of 29
S
1
Supporting
Information
Ruthenium Olefin Metathesis Catalysts Featuring a
Labile Carbodicarbene Ligand
Allegra L. Liberman
-
Martin and Robert H. Grubbs
Arnold and Mab
e
l
Beckman Laboratories of Chemical Synthesis, California Institute of
Technology, Pasadena, California 91125, United States
Table of Contents:
1.
General Considerations
S2
2.
Synthesis of
2
and
3
S2
S3
3.
Attempted Syntheses and Observat
ion of
CDC
H
+
Formation
S
4
4.
Ring
-
Closing Metathesis of Diethyl Diallylmalonate
S4
5.
Ring
-
Opening Metathesis Polymerization of
endo
,
exo
-
N
orbornenyl D
iethyl D
iester
S5
6.
Reaction
s of
2
and
3
with
2
-
I
sopropoxy
-
β
-
methylstyrene
S6
7.
Reaction of
2
and
3
wit
h Excess Tricyclohexylphosphine
S6
8.
N
MR Kinetics of Initiation Rates
S7
S
8
9.
CDC Dependence Experiments to D
etermine
k
1
/
k
2
S8
S9
10.
X
-
Ray Structure Determination
S10
S14
11.
NMR
Spectra
S15
S2
8
12.
References
S2
9
S
2
General
Considerations
.
All experiments were conducted using standard Schlenk techniques or in a nitrogen
atmosphere glovebox. All solvents were dried by passage through solvent purificat
ion columns,
further degassed with argon, and stored over activated 3Å molecular sieves. Deuterated solvents
were purchased from Cambridge Isotope Laboratory and were degassed and dried prior to use.
Ethyl vinyl ether was degassed and stored over 3Å
molecular sieves.
(H
2
IMes)(py)
2
(Cl)
2
Ru=CHPh
,
1
(H
2
IPr
)(py)
2
(Cl)
2
Ru=CHPh
,
2
carbodicarbene
1
,
3
endo
,
exo
-
norbornenyl diethyl diester
,
4
and
2
-
isopropoxy
-
β
-
methylstyrene
5
were prepared
according to literature procedures.
Standard NMR spectroscopic experiments we
re performed using a Varian Inova 400
MHz spectrometer, and kinetic
s
experiments were conducted on a Varian 600 MHz spectrometer
with an AutoX probe.
1
H were calibrated internally to the residual proteo solvent relative to
tetramethylsilane. Spectra were a
nalyzed using MestReNova Ver. 10.0 software.
SEC data were collected using two Agilent PLgel MIXED
-
B 300
×
7.5 mm columns with
10 μm beads, connected to an Agilent 1260 Series pump, a Wyatt 18
-
angle DAWN HELEOS
light scattering detector, and Optilab rEX
differential refractive index detector.
The SEC mobile
phase was THF.
Online determination of
dn
/
dc
assumed 100% mass elution under the peak of
interest.
High
-
resolution mass spectrometry (HRMS) data was obtained using an Autoflex
MALDI
-
TOF instrument
for
solvent free samples with a benzylidene malononitrile matrix
(complexes
2
and
3
) or on a JEOL MSRoute mass spectrometer using FAB+ ionization
(complexes
4
and
5
).
The purity of complexes
2
and
3
was established by NMR spectroscopy.
Synthesis of
(H
2
IMes
)(CDC)(Cl)
2
Ru=CHPh
(2).
In a glovebox, a 20 mL scint
illation vial was charged with
(H
2
IMes)(py)
2
(Cl)
2
Ru=CHPh
(68.2 mg, 0.094 mmol), carbodicarbene
1
(31.4 mg, 0.103 mmol) and benzene (8 mL). Over 5
minutes, the solution changed in color from green to orange. After stirring at 25 °C for 3 hours,
the solution was concentrated
in vacuo
to afford an orange solid
and
was triturated twice with
pentane (5 mL
). The orange powder was dissolved in 2 mL of THF, filtered through Celite,
layered with diethyl ether (8 mL), and stored at
30 °
C to afford orange crystals of
(H
2
IMes)(CDC)(Cl)
2
Ru=CHPh
(
2
,
76.1 mg,
93% yield).
