Synthesis of the phosphino-fullerene PPh2(o-C6H 4)(CH2NMeCH)C60 and its function as an η1-P or η3-P,C2 ligand

Article abstract of DOI:10.1039/c1dt11769f

Following the method of Prato et al., reaction of C₆₀, N-methylglycine and o-(diphenylphosphino)benzaldehyde affords PPh ₂(o-C₆H₄)(CH₂NMeCH)C₆₀ (1) in moderate yield. Compound 1 reacts with W(CO)₄(NCMe) ₂ to produce W(CO)₄(η³-PPh ₂(o-C₆H₄)(CH₂NMeCH)C₆₀) (2), through coordination of the phosphine group and one 6:6-ring junction of fullerene. Reaction of 1 and Os₃(CO)₁₁(NCMe) affords Os₃(CO)₁₁(PPh₂(o-C₆H ₄)(CH₂NMeCH)C₆₀) (3), which undergoes a cluster fragmentation reaction in refluxing toluene to produce Os(CO) ₃(η³-PPh₂(o-C₆H ₄)(CH₂NMeCH)C₆₀) (4). Thermal reaction of 1 and Os₃(CO)₁₂ affords 3 and 4. On the other hand, reaction of 1 and Ru₃(CO)₁₂ yields only the mononuclear complex Ru(CO)₃(η³-PPh₂(o-C₆H ₄)(CH₂NMeCH)C₆₀) (5). The structures of 1-3 and 5 were determined by an X-ray diffraction study.

Full text of DOI:10.1039/c1dt11769f

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PAPER
Synthesis of the phosphino–fullerene PPh2(o-C6H4)(CH2NMeCH)C60 and its
function as an η1-P or η3-P,C2 ligand†
Chia-Hsiang Chen, Chi-Shian Chen, Huei-Fang Dai and Wen-Yann Yeh*
Received 18th September 2011, Accepted 21st November 2011
DOI: 10.1039/c1dt11769f
Following the method of Prato et al., reaction of C60, N-methylglycine and o-(diphenylphosphino)
benzaldehyde affords PPh2(o-C6H4)(CH2NMeCH)C60 (1) in moderate yield. Compound 1 reacts with
W(CO)4(NCMe)2 to produce W(CO)4(η3-PPh2(o-C6H4)(CH2NMeCH)C60) (2), through coordination of
the phosphine group and one 6 : 6-ring junction of fullerene. Reaction of 1 and Os3(CO)11(NCMe) affords
Os3(CO)11(PPh2(o-C6H4)(CH2NMeCH)C60) (3), which undergoes a cluster fragmentation reaction in
refluxing toluene to produce Os(CO)3(η3-PPh2(o-C6H4)(CH2NMeCH)C60) (4). Thermal reaction of 1 and
Os3(CO)12 affords 3 and 4. On the other hand, reaction of 1 and Ru3(CO)12 yields only the mononuclear
complex Ru(CO)3(η3-PPh2(o-C6H4)(CH2NMeCH)C60) (5). The structures of 1–3 and 5 were determined
by an X-ray diffraction study.
afforded PPh2(o-C6H4)(CH2NMeCH)C60 (1) in 34% yield after
purification by column chromatography (silica gel) and crystalli-
zation from CS2/n-hexane (eqn (1)). Compound 1 forms a
Introduction
The discovery of fullerenes in 1985 marked the beginning of a
new field of chemical research.1 Attachment of organometallic
slightly air-sensitive, brown crystalline solid. The molecular ion
peak at m/z 1038 agrees with the expected formula. The 1H
complexes to fullerenes is an important area within fullerene
chemistry, due to its potential application in biological, mag-
netic, electronic, catalytic and optical devices.2,3 With the devel-
opment of an extensive organic chemistry of fullerenes, it is now
possible to construct a variety of modified fullerenes that incor-
porate metal-binding groups into their structures.4 The syntheses
of such fullerene-containing ligands offer the potential to exploit
the chemical reactivity, redox and electron acceptor character-
istics, photochemical behavior, electron withdrawing properties,
and novel structural features that a fullerene group provides.5
One of the most valuable preparative methods to functionalize
fullerenes is the Prato reaction.6 The versatility of this reaction
arises from the possibility of introducing different substituents
into three different positions of the pyrrolidine ring depending
on the use of aldehyde/ketone and respective amino acid.2a Pre-
viously, the phosphine-functionalized fullerenes C60H(PR2) were
prepared through addition of phosphide nucleophiles to C60 and
subsequent protonation of the resulting anion.7 In our continuing
interest in phosphine and fullerene chemistry,8 herein we present
the synthesis of a new phosphino–fullerene molecule by Prato’s
method and its complexation with transition metal carbonyls.
