Supplementary Materials for
Catalytic transfer hydrogenation of N
2
to NH
3
via a photoredox
catalysis strategy
Christian M. Johansen, Emily A. Boyd, Jonas C. Peters
Corresponding author: Jonas C. Peters, jpeters@caltech.edu
Sci. Adv.
8
, eade3510 (2022)
DOI: 10.1126/sciadv.ade3510
This PDF file includes:
Sections S1 to S9
Figs. S1 to S24
Tables S1 to S11
References
S1 Ammonia production and quantification studies
The ammonia generation procedures are also described in the
Methods and Materials
section but are
redescribed with some additional detail here for the benefit of the reader
.
S1.1 Standard NH
3
Generation Reaction Procedure
All solvents are stirred with Na/K for ≥2 hours and filtered prior to use. In a nitrogen
-filled
glovebox, the precatalysts (
[Mo]Br
3
and/or [Ir]
BAr
F
4
) (2.3 μmol)
are weighed in individual vials.
* The
precatalysts
are then transferred quantitatively into a Schlenk tube using THF. The THF
is then
evaporated to provide a thin film of precatalyst at the bottom of the Schlenk tube. The tube is then
charged with a stir bar and the acid and
Hantzsch ester (HEH
2
) are added as solids. The tube is cooled to
77 K in a cold well.
The base ([Col])
is dissolved in 1 mL solvent.
To the cold tube is added
the 1 mL
solution of base and solvent
to produce a concentration of precatalyst of 2.3 mM. The temperature of the
system is allowed to equilibrate for 5 minutes and then the tube is sealed with a Teflon
screw- valve. This
tube is passed out of the box into a liquid N
2
bath and transported to a fume hood.
For experiments run at
-78 °C the tube is then transferred to a dry ice/
isopr opanol bath where it thaws and is allowed to stir
under
blue LED irradiation
at -78 °C for minimum
three hours
before warming
. For experiments run at 2
3
°C
the tube is
instead transferred to a water bath where it thaws and is allowed to stir for 1
2 hours. To ensu
re
reproducibility, all experiments were conducted in 200 mL Schlenk tubes (5
0 mm OD) using
10
mm
eggshaped-
stir bars and stirring was conducted at ~600 rpm.
Both the water bath and the
dry
ice/isopropanol bath w
ere contained in
highly reflective dewar
s. The Blue LED was placed above the bat
h
as close to the stirring reaction as possible.
* In cases where less than 2.3 μmol of precatalyst
were used, stock solution
s were used to avoid having to
weigh very small amounts.
S1.2 NH
3
Generation Reaction Procedure under Partial H
2
Atmosphere
Catalytic runs done under a mixture of H
2
and N
2
were conducted similarly to those under N
2
atmosphere, with a few differences descri
bed below. The loadings were the same as in
Figure 2, Entry 10.
Catalysis is performed in the same
Schlenk
tubes as under N
2
, which are charged with precatalyst,
HEH
2
, [ColH]OTf, and a stirbar in a nitrogen
-filled glovebox as described above. After additio
n of the
solids, the tube is wrapped in aluminum foil and the base (Col) is added in 1 mL of Na/K dried THF at
room temperature.
Half of the headspace volume is then removed
using a calibrated bulb
and then
backfilled with H
2
which has been passed through a liquid nitrogen trap.
The aluminum foil is removed
and the reaction
is allowed to stir under Blue LED irradiation for 12 hours.
Variation from the standard
procedure (addition of THF/Col at room temperature and allowing to
stir without irradiation for 30 min
before exposing to blue LED) were found to not perturb the yield of NH
3
.
Figure
S1.
Set-u p for catalysis
with Schl
enk tube, stir
plate, Kessil®
34 W 150 Blue lamp
and dewar.
Lamp is
turned off for clarity.
S1.3
NH
3
detection by
opt
ical
methods
Reaction
mixtures
are cooled to 77 K and allowed
to freeze. The reaction
vessel is then opened
t
o
atmospher
e and to the fr ozen soluti on is slowl y added
exces
s
of a solution o
f HCl (3 m
L
o f a 2 .0 M
so
lution in E
t
2
O,
6 mmol) over 1
-2 minutes.