1
H NMR (400 MHz, C
6
D
6
)
δ
19.62
(s,
1H, Ru=C
H
Ph)
, 9.17
(br s, 1H,
o
-
Ph)
, 6.91
(overlapping m, 4H, CDC and
m
-
Mes)
, 6.81
(s, 1H,
m
-
Mes)
, 6.65
(overlapping m, 4H, CDC and Ph)
, 6.43
(overlapping m, 4H, CDC and Ph)
, 6.18
(br s, 2H, CDC)
, 5.84
(s, 1H,
m
-
Mes)
, 3.36
(m, 4H,
H
2
IMes
NC
H
2
C
H
2
N)
,
3.25 (br, 12H, C
DC),
Ru
N
Cl
Cl
N
N
Ph
N
1
benzene,
rt
Ru
Cl
Cl
N
N
Ph
N
N
N
N
2
S
3
3.10
(s, 3H, Mes)
, 2.86
(s, 3H, Mes)
, 2.71
(s, 3H, Mes)
, 2.23
(s, 3H, Mes)
, 2.05
(s, 3H, Mes)
,
1.89
(s, 3H, Mes);
13
C
{
1
H}
NMR (101 MHz, C
6
D
6
)
δ
291.80
(Ru=
C
HPh)
, 224.58
(H
2
I
M
es
N
C
N)
, 163.40
(CDC N
C
N)
, 151.62
(Ph)
, 148.05
(Ph)
, 139.75
(Mes)
, 139.37
(Mes)
, 138.96
(Mes)
, 138.92
(Mes)
, 138.26
(Mes)
, 138.06
(Mes)
, 137.66
(Mes)
, 137.15
(Mes
)
, 131.14
(Ph)
,
130.65
(
m
-
Mes)
, 130.30
(
m
-
Mes)
, 129.61
(
m
-
Mes)
,
129.08 (
m
-
Mes),
122.38
(Ph)
, 119.37
(CDC
)
,
109.61
(CDC)
,
104.05
(CDC)
, 73.01
(CDC central carbon)
,
51.74
(H
2
IMes N
C
H
2
CH
2
N)
, 51.46
(H
2
IMes N
C
H
2
CH
2
N)
, 31.23
(CDC N
-
C
H
3
)
, 21.16
(Mes)
, 21.05
(Mes)
, 2
0.43
(Mes)
, 20.13
(Mes)
, 19.32
(Mes)
, 18.74
(Mes)
.
HRMS (MALDI
-
TOF)
m/z
Calculated for C
47
H
52
N
6
RuCl
[M
HCl]: 837.299; Found: 837.299.
Synthesis of
(H
2
IPr)(CDC)(Cl)
2
Ru=CHPh
(3).
In a glovebox, a 20 mL scint
illation vial was charged with
(H
2
IPr)(py)
2
(Cl)
2
Ru=CHPh
(58.6 mg, 0.0722 mmol), carbodicarbene
1
(25.2 mg, 0.0828 mmol) and benzene (8 mL). Over 5
minutes, the solution changed in color from green to orange. After stirring at 25 °C for 2 hours,
the solution was concentrated
in vacuo
and triturated twice with pentane (5 mL). The orange
powder was diss
olved in benzene (4 mL) and additional carbodicarbene
1
(10.2 mg, 0.0316
mmol) was added. After 30 minutes, volatile components were removed
in vacuo
. The solid was
dissolved in a mixture of diethyl ether (10 mL) and THF (3 mL), filtered through Celite, an
d
stored at
30 °
C to afford orange crystals of
(H
2
IPr)(CDC)(Cl)
2
Ru=CHPh
(
3
,
52.2 mg, 75
%
yield).
