Re-Re bond breaking of (μ-H)3Re3(CO) 11(NCMe) upon reaction with PPh2(o-C6H 4)(CH2NMeCH)C60 to generates monorhenium and dirhenium phosphino-fullerene complexes

Article abstract of DOI:10.1039/c2dt32291a

Reaction of PPh₂(o-C₆H₄)(CH ₂NMeCH)C₆₀ (1) and (μ-H)₃Re ₃(CO)₁₁(NCMe) in refluxing chlorobenzene affords the monorhenium complex HRe(CO)₃(η³-PPh

Full text of DOI:10.1039/c2dt32291a

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PAPER
Re–Re bond breaking of (μ-H)3Re3(CO)11(NCMe) upon
reaction with PPh2(o-C6H4)(CH2NMeCH)C60 to
generates monorhenium and dirhenium phosphino–
fullerene complexes†
Cite this: Dalton Trans., 2013, 42, 2488
Chia-Hsiang Chen and Wen-Yann Yeh*
Reaction of PPh2(o-C6H4)(CH2NMeCH)C60 (1) and (μ-H)3Re3(CO)11(NCMe) in refluxing chlorobenzene
affords the monorhenium complex HRe(CO)3(η3-PPh2(o-C6H4)(CH2NMeCH)C60) (2), and the dirhenium
Received 29th September 2012,
Accepted 13th November 2012
complexes (μ-H)Re2(CO)7(μ,η3-PPh(o-C6H4)2(CH2NMeCH)C60
)
(3) and (μ-H)Re2(CO)5(μ-SSOH)(μ,η5-PPh2-
(o-C6H4)(CH2NMeCH)C60) (4). The structures of 2–4 have been determined by an X-ray diffraction study.
The oxatrisulfanyl (–SSOH) ligand of 4 likely arises from decomposition of CS2 on silica gel during the
purification processes.
DOI: 10.1039/c2dt32291a
www.rsc.org/dalton
generate the face-capping complex (μ-H)3Re3(CO)9(η2,η2,η2-C60).9
In contrast, compound 1 reacts with (μ-H)3Re3(CO)11(NCMe)
Introduction
The discovery of fullerenes in 1985 marked the beginning of a under similar conditions to result in Re–Re bond activation
new field of chemical research.1 Attachment of organometallic and afford the monorhenium complex HRe(CO)3(η3-PPh2-
complexes to fullerenes is an important area within fullerene (o-C6H4)(CH2NMeCH)C60) (2; 22%), and two dirhenium
chemistry, due to its potential application in biological, mag- complexes (μ-H)Re2(CO)7(μ,η3-PPh(o-C6H4)2(CH2NMeCH)C60)
netic, electronic, catalytic and optical devices.2,3 With the (3; 14%) and (μ-H)Re2(CO)5(μ-SSOH)(μ,η5-PPh2(o-C6H4)(CH2-
development of an extensive organic chemistry of fullerenes, it NMeCH)C60) (4; 2%) after purification by TLC, HPLC, and
is now possible to construct a variety of modified fullerenes recrystallization. The results are summarized in Scheme 1.
that incorporate metal-binding groups into their structures.4 This reaction did not proceed at room temperature, and at
The syntheses of such fullerene-containing ligands offer the 60 °C only slow decomposition of (μ-H)3Re3(CO)11(NCMe) was
potential to exploit the chemical reactivity, redox and electron- observed. It appears that the bridging hydrides play an impor-
acceptor characteristics, photochemical behavior, electron- tant role in maintaining the Re2 skeleton, since the reaction
withdrawing properties, and novel structural features that a of 1 and M3(CO)12 (M = Ru, Os) was found to produce
fullerene group provides.5 We recently prepared the phos-
phine-functionalized fullerene PPh2(o-C6H4)(CH2NMeCH)C60
(1) according to Prato’s method6 and describe the reactivity
towards tungsten, triruthenium, and triosmium carbonyl com-
plexes.7 With our continued interest in phosphine and fuller-
ene chemistry,8 herein we present the results from the reaction
of 1 and (μ-H)3Re3(CO)11(NCMe), which leads to different-style
products bearing uncommon architectures.