This soluti on is allow ed to f
reeze,
then the headspace of the
tu
be is evacuated a
nd th e tu be is sealed.
Th
e tube is then allowed
to warm to RT and stirred at RT for at
least 10 m
in
utes. Solvent is removed
in v acuo
, and th e so lids are e xtracted w
ith 1 M H
Cl(aq) and filtered
to g ive a to tal solution
volum e
of 10 mL. A 5 mL aliquot is
ta
ken a
n
d w ashed re
peatedly w
ith n -butanol
to re move Hantzsch
p
yridine
(HE) and collidinium.
After n-butanol
washi ng additional
1 M H
Cl(aq)
is
added to give
a final total volum e of 5 m
L. From thes
e 5 mL solution
s, a 100 μL aliquot
is
analyzed
f
or
the p resence o
f NH
3
(present as [NH
4
][Cl]) by th
e in dophenol method. Quantification w
as performed w
ith
UV- vis spectros
copy by
anal
yzing
the absorbanc
e at
635 nm.(
46
) When specified
a further aliquot of this
solution w
as analyzed fo
r the p resence o
f N
2
H
4
(present as [N
2
H
5
][Cl]) by a sta
ndard c olorimetric
method .(
47
) Quantification
was performed
with UV-vis spectros
copy by
anal
yzing
the abs
or
bance at
458
nm
.
S1.4
NH
3
detection
by
1
H NMR
Reaction
mixtures
are cooled to 77 K and allowed
to freeze. The reaction
vessel is then opened
to
atmospher
e and to the fr ozen s
oluti on is slowl y added an
exces
s (wit h respect to acid) soluti on of a
Na
O
t
Bu solution in MeOH (0.25 mM) over 1
-2 minutes. This solution is allowed to freeze, then the
headspace of the tube is evacuated and the tube is sealed. The tube is then allowed to warm to RT and
stirred at RT for at least 10 minutes. An additional Schlenk tube is charged with HCl (3 mL of a 2.0 M
solution in Et
2
O, 6 mmol) to serve as a collection flask. The volatiles of the reaction mixture are vacuum
transferred at RT into this collection flask. After completion of the vacuum transfer, the collection flask
is
sealed and warmed to RT.
Solvent is removed in vacuo, and the remaining residue is dissolved in 0.7 mL
of DMSO
-
d
6
containing
20 mM
1,3,5- trimethoxybenzene as an internal standard. Integration of the
1
H
NMR peak observed for NH
4
+
is then integrated agai
nst the two peaks of trimethoxybenzene to quantify
the ammonium present. This
1
H NMR detection method was also used to differentiate [
14
NH
4
][Cl] and
[
15
NH
4
][Cl] produced in the control reactions conducted with
15
N
2
,
15
N- Col/[ColH]OTf,
or
15
N- HEH
2
.
S1.5
NH
3
detection results
S1.5 .1 Catalytic results in main text (
Figure 2
)
Table S1: Catalytic yields for photodriven transfer hydrogenation of N
2
to NH
3
.