1
H NMR (400 MHz, C
6
D
6
)
δ
19.67
(s, 1H, Ru=C
H
Ph)
, 7.39
(s, 4H, Ph and DIPP)
, 7.22
(br d, 1H, DIPP)
, 6.97
(t,
J
= 8Hz, 1H, Ph)
, 6.87
(m, 2H, CDC)
, 6.64
(m, 3H, CDC and Ph)
, 6.53
(br d, 1H, DIPP)
, 6.46
(t,
J
= 8Hz, 2H, DIPP)
, 6.38
(br m, 2H, CDC)
, 6.17
(m, 2H, CDC)
, 4.77
(br s, 1H, C
H
(CH
3
)
2
)
, 4.39
(br s, 1H, C
H
(CH
3
)
2
)
, 3.97
(s, 2H
, H
2
IPr NC
H
2
CH
2
N
)
, 3.85
(m, 2H
,
C
H
(CH
3
)
2
)
,
3.76 (m, 1H, H
2
IPr NC
H
2
CH
2
N),
3.52
(m, 1H
, H
2
IPr NC
H
2
CH
2
N
)
, 3.28
(m, 1H
,
C
H
(CH
3
)
2
)
, 3.17
(s, 6H
, CDC N
C
H
3
)
, 2.75
(br s, 6
H
, CDC N
C
H
3
)
, 2.01
(s, 3H
, CH(C
H
3
)
2
)
,
1.71
(br s, 6H
, CH(C
H
3
)
2
)
, 1.36
(m, 3H
, CH(C
H
3
)
2
)
, 1.28
(m, 3H
, CH(C
H
3
)
2
)
, 1.19
(m, 3H
,
CH(C
H
3
)
2
)
, 1.05
(m, 3H
, CH(C
H
3
)
2
)
,
0.98
(m, 3H
, CH(C
H
3
)
2
);
13
C
{
1
H}
NMR (101 MHz, C
6
D
6
)
δ
294.30
(Ru=
C
HPh)
, 227.09
(H
2
IPr N
C
N)
, 162.36
(CDC N
C
N)
, 150.85
(Ph)
, 149.74
(DIPP)
,
147.54 (Ph),
139.89
(DIPP)
, 139.29
(DIPP)
, 136.43
(DIPP)
, 130.97
(CDC)
, 129.27
(Ph)
, 125.62
(DIPP)
, 124.87
(Ph)
,
124.22
(DIPP)
, 123.91
(DIPP)
, 121.89
(CDC)
, 119.34
(CDC)
, 108.90
(CDC)
, 104.23
(CDC)
, 73.37
(CDC central C)
,
54.70
(H
2
IMes N
C
H
2
CH
2
N)
, 54.21
(H
2
IMes
N
C
H
2
CH
2
N)
, 30.65
(CDC N
C
H
3
)
, 30.24
(CDC N
C
H
3
)
, 28.64
(
C
H(CH
3
)
2
)
, 28.24
(
C
H(CH
3
)
2
)
,
27.61
(
C
H(CH
3
)
2
), 26.91
(CH(
C
H
3
)
2
)
, 26.58
(CH(
C
H
3
)
2
)
, 26.
56
(CH(
C
H
3
)
2
)
, 26.40
(CH(
C
H
3
)
2
)
,
26.32
(CH(
C
H
3
)
2
)
, 26.08
(CH(
C
H
3
)
2
)
,
24.59
(CH(
C
H
3
)
2
)
, 24.10
(CH(
C
H
3
)
2
)
, 22.97
(CH(
C
H
3
)
2
)
.
HRMS
(MALDI
-
TOF)
m/z
Calculated for C
53
H
64
N
6
RuCl
[M
HCl]: 921.392; Found: 921.394
.
Ru
Cl
Cl
N
N
Ph
N
N
N
N
Ru
N
Cl
Cl
Ph
N
1
benzene,
rt
3
N
N
S
4
Attempted
Syntheses and Observation of CDC
H
+
Formation.
Representative procedure: A solution of (PCy
3
)
2
(Cl)
2
Ru=CHPh (6.6 mg, 0.0080 mmol) and CDC
1
(2.5 mg, 0.0080 mmol) was prepared in benzene
-
d
6
(0.8 mL). After 24 hours, CDC
H
+
had
precipitated as a pale yellow powder, and was washed with Et
2
O (5 mL) and dried
in vacuo
.
1
H
NMR (400 MHz, CD
2
Cl
2
)
δ
7.38
(m, 8H)
, 5.23
(s, 1H)
, 3.64
(s, 12H);
13
C
{
1
H}
NMR (101 MHz,
CD
2
Cl
2
)
δ
153.89, 133.58, 124.53, 110.43, 51.47, 33.06.
HRMS (FAB+)
:
m/
z
Calculated
for
C
19
H
21
N
4
[M
+
]
:
305.1766; Found: 305.1762
.
Ring
-
Closing Metathesis of Diethyl Diallylmalonate.
In a glovebox, a solution of catalyst
2
or
3
(0.00080 mmol) in 0.80 mL of benzene
-
d
6
was
prepared in a J. Young NMR tube and frozen using a glovebox cold well. An internal standard,
1,3,5
-
tris(trifluoromethyl)benzene (1 μL) and diethyl diallylmalonate (19.3 μL, 0.0800 mmol)
were
added, and the NMR tube was stored at 0 °C before use. The t
ube was placed in an NMR
spectrometer with the temperature pre
-
equilibrated to 40 °C. Disappearance of diethyl
diallylmalonate and appearance of 4,4
-
dicarbethoxy
-
1
-
cyclopentene were monitored by
comparing the ratio of integrals for the methylene protons of
these compounds (
δ
= 2.86
(
dt
)
and
3.16 (s), respectively).
