Argentivorous molecules with two kinds of aromatic side-arms: Intramolecular competition between side-arms

Article abstract of DOI:10.1039/c3dt00034f

Three tetra-armed cyclens with two kinds of side-arms, 3′,5′- difluorobenzyl/4′-methylbenzyl, 3′,5′-difluorobenzyl/1′- naphthylmethyl, and 3′,5′-difluorobenzyl/9′-anthrylmethyl groups, were prepared by reductive amination of 1,7-bis(3′,5′- difluorobenzyl)

Full text of DOI:10.1039/c3dt00034f

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An international journal of inorganic chemistry
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Volume 42 | Number 23 | 21 June 2013 | Pages 8149–8520
ISSN 1477-9226
COVER ARTICLE
Habata et al.
Argentivorous molecules with two kinds of aromatic side-arms: intramolecular
competition between side-arms

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Argentivorous molecules with two kinds of aromatic
side-arms: intramolecular competition between
side-arms†
Cite this: Dalton Trans., 2013, 42, 8212
Yoichi Habata,*a,b Yosuke Oyama,a Mari Ikedaa,b and Shunsuke Kuwaharaa,b
Three tetra-armed cyclens with two kinds of side-arms, 3’,5’-difluorobenzyl/4’-methylbenzyl, 3’,5’-difluoro-
benzyl/1’-naphthylmethyl, and 3’,5’-difluorobenzyl/9’-anthrylmethyl groups, were prepared by reduc-
tive amination of 1,7-bis(3’,5’-difluorobenzyl)-1,4,7,10-tetraazacyclododecane and the corresponding
aromatic aldehydes in the presence of NaBH(OAc)3. The X-ray structures of the Ag+ complexes and Ag+-
ion-induced 1H NMR spectral changes suggest that (i) the chemical shift changes of the protons at the
2’- and 6’-positions in the 3’,5’-difluorobenzyl/4’-methylbenzyl side-arms are dependent on the electron
density on the adjacent substituted benzenes, and (ii) in the tetra-armed cyclens with 3’,5’-difluoro-
benzyl/1’-naphthylmethyl and 3’,5’-difluorobenzyl/9’-anthrylmethyl groups as side-arms, electron-rich
aromatic rings preferentially cover the Ag+ ions incorporated into the ligand cavities, and 3’,5’-difluoro-
benzyl groups do not participate in the Ag+ interactions. The log K values were estimated using Ag+-ion-
induced UV-vis spectral changes.
Received 4th January 2013,
Accepted 6th February 2013
DOI: 10.1039/c3dt00034f
www.rsc.org/dalton
a combination of two kinds of aromatic rings, such as 3′,5′-
difluorobenzyl and 1′-naphthylmethyl groups, and 3′,5′-difluoro-
Introduction
Weak interactions such as metal-cation–π1 and CH–π2 inter- benzyl and 9′-anthrylmethyl groups, is introduced into a
actions are important not only in supramolecular chemistry, cyclen, do the aromatic rings with higher electron densities
but also in biochemistry. In some cases, weak interactions are preferentially cover the Ag+ ions incorporated into the ligand
key interactions in supramolecular chemistry.
cavities? Here, we report the structures in the solid-state and
Recently, we reported that tetra-armed and double-armed in solution of Ag+ complexes with argentivorous molecules
cyclens act as argentivorous molecules by Ag+–π and CH–π with two kinds of aromatic side-arms.
interactions.3–5 Ag–π and CH–π interactions in solution were
shown based on the chemical shift changes in the 1H NMR
spectra of the protons at the 2′- and 6′-positions in the aro-
matic side-arms. In a continuation of our previous work, we
prepared new tetra-armed cyclens with two kinds of aromatic
side-arms to answer the following questions. (i) When a tetra-
Results and discussion
New tetra-armed cyclens (1, 2, and 3 in Fig. 1) were prepared
by the reductive amination of 1,7-bis(3,5-difluorobenzyl)-
1,4,7,10-tetraazacyclododecane5 and the corresponding aro-
armed cyclen with two kinds of substituted-benzyl groups, i.e.,
matic aldehydes. The structures of the new armed cyclens were
3′,5′-difluorobenzyl and 4′-methylbenzyl groups, which have
1
confirmed by H NMR spectroscopy, FAB-MS, elemental analy-
electron-withdrawing groups and electron-donating groups,
respectively, forms an Ag+ complex, are the chemical shift
sis, and X-ray crystallography (Fig. S2–S7 in the ESI†).