Run
Conditions
[Mo]
load
(μmol)
acid
(μmol)
base
(μmol)
Ir
(μmol)
HEH
2
equiv
/Mo
NH
3
equiv
/Mo
N
2
H
4
equiv/
Mo
NH
3
yield/
HEH
2
(%)
Figure 2
, entry 1: Standard conditions
A1
THF,
23 °C
2.3
124.2
124.2
0
54
9.5
-
B1
THF,
23 °C
2.3
124.2
124.2
0
54
8.3
-
C1
THF,
23 °C
2.3
124.2
124.2
0
54
10.8
-
THF,
23 °C
2.3
124.2
124.2
0
54
9.5±1
26.5±3
Figure 2
, entry 2: 0.575 mM [Mo]Br
3
D1
THF,
23 °C
0.575
124.2
124.2
0
216
22.6
-
E1
THF,
23 °C
0.575
124.2
124.2
0
216
20.9
-
THF,
23 °C
0.575
124.2
124.2
0
216
21.8±0.8
15.1±06
Figure 2
, entry 3: No Mo
F1
THF,
23 °C
0
124.2
124.2
0
54
<0.1
<0.1
G1
THF,
23 °C
0
124.2
124.2
0
54
<0.1
<0.1
THF,
23 °C
2.3
124.2
124.2
0
54
<0.1
<0.1
<0.3
Figure 2
, entry 4: No light
H1
THF,
23 °C
no light
2.3
124.2
124.2
0
54
<0.1
<0.1
I1
THF,
23 °C
no light
2.3
124.2
124.2
0
54
<0.1
<0.1
THF,
23 °C
no light
2.3
124.2
124.2
0
54
<0.1
<0.1
<0.3
Figure 2
, entry 5: No buffer
J1
THF,
23 °C
2.3
0
0
0
54
0.74
-
K1
THF,
23 °C
2.3
0
0
0
54
1.11
-
THF,
23 °C
2.3
0
0
0
54
0.9±0.2
2.6±0.5
Figure 2
, entry 6: 5 equiv Col/[ColH]OTf
L1
THF,
23 °C
2.3
11.5
11.5
0
54
2.7
<0.1
M1
THF,
23 °C
2.3
11.5
11.5
0
54
3.2
<0.1
N1
THF,
23 °C
2.3
11.5
11.5
0
54
2.8
-
THF,
23 °C
2.3
11.5
11.5
0
54
2.9±0.2
<0.1
8.1±0.6
Figure 2
, entry 7: benzene instead of THF
O1
C
6
H
6
,
23 °C
2.3
124.2
124.2
0
54
4.8
-
P1
C
6
H
6
,
23 °C
2.3
124.2
124.2
0
54
4.6
-
C
6
H
6
,
23 °C
2.3
124.2
124.2
0
54
4.7±0.1
13±0.3
Run
Conditions
[Mo]
load
(μmol)
acid
(μmol)
base
(μmol)
Ir
(μmol)
HEH
2
equiv
/Mo
NH
3
equiv
/Mo
N
2
H
4
equiv
/Mo
NH
3
yield/
HEH
2
(%)
Figure 2
, entry 8: 216 equiv Col/[ColH]OTf
Q1
THF,
23 °C
2.3
496.8
496.8
0
54
19.5
-
R1
THF,
23 °C
2.3
496.8
496.8
0
54
21.1
-
THF,
23 °C
2.3
496.8
496.8
0
54
20.3±0.8
56±2
Figure 2
, entry 9: with 10 equiv TBABr
S1
THF,
23 °C
2.3
124.2
124.2
0
54
9
-
T1
THF,
23 °C
2.3
124.2
124.2
0
54
8.6
-
THF,
23 °C
2.3
124.2
124.2
0
54
8.8±0.3
23.6±0.8
Figure 2
, entry 10: Added
[Ir]BAr
F
4
U1
THF,
23 °C
2.3
124.2
124.2
2.3
54
29.8
-
V1
THF,
23 °C
2.3
124.2
124.2
2.3
54
20.6
-
W1
THF,
23 °C
2.3
124.2
124.2
2.3
54
20.5
-
X1
THF,
23 °C
2.3
124.2
124.2
2.3
54
25.4
-
THF,
23 °C
2.3
124.2
124.2
2.3
54
24±4
67±10
Figure 2
, entry 11: Added [Ir]BAr
F
4
, 5 equiv Col/[ColH]OTf
Y1
THF,
23 °C
2.3
11.5
11.5
2.3
54
16.02
<0.1
Z1
THF,
23 °C
2.3
11.5
11.5
2.3
54
16.6
<0.1
AA1
THF,
23 °C
2.3
11.5
11.5
2.3
54
14.7
THF,
23 °C
2.3
11.5
11.5
2.3
54
15.8±0.8