NMR spectrum displays multiplets in δ 8.28–7.09 for the aro-
matic protons, a doublet at δ 6.18 (4JP–H = 8 Hz) for the methy-
nyl proton, two doublets at δ 4.94 and 4.28 (JH–H = 9 Hz) for
the diastereotopic methylene protons, and a singlet at δ 2.57 for
the methyl protons. The 31P resonance of 1 at δ −19.47 is
8.5 ppm upfield of PCHO (δ −11.0), but is ca. 50 ppm shielded
relative to the fullerene-bound phosphine in (PPh2)C60H (δ
30.1).7 The molecular structure of 1 is illustrated in Fig. 1. It
appears that a pyrrolidine unit is fused with one 6 : 6-ring junc-
tion of C60 molecule. The distances C21–C22 = 1.571(6) Å,
C22–C23 = 1.593(6) Å and C19–C23 = 1.614(6) Å are typical
C–C single bonds, while the remaining C–C lengths of C60 are
av. 1.38 Å (6 : 6-junctions) and 1.45 Å (6 : 5-junctions). The
C22 and C23 atoms are sp3 hybridized and show a distorted
tetrahedral bonding, where the C–C–C angles centered on the
C22 atom are in the range 102.9(3)–113.6(4)°, and on the
C23 atom are 103.1(3)–111.7(3)°. The pyrrolidine ring displays
an envelope shape, of which the C19, C21, C22 and C23 atoms
are coplanar with the N1 atom 0.66 Å away from the plane, and
the N1–C20 and C19–C18 bonds occupy the equatorial
positions.
Results and discussion
Compound 1 has the tertiary phosphine linked to a rigid fuller-
ene backbone. Treatment of 1 with a slight excess of
W(CO)4(NCMe)2 in hot toluene resulted in displacement of the
labile acetonitrile ligands to afford W(CO)4(η3-PPh2(o-C6H4)
(CH2NMeCH)C60) (2) in 51% yield, after purification by
column chromatography (silica gel) and crystallization from
CS2/n-hexane (eqn(2)). The IR spectrum of 2 in the carbonyl
region displays an absorption pattern similar to the starting
Heating a toluene solution of C60, N-methylglycine, and
o-(diphenylphosphino)benzaldehyde (abbreviated as PCHO)
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung,
804, Taiwan
†CCDC reference numbers 843720–843723. For crystallographic data
in CIF or other electronic format see DOI: 10.1039/c1dt11769f
3030 | Dalton Trans., 2012, 41, 3030–3037
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ð1Þ
Fig. 2 ORTEP diagram of 2 with 30% probability ellipsoids. Selected
bond distances (Å): C1–W1 1.965(9), C2–W1 2.042(8), C3–W1 2.016
(7), C4–W1 2.013(8), P1–W1 2.563(2), C28–W1 2.422(6), C29–W1
2.376(6), C23–C27 1.590(9), C25–C26 1.563(9), C26–C27 1.613(9),
C26–C34 1.51(1), C27–C28 1.55(1), C28–C29 1.412(9), C29–C33
1.496(9), C33–C34 1.371(9). Selected bond angles (°): P1–W1–C1
163.2(2), P1–W1–C2 92.9(2), P1–W1–C3 80.9(2), P1–W1–C4 89.3(2),
P1–W1–C28 88.6(2), P1–W1–C29 122.4(2), C1–W1–C2 85.9(3), C1–
W1–C3 82.3(3), C1–W1–C4 91.3(3), C28–W1–C29 34.2(2), C5–P1–
C17 105.0(3), C11–P1–C17 100.3(3), C5–P1–W1 111.2(3), C11–P1–
W1 115.0(2), C17–P1–W1 120.7(2), C25–C26–C27 103.7(5), C25–
C26–C34 116.5(6).