changes of the protons at the 2′- and 6′-positions dependent
on the electron density on the substituted benzenes? (ii) When
aDepartment of Chemistry, Faculty of Science, Toho University, 2-2-1 Miyama,
Funabashi, Chiba 274-8510, Japan. E-mail: habata@chem.sci.toho-u.ac.jp;
Fax: +81 47 472 4322
bResearch Centre for Materials with Integrated Properties, Toho University,
2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
†Electronic supplementary information (ESI) available. CCDC CCDC
917307–917313. For ESI and crystallographic data in CIF or other electronic
format see DOI: 10.1039/c3dt00034f
Fig. 1 Argentivorous molecules with two kinds of side-arms.
8212 | Dalton Trans., 2013, 42, 8212–8217
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Fig. 2 Electrostatic potential maps of (a) 1,3-difluoro-4-methylbenzene, (b)
1,4-dimethylbenzene, (c) 1-methylnaphthalene, and (d) 9-methylanthracene.
−
Fig. 4 X-ray structure of 2/AgBF4 [(a) top and (b) side views]. CF3SO3 is
omitted. Meshed hydrogen atoms are the protons at the 2’- and 6’-positions of
3’,5’-difluorobenzyl side-arms (Hh protons in Fig. 1).
−
Fig. 3 X-ray structure of 1/AgCF3SO3 [(a) top and (b) side views]. CF3SO3 is
omitted. Meshed hydrogen atoms are the hydrogens at the 2’- and 6’-positions
(the Hb and Hc protons, respectively, in Fig. 1).
Fig. 2 shows electrostatic potential maps, calculated using
the HF/6-31G(*) method,5 of the aromatic rings we used. The
electrostatic potential maps show that the electron densities
in 1,4-dimethylbenzene (b), 1-methylnaphthalene (c) and
9-methylanthracene (d) are higher than that in 1,3-difluoro-
4-methylbenzene (a). In addition, the areas of higher electron
density in 1-methylnaphthalene and 9-methylanthracene are
wider than those in 1,4-dimethylbenzene. We therefore
expected that 4′-dimethylbenzyl, 1′-naphthylmethyl, and
9′-anthrylmethyl side-arms would cover the Ag+ ions incor-
−
porated into the ligand cavities, but a 3′,5′-difluorobenzyl side- Fig. 5 X-ray structure of 3/AgCF3SO3 [(a) top and (b) side views]. CF3SO3 is
arm would not.
omitted. Meshed hydrogen atoms are the protons at the 2’- and 6’-positions of
3’,5’-difluorobenzyl side-arms (Hf protons in Fig. 1).
Fig. 3 shows the X-ray structure of the 1/AgCF3SO3 complex.
Contrary to our expectations, the four aromatic side-arms cover
the Ag+ ion incorporated into the ligand cavity. The Ag1–C22
(C37) and Ag1–C15(C30) distances are 3.295(3.215) and 3.400
(3.537) Å, respectively. The distances indicate that the strength
of the Ag+–π interaction depends on the electron densities on
the aromatic rings. In addition, the distances between the
hydrogen atoms at the 2′- and 6′-positions of the side-arms
and the adjacent benzene planes are in the range
2.687–2.905 Å. The distances are typical CH–π bond distan-
ces.2d,4 In contrast, the side-arms in the 1/Cu(CF3SO3)2
complex never cover the Cu2+ ions incorporated into the ligand
cavities (Fig. S8 in the ESI†).
Fig. 4 shows the X-ray structure of the 2/AgBF4 complex.
When 1′-naphthyl groups are used as side-arms with 3′,5′-
difluorobenzyl groups, only 1′-naphthylmethyl groups cover
the Ag+ ions. The C25–Ag1 and C36–Ag1 distances are 2.432
and 3.325 Å, respectively. In addition, the H36–naphthalene
(including the C25 carbon)-plane distance is 2.797 Å. The X-ray
data suggest that the naphthalene side-arms cover the Ag+ ions
by Ag+–π interactions, and there are intramolecular CH–π inter-
actions between the naphthalene side-arms. The X-ray data
support our expectation of intramolecular competition
between aromatic side-arms.