Results and discussion
Reaction of the pristine fullerene C60 with (μ-H)3Re3-
(CO)11(NCMe) in refluxing chlorobenzene has been shown to
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
†CCDC 903345 for 2, 903346 for 3 and 903347 for 4. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/c2dt32291a
Scheme 1 Reaction of 1 and (μ-H)3Re3(CO)11(NCMe).
2488 | Dalton Trans., 2013, 42, 2488–2494
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Fig. 1 ORTEP diagram of 2 with 30% probability ellipsoids. Selected bond dis-
tances (Å): Re1–P1 2.470(2), Re1–C1 1.962(9), Re1–C2 1.949(7), Re1–C3 2.018
(7), Re1–C27 2.296(9), Re1–C28 2.262(9), C22–C26 1.58(1), C21–C22 1.52(1),
C16–C21 1.38(1), C24–C25 1.55(1), C25–C26 1.61(1), N1–C22 1.47(1), N1–C23
1.45(1), N1–C24 1.46(1). Selected bond angles (°): Re1–C1–O1 177.3(6), Re1–
C2–O2 171.4(8), Re1–C3–O3 168.7(2), C1–Re1–C2 88.9(3), C1–Re1–C3 86.9(3),
C2–Re1–C3 173.6(4), C1–Re1–P1 151.9(3), C2–Re1–P1 92.0(3), C3–Re1–P1 89.4(2),
C27–Re1–P1 90.7(2), C28–Re1–P1 127.6(2), C27–Re1–C28 37.2(3), C4–P1–
C10 103.0(4), C4–P1–C16 102.1(4), C10–P1–C16 104.4(4).
predominantly the mononuclear complexes M(CO)3(η3-PPh2-
(o-C6H4)(CH2NMeCH)C60).7
Compound 2 forms an air-stable, dark green crystalline
solid. The MALDI mass spectrum presents the molecular ion
Fig. 2 ORTEP diagram of 3 with 30% probability ellipsoids. The bridging
hydride is not located, but is believed at the position trans to Re1–C2 and Re2–
peak at m/z 1309 (187Re), corresponding to the combination of C6 bonds. Selected bond distances (Å): Re1–P1 2.449(4), Re1–N1 2.34(1), Re1–
1 and an HRe(CO)3 unit. The 1H NMR spectrum displays multi-
C1 2.01(2), Re1–C2 1.76(2), Re1–C3 1.95(2), Re2–C4 2.00(2), Re2–C5 2.00(3),
Re2–C6 2.01(2), Re2–C7 2.02(2), Re2–C8 2.21(2), C8–C13 1.38(2), C13–P1 1.85(1),
plets in δ 8.00–6.98 for the aromatic protons, a doublet at
C26–N1 1.49(2), C27–N1 1.49(2), C28–N1 1.49(2), C28–C29 1.56(2), C26–
δ 5.98 (4JP–H = 4 Hz) for the methynyl proton, two doublets at
C30 1.58(2), C29–C30 1.65(2), Re1⋯Re2 = 3.337. Selected bond angles (°): Re1–
C1–O1 177(2), Re1–C2–O2 175(2), Re1–C3–O3 176(2), Re2–C4–O4 176(2), Re2–
δ 4.50 and 4.09 (JH–H = 9 Hz) for the diastereotopic methylene
protons, a singlet at δ 2.42 for the methyl protons, and a C5–O5 177(2), Re2–C6–O6 172(2), Re2–C7–O7 173(2), P1–Re1–N1 86.6(3), P1–
Re1–C1 171.5(6), P1–Re1–C2 96.1(7), C3–Re1–N1 176.5(6), C5–Re2–C8 172.4(7),
doublet at δ −4.25 (JP–H = 34 Hz) assigned to the terminal
C4–Re2–C7 166.4(8), Re2–C8–C13 128(1), C8–C13–P1 120(1), Re1–N1–C27
hydride ligand. The 31P resonance of 2 at δ −3.17 is 16.3 ppm
110.9(8), C26–N1–C27 114(1), C27–N1–C28 105(1).
upfield of the free ligand 1 (δ −19.47).