Fig. 1 ORTEP diagram of 1 with 30% probability ellipsoids. Selected
bond distances (Å): C1–P1 1.839(5), C7–P1 1.843(5), C13–P1 1.855(5),
C18–C19 1.500(6), C19–C23 1.614(6), C19–N1 1.473(6), C20–N1
1.488(6), C21–N1 1.452(6), C21–C22 1.571(6), C22–C23 1.593(6),
C22–C27 1.533(6), C22–C30 1.521(6), C23–C24 1.547(6), C23–C33
1.510(6). Selected bond angles (°): C1–P1–C7 100.9(2), C1–P1–C13
104.5(2), C7–P1–C13 100.3(2), P1–C13–C18 120.2(4), C13–C18–C19
123.7(4), C18–C19–C23 115.3(3), C18–C19–N1 112.0(4), C19–N1–
C20 111.4(4), C19–N1–C21 104.3(4), C19–C23–C22 103.1(3), C19–
C23–C24 109.5(3), C19–C23–C33 111.7(3), C20–N1–C21 110.8(4),
N1–C21–C22 104.6(4), C21–C22–C23 102.9(3), C21–C22–C27 112.0
(4), C21–C22–C30 113.6(4).
significantly shorter than the other W–CO distances (2.013(8)–
2.042(8) Å), consistent with enhancement of W→CO back
donation with the carbonyl group trans to a better σ-donating
phosphorus atom. Meanwhile, the distance C28–C29 = 1.412(9)
Å is elongated (ca. 0.03 Å) in comparison with other unper-
turbed (6 : 6)-double bonds, and may be attributed to π back
donation from the tungsten atom. Apparently, steric constraints
of the pyrrolidine group forces the tungsten atom to bind the
CvC bond of the same hexagonal ring, causing a substantial
distortion surrounding the tungsten atom. Such that the bond
angles P1–W1–C3 = 80.9(2)° and C1–W1–C3 = 82.3(3)° are
acute, and the trans P1–W1–C1 angle becomes 163.2(2)°.
compound, indicating retention of the cis-L2W(CO)4 configur-
1
ation. The H NMR of 2 closely resembles 1, except the separ-
ation between the two methylene proton resonances (δ 4.51 and
4.30) is 0.45 ppm less than that observed for 1. The molecular
structure for 2 is depicted in Fig. 2, where the W(CO)4 moiety is
cis-chelated by the phosphine ligand and one 6 : 6-ring junction
of the fullerene, with P1–W1 = 2.563(2) Å, C28–W1 = 2.422(6)
Å and C29–W1 = 2.376(6) Å. The W1–C1 bond (1.965(9) Å) is
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Scheme 1 Reaction of 1 and Os3(CO)11(NCMe).
The structure of 3 was determined by a single-crystal X-ray
diffraction study. There are two independent but structurally
similar complexes in the asymmetric unit, with the ORTEP
diagram of one shown in Fig. 3. It is derived from the mother
molecule Os3(CO)12 by replacing an equatorial carbonyl group
with a phosphine ligand. The Os1–P1 bond is slightly tilted
from the trimetallic plane by 2.2°. The Os3 unit forms an iso-
sceles triangle with the Os1–Os2 distance (2.923(1) Å) being
slightly longer (ca. 0.03 Å) than the other two Os–Os bonds.
The average Os–Os distance for 3 (2.902 Å) is ca. 0.03 Å longer
than that determined for Os3(CO)11(η2-C60),10 and may be attrib-
uted to the stronger net donor but weaker acceptor capability of
phosphine compared with olefin. The Os1, Os2 and Os3 atoms
are each linked to three, four and four terminal carbonyl groups.
Individual Os–CO distances range from 1.78(3) Å to 2.05(3) Å,
C–O distances range from 1.08(3) Å to 1.24(3) Å, and the Os–
C–O angles are in the range 166(2)–178(2)°. The axial carbonyls
are roughly orthogonal to the Os3 surface and eclipsed to each
other.
Different reactivity of (PPh2)C60H and 1 towards the Os3 clus-
ters can be rationalized by the configurations shown in Fig. 4.
