of 21
S
1
Heterometallic Triiron
-
Oxo/Hydroxo Clusters: Effect of Redox
-
Inactive Metals
David E. Herbert
,
Davide Lionetti
,
Jonathan Rittle
, Theodor Agapie*
Division of Chemistry and Chemical Engineering
, California Institute of Technology,
Pasadena, California 9112
5
e
-
mail: agapie@caltech.edu
Supporting Information
Contents
General Considerations
S3
Synthetic Procedures
S3
Figure S1
.
1
H NMR spectrum of
1
-
Ca in CD
2
Cl
2
at 25
°
C.
S5
Figure S2
.
1
H NMR spectrum of
2
-
Ca
in CD
2
Cl
2
at 25
°
C.
S5
Fi
gure S3
.
1
H NMR spectrum of
1
-
Sr
in CD
2
Cl
2
at 25
°
C.
S6
Figure S4
.
1
H NMR spectrum of
2
-
Sc
in CD
2
Cl
2
at 25
°
C.
S6
Figure S5
.
1
H NMR spectrum of
1
-
Zn
in CD
2
Cl
2
at 25
°
C.
S7
Figure S6
.
1
H NMR spectrum of
1
-
La
in CD
2
Cl
2
/CD
3
CN at 25
°
C.
S7
Figur
e S7
.
1
H NMR spectrum of
2
-
La
in CD
2
Cl
2
at 25
°
C.
S8
Mossbauer Spectroscopy
S9
Figure S8
.
Zero
-
field
57
Fe Mössbauer spectrum for
2
-
Sc, 80 K.
S9
Figure S9
.
Zero
-
field
57
Fe Mössbauer spectrum for
1
-
Sr, 80 K.
S9
Figure S10
.
Zero
-
field
57
Fe
Mössbauer spectrum for
1
-
Zn, 80 K.
S10
Figure S11.
Zero
-
field
57
Fe Mössbauer spectrum for
1
-
La, 80 K.
S10
Figure S12
.
Zero
-
field
57
Fe Mössbauer spectrum for
2
-
La, 80 K.
S11
Table S1
.
Mössbauer spectral properties for compounds
1
-
2
.
S11
Electro
chemical Measurements
S12
Table S2
. Table of relevant potentials
S12
Crystallographic Information
S13
Table S3
. Crystal and refinement data.
S13
Table S4.
Comparison of structural parameters for
complexes
1
-
2
S13
Figure S13
.
Structural drawing of
1
-
Ca.
S1
5
Figure S14
. Structural drawing of
2
-
Ca.
S1
6
Figure S15
. Structural drawing of
1
-
Sr.
S1
7
Figure S16
. Structural drawing of
2
-
Sc.
S1
8
Figure S17
. Structural drawing of
1
-
Zn.
S1
9
Figure S18
. S
tructural drawing of
2
-
La.
S
20
References
S
20
S
2
General Considerations
Unless indicated otherwise, reactions performed under inert atmosphere were carried out in
oven
-
dried glassware in a glovebox under a nitrogen atmosphere. Anhydrous
tetrahydrofuran
(THF) was purchased from Aldrich in 18 L Pure
-
Pac
TM
containers. Anhydrous dichloromethane,
diethyl ether, and THF were purified by sparging with nitrogen for 15 minutes and then passing
under nitrogen pressure through a column of activated
A2 alumina (Zapp’s).
Anhydrous 1,2
-
dimethoxyethane (DME) was dried over sodium/benzophenone ketyl and vacuum
-
transferred
onto molecular sieves
. CD
2
Cl
2
and CD
3
CN were
purchased from Cambridge Isotope
Laboratories, dried over calcium hydride, then degassed b
y three freeze
-
pump
-
thaw cycles and
vacuum
-
transferred prior to use.
1
H NMR spectra were recorded on a Varian 300 MHz
instrument, with shifts reported relative to the residual solvent peak.