The molecular structure for 2 is depicted in Fig. 1. It con-
sists of discrete molecules with each rhenium atom bonded to
three terminal CO, one 6 : 6-ring junction of the fullerene, a
hydrogen atom, and a phosphine ligand. Taking the center of
the C27–C28 bond, the coordination about the rhenium atom
can be described as a distorted octahedron. Apparently, steric
constraints of the pyrrolidine group allows the rhenium
atom to bind the 6 : 6-ring junction at the 3,4-position, with
Re1–C27 = 2.296(9) Å and Re1–C28 = 2.262(9) Å. This bonding
comparison with other unperturbed (6 : 6)-double bonds, and
may be attributed to π-back-donation from the electron-rich
rhenium center.
Compound 3 forms an air-stable, green solid. The solution
IR spectrum displays seven absorption peaks in the range
2085–1930 cm−1 for terminal carbonyl stretch. The isotope dis-
tribution for the molecular ion peaks around m/z
1607 matches a Re2 pattern, so a composition of [1 + Re2(CO)7]
can be postulated for 3. However, the 1H NMR spectrum
depicts a bridging hydride resonance at δ −10.43, and the
N–CH3 resonance at δ 4.02 is deshielded by 1.45 ppm com-
pared to 1 (δ 2.57). Crystals of 3 suitable for an X-ray diffraction
study were grown from CS2–n-hexane at ambient temperature.
An ORTEP diagram is illustrated in Fig. 2. Compound 3 con-
tains two rhenium atoms which are not directly bonded to
each other and to the fullerene surface. The Re1 atom is linked
feature causes
a substantial distortion surrounding the
rhenium atom, such that the trans P1–Re1–C1 angle is 151.9(3)°,
and the angles Re1–C3–O3 = 168.7(2)° and Re1–C2–O2 =
171.4(8)° are not linear. The average Re–Cfullerene distance,
2.27(1) Å, is comparable with (μ-H)3Re3(CO)8(PMe3)(η2,η2,η2-
C60) (av. 2.27(2) Å)10 but slightly longer than that measured for
H8Re2(PMe3)4(η2,η2-C60) (av. 2.20(1) Å).11 Meanwhile, the
distance C28–C29 = 1.45(1) Å is elongated (ca. 0.07 Å) in
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to three terminal carbonyls, the nitrogen atom of the pyrroli- Re2–C31 = 2.37(1) Å and Re2–C32 = 2.39(1) Å. The C–C
dine ring, and a phosphine ligand, while the Re2 atom is distances within the coordinated hexagon are varying, such as
linked to four terminal carbonyls and the ortho-carbon of one C29–C30 = 1.43(1) Å, C30–C31 = 1.51(1) Å, C31–C32 = 1.42(1) Å,
phenyl ring. The bridging hydride ligand, which occupies a C32–C33 = 1.49(2) Å, C33–C34 = 1.39(1) Å and C34–C29 = 1.48
distinct coordination site, has not been located, and is (1) Å. The SSOH ligand spans the Re–Re edge with Re1–S1 =
believed to be at the position trans to the Re1–C2 and Re2–C6 2.464(3) Å, Re2–S1 = 2.481(3) Å, and Re1–S1–Re2 = 75.83(9)°,
bonds, forming a two-electron three-centered bond to the two where the Re2, S1, S2, and O6 atoms are nearly coplanar.
