Heterobimetallic samarium(III) and titanium(IV) complexes with bifunctional catalytic properties

Article abstract of DOI:10.1021/om1010935

Reaction of the bis-ligand-chelated samarium complex [Sm(Hbptd)(H ₂bptd)] (1; H₃bptd =1,9-bis(2-pyrrolyl)-2,5,8-triazanona- 1,8-diene), in which a pyrrolyl ring is dangling and metal-free, with Ti(NMe₂)₄ yielded

Full text of DOI:10.1021/om1010935

COMMUNICATION
pubs.acs.org/Organometallics
Heterobimetallic Samarium(III) and Titanium(IV) Complexes with
Bifunctional Catalytic Properties
Fengying Zhou,† Miaoshui Lin,† Lei Li,† Xueqing Zhang,† Zhou Chen,‡ Yahong Li,*,†,§ Yang Zhao,† Jin Wu,†
Guimin Qian,‡ Bin Hu,‡ and Wu Li‡
†Key Laboratory of Organic Synthesis of Jiangsu Province, Department of Chemistry and Chemical Engineering, Soochow University,
Suzhou 215006, People's Republic of China
‡Key Laboratory of Salt Lake Resources and Chemistry of Chinese Academy of Sciences, Qinghai Institute of Salt Lakes,
Xining 810008, People's Republic of China
§State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, People's Republic of China
S Supporting Information
b
ABSTRACT: Reaction of the bis-ligand-chelated samarium complex
[Sm(Hbptd)(H2bptd)] (1; H3bptd =1,9-bis(2-pyrrolyl)-2,5,8-triazanona-
1,8-diene), in which a pyrrolyl ring is dangling and metal-free, with
Ti(NMe2)4 yielded the heterometallic complex [Sm(Hbptd)(THF)
(bptd)Ti(NMe2)2] (2). Treatment of the H3bptd ligand with 1 equiv of
Ti(NMe2)4 gave the titanium amido complex [Ti(bptd)(NMe2)] (3).
Complexes 2 and 3 were able to catalyze the hydroamination of phenyla-
cetylene with 2,4-dichloroaniline and 4-methoxyaniline, and high regios-
electivities were observed for the two amines. Both 1 and 2 were active
catalysts for the ring-opening polymerization of ε-caprolactone. 2 showed
higher activity for the polymerization reactions, due to a decrease in the
coordination number of the samarium atom (from 9 in 1 to 8 in 2) by sharing
its ligand with the titanium center.
he studies of heterobimetallic complexes have recently
received great attention, because the heterometallic systems
is very active for both polymerization and hydroamination
reactions.
T
offer prospects for advantageous synergistic effects where the
reactivity of the whole can be greater than the sum of the parts.1
Recent advances have revealed the potential applications of these
complexes in catalysis, optical devices, magnetism, and semi-
conductors.2 Although a variety of heterometallic complexes
composed of transition metal-transition metal3,2a and transition
metal-main group metal4 have been documented, those con-
structed with rare earth metal-transition metal are more un-
common due to synthetic difficulties,5 and the complexes com-
prised of rare earth metal-early transition metal are even more
sparse.6 To date, there are only limited examples of alkoxide-,7
carboxylate-,8 and diolate-supported9 lanthanide-early transition
metal complexes.