Apparently, the P–Os bond of Os3(CO)11(PPh2C60H) can rotate
to place an adjacent osmium atom nearby one 6 : 6-junction of
the fullerene and facilitate their ligation. In contrast, the Os3
cluster of 3 is far away from the fullerene surface, and only the
osmium atom bonded to the phosphine group can interact with
fullerene, likely generating a sterically congested intermediate,
which then carries out a cluster fragmentation reaction to release
the strains and form 4.
ð2Þ
We previously described the reaction of Os3(CO)11(NCMe)
and (PPh2)C60H to give Os3(CO)11(PPh2C60H),9 which carried
out a decarbonylation reaction to produce Os3(CO)10(PPh2C60-
H), with the CvC bond from the adjacent hexagonal ring co-
ordinated to a separate osmium atom (eqn (3)). It is therefore of
interest to compare the reactivity of 1 towards Os3 clusters.
Thus, Os3(CO)11(NCMe) reacted with 1 in hot toluene solution
to yield a brown crystalline solid of Os3(CO)11(PPh2(o-C6H4)
(CH2NMeCH)C60) (3; 33%) after purification by TLC (silica
gel) and crystallization from CS2/n-hexane. On thermolysis in
refluxing toluene, 3 underwent a cluster fragmentation reaction
to produce the mononuclear complex Os(CO)3(η3-PPh2(o-C6H4)
(CH2NMeCH)C60) (4) in 17% yield, together with Os3(CO)12
and the free ligand 1. There is no evidence for the formation of
Os3(CO)10(PPh2(o-C6H4)(CH2NMeCH)C60). Alternatively, treat-
ing 3 with one equivalent of Me3NO (to remove a CO ligand)
under milder conditions (toluene solution at 60 °C) also pro-
duced 4 and Os3(CO)12. These results are summarized in
Scheme 1. Direct thermal reaction of Os3(CO)12 and 1 in
refluxing toluene solution afforded a mixture of 3 and 4.
We then investigated the reaction of 1 and Ru3(CO)12, which
proceeded in benzene solvent at 80 °C to produce only the
ð3Þ
3032 | Dalton Trans., 2012, 41, 3030–3037
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Fig. 3 ORTEP diagram of 3 with 30% probability ellipsoids. Selected bond distances (Å): C23–P1 1.86(3), C29–P1 1.85(2), C35–P1 1.83(2), P1–
Os1 2.393(6), Os1–Os2 2.923(1), Os1–Os3 2.893(2), Os2–Os3 2.890(2), C44–C45 1.55(3). Selected bond angles (°): Os1–Os2–Os3 59.68(4), Os1–
Os3–Os2 60.72(4), Os2–Os1–Os3 59.60(4), P1–Os1–Os2 101.8(1), P1–Os1–Os3 161.3(1), Os1–P1–C23 114.4(9), Os1–P1–C29 117(1), Os1–P1–
C35 112.3(7), C23–P1–C29 101(1), C23–P1–C35 104(1), C29–P1–C35 107(1), P1–C35–C40 136(2), C41–C45–C44 103(2), C43–C44–C45 105(2).
Fig. 5 ORTEP diagram of 5 with 30% probability ellipsoids. Selected
bond distances (Å): C1–Ru1 1.89(3), C2–Ru1 1.93(2), C3–Ru1 1.93(2),
P1–Ru1 2.417(4), C27–Ru1 2.24(2), C28–Ru1 2.18(1), C22–C26 1.59
Fig. 4 Comparison for the structures of 3 and Os3(CO)11(PPh2HC60).
(2), C24–C25 1.55(2), C25–C26 1.64(2), C26–C27 1.55(2), C27–C28
1.42(2), N1–C22 1.44(2), N1–C23 1.47(2), N1–C24 1.48(2). Selected
bond angles (°): P1–Ru1–C1 95.2(6), P1–Ru1–C2 108.1(6), P1–Ru1–
mononuclear complex Ru(CO)3(η3-PPh2(o-C6H4)(CH2NMeCH)
C3 91.2(6), P1–Ru1–C27 97.9(4), P1–Ru1–C28 135.0(4), C1–Ru1–C2
84.1(9), C1–Ru1–C3 169.1(9), C2–Ru1–C3 85.6(9), C27–Ru1–C28
C60) (5) in 45% yield (eqn (4)). Compound 5 forms an air-
37.5(6), C4–P1–C10 101.4(7), C4–P1–C16 103.0(7), C10–P1–C16
displays three absorptions at 2076, 2004 and 1981 cm−1. The
102.7(7).