rhenium atoms. The Re1⋯Re2 distance (3.337 Å) is compar-
Origin of the oxatrisulfanyl ligand in 4 attracted our atten-
able with (μ-H)Re2(CO)8(μ-SC12H7) (3.345 Å),12 but is substan- tion. We have carried out the purification processes by TLC
tially longer than those measured for (μ-H)Re2(CO)8(μ-PBut2) without using CS2 as eluent and found no formation of 4, as
(3.1291(2) Å),13 (μ-H)Re2(CO)8(μ-SC6H11) (3.093(1) Å),14 and evidenced by HPLC and MALDI mass spectroscopy. Thus, we
(μ-H)Re2(CO)8(μ-PFu2) (3.1571(3) Å).15 For comparison, the suggest the SSOH species arising from decomposition and/or
Re–Re single bond distance is 3.041(1) Å in Re2(CO)10.16 It is of hydrolysis of CS2 solvent on silica gel. Although oxatrisulfane
interest that the pyrrolidine nitrogen atom is coordinated to (HSSOH) has been prepared and studied from flash vacuum
the rhenium atom, with Re1–N1 = 2.34(1) Å, which accounts pyrolysis of ButS(O)SBut at 700 °C,19 its coordination chemistry
for deshielding of the methyl proton resonance, and one to metal ions or complexes is unprecedented. Noteworthy, dis-
phenyl group connected to the phosphorus atom has under- solving the single crystals of 4 in chlorobenzene-d5 at 25 °C
gone an orthometallation reaction to the Re2 atom, with exhibits two methyl proton resonances at δ 2.59 and 2.58, two
Re2–C8 = 2.21(2) Å. Finally, we note that, for electron counting, hydride resonances at δ −12.04 and −12.09, and two 31P reson-
the bridging hydride can be portrayed by a half-arrow notation ances at δ −6.44 and −6.78 in an approximate ratio of 2 : 3.
(shown below), originally described by Green.17 This combi- These peaks start broadening at 60 °C, but the fast-exchange
nation of electron donation can be considered to cause the region cannot be reached due to severe decomposition of 4 at
hydride to act as a three-electron ligand.18
higher temperatures. This suggests the existence of two confor-
mers for 4 in solution, likely having a dynamic process with
the SOH segment flipping up-and-down of the Re2S plane
shown below.
Compound 4 was obtained in low yield after purification of
the products by TLC (silica gel, eluting with CS2) and HPLC
(Cosmosil 5PBB column, eluting with toluene). The IR spec-
The UV-vis spectra of 1–4 in dichloromethane (10−5 M) are
trum displays five CO stretches ranging from 2040 to displayed in Fig. 4, with the data summarized in Table 1. The
1
1902 cm−1, and the H NMR spectrum indicates the presence spectral features are similar where the absorptions between
of a bridging hydride ligand. The MALDI mass spectrum 250 and 410 nm are due to π → π* transitions of fullerene and
shows the molecular ion peaks around m/z 1632, which phenyl groups.20 These features are typical of a fullerene cage
matches a Re2 isotope distribution but its composition cannot which has been modified only slightly by complexation.21
be figured out. Because of the absence of diagnostic spectral Compounds 2 and 3 contain a redox-active fullerene core, and
features to reveal the structure of 4, single-crystal X-ray diffrac- their electrochemical properties were measured by cyclic vol-
tion study was performed. An ORTEP drawing of 4 is shown in tammetry in dry, oxygen-free CS2–CH2Cl2 (3 : 2, v/v) solution at
Fig. 3. It consists of a dirhenium system where the Re1 atom is 27 °C. CS2 was added as the co-solvent to improve the solubi-
linked to two terminal carbonyls, a phosphine ligand, and one lity of the complexes. Under these conditions, two irreversible
6 : 6-ring junction of the fullerene, while the Re2 atom is fullerene reduction waves ranging from −1100 to −1800 mV
linked to three terminal carbonyls and one 6 : 6-ring junction. (vs. Fc/Fc+ couple) were recorded for 1–3 (Fig. 5).22 In compari-
Quite surprisingly, an oxatrisulfanyl (–SSOH) ligand was found son with 1, the first reduction potential of 2 is ca. 36 mV more
to bridge the Re–Re edge. The bridging hydrogen atom was positive while 3 is 23 mV more negative. It is expected that
not located, which likely lies on the (Re1, S1, Re2) plane metal coordination affects fullerene reduction in two ways. Dis-
against the S1 atom. The Re1–Re2 length (3.0381(7) Å) is ruption of C–C conjugation caused byπ-backbonding electron
within the Re–Re single bond distances. Individual Re–CO dis- acceptance from the metal may disfavor reduction (negative
tances range from 1.91(1) Å to 1.97(2) Å, C–O distances range shifts), whereas delocalization of negative charge from fuller-
from 1.12(1) Å to 1.14(1) Å, and the Re–C–O angles are in the ene to the metal center and/or metal coordination-induced
range 174(1)–179(1)°. The fullerene core binds the two fullerene surface distortion may favor reduction (positive
rhenium atoms through two 6 : 6-ring junctions at the 3,4- and shifts).9,11,23 In general these potential shifts are a conse-
16,17-position, with Re1–C29 = 2.34(1) Å, Re1–C30 = 2.26(1) Å, quence of not easily separated factors.