We have been interested in heterobimetallic titanium(IV) and
samarium(III) complexes supported by pyrrole-based ligands. It
has been found that most of the pyrrole based ligand chelated
samarium complexes exhibited high activity for the polymeriza-
tion of MMA and ε-caprolactone.10 Titanium imido or amido
compounds incorporating a pyrrole-based ligand have proved to
be some of the most useful catalysts thus far for the hydroamina-
tion of alkynes.11 The combination of samarium(III), titanium-
(IV), and a pyrrole-based ligand in one compound offers
the possibility of affording a bifunctional catalytic system, which
With the idea of approaching the bifunctional heterobimetallic
system in mind, we chose H3bptd (H3bptd = 1,9-bis(2-pyrrolyl)-
2,5,8-triazanona-1,8-diene;12 Scheme 1) as our target ligand in this
study. We envisioned that use of the pentadentate ligand would
provide a dangling and metal-free pyrrolyl ring, provided that 2 equiv
of H3bptd would chelate to 1 equiv of the samarium atom in order to
meet the high coordination number (usually 9) of the samarium
atom. This dangling and metal-free pyrrolyl ring would further
coordinate with a titanium atom to yield a heterobimetallic samarium-
(III) and titanium(IV) complex. Along this line, we carried out a
reaction involving Sm(N(SiMe3)2)3, Ti(NMe2)4, and H3bptd. The
three complexes [Sm(Hbptd)(H2bptd)] (1), [Sm(Hbptd)
(THF)(bptd)Ti(NMe2)2] (2), and [Ti(bptd)(NMe2)] (3) were
synthesized. Herein, we report the syntheses and characterizations of
1-3, the catalytic activities of 1 and 2 toward the ring-opening
polymerization of ε-caprolactone, and the hydroamination of
phenylacetylene catalyzed by 2 and 3.
Readily accessible samarium(III), heterobimetallic samarium-
(III)/titanium(IV), and titanium(IV) complexes (see Scheme 1)
with interesting structural features have been realized. The
Received: November 20, 2010
Published: February 25, 2011
r
2011 American Chemical Society
1283
dx.doi.org/10.1021/om1010935 Organometallics 2011, 30, 1283–1286
|

Organometallics
COMMUNICATION
reaction of Sm(N(SiMe3)2)3 with 2 equiv of H3bptd in THF at
room temperature yielded Sm(H2bptd)(Hbptd) (1) after 16 h,
with loss of 3 equiv of HN(SiMe3)2. Yellow 1 was synthesized in
76% of the theoretical yield.
In the doubly deprotonated ligand, the donor amine exhibits the
longest bond length (Sm-N4 = 2.714(12) Å); a slight difference
between Sm-N(pyrrolyl) and Sm-N(imine) is observed. The
average Sm-N(pyrrolyl) bond distance is found to be 0.028 Å
shorter than the average distance of the Sm-N(imine) bonds. In the
singly deprotonated ligand, the trend of the Sm-N bond length is
totally altered: one of the Sm-N(imine) bonds shows the longest
bond distance, reaching 2.829(12) Å; the Sm-N(donor amine) is
slightly shorter, being 2.671(12) Å.
Single-crystal X-ray diffraction studies reveal that complex 1 crystal-
lizes in the monoclinic crystal system of the P21/c space group.13 The
ORTEP representation of the crystal structure of 1 (Figure 1a)
displays several interesting features. The overall structure is a bis-
ligand-chelated mononuclear samarium complex. The two chelating
ligands exhibit different coordination behaviors; i.e., 1 equiv of ligand
is doubly deprotonated (the amine hydrogen atoms of the two
pyrroles are deprotonated) and the doubly deprotonated ligand
pentacoordinates (N1-N5) to the metal center, while the other 1
equiv of ligand is singly deprotonated and the deprotonated ligand
tetracoordinates (N6, N8, N9, and N10) to the samarium atom. The
coordination geometry of 1 is well described as either a distorted
tricapped trigonal prism with theN2, N4, andN9atomsascapsorasa
distorted square monocapped antiprism, with the N2 atom as a cap
(Figure S1, Supporting Information).
The N8 and N9 atoms of the H2bptd- ligand are weakly bonded
with the metal center, and the N7 atom is protonated and metal-free.
It seemed plausible that the protonated pyrrole might coordinate
with another metal atom to form a new heterometallic complex.