<0.1
44±2
Figure 2
, entry 12
: Added [Ir]BAr
F
4
, t = ½ h
AB1
THF,
23 °C
t = ½ h
2.3
124.2
124.2
2.3
54
19.5
-
AC1
THF,
23 °C
t = ½ h
2.3
124.2
124.2
2.3
54
17.7
-
THF,
23 °C
t = 1/2 h
2.3
124.2
124.2
2.3
54
18.6±0.9
52±3
~75 % completion compared to entry
10
Figure 2
, entry 1
3: t = 2 h
AD1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
0
54
4.9
-
AE1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
0
54
7.9
-
AF1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
0
54
10
-
THF,
23 °C
t = 2 h
2.3
124.2
124.2
0
54
7.6±2
21±6
~80 % completion compared to entry 1
Figure 2
, entry 1
4
: Added [Ir]BAr
F
4
, 5 equiv Col/[ColH]OTf, 0.575
mM [Mo]Br
3
AG1
THF,
23 °C
0.575
11.5
11.5
2.3
216
26.83
-
AH1
THF,
23 °C
0.575
11.5
11.5
2.3
216
25.96
-
THF,
23 °C
0.575
11.5
11.5
2.3
216
26±0.4
18.4±0.4
Figure 2
, entry 1
5: Added [Ir]BAr
F
4
, 5 equiv Col/[ColH]OTf, no light
AI1
THF,
23 °C
no light
2.3
11.5
11.5
2.3
54
<0.1
<0.1
AJ1
THF,
23 °C
no light
2.3
11.5
11.5
2.3
54
<0.1
<0.1
THF,
23 °C
no light
2.3
11.5
11.5
2.3
54
<0.1
<0.1
<0.3
Run
Conditions
[Mo]
load
(μmol)
acid
(μmol)
base
(μmol)
Ir
(μmol)
HEH
2
equiv
/Mo
NH
3
equiv
/Mo
N
2
H
4
equiv/
Mo
NH
3
yield/
HEH
2
(%)
Figure 2
, entry 1
6: Added [Ir]BAr
F
4
, 5 equiv Col/[ColH]OTf, no [Mo]Br
3
AK1
THF,
23 °C
0
11.5
11.5
2.3
54
<0.1
<0.1
AL1
THF,
23 °C
0
11.5
11.5
2.3
54
<0.1
<0.1
THF,
23 °C
0
11.5
11.5
2.3
54
<0.1
<0.1
<0.3
Figure 2
, entry 1
7: Added [Ir]BAr
F
4
, 5 equiv Col/[ColH]OTf, no HEH
2
AM1
THF,
23 °C
2.3
11.5
11.5
2.3
0
<0.1
<0.1
AN1
THF,
23 °C
2.3
11.5
11.5
2.3
0
<0.1
<0.1
THF,
23 °C
2.3
11.5
11.5
2.3
0
<0.1
<0.1
<0.3
Figure 2
, entry 1
8: Added [Ir]BAr
F
4
, subH
2
= 9,10-
dihydroacridine
AO1
THF,
23 °C
2.3
124.2
124.2
2.3
54
a
6.7
-
AP1
THF,
23 °C
2.3
124.2
124.2
2.3
54
a
6.1
-
THF,
23 °C
2.3
124.2
124.2
2.3
54
a
6.4±0.3
17.7±0.8
a
9,10
-
dihydroacridine used instead of HEH
2
Figure 2
, entry 1
9
: Added [Ir]BAr
F
4
, subH
2
= 5,6
-
dihydrophenanthridine
AQ1
THF,
23 °C
2.3
124.2
124.2
2.3
54
b
4.5
-
AR1
THF,
23 °C
2.3
124.2
124.2
2.3
54
b
5.1
-
THF,
23 °C
2.3
124.2
124.2
2.3
54
b
4.6±0.8
13±2
b
5,6
-
dihydrophenanthridine used instead of HEH
2
Figure 2
, entry
20: Added [Ir]BAr
F
4
, subH
2
= 1- benzyl
-1,4- dihydronicotinamide
AS1
THF,
23 °C
2.3
124.2
124.2
2.3
54
c
1.31
-
AT1
THF,
23 °C
2.3
124.2
124.2
2.3
54
c
1.12
-
THF,
23 °C
2.3
124.2
124.2
2.3
54
c
1.2±0.1
3.3±0.3
c
1
-
benzyl
-
1,4