2490 | Dalton Trans., 2013, 42, 2488–2494
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Fig. 3 (a) ORTEP diagram of 4 with 30% probability ellipsoids. (b) Configuration surrounding the rhenium atoms, showing the probable position of the bridging
hydride. Selected bond distances (Å): Re1–P1 2.435(4), Re1–C1 1.97(2), Re1–C2 1.91(1), Re1–C29 2.34(1), Re1–C30 2.26(1), Re1–Re2 3.0381(7), Re1–S1 2.464(3),
Re2–S1 2.481(3), S1–S2 2.076(5), S2–O6 1.84(1), Re2–C3 1.95(2), Re2–C4 1.94(1), Re2–C5 1.96(1), Re2–C31 2.37(1), Re2–C32 2.39(1), C29–C30 1.43(1), C30–C31
1.51(1), C31–C32 1.42(1) C32–C33 1.49(2), C33–C34 1.39(1), C34–C29 1.48(1). Selected bond angles (°): Re1–C1–O1 179(1), Re1–C2–O2 174(1), Re2–C3–O3 175(1),
Re2–C4–O4 176(1), Re2–C5–O5 178(1), P1–Re1–S1 161.7(1), C2–Re1–Re2 146.1(3), C29–Re1–C30 36.2(4), C4–Re2–Re1 144.7(3), C5–Re2–S1 173.3(4), C31–
Re2–C32 34.7(3), Re1–S1–Re2 75.83(9), S1–S2–O6 106.3(4), C29–C30–C31 120.8(9), C30–C31–C32 120.6(9), P1–Re1–C1 81.5(4), P1–Re1–C2 98.3(4), C3–Re2–C5
86.1(5), C4–Re2–C5 92.7(5).
dirhenium complexes. Compound 1 is able to act as an η3-P,C2
chelating agent in 2, an η3-P,N,C bridging ligand in 3, and an
η5-P,C2,C2 multidentate ligand in 4, demonstrating a flexible
binding capacity. The versatile bonding properties of 1 are
applicable to split polynuclear complexes, or serve as a hemila-
bile chelating agent to alter the activity of the bound metal
centers and may find an application in homogeneous catalytic
systems.
Experimental section
Fig. 4 Absorption spectra of 1–4 in dichloromethane.
General methods
All manipulations were carried out under an atmosphere of
purified dinitrogen with standard Schlenk techniques.
Table 1 UV-vis data of 1–4
(μ-H)3Re3(CO)11(NCMe)24 and PPh2(o-C6H4)(CH2NMeCH)C60
Compound
λmax, nm (ε, 103 M−1 cm−1
)
(1)7 were prepared as described in the literature. Preparative
thin-layer chromatographic (TLC) plates were prepared from
silica gel (Merck). Infrared spectra were recorded on a Jasco
1
2
3
4
228 (160), 256 (180), 308 (60), 326 (56)
230 (161), 253 (151), 327 (54)
229 (177), 256 (190), 314 (61), 431(5)
228 (202), 255 (183), 328 (44), 408 (25)
1
FT/IR-4100 IR spectrometer. H and 31P spectra were obtained
on
a
Bruker ADVANCE-300 spectrometer at 300 and
121.5 MHz. UV-Vis spectra were recorded from 200 to 700 nm
in dichloromethane by using a 1.0 cm quartz cell with an
Agilent 8452 spectrophotometer. Matrix-assisted laser deso-
rption ionization (MALDI) mass spectra were recorded on a
Bruker Microflex-LT mass spectrometer. High-resolution mass
In summary, we have shown that the phosphine-functiona-
lized fullerene molecule 1 can activate the metal–metal bond
of (μ-H)3Re3(CO)11(NCMe) and generate monorhenium and
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spectra (HRMS) were measured with Finnigan/Thermo Quest vacuum, and the residue was subjected to TLC, with carbon
MAT and JMS-700 HRMS mass spectrometers. disulfide–dichloromethane–n-hexane (8 : 1 : 3, v/v) as eluent.