Accordingly, stirring a 1:1 mixture of 1 and Ti(NMe2)4 in THF
overnight led to quantitative formation of the desired complex
[Sm(Hbptd)(THF)(bptd)Ti(NMe2)2] (2) (Scheme 1), which
was isolated in 66% yield as an orange solid. Single-crystal X-ray
analysis reveals 2 crystallizes in the triclinic crystal system of the P1
space group.13 The crystal structure of 2 is formed by one octacoor-
dinated samarium atom and a pentacoordinated titanium atom
(Figure 1b). The samarium atom is bound to five nitrogen atoms
(N1 to N5) from one Hbptd2- ligand, one deprotonated pyrrolyl
nitrogen atom (N6), and one imine nitrogen atom (N7) from
another bridging bptd3- ligand. The remaining coordination position
of the samarium atom is occupied by one oxygen atom of the solvate
THF molecule. The overall geometry of the samarium atom is close
to a distorted bicapped trigonal prism, with the N3 and O1 atoms as
caps (Figure S2, Supporting Information). The average bond length of
Sm-N(pyrrolyl) (2.496 Å) is shorter than the Sm-N(amine)
(2.696 Å) bond length and the average Sm-N(imine) (2.548 Å)
bond distance.
The Sm-N bond distances displayed by the doubly deprotonated
ligand and the singly deprotonated ligand are remarkably different.
Scheme 1. Syntheses of Complexes 1-3
The titanium atom is bound to three nitrogen atoms from the
bridging bptd3- ligand (N8, N9, and N10) and two amide nitrogen
atoms. The overall geometry of the titanium atom is remarkably close
to tbp. Angles between equatorial nitrogen atoms add up to
353.46(20)°. The axial position occupied by dimethylamide is nearer
to perpendicular with respect to the equatorial plane, having angles of
100.45(7), 101.75(7), and 93.85(7)° relative to those equatorial
nitrogens. As expected, the imine exhibits the longest Ti-N bond in
the complex: 2.1666(17) Å. A slight difference between Ti-N-
(pyrrolyl) and Ti-N(dimethylamide) bond lengths is observed.
The Ti-N(pyrrolyl) bond distance is found to be 0.213 Å longer
Figure 1. Molecular structures of (a) complex 1 and (b) complex 2. H atoms have been omitted for clarity. Selected bond lengths and angles are given in
the Supporting Information.
1284
dx.doi.org/10.1021/om1010935 |Organometallics 2011, 30, 1283–1286

Organometallics
COMMUNICATION
than the average Ti-N(amide) bond length. The axial Ti-N-
(NMe2) bond is 1.8871(17) Å and is 0.014 Å shorter than the
equatorial Ti-N(NMe2) distance of 1.9015(17) Å.
Treatment of Ti(NMe2)4 with 1 equiv of the H3bptd ligand in
THF overnight gave [Ti(bptd)(NMe2)] (3) in near-quantitative
yield (Scheme 1). Complex 3 was characterized by 1H NMR and
elemental analysis (Supporting Information).
results of the heterometallic complex 2 were quite similar to those of
complex 3. The anti-Markovnikov products were favored for both
4-methoxyaniline and 2,4-dichloroaniline hydroamination reactions;
the yield of 4-methoxyaniline was improved (60%), and the yield of
2,4-dichloroaniline was nearly the same (31%).
The results of the complex 4 catalyzed reactions were in contrast
to utilizing 2 and 3 as catalysts. Hydroamination of phenylacetylene
by 4-methoxyaniline gave predominantly Markovnikov product
(M:anti-M = 78:22). No detectable catalytic activity was observed
for the hydroamination reaction of 2,4-dichloroaniline under exactly
similar reaction conditions.
A comparison of 2-4as hydroamination catalysts leads to several
conclusions. First, the active species in the complex 4 catalyzed
reactions are not the same as those of 2 and 3, for the regioselec-
tivities and activities of these three complexes are different. Second,
the titanium center of 2 retained its individual reactivity toward the
hydroamination of phenylacetylene. Third, due to the fact that the
coordination environment of the titanium atom in 2 is more open
than that in 3, 4-methoxyaniline hydroamination of phenylacetylene
catalyzed by 2 gave higher yield.
The application of structurally well-defined organolanthanide
complexes as initiators for the synthesis of poly(ε-caprolactone)
(PCL) via the ring-opening polymerization of lactones has
attracted particular interest.15 These catalyst systems provide
the possibility of understanding the catalyst structure/reactivity
relationships.16 To confirm the expected cooperativity of the two
metal centers, the catalytic behavior of complexes 1 and 2 for the
ring-opening polymerization of ε-caprolactone was examined.