Figure S1.
Log plots for the ring
-
closing metathesis of diethyl diallylmalonate
with catalysts
2
and
3
.
Ru
Cl
Cl
PCy
3
O
N
N
N
N
C
[Ru]
+
C
6
D
6
N
N
N
N
C
H
+
unidentified
decomposition
products
[Ru]
=
Ru
N
Cl
Cl
PCy
3
Ph
N
Ru
PCy
3
Cl
Cl
PCy
3
Ph
EtO
2
C
CO
2
Et
1
mol%
2
or
3
C
6
D
6
(0.1
M),
40
°
C
EtO
2
C
CO
2
Et
0
0.5
1
1.5
2
2.5
3
3.5
0
500
1000
1500
2000
2500
ln[M
0
/M
t
]
time (s)
2
3
S
5
Ring
-
Opening Metathesis Polymerization of
endo
,
exo
-
N
orbornenyl D
iethyl D
iester (DEE
)
A solution of
DEE
(23.8 mg, 0.100 mmol) in dichloromethane (1.75 mL) was prepared in
a glovebox. While stirring, a solution of catalyst
2
or
3
(0.00080 mmol) in dichloromethane (0.25
mL) was added. Aliquots (~50 μL) were taken at different time points thr
oughout the reaction
and immediately quenched in separate vials containing ethyl
vinyl
ether (0.1 mL) in THF (0.9
mL). The quenched aliquots were analyzed by SEC and
1
H NMR spectroscopy.
Figure S2
.
Size exclusion chromatograms for ROMP of
DEE
by catalyst
2
.
Figure S3
.
Size exclusion chromatograms for ROMP of
DEE
by catalyst
3
.
O
O
Et
O
O
Et
2
or
3
O
O
Et
O
O
Et
n
CH
2
Cl
2
0
0.2
0.4
0.6
0.8
1
14
14.5
15
15.5
16
16.5
17
Normalized dRI
Ret. Vol. (mL)
1 min
3 min
5 min
7 min
10 min
12 min
20 min
0
0.2
0.4
0.6
0.8
1
14
15
16
17
18
Normalized dRI
Ret. Vol. (mL)
5 min
10 min
15 min
20 min
30 min
45 min
60 min
120 min
S
6
Reaction of 2 with
2
-
I
sopropoxy
-
β
-
methylstyrene
.
In a glovebox,
a
solution of complex
2
(2.6 mg, 0.0030 mmol),
2
-
isopropoxy
-
β
-
methylstyrene
(1.6 μL, 0.0090 mmol), and 1,3,5
-
tris(trifluoromethyl)benzene (1 μL) as an
internal standard was prepared in 0.60 mL of benzene
-
d
6
and transferred to a J. Young NMR
tube. The NMR tube was heated to 40 °C in a temperature
-
controlled oil bath. After 7 hours
,
complete conversion of
2
to
4
was observed by
1
H NMR spectroscopy.
6
The identity of
4
was
verified by HRMS (FAB+):
m/z
Calculated
for C
31
H
38
ON
2
RuCl
2
[M+H]
H
2
: 626.1405; Found:
626.1397.
Reaction of 3 with
2
-
I
sopropoxy
-
β
-
methylstyrene
.
In a glovebox,
a
solution of complex
3
(2.9 mg, 0.0030 mmol),
2
-
isopropoxy
-
β
-
methylstyrene
(1.6 μL, 0.0090 mmol), and 1,3,5
-
tris(trifluoromethyl)benzene (1 μL) as an
internal standard was prepared in 0.60 mL of benzene
-
d
6
and transferred to a J. Young NMR
tube. The NMR t
ube was heated to 40 °C in a temperature
-
controlled oil bath. After 7 hours,
complete conversion of
3
to
5
was observed by
1
H NMR spectroscopy.
7
The identity of
5
was
verified by HRMS (FAB+):
m/z
Calculated
for C
37
H
50
ON
2
RuCl
2
[M+H]
H
2
: 710.2344; Found:
710.2362
.
Reaction of 2 and 3 with Excess Tricyclohexylphosphine.