Reaction of 1 and (μ-H)Re3(CO)11(NCMe). Compound 1 Isolation of the material forming the first brown band afforded
(50 mg, 0.048 mmol) and (μ-H)Re3(CO)11(NCMe) (44 mg, (μ-H)Re2(CO)7(μ,η3-PPh(o-C6H4)2(CH2NMeCH)C60) (3; 10.7 mg,
0.048 mmol) were placed in an oven-dried 100 mL Schlenk 13.8%) and the second green band afforded HRe(CO)3(η3-
flask, equipped with a condenser, under a dinitrogen atmos- PPh2(o-C6H4)(CH2NMeCH)C60) (2; 13.1 mg, 21.7%). The third
phere. Chlorobenzene (30 mL) was introduced into the flask brown band gave a mixture, which was further purified by pre-
via a syringe, and the solution was heated to reflux for 20 min. parative HPLC with a Cosmosil 5PBB column (10 × 250 mm),
The solution was cooled to room temperature, dried under eluting with toluene (flow rate: 0.3 mL min−1). The brown
complex (μ-H)Re2(CO)5(μ-SSOH)(μ,η5-PPh2(o-C6H4)(CH2NMeCH)-
C60) (4; 1.5 mg, 2%) was collected at the retention time of
103 min.
Characterization of 2. MS (MALDI) m/z 1309 (M+, 187Re); IR
1
(CS2) ν(CO) 2060 m, 2003 m, 1941 s cm−1; H NMR (CD2Cl2 +
CS2, 25 °C) δ 8.00–6.98 (m, 14H, Ph, C6H4), 5.98 (d, 1H, JP–H
4.2 Hz, CH), 4.50 (d, 1H, JH–H = 9 Hz, CH2), 4.09 (d, 1H, JH–H
=
=
9 Hz, CH2), 2.42 (s, 3H, CH3), −4.25 (d, 1H, JP–H = 34 Hz, Re–H);
31P{1H} NMR (CD2Cl2 + CS2, 25 °C) δ −3.17 (s). HRMS (ESI)
Calcd for C84H22NO3PRe (MH+): 1310.0889. Found: 1310.0858.
Characterization of 3. MS (MALDI) m/z 1607 (M+, 187Re); IR
(methylcyclohexane) ν(CO): 2085 m, 2028 s, 1990 s, 1972 vs,
1950 s, 1940 m, 1930 m cm−1 1H NMR (CD2Cl2, 25 °C)
;
δ 8.54–6.70 (m, 13H, Ph, C6H4), 6.33 (s, 1H, CH), 6.14 (d, 1H,
JH–H = 13 Hz, CH2), 5.49 (d, 1H, JH–H = 13 Hz, CH2), 4.02 (s, 3H,
CH3), −10.43 (d, 1H, JP–H = 9 Hz, μ-H); 31P{1H} NMR (CD2Cl2,
25 °C) δ 22.05 (s). HRMS (FAB) Calcd for C88H21NO7PRe2
(MH+): 1608.0179. Found: 1608.0182.
Characterization of 4. MS (MALDI) m/z 1632 (M+, 187Re); IR
(CS2) ν(CO) 2040 s, 2001 m, 1970 w, 1950 m, 1902 w cm−1
.