-
dihydronicotinamide used instead of HEH
2
Figure 2
, entry 2
1: Added [Ir]BAr
F
4
, 0.5 atm H
2
, 0.5 atm N
2
AU1
THF,
23 °C
P
N2
= P
H2
= 0.5 atm
2.3
124.2
124.2
2.3
54
16.1
-
AV1
THF,
23 °C
P
N2
= P
H2
= 0.5 atm
2.3
124.2
124.2
2.3
54
11.0
-
THF,
23 °C
P
N2
= P
H2
= 0.5 atm
2.3
124.2
124.2
2.3
54
14±4
36±9
Figure 2
, entry 22: Added [Ir(dF(CF
3
)ppy)
2
(dtbbpy)]PF
6
, t = 2
h
A
W
1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
1.8
-
AX1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
2.6
-
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
2.2±0.6
6±1
Figure 2
, entry 23: Added [Ir]PF
6
, t = 2 h
AY1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
18.4
-
AZ1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
23.5
-
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
21±4
58±10
Figure 2
, entry 24: Added [Ir(
p
-F(Me)ppy)
2
(dtbbpy)]PF
6
, t = 2 h
BA1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
21.5
-
BB1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
23.1
-
THF,
23 °C
t = 2
h
2.3
124.2
124.2
2.3
54
22±1
62±3
Figure 2
, entry 2
5: Added Ir(ppy)
3
, t = 2 h
BC1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
7.8
-
BD1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
5.8
-
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
7±1
19±4
Figure 2
, entry 26
: Added [Ir]BAr
F
4
, no Col/[ColH]OTf
BE1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
7.03
-
BF1
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
7.83
-
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
7.4±0.4
20.7±1
S1.5 .2 Additional catalytic
experiments
Table S2 Canvassing H
2
carriers
Ru
n
subH
2
[Mo]Br
3
load
(μmol)
acid
(μmol)
base
(μmol)
Ir
(μmol)
subH
2
equiv
/Mo
NH
3
equiv
/Mo
N
2
H
4
equiv/Mo
NH
3
yield/
sub H
2
(%)
A2
BNAH
2.3
124.2
124.2
0
54
0.55
-
B2
BNAH
2.3
124.2
124.2
0
54
0.30
-
BNAH
2.3
124.2
124.2
0
54
0.4±0.1
1.2±0.3
C
2
Phenaz
H
2
2.3
124.2
124.2
2.3
54
<0.1
-
D2
Phenaz
H
2
2.3
124.2
124.2
2.3
54
<0.1
-
Phen
azH
2
2.3
124.2
124.2
2.3
54
<0.1
<0.1
E2
BTH
2
2.3
124.2
124.2
2.3
54
<0.1
-
F2
BTH
2
2.3
124.2
124.2
2.3
54
<0.1
-
BTH
2
2.3
124.2
124.2
2.3
54
<0.1
<0.1
G2
AcrH
2
2.3
124.2
124.2
0
54
0.09
-
H2
AcrH
2
2.3
124.2
124.2
0
54
0.24
-
AcrH
2
2.3
124.2
124.2
0
54
0.16±0.08
0.5±0.2
I2
PhenH
2
2.3
124.2
124.2
0
54
0.
216
-
J2
PhenH
2
2.3
124.2
124.2
0
54
0.
205
-
PhenH
2
2.3
124.2
124.2
0
54
0.
211
±0.0
0
8
0.
66
±0.