19
F NMR spectra were
recorded on a Varian 300 MHz instrument, with
shifts reported relative to the internal lock
signal. Elemental analyses were performed by
Robertson Microlit Laboratories, NJ
. Electrospray
ionization mass spectrometry (ESI
-
MS) was performed in the positive ion mode using a LCQ ion
trap mass spectromete
r (Thermo) at the California Institute of Technology Mass Spectrometry
Facility.
Unless indicated otherwise, all commercial chemicals were used as received. Ca(OTf)
2
,
and Zn(OTf)
2
were purchased from Aldrich.
Cobaltocene
was purchased from
Strem
and
sublim
ed before use.
La(OTf)
3
was purchased from Strem. Iodosobenzene,
1
Sr(OTf)
2
,
2
and
Sc(OTf)
3
were prepared accordi
ng to literature procedures. LFe
3
(OAc)
3
was
prepared according
to previously published procedures.
4
Caution!
Iodosobenzene is potentially explosi
ve and
should be used only in small quantities.
Synthesis of 1
-
Ca
In the glovebox, a round
-
bottom flask equipped with
a stir bar was charged with LFe
3
(OAc)
3
(0.600
g,
0.500
mmol) and
suspended in 50 mL of DME.
Ca(OTf)
2
(0.270
g,
0.798 mmol, 1.6
equiv) wa
s added
leading the orange suspension to lighten in color, and the yellow
-
orange
suspension was stirred at room temperature for
10 min. Iodosobenzene (0.242
g,
1.10
mmol, 2.2
equiv) was added as a solid, and the mixture was stirred at room temperature for
10
h, turning
from yellow
-
orange
to
dark
-
brown and ultimately to a orange
-
brown suspension
. The
orange
-
brown
solid was c
ollected via filtration, washed
with DME
(3 x 10 mL)
, then extracted with
dichloromethane
(~ 10 mL)
. The
orange
-
brown
solution was
dried
, re
-
extracted with
dichloromethane, filtered over Celite and layered with diethylether to yield an orange
-
brown
solid (
0.650
g,
7
4%).
1
H NMR (CD
2
Cl
2
, 300 MHz):
δ
85 (v br overlapped), 80 (v br overlapped),
74 (v br overlapped), 68 (v br overlapped), 63 (v
br overlapped), 39 (v br), 16 (br), 14, 13, 9, 4
(br, overlapped), 3 (br overlapped), 1, 0 ppm (v br)
.
19
F NMR (CD
2
Cl
2
):
δ
76.6 (br)
ppm. Anal.
Calcd. For
C
68
H
56
CaF
9
Fe
3
N
6
O
20
S
3
: C,
46.62
; H,
3.22
; N,
4.80
. F
ound: C, 46.35; H, 3.01; N,
4.69
.
Synthesis of
2
-
Ca
In the glovebox, a
20 mL vial
equipped with a stir bar was charged with
1
-
Ca
(0.246 g, 0.140
mmol) and 8 mL of CH
2
Cl
2
. A solution of cobaltocene (0.0277 g, 0.148
mmol, 1
.06 equiv; 2 mL
CH
2
Cl
2
) was added drop
-
wise. The mixture was stirred for 45 min t
hen dried
in vacuo
.
The
residue was washed with DME until the washings were colorless to remove cobaltocenium
triflate (identified by
1
H,
19
F NMR). The dark brown residue was
recrystallized from
DME/CH
2
Cl
2
/
Et
2
O
to yield the product as a
dark brown solid (0
.172 g, 76
%).
1
H NMR (CD
2
Cl
2
,
S
3
300 MHz):
δ
144 (br, overlapped), 139 (br, overlapped), 129 (br, overlapped), 126 (br,
overlapped), 123 (br, overlapped), 74.6, 68.8, 65.4, 62.9 (overlapped), 62.1 (overlapped), 58.5
(overlapped), 57.5 (overlapped), 54.6, 52.1
(overlapped), 51.3 (overlapped), 33.8 (overlapped),
32.3 (overlapped), 22.8, 17.0, 13.1, 12.4, 11.6, 11.1, 10.6 (overlapped), 10.2 (overlapped), 9.9
(overlapped), 8.7, 8.0, 4.7 (br, overlapped with solvent), 3.6 (overlapped), 3.3 (overlapped), 2.8,
1.2, 0
.9,
-
1.9
ppm.