The polymerization results are summarized in Table 2. It is
found that both 1 and 2 can effectively initiate ε-caprolactone
polymerization, and all of the obtained polymers have high
molecular weights and relatively narrow molecular weight distri-
butions (PDIs). The solvent has an obvious effect on the PDIs of
the polymers. When the polymerization was conducted in ethereal
solvent, such as DME and THF, relatively smaller PDIs of the
polymers were found (1.26 and 1.33 for 1 in DME and THF; 1.46
and 1.58 for 2 in DME and THF), whereas the PDIs increased to
1.49 for 1 and 1.72 for 2 when the solvent was changed to toluene.
Complex 2 showed higher activity for the polymerization than
compound 1. Using 2 as the initiator, nearly quantitative yield was
obtained in 2 h in DME at room temperature. In contrast, employing
1 as the initiator in the same solvent, no obvious catalytic polymer-
ization reaction was observed at room temperature, and the system
had to be heated to 60 °C to get a satisfactory yield (92%). The same
trends were observed when the polymerization reactions were
conducted in other solvents. The lower activity shown by complex
1 might be attributed to the fact that the nine nitrogen atoms of
the two different ligands around the samarium atom make the
The successful isolation of the titanium amido complexes 2 and 3
prompted us to explore the catalytic activity of these two complexes
in the hydroamination of alkynes, which has received intense
attention.14 The catalytic reactions were carried out at 80 °C in
toluene for 8 h with a 2:3 molar ratio of phenylacetylene and amines
(2,4-dichloroaniline and 4-methoxyaniline) in the presence of
10 mol % of catalyst (Table 1). Because the resulting imines are
not stable to column chromatography, the hydroamination products
were directly reduced to amines by LiAlH4 in THF for 3 h. For
comparison purposes, the results of hydroamination reactions
catalyzed by Ti(NMe2)4 (4) are given in Table 1 as well.
The results shown in Table 1 indicated that 2-4exhibited different
catalytic activities and regioselectivities for the hydroamination of
phenylacetylene by 2,4-dichloroaniline and 4-methoxyaniline. When
complex 3 was employed as the catalyst, the two amines showed very
good regioselectivity. The reaction of 2,4-dichloroaniline with phenyl-
acetylene gave the anti-Markovnikov addition product and Markov-
nikov product with a ratio of 91:9. When 4-methoxyaniline was used
for the reaction, the ratio of anti-Markovnikov to Markovnikov
products changed to 99:1. The yields of 4-methoxyaniline (43%)
and 2,4-dichloroaniline (35%) were moderate. The hydroamination
Table 1. Hydroamination of Phenylacetylene with Amines
Catalyzed by Complexes 2-4
yield (%)
regioselectivity
M:anti-Ma
cat.
amine
(anti-M þ M)
2
2,4-dichloroaniline
4-methoxyaniline
2,4-dichloroaniline
4-methoxyaniline
2,4-dichloroaniline
4-methoxyaniline
31
60
35
43
0
26:74
1:99
9:91
1:99
3
4
49
78:22
a Ratio of the Markovnikov and anti-Markovnikov products determined
by GC-MS.
Table 2. Polymerization of ε-Caprolactone Initiated by 1 and 2
yielda (%)
temp (° C)
10-4Mn (calcd) b
10-4Mn
10-4Mn
PDI
efficiency (%)
c
d
entry
initiator
solvent
[M]/[I]
T (h)
1
2
3
4
5
6
1
2
1
2
1
2
DME
DME
THF
THF
Tol
200
200
200
200
200
200
2
92
97
90
93
92
96
60
20
60
20
60
40
2.10
2.21
2.05
2.12
2.10
2.19
3.08
3.79
3.50
4.07
5.77
7.49
1.72
2.12
1.96
2.28
3.23
4.19
1.26
1.46
1.33
1.58
1.49
1.72
67.9
61.9
58.6
55.3
36.3
31.0
2
1
1
0.4
Tol
0.3
a Yield: weight of polymer obtained/weight of monomer used. b Mn(calcd) = Mmono ꢀ [M]/[I] ꢀ conv. c Measured by GPC relative to polystyrene
standards. d Measured by GPC relative to polystyrene standards with Mark-Houwink corrections17 for Mn(obsd) = 0.56Mn (GPC) for ε-caprolactone.