stable, dark green solid. Its IR spectrum in the carbonyl region
molecular structure of 5 (Fig. 5) contains a ruthenium atom in a
distorted trigonal bipyramidal geometry, where the phosphorus
atom and one 6 : 6-junction of the fullerene are bonded to two
equatorial sites, with P1–Ru1 = 2.417(4) Å, C27–Ru1 = 2.24(2)
Å and C28–Ru1 = 2.18(1) Å, and the C27 and C28 atoms are
displaced from the (P1, Ru1, C2) plane oppositely by 0.1 Å. The
equatorial P1–Ru1–C2 angle (108.1(6)°) and the axial C1–Ru1–
C3 angle (169.1(9)°) are 12° deviated from the ideal value of
120° and 180°, respectively, apparently arising from steric con-
ð4Þ
straints of the ligands.
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Table 1 UV-Vis data of C60 and 1–5
Compound λmax, nm (ε, 10−3 M−1 cm−1
)
C60
1
2
230 (190), 257 (352), 330 (92), 406(5)
228 (160), 256 (180), 308 (60), 326 (56)
229 (195), 253 (190), 349 (45), 415(22), 438(21)
231 (239), 256 (258), 312 (96), 330 (85), 407(20), 431
(15)
3
4
5
228 (256), 255 (203), 330 (72)
235 (176), 255 (166), 330 (60)
Fig. 7 Cyclic voltammograms for C60, 1, 2, 3 and 5 in carbon
disulfide/dichloromethane (3 : 2, v/v). The potential was scanned at
10 mV s−1 at 27 °C, with arrows indicating the direction of current. The
potentials are vs. the Fc/Fc+ couple.
This can be attributed to the added pyrrolidine that decreases the
electron affinity of the C60 sphere.2a The first reduction potentials
for 2 and 3 are comparable, ca. 70 mV more positive than 1, and
can be ascribed to donation of electrons to the metal carbonyl
moieties. Compound 5 exhibits an irreversible two-electron
reduction at −1315 mV, which is likely associated with reduction
of the ruthenium metal.13
In conclusion, we have synthesized a new phosphine-functio-
nalized fullerene molecule 1 by Prato’s method. Compound 1
can act as an η1-P ligand in 3, or as an η3-P,C2 chelating agent in
2, 4 and 5 (bite angle 90–120°), demonstrating a flexible binding
capacity. The latter bonding mode is contrary to the (PPh2)C60H
molecule, which prefers an η3-P,C2 bridging mode in coordi-
nation to Os3 clusters. The versatile bonding properties of 1 are
applicable to split polynuclear complexes, or serve as a hemi-
labile chelating agent to alter the activity of the bound metal
centers and may find an application in homogeneous catalytic
systems.
Fig. 6 Absorption spectra of C60 and 1–5 in dichloromethane.
Compound 4 forms an air-stable, green solid. The molecular
ion peak at m/z 1314 (192Os) is the combination of 1 and one
Os(CO)3 moiety. The IR spectrum in the carbonyl region dis-
plays three peaks at 2076, 1996 and 1973 cm−1, with an absorp-
tion pattern almost identical to that of 5. The 31P resonance at δ
−16.03 is 21 ppm upfield of 3 (δ 5.05). Though the structure of
4 was not determined, the Os(CO)3 unit is presumed to link to
the phosphine ligand and one 6 : 6-junction of fullerene, in a
fashion similar to 5.
The UV-Vis spectra of C60 and 1–5 in dichloromethane (10−5
M) are displayed in Fig. 6, with the data summarized in Table 1.