The X-ray structure of the 3/AgCF3SO3 complex is shown in
Fig. 5. In this complex, two anthracene side-arms cover the Ag+
ions incorporated into the ligand cavities. The C51–Ag1 and
C29–Ag1 distances are 2.591 and 3.102 Å, respectively, and the
dihedral angle between the anthracene planes is 32.85°. The
dihedral angle is comparable with that in a double-armed
cyclen with two anthrylmethyl groups.5 The two 3′,5′-difluoro-
benzyl side-arms do not participate in Ag+–π interactions. The
X-ray data also support the expectation of intramolecular com-
petition between aromatic side-arms. The distances between
the Ag ions and the mean planes of the four nitrogen atoms in
1, 2, and 3 are 1.173, 1.198, and 1.240 Å, respectively. The dis-
tances are shorter than that of the cyclen having 2-(methylsul-
fanyl)ethyl groups as side-arms (1.346–1.329 Å) which have
strong binding ability towards Ag+ ions.6 The results indicate
that the aromatic side-arms with higher electron density are
more strongly bound to Ag+ ions.
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Fig. 6 Ag+-ion-induced 1H NMR spectral changes of 1 (in CD2Cl2/CD3OD).
Fig. 8 Ag+-ion-induced UV-vis spectral changes of 1. [1] = 1.0 × 10−4 mol L−1
(CH3CN).
conformations of the aromatic side-arms in solution are
similar to those in the X-ray structure. Ag+-ion-induced 1H
NMR chemical shift changes of 2 and 3 were also examined.
Titration experiments using 2 indicate that the Hg protons of
the 1′-naphthylmethyl side-arms and the Hh protons of the
3′,5′-difluorobenzyl side-arms shifted to higher field by ca. 0.31
and 0.91 ppm, respectively (Fig. S10†). When 3 was used as the
ligand for titration experiments, the Hf proton of the 3′,5′-
difluorobenzyl side-arms shifted to higher field by ca.
0.95 ppm (Fig. S11†). The X-ray structures of the 2/AgBF4 and
3/AgCF3SO3 complexes indicate that the meshed hydrogen
atoms in Fig. 4 and 5 are located in the shielding area of
the nearest neighbor aromatic rings. The X-ray structures and
1H NMR titration experiments strongly support the suggestion
that the structures of the complexes in solution are similar to
the solid-state structures.
Fig. 8 and Fig. S12–S13 in the ESI† show Ag+-ion-induced
UV spectral changes of 1 (and 2 and 3). Nonlinear least-
squares analyses of the titration profiles (absorbance versus
equivalents of Ag+ added, see Fig. S14–S16 in the ESI†) clearly
indicated the formation of 1 : 1 complexes, and allowed us to
estimate the association constants. The log K values between
the ligands (1, 2, and 3) and Ag+ ions in CH3CN were estimated
to be ca. 6.6, 8.4, and 10.1, respectively.
Fig. 7 ROESY spectrum of a 1 : 1 mixture of 1 and AgCF3SO3 in CD2Cl2/CD3OD.
To confirm the structures of the Ag+ complexes in solution,
1
Ag+-ion-induced H NMR chemical shift changes were investi-
gated. As shown in Fig. 6, the protons at the 2′- and 6′-posi-
tions of the 3′,5′-difluorobenzyl and 4′-methylbenzyl side-arms
shifted to higher field by ca. 0.25 and 0.82 ppm, respectively.
These chemical shift changes indicate that the protons at the
2′- and 6′-positions are located in the shielding area of the
adjacent aromatic rings, i.e., the protons at the 2′- and 6′-posi-
tions of the 3′,5′-difluorobenzyl groups are significantly shifted
by the adjacent 4′-methylbenzyl groups, which have higher
electron densities, and the protons at the 2′- and 6′-positions
of the 4′-methylbenzyl groups are not shifted so much by the
adjacent 3′,5′-difluorobenzyl groups, which have lower electron
densities.
To visualize the Ag+–π interactions, the isosurfaces of the
LUMOs and HOMOs of the Ag+ complexes were calculated
using the B3LYP/3-21G(*) theoretical level.7 Fig. 9 and Fig. S17
in the ESI† show the LUMO (mesh) and HOMOs (solid) of the
X-ray structures of the 1/Ag+–3/Ag+ complexes. In all cases, the
LUMO of the Ag+ ion is distorted by interaction with the
HOMOs of the aromatic side-arms. These graphics clearly
support Ag+–π interactions between the Ag+ ion and the aro-
matic side-arms.