1285
dx.doi.org/10.1021/om1010935 |Organometallics 2011, 30, 1283–1286

Organometallics
COMMUNICATION
coordination sphere of the central metal much more crowded and
the nonacoordinated samarium atom is relatively stable, which
results in the difficulty in coordination and insertion of ε-capro-
lactone to the initiator. When the Ti(IV) atom was coordinated by
the dangling pyrrolyl, amine, and imine nitrogen atoms of the
ligand of 1, the coordination environment of Sm(III) in 2 is less
crowded, which allows facile attack by ε-caprolactone.
In summary, toward our goal of synthesis of a heterobimetallic
complex and exploration of the cooperativity between the metal
centers of the heterometallic complex, we have prepared the bis-
ligand-chelated samarium complex 1, the heterobimetallic samarium-
(III)/titanium(IV) complex 2, and the titanium amido complex 3 by
selecting H3bptd as the ligand. The hydroamination of phenylace-
tylene catalyzed by 2 and 3 and the ring-opening polymerization
reaction of ε-caprolactone initiated by 1 and 2 were carried out. The
results of the catalytic reactions indicated that the titanium center and
the samarium center retained their individual reactivities, and the
heterobimetallic complex 2 showed higher activity in both hydro-
amination and polymerization reactions. This study could provide a
rational method for the design of a heterobimetallic system with
desirable properties.
(4) (a) Gorinchoy, V. V.; Zubareva, V. E.; Shova, S. G.; Szafranski,
V. N.; Lipkowski, J.; Stanica, N.; Simonov, Y. A.; Turta, C. I. Russ. J.
Coord. Chem. 2009, 35, 731. (b) Yang, X.-J.; Wang, Y.; Quillian, B.; Wei,
P.; Chen, Z.; Schleyer, P. v. R.; Robinson, G. H. Organometallics 2006,
25, 925. (c) Turta, C.; Shova, S.; Prodius, D.; Mereacre, V.; Gdaniec, M.;
Simonov, Y.; Lipkowski, J. Inorg. Chim. Acta 2004, 357, 4396. (d)
Bardaji, M.; Laguna, A. Eur. J. Inorg. Chem. 2003, 3069.
(5) (a) He, F.; Tong, M. L.; Chen, X. M. Inorg. Chem. 2005, 44, 8285.
(b) Wu, J. Y.; Yin, J. F.; Tseng, T. W.; Lu, K. L. Inorg. Chem. Commun.
2008, 11, 314. (c) Zaleski, C. M.; Depperman, E. C.; Kampf, J. W.; Kirk,
M. L.; Pecoraro, V. L. Angew. Chem., Int. Ed. 2004, 43, 3912. (d) Zhao,
X. Q.; Zhao, B.; Ma, Y.; Shi, W.; Cheng, P.; Jiang, Z. H.; Liao, D. Z.; Yan,
S. P. Inorg. Chem. 2007, 46, 5832. (e) Yue, Q.; Yang, J.; Li, G. H.; Xu, W.;
Chen, J. S.; Wang, S. N. Inorg. Chem. 2005, 44, 5241.
(6) (a) Pevec, A.; Mrak, M.; Demsar, A.; Petricek, S.; Roesky, H. W.
Polyhedron 2003, 22, 575. (b) Getsova, M.; Todorovsky, D.; Enchev, V.;
Wawer, I. Monats. Chem. 2007, 138, 389. (c) Veith, M.; Mathur, S.;
Huch, V. Inorg. Chem. 1997, 36, 2391.
(7) (a) Westin, G.; Norrestam, R.; Nygren, M.; Wijk, M. J. Solid State
Chem. 1998, 135, 149. (b) Moustiakimov, M.; Kritikos, M.; Wesrin, G.