The spectral features are similar where the absorptions between
250 and 410 nm are due to π→π* transitions of fullerene and
phenyl groups,11 whereas those between 410 and 500 nm are
mainly arising from MLCT transitions. These compounds
contain a redox-active fullerene core, and their electrochemical
properties were measured by cyclic voltammetry in dry, oxygen-
free CS2/CH2Cl2 (3 : 2, v/v) solution at 27 °C (Fig. 7). CS2 was
added as the co-solvent to improve the solubility of the com-
plexes. Under these conditions, C60 has three consecutive
Experimental section
General methods
All manipulations were carried out under an atmosphere of
purified dinitrogen with standard Schlenk techniques.
14
W(CO)4(NCMe)2 and Os3(CO)11(NCMe)15 were prepared as
described in the literature. N-methyl glycine (TCI), PCHO
(Aldrich), C60 (99%; Bucky USA), Os3(CO)12 and Ru3(CO)12
(Strem) were used as received. Preparative thin-layer chromato-
graphic (TLC) plates were prepared from silica gel (Merck).
Infrared spectra were recorded on a Jasco FT/IR-4100 IR spec-
trometer. 1H and 31P spectra were obtained on a Bruker
AVANCE-300 spectrometer at 300 and 121.5 MHz. UV-Vis
spectra were recorded from 200 to 700 nm in dichloromethane
reduction waves within the solvent cutoff, corresponding to the
−/2−/3–
C60
states.12 The first reduction potential for the free
ligand 1 is shifted cathodically by 182 mV compared to C60.
3034 | Dalton Trans., 2012, 41, 3030–3037
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by using a 1.0 cm quartz cell with an Agilent 8452 spectropho-
tometer. Matrix-assisted laser desorption ionization (MALDI)
mass spectra were recorded on a Bruker Microflex-LT mass spec-
trometer. High-resolution mass spectra (HRMS) were measured
with Finnigan/Thermo Quest MAT and JMS-700 HRMS mass
spectrometers. Elemental analyses were performed at the
National Science Council Regional Instrumentation Center at
National Chung-Hsing University, Taichung, Taiwan.
material forming the third brown band yielded brown crystals of
Os3(CO)11(PPh2(o-C6H4)(CH2NMeCH)C60) (3; 7.5 mg, 33%
based on Os atoms) after crystallization from CS2/n-hexane. MS
(MALDI) m/z 1837 (M+ − 3CO, 192Os); IR (cyclohexane)
ν(CO) 2106 m, 2084 vw, 2055 s, 2035 s, 2019 vs, 1999 w(sh),
1992 m, 1979 m, 1955 w cm−1; 1H NMR (CDCl3, 25 °C) δ 8.49
(m, 1H, C6H4), 7.48–7.85 (m, 13H, Ph, C6H4), 5.04 (s, 1H,
CH), 4.69 (d, 1H, JH–H = 9.3 Hz, CH2), 3.65 (d, 1H, JH–H = 9.3
Hz, CH2), 2.69 (s, 3H, CH3); 31P{1H} NMR (CDCl3, 25 °C) δ
5.05 (s). Anal. Calcd for C92H20O11NOs3P: C, 57.65; H, 1.05;
N, 0.73. Found: C, 58.03; H,1.25; N, 0.69%.
Synthesis of 1
C60 (120 mg, 0.167 mmol), N-methyl glycine (16 mg,
0.18 mmol) and PCHO (240 mg, 0.828 mmol) were placed in
an oven-dried 250 mL Schlenk flask, under a dinitrogen atmos-
phere. Toluene (90 mL) was introduced into the flask via a
syringe, and the solution was heated to reflux for 4 h. The sol-
ution was cooled to room temperature, dried under vacuum, and
the residue was subjected to column chromatography (silica gel),
with toluene/n-hexane (3 : 2, v/v) as eluant. Isolation of the
material forming the second brown band gave brown crystals of
PPh2(o-(C6H4)(CH2NMeCH)C60 (1; 59 mg, 34% based on C60)
after crystallization from CS2/n-hexane. 1H NMR (CD2Cl2,
25 °C): δ 8.28 (m, 1H, C6H4), 7.09–7.54 (m, 13H, Ph, C6H4),
6.18 (d, 1H, JP–H = 8.1 Hz, CH), 4.94 (d, 1H, JH–H = 9.3 Hz,
CH2), 4.28 (d, 1H, JH–H = 9.3 Hz, CH2), 2.57 (s, 3H, CH3). 31P
{1H} NMR (CD2Cl2, 25 °C): δ −19.47 (s). HRMS (FAB) Calcd
for C81H21N1P1 (MH+): 1038.1412. Found: 1038.1426.