Complex
2
or
3
(0.0013 mmol) and tricyclohexylphosphine (0.0065 mmol) were
dissolved in benzene
-
d
6
in a J. Young tube. Exchange of CDC
1
for PCy
3
was monitored by
1
H
and
31
P NMR spectrosco
py at 25
o
C.
8
After 12 hours, 50% conversion of
2
or
3
was observed,
along with concomitant formation of the analogous (NHC)(PCy
3
)(Cl)
2
Ru=CHPh complex and
free CDC
1
.
C
6
D
6
,
40
°
C,
7
h
Ru
Cl
Cl
N
N
Mes
Mes
4
Ru
Cl
Cl
N
N
Mes
Mes
Ph
N
N
N
N
2
O
O
C
6
D
6
,
40
°
C,
7
h
Ru
Cl
Cl
N
N
Dipp
Dipp
5
Ru
Cl
Cl
N
N
Dipp
Dipp
Ph
N
N
N
N
3
O
O
S
7
NMR Kinetics of Initiation Rates.
Complex
2
or
3
(0.0020 mmol) and 0.5 μL of 1,3,5
-
tris(trifluoromethyl)benzene as an
internal standard were dissolved in benzene
-
d
6
(0.60 mL)
in a screw
-
capped NMR tube. The
temperature of the NMR tube was allowed to equilibrate in the NMR probe at 40
o
C. Ethyl vinyl
eth
er (26 μL, 0.27 mmol) was injected into the NMR tube, and disappearance of the
1
H NMR
signal for the ruthenium benzylidene was monitored as a function of time for three half lives.
Reactions performed in triplicate provided rate constants (
k
obs
=
k
1
) of (4.04
±
0.04)
×
10
4
s
1
for
complex
2
and (9.48
±
0.07)
×
10
3
s
1
for
3
.
Table S1.
Temperature dependence of
k
obs
for the reaction of
2
(0.0020 mmol) with ethyl vinyl
ether (0.27 mmol) in benzene
-
d
6
(0.60 mL).
Temp. (
o
C)
1/T
(K
1
)
k
obs
(s
1
)
ln
(
k
/T)
40
0.00319
4.04
×
10
4
-
13.56
50
0.00309
1.73
×
10
3
-
12.14
58
0.00302
5.48
×
10
3
-
11.01
64
0.00297
1.59
×
10
2
-
9.96
70
0.00291
2.54
×
10
2
-
9.51
The plot of ln(
k
/T) as a function of T
1
(Figure S3) was linearly fit to the expression
ln
T
=
H
!
R
1
T
+
ln
!
h
+
Δ
S
!
R
The enthalpy and entropy of activation were extracted from the slope and intercept, respectively.
Standard deviations for
H
and
S
were evaluated using the LINEST routine in Excel.
Figure S4
. Eyring plot for the reaction of
2
with ethyl vinyl ether.
y = -14978x + 34.26
R
²
= 0.99445
-14.0
-13.0
-12.0
-11.0
-10.0
-9.0
0.0029
0.003
0.0031
0.0032
ln(
k
/T)
1/T
S
8
Table S2.
Temperature dependence of
k
obs
for the reaction of
3
(0.0020 mmol) with ethyl vinyl
ether (0.27 mmol) in benzene
-
d
6
(0.60 mL).
Temp. (
o
C)
1/T (K
1
)
k
obs
(s
1
)
ln(
k
/T)
25
0.00335
1.05
×
10
3
-
12.56
35
0.00325
5.17
×
10
3
-
11.00
40
0.00319
9.48
×
10
3
-
10.41
55
0.0030
5
5.42
×
10
2
-
8.71
48
0.00311
2.89
×
10
2
-
9.32
Figure S5
. Eyring plot for the reaction of
3
with ethyl vinyl ether.
CDC Dependence Experiments to D
etermine
k
1
/
k
2
.
Complex
2
or
3
(0.0020 mmol)
,
CDC (
1
,
0.0040 to 0.011 mmol), and 1 μL of 1,3,5
-
tris(trifluoromethyl)benzene as an internal standard were dissolved in benzene
-
d
6
(0.60 mL) in a
screw
-
capped NMR tube. Each sample was thermally equilibrated in the NMR probe, and
olefin
(
eth
yl vinyl ether,
0.021 to 0.26 mmol) was injected into the NMR tube. Disappearance of the
1
H
NMR signal for the ruthenium benzylidene was monitored as a function of time for three half
lives.