1H NMR (C6D5Cl, 25 °C) δ 8.16–7.10 (m, 14H, Ph, C6H4), 6.91
(m, 1H, CH), 4.55 (m, 1H, CH2), 4.33 (m, 1H, CH2), 3.71 (br,
1H, OH), 2.59 (s, 1.2H, CH3), 2.58 (s, 1.8H, CH3), −12.05
(d, 0.4H, JP–H = 10 Hz, μ-H), −12.08 (d, 0.6H, JP–H = 10 Hz, μ-H);
31P{1H} NMR (CD2Cl2, 25 °C): δ −6.44 (s, 0.4P), −6.78 (s, 0.6P).
Cyclic voltammetric measurements for 2 and 3. Electroche-
mical measurements were taken with a CV 50 W system. Cyclic
voltammetry was performed with a Pt button working elec-
trode, a Pt-wire auxiliary electrode and an Ag/AgCl reference
Fig. 5 Cyclic voltammograms for 1–3 in carbon disulfide–dichloromethane
(3 : 2, v/v). The potential was scanned at 10 mV s−1 at 27 °C, with arrows indicat-
ing the direction of current. The potentials are vs. the Fc/Fc+ couple.
Table 2 Crystallographic data for compounds 2·CS2, 3, and 4·CS2
2·CS2
3
4·CS2
Formula
Cryst solvent
C85H21NO3PReS2
CS2
C88H19NO7PRe2
C173H42N2O12P2Re4S6
0.5CS2
Formula weight
Crystal system
Space group
1385.32
Triclinic
ˉ
P1
1605.41
Monoclinic
C2/c
3339.19
Monoclinic
P21/n
a/Å
b/Å
c/Å
α/°
10.1313(5)
16.7505(10)
17.0644(8)
116.909(3)
100.253(2)
90.025(3)
2530.3(2)
200(2)
32.402(3)
18.559(2)
22.676(3)
90
103.232(8)
90
10.0769(2)
22.5349(7)
24.5205(6)
90
98.086(2)
90
β/°
γ/°
V/Å3
T/K
13 275 (3)
200(2)
5512.8(2)
200(2)
Z
2
8
2
μ, mm−1
R1, wR2
GOF on F2
2.583
0.0596/0.1206
1.070
3.729
0.0725/0.1471
0.868
4.602
0.0597/0.1378
1.099
2492 | Dalton Trans., 2013, 42, 2488–2494
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electrode. The experiments were carried out with 1 mM sol-
ution of 2 and 3, respectively, in dry carbon disulfide–dichloro-
methane (3 : 2, v/v) solvents containing 0.1 M (n-C4H9)4NPF6 as
the supporting electrolyte. Potential was scanned at 10 mV s−1
at 27 °C. Under these conditions, ferrocene shows a reversible
one-electron redox wave with E1/2 = 420 mV.
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Structure determination for 2–4. The crystals of 2–4 suitable
for X-ray analysis were each mounted in a thin-walled glass
capillary and aligned on the Nonius Kappa CCD diffracto-
meter, with graphite-monochromated Mo Kα radiation (λ =
0.71073 Å). The θ range for data collection is 2.05 to 25.02° for
2·CS2, 1.27 to 25.02° for 3 and 1.68 to 25.04° for 4·0.5CS2. Of
the 18 575, 43 871 and 36 284 reflections collected, 8852,
11 665 and 9680 reflections were independent for 2·CS2, 3 and
4·0.5CS2, respectively. All data were corrected for Lorentz and
polarization effects and for the effects of absorption. Heavily
disordered solvent molecules (maybe one hexane) were
removed from the diffraction data for 3 using the SQUEEZE
program.25 The structures were solved by the direct method
and refined by least-square cycles. The non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were included
but not refined. All calculations were performed using the
SHELXTL-97 package. The data collection and refinement
parameters are presented in Table 2.
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Acknowledgements
We are grateful for support of this work by the National Science
Council of Taiwan. We thank Mr Ting-Shen Kuo (National 10 H. Kang, B. K. Park, M. A. Song, H. Miah, D. G. Churchill,
Taiwan Normal University, Taipei) for X-ray diffraction
analysis.
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2005, 690, 4704.
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2494 | Dalton Trans., 2013, 42, 2488–2494
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