19
F NMR (CD
2
Cl
2
):
δ
74.4
ppm.
Anal. Calcd. for
C
67
H
56
CaF
6
Fe
3
N
6
O
17
S
2
:
C, 50.20; H, 3.52; N, 5.24. Found: C,
50.04
; H,
3.70
; N,
5.15
.
Synthesis of
1
-
Sr
In the glovebox, a round bottom flask equipped with a stir bar was charged with LFe
3
(OAc)
3
(0.400 g, 0.333 mmol) and 40 mL DME. Solid Sr(OTf)
2
(0.206 g, 0.534 mmol, 1.6 equiv) was
added and the mixture was stirred at room temperature for 10 min. PhIO (0.161 g, 0.733 mmol,
2.2 equiv) was added as a solid to the vial, and the yellow suspension
was stirred at room
temperature for 10 h, turning dark brown then to an orange
-
brown suspension. The brown
-
orange precipitate was collected over Celite and washed with DME (2 x 10 mL), then extracted
with CH
2
Cl
2
. The brown
-
orange CH
2
Cl
2
filtrate was dried
in vacuo
, redissolved in CH
2
Cl
2
and
filtered once more over Celite. DME (1 mL) was added to the solution and diffusion of ether into
the mixture led to formation of the product as an orange
-
brown solid
(0.476 g, 79%).
1
H NMR
(CD
2
Cl
2
, 300 MHz):
δ
79 (br ove
rlapped),
73 (br overlapped), 71 (br overlapped), 68 (br
overlapped), 65 (br overlapped), 63 (br overlapped), 38 (v br),
16 (overlapped), 14.5
(overlapped), 13.3 (overlapped), 9.6 (br overlapped), 9.5 (br overlapped), 4.3 (br overlapped with
solvent), 3.6
(overlapped), 3.5 (overlapped), 1.2,
-
0.1 ppm (br)
.
19
F NMR (CD
2
Cl
2
):
δ
75.7
ppm.
Anal. Calcd. for
C
68
H
56
F
9
Fe
3
N
6
O
20
S
3
Sr
:
C,
45.39
; H, 3.
14
; N,
4.67
. Found: C,
45.15
; H,
3.00; N, 4.60
.
Synthesis of 2
-
Sc
In the glovebox, a scintillation vial equipped with
a stir bar was charged with LFe
3
(OAc)
3
(0.1108 g, 0.0908 mmol), Sc(OTf)
3
(0.0594 g, 0,1208 mmol, 1.33 equiv), and 10 mL 1:1
THF/DME. The mixture was stirred at room temperature for 10 minutes during which time the
orange suspension turned into a nearly hom
ogenous yellow solution. PhIO (0.0419 g, 0.1906
mmol, 2.1 equiv) was added as a solid to the reaction mixture. While stirring at room
temperature for 15 h, a brown precipitate formed, leaving a light brown solution behind. The
precipitate was collected ove
r Celite and washed with 3 x 10 mL DME, then extracted with
CH
2
Cl
2
. The filtrate was dried
in vacuo
. The resulting powder was redissolved in CH
2
Cl
2,
; DME
(2 mL) was added, and diffusion of diethyl ether into the mixture led to precipitation of the
product
as a brown solid (0.1049 g, 66%).
1
H NMR (CD
2
Cl
2
,
300 MHz):
δ
179 (br overlapped),
173 (br overlapped), 156 (br), 146 (br), 94 (br overlapped), 92 (br overlapped), 88, 86, 76
(overlapped), 74, 73, 59, 48, 46, 42, 36, 19.5, 17.2, 16.5, 14.8, 11.1 (br overl
apped), 9.7 (br
overlapped), 8.7 (br overlapped), 8.1 (br overlapped), 4.8 (overlapped with solvent), 2.8, 0.4
(overlapped with solvent),
-
1.6 (br) ppm.