Table S3
.
[CDC]/[olefin
] experiments for
2
at 60
o
C
.
[CDC]
(mmo
l)
[olefin
]
(mmol)
[CDC]/[olefin
]
k
obs
(s
1
)
1/
k
obs
(s)
0.011
0.2
2
0.050
7.86
×
10
3
127
0.011
0.09
4
0.1
2
7.37
×
10
3
136
0.011
0.057
0.19
6.65
×
10
3
150
0.011
0.031
0.35
5.91
×
10
3
169
0.011
0.02
1
0.5
3
5.39
×
10
3
186
y = -12664x + 30.012
R
²
= 0.99504
-13.0
-12.0
-11.0
-10.0
-9.0
-8.0
0.003
0.0031
0.0032
0.0033
0.0034
ln(
k
/T)
1/T
S
9
Figure S6.
1/
k
obs
versus [CDC]/[olefin] for complex
2
.
Table S4
.
[CDC]/[olefin
] experiments for
3
at
40
o
C
.
[CDC]
(mmol)
[olefin
]
(mmol)
[CDC]/[olefin
]
k
obs
(s
1
)
1/
k
obs
(s)
0.004
0
0.26
0.015
9.49
×
10
3
105
0.011
0.09
0.12
6.58
×
10
3
152
0.011
0.031
0.35
3.77
×
10
3
265
0.015
0.035
0.4
3
3.02
×
10
3
331
0.011
0.021
0.52
2.79
×
10
3
358
Figure S7.
1/
k
obs
versus [CDC]/[olefin] for complex
3
.
y = 123.51x + 123.06
R
²
= 0.9846
120
140
160
180
200
0
0.1
0.2
0.3
0.4
0.5
0.6
1/
k
obs
(s)
[CDC]/[olefin]
y = 515.91x + 93.351
R
²
= 0.99046
0
100
200
300
400
0
0.1
0.2
0.3
0.4
0.5
0.6
1/
k
obs
(s)
[CDC]/[olefin]
S
10
X
-
Ray Structure Determination.
Complex 2.
Low
-
temperature diffraction data (
φ
-
and
ω
-
scans) were collected on a Bruker
AXS D8 VENTURE KAPPA diffractometer coupled to a PHOTON 100 CMOS detector with
Mo
K
α
radiation (
λ
= 0.71073 Å) from an I
μ
S micro
-
source for the structure of compound
2
. The
structure was solved by direct methods using
SHELXS
9
and refined against
F
2
on all data by
full
-
matrix least squares with SHELXL
-
201
6
10
using established refinement techniques.
1
1
All
non
-
hydrogen atoms were refined anisotropically. All hydrogen atoms were included into the
model at geometrically calc
ulated positions and refined using a riding model. The isotropic
displacement parameters of all hydrogen atoms were fixed to 1.2 times the
U
value of the atoms
they are linked to (1.5 times for methyl groups).
Complex
2
crystallizes in the monoclinic spac
e group
P
2
1
/
n
with one molecule in the
asymmetric unit.
Complex 3.
Low
-
temperature diffraction data (
φ
-
and
ω
-
scans) were collected on a Bruker
AXS D8 VENTURE KAPPA diffractometer coupled to a PHOTON 100 CMOS detector with
Cu
K
α
radiation (
λ
= 1.54178 Å) from an I
μ
S micro
-
source for the structure of compound
3
. The
structure was solved by direct methods using SHELXS
9
and refined against
F
2
on all data by
full
-
matrix least squares with SHELXL
-
201
6
10
using established refinement techniques.
1
1
A
ll
non
-
hydrogen atoms were refined anisotropically. All hydrogen atoms were included into the
model at geometrically calculated positions and refined using a riding model. The isotropic
displacement parameters of all hydrogen atoms were fixed to 1.2 times
the
U
value of the atoms
they are linked to (1.5 times for methyl groups).
All disordered atoms were refined with the help
of similarity restraints on the 1,2
-
and 1,3
-
distances and displacement parameters as well as
enhanced
rigid bond restraints for anis
otropic displacement parameters.
Complex
3
crystallizes in the monoclinic space group
P
2
1
/
c
with one molecule in the
asymmetric unit
along with 2.588 molecules of diethyl ether
.
The crystal was pseudo
-
merohedrally twinned. The structure was refined using
the twin matrix [
-
1 0 0 0
-
1 0 0 0 1] and
the twin ratio converged at a value of 0.400(2).