In a glo ebox, a J.Young- al ed NMR ube was cha ged wi h a
solu ion o
2a
/
2b
(1.6 mg, 2.3

mol) and hexame hylbenzene
(3.8 mg, 0.023 mmol) in THF-d
8
con aining 0.2% o wa e (0.5
mL) ( o al wa e con en : 5 mol%), and ca echolbo ane (25

L,
0.23 mmol) was added. The NMR ube was submi ed o
acuum o emo e he N
2
a mosphe e, cha ged wi h CO
2
(2
ba ) and hea ed o 30
o
C. Reac ion p og ess was moni o ed by
1
H{
11
B} and
11
B NMR spec oscopies.
Rep esen a i e p ocedu e o CO
2
hyd obo a ion wi h HBpin
In a glo ebox, a J.Young- al ed NMR ube was cha ged wi h
300

L o a eshly p epa ed 1.3 mM s ock solu ion o
2a
/
2b
(0.4

mol) in THF-d
8
con aining 0.2% o wa e ,
hexame hylbenzene (3.8 mg, 0.023 mmol) and THF-d
8
(0.2 mL)
con aining 0.2% o wa e ( o al wa e con en : 5 mol%).
Pinacolbo ane (32

L, 0.22 mmol) was added, and he NMR
ube was submi ed o acuum o emo e he N
2
a mosphe e,
cha ged wi h CO
2
(1 ba ) and hea ed o 30
o
C. Reac ion
p og ess was moni o ed by
1
H{
11
B} and
11
B NMR
spec oscopies.
DFT calcula ions
DFT calcula ions we e ca ied ou wi h he Gaussian 09
p og am.
42
The hyb id unc ional B3LYP
43
was used, wi h
dispe sion e ec s aken in o accoun by adding he D3 e sion
o G imme’s empi ical dispe sion.
44
C, H, N, B, O and P a oms
we e ep esen ed by he 6-31g(d,p) basis se ,
45
whe eas I was
desc ibed using he S u ga /D esden E ec i e Co e Po en ial
and i s associa ed basis se SDD.
46
All geome y op imiza ions
we e pe o med wi hou es ic ions in THF (bulk sol en
e ec s modelled wi h he SMD con inuum model).
47
Con lic s o in e es
The e a e no con lic s o decla e.
Acknowledgemen s
Financial suppo (FEDER con ibu ion) om he Spanish
MINECO (CTQ2016-80814-R and CTQ2016-81797-REDC) is
g a e ully acknowledged. M.H.J. hanks SECITI-DF o a
pos doc o al ellowship and CONACyT Mexico o pos doc o al
unding (263719). The use o compu a ional acili ies o he
Supe compu ing Cen e o Galicia (CESGA) is g a e ully
acknowledged.
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