Thermolysis of 3
Compound 3 (12 mg, 0.0063 mmol) and toluene (10 mL) were
placed in a 50 mL Schlenk tube under a dinitrogen atmosphere,
and the solution was refluxed for 12 h. The solvent was removed
under vacuum, and the residue was subjected to TLC, eluting
with carbon disulfide/dichloromethane/n-hexane (4 : 1 : 1, v/v).
The first yellow band gave Os3(CO)12 (1 mg, 18%), the second
brown band yielded the free ligand 1 (2.4 mg, 37%), and the
third
green
band
afforded
Os(CO)3(η3-PPh2(o-C6H4)
(CH2NMeCH)C60) (4; 1.4 mg, 17%). MS (ESI) m/z 1314 (MH+,
192Os); IR (methylcyclohexane) ν(CO) 2076 m, 1996 s, 1973 s
cm−1 1H NMR (CD2Cl2, 25 °C) δ 7.13–7.96 (m, 14H, Ph,
;
C6H4), 5.68 (d, 1H, JP-H = 3.6 Hz, CH), 4.45 (d, 1H, JH–H = 9.6
Hz, CH2), 3.91 (d, 1H, JH–H = 9.6 Hz, CH2), 2.28 (s, 3H,
CH3);31P{1H} NMR (CD2Cl2, 25 °C): δ −16.03 (s). HRMS
(ESI) Calcd for C84H21O3NOsP (MH+): 1314.0868. Found:
1314.0889.
Reaction of 1 and W(CO)4(NCMe)2
Compound 1 (37 mg, 0.036 mmol), W(CO)4(NCMe)2 (26 mg,
0.069 mmol) and toluene (6 mL) were introduced into a 25 ml
Schlenk flask under a dinitrogen atmosphere. The flask was
placed in an oil bath at 100 °C for 1 h. The solvent was removed
under vacuum and the residue subjected to column chromato-
graphy (silica gel), with carbon disulfide/dichloromethane/n-
hexane (2 : 1 : 1, v/v) as eluant. Isolation of the material forming
the second green band afforded dark green crystals of
W(CO)4(η3-PPh2(o-C6H4)(CH2NMeCH)C60) (2; 24 mg, 51%
based on C60) after crystallization from CS2/n-hexane. MS
(MALDI) m/z 1277 (M+ − 2CO, 184W); IR (CS2) ν(CO) 2039 s,
Reaction of 1 and Os3(CO)12
Compound 1 (50 mg, 0.048 mmol), Os3(CO)12 (43 mg,
0.048 mmol) and toluene (15 mL) were introduced into a 50 ml
Schlenk flask under a dinitrogen atmosphere. The solution was
heated to reflux for 3 h. The solvent was removed under vacuum
and the residue subjected to TLC, eluting with carbon disulfide.
Isolation of the material forming the yellow band recovered
Os3(CO)12 (29.4 mg, 68%), the brown band gave compound 3
(23.7 mg, 26%), and the green band gave compound 4 (10 mg,
16%).
1946 s, 1919 s cm−1 1H NMR (CD2Cl2+CS2, 25 °C) δ
;
7.33–8.03 (m, 14H, Ph, C6H4), 6.27 (d, 1H, JP–H = 6 Hz, CH),
4.51 (d, 1H, JH–H = 9.3 Hz, CH2), 4.30 (d, 1H, JH–H = 9.3 Hz,
CH2), 2.30 (s, 3H, CH3); 31P{1H} NMR (CD2Cl2+CS2, 25 °C) δ
0.76 (s, with 183W satellites, JW–P = 224.2 Hz). Anal. Calcd for
C85H20O4NPW: C, 76.54; H, 1.51; N, 1.05. Found: C, 76.50; H,
2.01; N, 1.00%.