A ROESY spectrum was obtained (Fig. 7) to confirm the con-
formations of the side-arms in solution. A cross-peak was
observed between the Hd protons of the 3′,5′-difluorobenzyl
groups and the Ha protons of the 4′-methylbenzyl groups
in the side-arms. This result clearly indicates that the
Conclusions
In conclusion, we demonstrated that tetra-armed cyclens with
two kinds of aromatic side-arms behave like argentivorous
8214 | Dalton Trans., 2013, 42, 8212–8217
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1,7-Bis(3′,5′-difluorobenzyl)-4,10-bis(1′′-naphthylmethyl)-1,4,7,10-
tetraazacyclododecane (2). An eluent for column chromato-
graphy: toluene. Yield 27%. Mp: 95.1–96 °C. 1H NMR
(400 MHz, CDCl3): δ 8.37–8.30 (m, 2H), 7.86–7.80 (m, 2H), 7.74
(d, J = 8.0 Hz, 2H), 7.56 (d, J = 7.2 Hz, 2H), 7.50–7.44 (m, 4H),
7.37 (dd, J1 = 8.0 Hz, J2 = 7.2 Hz, 2H), 6.76 (d, J = 6.4 Hz, 4H),
6.61 (dd, J1 = 8.8 Hz, J2 = 2.4 Hz, 2H), 3.88 (s, 4H), 3.28 (s, 4H),
2.74 (t, J = 4.8 Hz, 8H), 2.66 (t, J = 4.8 Hz, 8H). FAB-MS (m/z)
(matrix: DTT–TG = 1 : 2): 705 ([M + 1]+, 75%). Anal. Calcd for
C44H44N4F4: C, 74.98; H, 6.29; N, 7.95. Found: C, 75.19; H,
6.41; N, 7.99.
Fig. 9 LUMO (mesh), HOMO[−4], HOMO[−5], HOMO[−6], and HOMO[−7]
(solid) from X-ray structures of Ag+ complexes with 1 (the isosurface value is
0.032 au).
1,7-Bis(9′-anthrylmethyl)-4,10-bis(3′′,5′′-difluorobenzyl)-1,4,7,10-
tetraazacyclododecane (3). An eluent for column chromato-
graphy: chloroform–methanol
= 20 : 1. Yield 10%. Mp:
173.8–174.9 °C. 1H NMR (400 MHz, CDCl3): δ 8.55 (d, J =
8.0 Hz, 4H), 8.38 (s, 2H), 7.98 (d, J = 8.0 Hz, 4H), 7.54–7.41 (m,
8H), 6.58 (dd, J1 = 8.8 Hz, J2 = 2.4 Hz, 2H), 6.52 (d, J = 6.4 Hz,
4H), 4.38 (s, 4H), 3.06 (s, 4H), 2.77 (t, J = 5.6 Hz, 8H), 2.56 (t,
J = 5.6 Hz, 8H). FAB-MS (m/z) (matrix: DTT–TG = 1 : 2): 805
([M + 1]+, 60%). Anal. Calcd for C38H44N4F40.5H2O: C, 76.73;
H, 6.07; N, 6.88. Found: C, 76.77; H, 6.09; N, 7.01.
molecules in the solid-state and in solution; aromatic side-
arms with high electron densities preferentially cover the Ag+
ions incorporated into the ligand cavities, whereas aromatic
side-arms with lower electron densities do not. This is the first
example showing the relative strengths of the Ag+–π inter-
actions between different aromatic rings within a molecule.
Experimental
General procedure of the preparation of metal complexes
1/AgCF3SO3 complex. 1 (0.0151 mmol) in chloroform (1 mL)
was added to the corresponding metal salt (AgCF3SO3, AgBF4,
or Cu(CF3SO3)2) (0.0153 mmol) in methanol (1 mL). Crystals
were obtained quantitatively on evaporation of the solvent.
Mp: 191–193 °C (dec.). Anal. Calcd for C39H44N4O3SF7Ag: C,
52.65; H, 4.98; N, 6.30. Found: C, 52.98; H, 5.05; N, 6.01.
1/Cu(CF3SO3)2 complex. Mp: 308–309.5 °C (dec.). Anal.
Calcd for C40H44N4O6S2F10Cu: C, 48.31; H, 4.46; N, 5.63.
Found: C, 48.29; H, 4.57; N, 5.89.
Melting points were obtained with a Mel-Temp capillary
apparatus and not corrected. FAB-MS was performed using a
JEOL 600 H spectrometer. H NMR spectra were measured in
CDCl3 on a JEOL ECP400 (400 MHz) spectrometer. Cold
ESI-MS were recorded on a JEOL JMS-T100CS spectrometer.