19
F NMR (CD
2
Cl
2
):
δ
76.7 ppm.
Anal. Calcd. For
C
68
H
56
F
9
Fe
3
N
6
O
20
S
3
Sc: C,
46.49
; H,
3.21
; N,
4.78
. F
ound
: C, 46.22; H, 3.46; N, 4.79
.
Synthesis of
1
-
Zn
In the glovebox, a scintillation vial equipped with a stir bar was charged with
1
-
Ca (0.
099
g,
0.
056
mmol) and Zn(OTf)
2
(0.0
21 g, 0.058
mmol, 1
.04
equiv) in CH
3
CN (10
mL). The
red
solution was stirred at roo
m temperature for
2 h
, then
dried
in vacuo
. The
resulting orange
-
red
S
4
solid was dissolved in CH
2
Cl
2
with a few drops of CH
3
CN and filtered over Celite.
The orange
-
red solution was dried, re
-
extracted with CH
2
Cl
2
and a few drops of CH
3
CN and concentrated.
Di
ffusion of Et
2
O into the solution at room temperature produced dark red crystals
(0.0
95
g,
98
%).
1
H NMR (CD
2
Cl
2
, 300 MHz):
δ
95 (br, overlapped), 88 (br, overlapped), 82 (br,
overlapped), 76 (br, overlapped), 73 (br, overlapped), 69 (br, overlapped), 46 (b
r), 16.8, 12.2
(overlapped), 10.1 (overlapped), 4.5 (overlapped with solvent), 3.4, 2.1, 1.2,
-
1.1,
-
2.2
ppm.
19
F
NMR (CD
2
Cl
2
):
δ
74.2 ppm.
Anal. Calcd. For
C
66
H
49
F
9
Fe
3
N
7
O
18
S
3
Zn
: C,
45.87
; H,
2.86
; N,
5.67
.
Found: C, 45.66; H, 2.98; N, 5.64
.
Synthesis of
1
-
La
In the glovebox, a scintillation vial equipped with a stir bar was charged with
1
-
Ca (0.
146
g,
0.
0832
mmol) and
5 mL CH
3
CN. La
(OTf)
2
(0.100 g, 0.171
mmol,
2 equiv) was added as a solid
and t
he
red
solution was stirred at room temperature for
2 h
, th
en
dried
in vacuo
. The
resulting
orange
-
red paste
was
washed with
neat
CH
2
Cl
2
then extracted with CH
2
Cl
2
with a few drops of
CH
3
CN and filtered over Celite.
The orange
-
red solution was concentrated and 1 mL of DME
was added. Diffusion of Et
2
O into the solu
tion at room temperature produced a dark red oil that
was dried extensively
in vacuo
to give an orange
-
red powder that was again washed with Et
2
O
(0.
100
g,
60
%).
1
H NMR (CD
2
Cl
2
, 300 MHz):
δ
102 (br overlapped), 94 (br, overlapped), 87 (br,
overlapped), 84
(br, overlapped), 81 (br, overlapped), 49 (br), 18, 15.7, 13.6, 9.9, 7.3, 4.3
(overlapped with solvent), 3.5 (overlapped), 3.3 (overlapped), 1.9, 1.1,
-
2.5 ppm.
19
F NMR
(CD
2
Cl
2
):
δ
76.5 ppm.
Synthesis of 2
-
La
In the glovebox, a
20 mL vial
equipped with
a stir bar was charged with
1
-
La
(0.1095 g, 0.0548
mmol) and 10 mL of CH
2
Cl
2
and a few drops of CH
3
CN. A solution of cobaltocene (0.0104 g,
0.0548
mmol, 1
equiv; 2 mL CH
2
Cl
2
) was added drop
-
wise. The mixture was stirred for 10 min
then dried
in vacuo
.
The
residue was washed with DME until the washings were colorless. The
dark brown residue was
extracted with CH
2
Cl
2
, and the solvent evaporate
in vacuo
. The resulting
brown powder was precipitated from DME/CH
2
Cl
2
/
Et
2
O
to yield the product as a
dark brown
solid
(0.0850 g, 84
%).