Reaction of 1 and Ru3(CO)12
Compound 1 (51 mg, 0.049 mmol), Ru3(CO)12 (31 mg,
0.049 mmol) and benzene (14 mL) were introduced into a 50 ml
Schlenk flask under a dinitrogen atmosphere. The flask was
placed in an oil bath at 80 °C for 1 h. The solvent was removed
under vacuum and the residue subjected to TLC, eluting with
carbon disulfide/dichloromethane/n-hexane (4 : 1 : 1, v/v). Iso-
lation of the material forming the first yellow band recovered
Ru3(CO)12 (12.9 mg, 25%), and the third green band afforded
Ru(CO)3(η3-PPh2(o-C6H4)(CH2NMeCH)C60) (5; 26.4 mg,
45%). MS (MALDI) m/z 1167 (M+ − 2CO, 102Ru); IR (methyl-
Reaction of 1 and Os3(CO)11(NCMe)
Compound 1 (13 mg, 0.013 mmol), Os3(CO)11(NCMe) (11 mg,
0.012 mmol) and toluene (5 mL) were introduced into a 25 ml
Schlenk flask under a dinitrogen atmosphere. The flask was
placed in an oil bath at 85 °C for 66 h. The solvent was removed
under vacuum and the residue subjected to TLC, eluting with
carbon disulfide. Isolation of the material forming the first
yellow band gave Os3(CO)12 (1.7 mg, 16%). Isolation of the
cyclohexane) ν(CO) 2076 m, 2004 s, 1981 s cm−1; H NMR
(CDCl3 + CS2, 25 °C) δ 7.12–7.94 (m, 14H, Ph, C6H4), 5.72 (d,
1H, JP-H = 4.5 Hz, CH), 4.44 (d, 1H, JH–H = 9.3 Hz, CH2), 3.88
1
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Table 2 Crystallographic data for compounds 1–3 and 5
1
2
3
5
Formula
Cryst solvent
Formula weight
Crystal system
Space group
a/Å
b/Å
c/Å
α/°
β/°
C81H20NP
C170H40N2O8P2W2
CS2
2743.81
C92H20NO11Os3P
C168H42N2O6P2Ru2
3CS2 + H2O
2692.51
1037.95
Monoclinic
C2/c
23.620(3)
14.2383(18)
30.475(4)
90
109.428(8)
90
9665(2)
200(2)
1916.66
Triclinic
ˉ
P1
Triclinic
Triclinic
ˉ
ˉ
P1
P1
10.0412(13)
16.747(2)
17.295(2)
62.545(2)
76.825(2)
89.449(2)
2497.5(5)
200(2)
17.4180(16)
19.6754(19)
23.140(2)
106.174(6)
95.677(6)
90.006(7)
7575.8(12)
200(2)
10.0828(13)
16.351(2)
16.5332(19)
84.296(7)
77.770(7)
77.840(9)
2599.8(6)
200(2)
γ/°
U/Å3
T/K
Z
8
1
4
1
μ, mm−1
R1, wR2
GOF on F2
0.114
0.0915, 0.2671
1.086
2.457
0.0504, 0.0903
0.847
5.103
0.1668, 0.3611
1.053
0.521
0.1196, 0.3090
1.059
(d, 1H, JH–H = 9.6 Hz, CH2), 2.29 (s, 3H, CH3); 31P{1H} NMR
(CDCl3 CS2, 25 °C) 17.41 (s). Anal. Calcd for
C171H42O7N2P2Ru2S6: C, 76.28; H, 1.57; N, 1.04. Found: C,
75.90; H, 2.48; N, 0.95%.
quality data sets, the bonding features for these compounds
should be unambiguous. Attempts to grow better crystals,
however, were not successful.
CCDC reference number 843722 for 1, 843720 for 2, 843721
for 3 and 843723 for 5.
+
δ
Electrochemical measurements
Acknowledgements
Electrochemical measurements were taken with a CV 50 W
system. Cyclic voltammetry was performed with a Pt button
working electrode, a Pt-wire auxiliary electrode and an Ag/AgCl
reference electrode. The experiments were carried out with
1 mM solution of 1–3 and 5, respectively, in dry carbon
disulfide/dichloromethane (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, ferro-
We are grateful for support of this work by the National Science
Council of Taiwan and thank Mr. Ting-Shen Kuo (National
Taiwan Normal University, Taipei) for X-ray diffraction analysis.
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This journal is © The Royal Society of Chemistry 2012
Dalton Trans., 2012, 41, 3030–3037 | 3037