Acta Crystallogr. 1998, C54, 29. (c) Hubert-Pfalzgraf., L. G.; Abada, V.;
Vaissermann, J. Polyhedron 1999, 18, 3497. (d) Kessler, V. G.; Turova, N. Y.;
Panov, A .N.; Yanovski, A. I.; Pisarevsky, A. P.; Struchkov, Y. T. Polyhedron
1996, 15, 335. (e) Daniele, S.; Hubert-Pfalzgraf, L. G.; Daran, J. C.
Polyhedron 1994, 13, 927. (f) Kessler, V. G.; Hubert-Pfalzgraf, L. G.; Halut,
S.; Daran, J. C. J. Chem. Soc., Chem. Commun. 1994, 705. (g) Daniele, S.;
Hubert-Pfalzgraf, L. G.; Daran, J. C.; Halut, S. Polyhedron 1993, 12, 2091.
(8) Gainsford, G. J.; Kemmitt, T.; Milestone, N. B. Inorg. Chem.
1995, 34, 5244.
’ ASSOCIATED CONTENT
S
Supporting Information. Text, tables, figures, and CIF
b
files giving experimental procedures and characterization and
crystallographic details for 1-3. This material is available free of
charge via the Internet at http://pubs.acs.org.
(9) Laaziz, I.; Labart, A.; Julbe, A.; Guizard, C.; Cot, L. J. Solid State
Chem. 1992, 98, 393.
(10) (a) Zhou, F. Y.; Wu, J.; Lin, M. S.; Zhao, Y.; Wu, J.; Zhang, Y.;
Li, W.; Li, Y. H. Z. Anorg. Allg. Chem. 2010, 637, 117. (b) Xiang, L.;
Wang, Q. W.; Song, H. B.; Zi, G. F. Organometallics 2007, 26, 5323.
(11) (a) Swartz, D. L., II; Odom, A. L. Organometallics 2006,
25, 6125. (b) Odom, A. L. Dalton Trans. 2005, 225. (c) Li, Y.; Shi, Y.;
Odom, A. L. J. Am. Chem. Soc. 2004, 126, 1794. (d) Cao, C.; Shi, Y.;
Odom, A. L. J. Am. Chem. Soc. 2003, 125, 2880. (e) Weitershaus, K.;
Ward, B. D.; Kubiak, R.; Muller, C.; Wadepohl, H.; Doye, S.; Gade, L. H.
Dalton Trans. 2009, 4586. (f) Zi, G.; Zhang, F.; Xiang, L.; Chen, Y.; Fang,
W.; Song, H. Dalton Trans. 2010, 39, 4048. (g) Zi, G. F.; Liu, X.; Xiang,
L.; Song, H. B. Organometallics 2009, 28, 1127.
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: liyahong@suda.edu.cn.
’ ACKNOWLEDGMENT
We appreciate the financial support of the Natural Science
Foundation of China (Nos. 20872105 and 40673022), the
National Key Technology R&D Program in the 11th Five Year
Plan of China (No. 2006BAB09B07), and “Qinglan Project” of
Jiangsu Province (No. Bu109805).
(12) Kwiatkowski, E.; Kwiatkowski, M.; Olechnowicz, A.; Bandoli,
G. J. Crystallogr. Spectrosc. Res. 1993, 23, 473.
(13) Crystallographic data are as follows. General information: all
data sets were collected with Mo KR radiation (graphite monochroma-
tor, λ = 0.710 73 Å). 1: C28H35N10Sm, monoclinic, space group P21/c,
T = 293 (2) K, a = 9.390(1) Å, b = 23.924(2) Å, c = 13.7190(14) Å, β =
113.470(2)°, V = 2827.0(5) Å3, Z = 4, F000 = 1340; θ range 2.3-26.7°,
12 555 measured and 4713 independent reflections, final R index R1 =
0.0980. 2: C39.2H53N12O1.8SmTi, triclinic, space group P1, a = 10.580(2) Å,
b = 13.715(3) Å, c = 15.855(3) Å, R = 102.19(3)°, β = 101.24(3)°, γ =
95.28(3)°, V = 2184.2(8) Å3, Z = 2, F000 = 941, θ range 1.79-20.6°, 11119
measured and 4402 independent reflections, final R index 0.0515.