1
General procedures for the reaction of 1,7-bis(3′,5′-
difluorobenzyl)-1,4,7,10-tetraazacyclododecane with
aromatic aldehydes
2/AgBF4 complex. Mp: 196–198 °C (dec.). Anal. Calcd for
After stirring a mixture of 1,7-bis(3′,5′-difluorobenzyl)-1,4,7,10- C49H44N4BF8Ag·0.5CH3CN: C, 58.75; H, 4.98; N, 6.85. Found:
tetraazacyclododecane (1.0 mmol) and aromatic aldehydes C, 58.76; H, 5.09; N, 6.93.
(4.1 mmol) in dry 1,2-dichloroethane (12 mL) at room tempera-
3/AgCF3SO3 complex. Mp: 218–219 °C (dec.). Anal. Calcd for
ture for 1 day under an argon atmosphere (1 MP), NaBH(OAc)3 C53H48N4O3SF7Ag: C, 59.95; H, 4.56; N, 5.28. Found: C, 59.86;
(4.0 mmol) was added and the mixture was stirred for 1 day at H, 4.63; N, 4.93.
room temperature. Saturated aqueous NaHCO3 was added and
the aqueous layer was extracted with chloroform thrice. The
combined organic layer was washed with water, dried over
Na2SO4, and concentrated. The residual solid was purified by
X-ray structure determination
column chromatography on silica-gel. The main fraction was Crystals of the AgCF3SO3, AgBF4, and Cu(CF3SO3)2 complexes
recrystallized from acetonitrile to give the following products.
with ligands were mounted on top of a glass fiber, and data
1,7-Bis(3′,5′-difluorobenzyl)-4,10-bis(4′′-methylbenzyl)-1,4,7,10- collections were performed using a Bruker SMART CCD area
tetraazacyclododecane (1). An eluent for column chromato- diffractometer at 90–298 K. Data were corrected for Lorentz
graphy: toluene–ethanol–ammonia = 5 : 2 : 0.07. Yield 54%. and polarization effects, and absorption corrections were
1
Mp: 111.7–112.5 °C. H NMR (400 MHz, CDCl3): δ 7.18 (d, J = applied using the SADABS8 program. Structures were solved by
8.0 Hz, 4H), 7.05 (d, J = 8.0 Hz, 4H), 6.91(d, J = 6.4 Hz, 4H), a direct method and subsequent difference-Fourier syntheses
6.66 (tt, J1 = 8.8 Hz, J2 = 2.4 Hz, 2H), 3.39 (s, 4H), 3.34 (s, 4H), using the program SHELEX.9 All non-hydrogen atoms were
2.64 (s, 8H), 2.63 (s, 8H), 2.30 (s, 6H). FAB-MS (m/z) (matrix: refined anisotropically and hydrogen atoms were placed at cal-
DTT–TG = 1 : 2): 633 ([M + 1]+, 100%). Anal. Calcd for culated positions and then refined using Uiso(H) = 1.2Ueq(C).
C38H44N4F4: C, 72.13; H, 7.01; N, 8.85. Found: C, 72.19; H, The crystallographic refinement parameters of the complexes
7.05; N, 8.79.
are summarized in Table 1.
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Table 1 Crystal data of 1, 1/AgCF3SO3, 1/Cu(CF3SO3)2, 2, 2/AgBF4, 3, and 3/Ag CF3SO3
Compound
1
1/AgCF3SO3
1/Cu(CF3SO3)2
2
2/AgBF4
3
3/AgCF3SO3
Formula
Mr
Temperature
C38H44F4N4
632.77
90 K
C78H89Ag2F14N8O7S2 C44H51CuF10N6O7S2 C44H44F4N4
C46H47AgBF8N5 C52H48F4N4
C53H48AgF7N4O3S
1061.88
223 K
1796.43
298 K
1093.57
90 K
704.83
298 K
940.57
223 K
804.94
90 K
Wavelength
Crystal system Triclinic
Space group
a(Å)
b(Å)
c(Å)
α(°)
β(°)
0.71073
0.71073
Monoclinic
P2(1)/c
10.0071(5)
15.1936(7)
27.0539(13)
90
93.5910(10)
90
4105.3(3)
2
0.71073
Triclinic
P1
0.71073
Triclinic
P1
0.71073