0
2
Table S3. Additional time course experiments
Run
Conditions
Mo
loading
(μmol)
acid
(μmol)
base
(μmol)
Ir
(μmol)
HEH
2
equiv
/Mo
NH
3
equiv
/Mo
N
2
H
4
equiv/Mo
NH
3
yield/
HEH
2
(%)
A3
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
24.5
-
B3
THF,
23 °C
t = 2 h
2.3
124.2
124.2
2.3
54
25.5
-
THF,
23 °C
t = 2 hours
2.3
124.2
124.2
2.3
54
25±0.5
69.4±1.5
Approximately 100% completion compared to
Figure 2
, entry
10
C3
THF, rt, 10
min
2.3
124.2
124.2
2.3
54
8.2
-
22.8
Approximately 30% completion compared to
Figure 2
, entry
10
Table S4 Catalysis using [ColH]OTf
or Col
instead of buffered solution
Run
Conditions
Mo
loading
(μmol)
acid
(μmol)
base
(μmol)
Ir
(μmol)
HEH
2
equiv
/Mo
NH
3
equiv
/Mo
N
2
H
4
equiv/Mo
NH
3
yield/
HEH
2
(%)
A4
THF, 23°C
2.3
496.8
0
0
54
5.8
-
B4
THF, 23°C
2.3
496.8
0
0
54
5.5
-
THF, 23°C
2.3
496.8
0
0
54
5.65±.15
15.7±0.4
C4
THF, 23°C
2.3
0
496.8
0
54
1.2
-
D4
THF, 23°C
2.3
0
496.8
0
54
2.0
-
THF, 23°C
2.3
0
496.8
0
54
1.6
±
0.4
4.7
±
1.1
Table S
5. Solvent screen
Run
Conditions
Mo
loading
(μmol)
acid
(μmol)
base
(μmol)
Ir
(μmol)
HEH
2
equiv
/Mo
NH
3
equiv
/Mo
N
2
H
4
equiv/Mo
NH
3
yield/
HEH
2
(%)
A5
THF,
-78
→23°C
2.3
11.5
11.5
2.3
54
15.47
-
B5
THF,
-78
→23°C
2.3
11.5
11.5
2.3
54
16.06
-
THF,
-78
→23°C
2.3
11.5
11.5
2.3
54
15.7±0.3
44.8±0.8
C5
Tol
,
23°C
2.3
11.5
11.5
2.3
54
7
-
D5
Tol,
23°C
2.3
11.5
11.5
2.3
54
7.3
-
Tol
23°C
2.3
11.5
11.5
2.3
54
7.15±0.15
19.8±0.8
E5
Tol, -78
→23°C
2.3
11.5
11.5
2.3
54
13.01
-
F5
Tol, -78
→23°C
2.3
11.5
11.5
2.3
54
14.24
-
Tol, -78
→23°C
2.3
11.5
11.5
2.3
54
13.6±0.6
38±2
G5
Et
2
O, -78
→
23°C
2.3
11.5
11.5
2.3
54
4.08
-
H5
Et
2
O, - 78
→
23°C
2.3
11.5
11.5
2.3
54
3.97
-
Et
2
O, - 78
→
23°C
2.3
11.5
11.5
2.3
54
4.0±0.1
11.2±0.2
I5
THF,
-78
→23°C
2.3
11.5
11.5
2.3
a
54
7.4
-
J5
THF,
-78
→23°C
2.3
11.5
11.5
2.3
a
54
11.7
-
THF,
-78
→23°C
2.3
11.5
11.5
2.3
a
54
9.6±2
27±7
K5
MeCy
, 23°C
2.3
124.2
124.2
0
54
<0.1
-
L5
MeCy
, 23°C
2.3
124.2
124.2
0
54
<0.1
-
MeCy
, 23°C
<0.1
<0.3
a
Ir(ppy)
3
used as photosensitizer
Tol = toluene; MeCy = methylcyclohexane
Solubility of reagents:
Collidine: Soluble in THF, Et
2
O, Toluene
, C
6
H
6
, MeCy
Collidinium triflate: Soluble in THF,
insoluble in Et
2
O, Toluene
and C
6
H
6
, MeCy
[Mo]Br
3
: Soluble in THF, Toluene
and C
6
H
6
. Sparingly soluble in Et
2
O, MeCy
HEH
2
: Partially soluble in THF, Et
2
O, T oluene and C
6
H
6
. Most soluble in THF, MeCy
[Ir]BAr
F
4
: Soluble in THF, Et
2
O, partially soluble in
C
6
H
6
and Toluene
Table S6 Attempted catalysis with [P
3
B
Fe]BAr
F
4
Run
Conditions
Fe
loading
(μmol)