1
H NMR (CD
2
Cl
2
, 300 MHz):
δ
173 (br), 165 (br), 153 (br), 131 (br), 100
(b), 90 (br), 81.9 (overlapped), 80.9 (overlapped), 76.0 (overlapped), 75.1 (overlapped), 72.8,
68.4, 58.7 (br, overlapped), 56.3 (br, overlapped), 36.3 (overlapped),
33.7 (br, overlapped), 21.5,
18.0, 16.4 (overlapped), 15.6 (overlapped), 15.0 (overlapped), 11.2, 8.5, 4.0 (br, overlapped), 3.4
(overlapped), 1.2,
-
0.5
ppm.
19
F NMR (CD
2
Cl
2
):
δ
74.8
ppm.
Anal. Calcd. for
C
68
H
56
LaF
9
Fe
3
N
6
O
20
S
3
: C, 44.13; H, 3.05; N, 4.54
. Found: C,
43.88
; H,
3.24
; N,
4.48
.
S
5
Figure S1
.
1
H NMR
(300 MHz,
25
°
C
)
spectrum of
1
-
Cain CD
2
Cl
2
.
Figure S2
.
1
H NMR
(300 MHz,
25
°
C
)
spectrum of
2
-
Ca
in CD
2
Cl
2
.
S
6
Figure S3
.
1
H NMR
(300 MHz,
25
°
C
)
spectrum of
1
-
Sr
in CD
2
Cl
2
.
Figure S4
.
1
H NMR
(300
MHz,
25
°
C
)
spectrum of
2
-
Sc
in CD
2
Cl
2
.
S
7
Figure S5
.
1
H NMR
(300 MHz,
25
°
C
)
spectrum of
1
-
Zn
in CD
2
Cl
2
.
Figure S
6
.
1
H NMR
(300 MHz,
25
°
C
)
spectrum of
1
-
La
in CD
2
Cl
2
/CD
3
CN.
S
8
Figure S
7
.
1
H NMR
(300 MHz,
25
°
C
)
spectrum of
2
-
La
in CD
2
Cl
2
.
S
9
M
össbauer Spec
troscopy
Spectra were recorded on a spectrometer from SEE Co. operating in the constant acceleration
mode in a transmission geometry. Spectra were recorded with the temperature of the sample
maintained at 80 K. The sample was kept in an SVT
-
400 Dewar from
Janis, at zero field.
Application of a magnetic field of 54 mT parallel to the
γ
-
beam did not cause detectable changes
in the spectra recorded at 80 K. The quoted isomer shifts are relative to the centroid of the
spectrum of a metallic foil of
α
-
Fe at room
temperature. Samples were prepared by grinding
polycrystalline material into a fine powder and then mounted in a cup fitted with a screw cap as a
boron nitride pellet. Data analysis was performed using the program WMOSS (
www.
wmoss.org
) and quadrupole dou
blets were fit to Lorentzian lineshapes.
Figure S8.
Zero
-
field
57
Fe Mössbauer spectrum for
2
-
Sc, 80 K. Data: black dots; spectral fit:
green line; deconvolution: red, blue and black lines; residual: grey dots.
S
10
Figure S9
. Zero
-
field
57
Fe Mössbauer spect
rum for
1
-
Sr, 80 K. Data: black dots; spectral fit:
green line; deconvolution: red and blue lines; residual: grey dots.
Figure S10
. Zero
-
field
57
Fe Mössbauer spectrum for
1
-
Zn, 80 K. Data: black dots; spectral fit:
green line; deconvolution: red and blue
lines; residual: grey dots.
S
11
Figure S11.
Zero
-
field
57
Fe Mössbauer spectrum for
1
-
La, 80 K. Data: black dots; spectral fit:
green line; deconvolution: red and blue lines; residual: grey dots.
Figure S12.
Zero
-
field
57
Fe Mössbauer spectrum for
2
-
La, 80
K. Data: black dots; spectral fit:
green line; deconvolution: red and blue lines; residual: grey dots.