(14) For reviews on hydroamination, see:(a) Hartwig, J. F. Nature
2008, 455, 314. (b) Muller, T. E.; Hultzsch, K. C.; Yus, M.; Foubelo, F.;
Tada, M. Chem. Rev. 2008, 108, 3795. (c) Severin, R.; Doye, S. Chem. Soc.
Rev. 2007, 36, 1407. (d) Muller, T. E.; Beller, M. Chem. Rev. 1998, 98, 675.
(15) (a) Yao, Y. M.; Xu, X. P.; Liu, B.; Zhang, Y.; Shen, Q.; Wong,
W. T. Inorg. Chem. 2005, 44, 5133. (b) Yao, Y. M.; Ma, M. T.; Xu, X. P.;
Liu, B.; Zhang, Y.; Shen, Q.; Wong, W. T. Organometallics 2005,
24, 4014. (c) Yamashita, M.; Takemoto, Y.; Ihara, E.; Yasuda, H.
Macromolecules 1996, 29, 1798.
’ REFERENCES
(1) (a) Yang, G.; Tsubaki, N.; Shamoto, J.; Yoneyama, Y.; Zhang., Y.
J. Am. Chem. Soc. 2010, 132, 8129. (b) Ammal, S. C.; Yoshikai, N.; Inada,
Y.; Nishibayashi, Y.; Nakamura, E. J. Am. Chem. Soc. 2005, 127, 9428.
(c) Chen, C. T.; Lin, Y. H.; Kuo, T. S. J. Am. Chem. Soc. 2008, 130, 12842.
(d) Sun, H. Y.; Huang, C. H.; Jin, X. L.; Xu, G. X. Polyhedron 1995, 14, 1201.
(e) Golodov, V. A.; Kashnikova, L. V. J. Mol. Catal. 1983, 19, 113.
(2) (a) Wheatley, N.; Kalck, P. Chem. Rev. 1999, 99, 3379. (b) Zanardi,
A.; Mata, J. A.; Peris, E. J. Am. Chem. Soc. 2009, 131, 14531. (c) Semeniuc,
R. F.; Thomas, J. R.; Jonathan, P. B.; Kraig, A. W.; Mark, D. S. Coord. Chem.
Rev. 1998, 178-180, 967. (d) Zhang, C.; Cao, Y.; Zhang, J.; Meng, S.;
Matsumoto, T.; Song, Y.; Ma, J.; Humphrey, M. G. Adv. Mater. 2008,
20, 1870. (e) Mishra, S.; Daniele, S.; Ledoux, G.; Jeanneau, E.; Joubert, M.-F.
Chem. Commun. 2010, 46, 3756. (f) Nippe, M.; Wang, J.; Bill, E.; Hope, H.;
Dalal, N. S.; Berry, J. F. J. Am. Chem. Soc. 2010, 132, 14261. (g) Singh, N.;
Prasad, A.; Sinha, R. K. Bull. Chem. Soc. Jpn. 2009, 82, 81.
(3) (a) Chibotaru, L. F.; Girerd, J. -J.; Blondin, G.; Glaser, T.;
Wieghardt, K. J. Am. Chem. Soc. 2003, 125, 12615. (b) Gehrmann, T.;
Fillol, J. L.; Wadepohl, H.; Gade, L. H. Organometallics 2010, 29, 28. (c)
Schley, M.; Fritzsche, S.; Lonnecke, P.; Hey-Hawkins, E. Dalton Trans.
2010, 39, 4090.
(16) O’Keefe, B. J.; Hillmayer, M. A.; Tolman, W. B. Dalton Trans.
2001, 2215.
(17) Kowalski, A.;Duda, A.;Penczek, S. Macromolecules 1998, 31, 2114.
1286
dx.doi.org/10.1021/om1010935 |Organometallics 2011, 30, 1283–1286