acid
(μmol)
base
(μmol)
Ir
(μmol)
HEH
2
equiv
/Fe
NH
3
equiv
/Fe
N
2
H
4
equiv/Fe
NH
3
yield/
HEH
2
(%)
A6
THF, 23°C
2.3
124.2
124.2
2.3
54
<0.1
<0.1
B6
THF, 23°C
2.3
124.2
124.2
2.3
54
<0.1
<0.1
THF, 23°C
2.3
124.2
124.2
2.3
54
<0.1
<0.1
<0.1
C6
THF, 23°C
2.3
124.2
124.2
0
54
<0.1
<0.1
D6
THF, 23°C
2.3
124.2
124.2
0
54
<0.1
<0.1
THF, 23°C
2.3
124.2
124.2
0
54
<0.1
<0.1
<0.1
S1.6
NH
3
d etection results from
15
N- HEH
2
,
15
N- Col /
15
N- [ColH]OTf and
15
N
2
experiments
S1.6 .1
15
N
2
experiments
Catalytic runs done under a
15
N
2
atmosphere were conducted similarly to those under a
14
N
2
atmosphere,
with a few differences described below.
The loadings were the same as in
Figure 2, Entry 1.
Catalysis
is performed in the same catalytic tubes as natural abundance experiment
s, which are
charged with precatalyst, HEH
2
, [ColH]OTf, and a stirbar
in a nitrogen
-filled glovebox
as described
above. After addition of the solids,
t he tube is then cooled to 77 K in a cold well. The base (
Col) is added
by micropipette
to the frozen tube by opening the Kontes
. T he Kontes was closed and the tube
is kept
frozen, then passed out of the
glovebox into a liquid N
2
bath. The headspace of the tube
is evacuated
while still submerged in liquid N
2
.
Na/K dried THF
is filtered and 1 mL
placed into a separate Schlenk tube. Th
e solvent undergoes
freeze -pump thaw
cycles (3 cycles) an
d is then vacuum transferred into the cataly
sis tube. This tube is
allowed to warm up briefly and charged with
15
N
2
v ia vacuum bridge
. The tube
is refrozen at 77 K
and
then tr ansferred to a water bath
where it thaws and is allowed to stir
under Blue LED irradiation for 12
hours.
S1.6.2
15
N- HEH
2
,
15
N- Col/
15
N- [ColH]OTf
experiments
Catalytic runs were set
-up as described in
S1 .1
but using either
15
N- HEH
2
as H
2
-carrier or
15
N-
Col/[ColH]OTf
as buffer
using the same conditions as
Figure 2, Entry 1
.
Figure
S2.
1
H NMR (DMSO-
d
6
, 400 MHz) of:
A)
14
NH
4
Cl obtained
from reaction
of natural abundance
reactants unde
r
14
N
2
(Ir- free c onditions in
Figur e 2, entry 1
); B)
14
NH
4
Cl
obtained
from reaction
o
f
15
N-
labeled H
EH
2
(otherwise n
atural abundance re
actan ts) under
14
N
2
(Ir- free c onditions in
Figur e 2, entry
1);
C)
14
NH
4
Cl
obtained
from reaction
o
f
15
N
-labeled C
ol/[ColH]OT
f (otherwise n
atura l abundance reactants)
under
14
N
2
(Ir- free c onditions in
Figur e 2, entry 1
); D)
15
NH
4
Cl
obtained
from reaction
u
nder
15
N
2
(o
therwise n
atural abundance re
actan ts, Ir- free c onditions in
Figur e 2, entry
1).