Monoclinic
P2(1)/c
10.0718(9)
30.925(3)
16.7058(11)
90
126.958(4)
90
4157.9(6)
4
0.71073
Triclinic
P1
0.71073
Monoclinic
P2(1)/c
14.8401(8)
14.3569(8)
23.2128(11)
90
112.169(3)
90
4580.1
P1
9.7254(8)
11.1668(10)
15.5750(14)
91.609(2)
99.574(2)
93.894(2)
1662.7(3)
2
11.7735(17)
13.944(2)
16.541(2)
108.029(3)
106.344(3)
102.841(3)
2331.1(6)
2
9.1992(10)
10.3017(11)
10.9195(11)
79.597(2)
88.318(2)
67.609(2)
940.18(17)
1
8.8124(8)
9.6778(9)
13.3655(12)
86.321(2)
71.759(2)
63.608(2)
965.98(15)
1
γ(°)
V(Å3)
Z
4
D calculated
1.264
1.453
1.558
1.245
1.503
1.384
1.540
(Mg m−3
μ/mm−1
F(000)
)
0.090
672
0.616
1842
0.656
1128
0.087
372
0.561
1982
0.094
424
0.565
2176
Crystal size
0.31 × 0.20 × 0.29 × 0.24 × 0.15
0.19
0.29 × 0.24 × 0.15
0.52 × 0.38 × 0.72 × 0.45 ×
0.29 0.39
0.42 × 0.18 × 0.77 × 0.75 × 0.39
0.18
(mm3)
θ range for
data collection
(°)
1.83 to 28.30 1.51 to 28.35
1.40 to 28.36
1.90 to 28.35 1.32 to 28.34
1.61 to 28.32 1.48 to 28.33
Index ranges
−9 ≤ h ≤ 12 −13 ≤ h ≤ 13
−14 ≤ k ≤ 13 −20 ≤ k ≤ 12
−20 ≤ l ≤ 20 −36 ≤ l ≤ 35
−15 ≤ h ≤ 15
−9 ≤ k ≤ 18
−22 ≤ l ≤ 22
16 839
−9 ≤ h ≤ 12 −12 ≤ h ≤ 13
−12 ≤ k ≤ 13 −41 ≤ k ≤ 40
−13 ≤ l ≤ 14 −22 ≤ l ≤ 22
−6 ≤ h ≤ 11 −19 ≤ h ≤ 13
−12 ≤ k ≤ 12 −19 ≤ k ≤ 17
−17 ≤ l ≤ 17 −30 ≤ l ≤ 30
Reflections
collected
11 994
30 203
7050
31 007
7261
33 769
Independent
reflections
8151
[R(int) =
0.0252]
10 249
[R(int) = 0.0745]
11 391
[R(int) = 0.0397]
4629
10 345
4723
11 379
[R(int) = 0.0202]
[R(int) =
0.0126]
0.9752,
0. 0.9562
Full-matrix
[R(int) = 0.0264] [R(int) =
0.0221]
0.9834,
0.9612
Max. and min. 0.9833,
0.9155, 0.8426
0.9104, 0.8336
0.8129, 0.6867
0.8094, 0.6715
transmission
Refinement
method
0.9722
Full-matrix
Full-matrix least-
Full-matrix least-
Full-matrix least- Full-matrix
Full-matrix least-
least-squares squares on F2
on F2
least-squares squares on F2
squares on F2
least-squares squares on F2
on F2
on F2
Data/restraints/ 8151/0/417
parameters
10 249/0/507
0.828
11 391/0/635
0.739
4629/0/235
1.034
10 345/36/551
1.050
4723/0/271
11 379/0/670
Goodness-of-fit 1.029
0.983
1.054
on F2
Final R indices 0.0518,
0.0516, 0.0882
0.0641, 0.1603
0.0565,
0.1475
0.0361, 0.0941
0.0552,
0.1314
0.0298, 0.0796
[I > 2σ(I)] R1,
wR2
0.1208
R indices (all
data) R1, wR2
Largest diff.
0.0801,
0.1342
0.332 and
0.1097, 0.1009
0.1011, 0.1821
0.0954,
0.1698
0.247 and
−0.157
0.0448, 0.0989
0.0789,
0.1449
0.425 and
−0.240
0.0357, 0.0833
1.183 and −0.357
1.421 and −0.986
0.820 and
−0.323
0.665 and −0.427
peak and hole −0.227
(e Å−3
)
E. S. Meadows, Coord. Chem. Rev., 2001, 222, 127;
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Acknowledgements
This research was supported by Grants-in-Aid (08026969 and
11011761), a High-Tech Research Center project (2005–2009),
and the Supported Program for Strategic Research Foundation
at Private Universities (2012–2016) from the Ministry of
Education, Culture, Sports, Science and Technology of Japan,
and the Futaba Memorial Foundation, for Y.H.
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