Reactivity study of a hydroxyl coordinated osmium vinyl complex OsCl 2(PPh3)2[CH=C(PPh3)CHPh(OH)]

Article abstract of DOI:10.1007/s11426-013-4876-y

We studied the reactivity of an osmium vinyl complex containing a coordinated hydroxyl group OsCl₂(PPh₃)₂[CH= C(PPh₃)-CHPh(OH)] (1) toward bidentate ligand 1,4- bis(diphenylphosphino)butane (DPPB), π acid ligand (CO), base (Cs ₂CO₃) and heat. Two osmium vinyl complexes OsCl ₂(dppb)[CH=C(PPh₃)CHPh(OH)] (2) and OsCl ₂(CO)₂(PPh₃)[CH=C(PPh₃)CHPh(OH)] (3), as well as two relatively rare phosphonium-containing osmafuran complexes Os(η²-OCOO)(PPh₃)₂[CHC(PPh ₃)CPhO] (4) and OsCl₂(PPh₃) ₂[CHC(PPh₃)CPhO] (5), were obtained in high yields from these reactions. All products were characterized by NMR spectroscopy, elemental analysis, and their structures were further confirmed by single crystal X-ray diffraction.

Full text of DOI:10.1007/s11426-013-4876-y

SCIENCE CHINA
Chemistry
August 2013 Vol.56 No.8: 1105–1111
doi: 10.1007/s11426-013-4876-y
• ARTICLES • Progress of Projects Supported by NSFC
Reactivity study of a hydroxyl coordinated osmium vinyl complex
OsCl2(PPh3)2[CH=C(PPh3)CHPh(OH)]†
LIU Bin, ZHAO QianYi, WANG HuiJuan, ZENG BiRong, CAO XiaoYu* & XIA HaiPing*
College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
Received February 1, 2013; accepted March 14, 2013; published online April 17, 2013
We studied the reactivity of an osmium vinyl complex containing a coordinated hydroxyl group OsCl2(PPh3)2[CH=C(PPh3)-
CHPh(OH)] (1) toward bidentate ligand 1,4-bis(diphenylphosphino)butane (DPPB),  acid ligand (CO), base (Cs2CO3) and
heat. Two osmium vinyl complexes OsCl2(dppb)[CH=C(PPh3)CHPh(OH)] (2) and OsCl2(CO)2(PPh3)[CH=C(PPh3)CHPh(OH)]
(3), as well as two relatively rare phosphonium-containing osmafuran complexes Os(2-OCOO)(PPh3)2[CHC(PPh3)CPhO] (4)
and OsCl2(PPh3)2[CHC(PPh3)CPhO] (5), were obtained in high yields from these reactions. All products were characterized by
NMR spectroscopy, elemental analysis, and their structures were further confirmed by single crystal X-ray diffraction.
osmium vinyl complex, osmafuran, aromatic cyclization, ligand substitution, metallaaromatics
which give osmium vinyl complexes OsCl2(dppb)[CH=C(PPh3)
1 Introduction
CHPh(OH)] (2) and OsCl2(CO)2(PPh3)[CH=C(PPh3)
CHPh(OH)] (3), as well as osmafurans Os(η2-OCOO)(PPh3)2
[CHC(PPh3)CPhO] (4) and OsCl2 (PPh3)2[CHC(PPh3)CPhO]
(5) in high yields.
Transition metal containing aromatic metallacycles [1] have
attracted more and more attention because they possess both
the reactivity of organometallic complexes and the aroma-
ticity of ring systems. Recently, considerable progresses
have been achieved in this field, and a lot of aromatic
metallacycles such as metallabenzene [2], metallabenzyne
[1a, 1e, 3], metallanaphthalene [4], metallapyridine [5],
metallapyridinium [5a, 5b], metallapyridyne [6] and metal-
lafuran [7] have been synthesized. In 2009, we reported the
synthesis of the first osmanaphthalene [4a] and metalla-
pyridinium [5b]. In those studies, treatment of a hydroxyl
coordinated osmium vinyl complex OsCl2(PPh3)2[CH=C(PPh3)
CHPh(OH)] (1) with HBF4 afforded the key intermediate
hydride osmium carbyne complex [OsHCl2(PPh3)
{≡CC(PPh3)=CHPh}]BF4 [4a, 5b]. As hydroxyl group is a
relatively weak ligand toward the central osmium, it can be
replaced by other ligands to afford ligand-exchanged prod-
ucts. Herein, we present a series of reactions of complex 1,
2 Experimental
2.1 General experimental section
All manipulations were carried out under a nitrogen atmos-
phere using standard Schlenk techniques, unless otherwise
stated. Solvents were distilled under nitrogen from sodium
and benzophenone (diethyl ether, THF), or calcium hydride
(CH2Cl2, CHCl3, ClCH2CH2Cl). The starting material com-
plex 1 was synthesized according to our previous commu-
nication [5b]. NMR experiments were performed on Bruker
1
AV300, AV400 or AV500 spectrometer. H and 13C NMR
chemical shifts are relative to TMS, and 31P NMR chemical
shifts are relative to 85% H3PO4. Elemental analyses data
were obtained on Thermo Quest Italia S.P.A. EA 1110.
Cs2CO3 and 1,4-bis(diphenylphosphino)butane (DPPB) were
purchased from Sigma-Aldrich and used as received.
*Corresponding authors (email: xcao@xmu.edu.cn, hpxia@xmu.edu.cn)
†Recommended by Prof. CAO Yong (South China University of Technology)
© Science China Press and Springer-Verlag Berlin Heidelberg 2013
chem.scichina.com www.springerlink.com

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Liu B, et al. Sci China Chem August (2013) Vol.56 No.8
2.2 Synthesis of complex 2
OsCH), 7.75–6.55 (m, 50 H, other aromatic protons).
31P{1H} NMR (162.0 MHz, CDCl3):  14.98 (s, CPPh3),
8.90 (d, 2J(PP) = 10.4 Hz, OsPPh3), 4.47 (d, 2J(PP) = 10.4
Hz, OsPPh3). 13C{1H} NMR (100.6 MHz, CDCl3):  247.6
(br, OsCH), 199.2 (d, 2J(PC) = 25.8 Hz, OsOCPh), 169.2 (s,
A red solution of complex 1 (400 mg, 0.34 mmol) in di-
chloromethane (10 mL) was treated with 1,4-bis(diphen-
ylphosphino)butane (DPPB) (724 mg, 1.7 mmol). After the
mixture was stirred for 5 h at room temperature, it was fil-
tered and the filtrate was evaporated. Addition of diethyl
ether gave complex 2 as a yellow precipitate, which was
washed with diethyl ether and dried in vacuo. Yield: 329
1
OCOO), 109.5 (d, J(PC) = 85.2 Hz, OsCHCPPh3), 139.2–
121.6 (m, other aromatic carbon atoms). Anal. Calcd for
C64H51O4P3Os: C, 65.86; H, 4.40. Found: C, 65.67; H, 4.25.
1
mg, 90%. H NMR (500.17 MHz, CD2Cl2):  11.70 (d,
3J(PH) = 23.5 Hz, 1H, OsCH), 8.09–6.70 (m, 40H, other
2.5 Synthesis of complex 5
4
aromatic protons), 5.43 (d, J(PH) = 7.5 Hz, 1H, OH), 4.46
A solution of complex 1 (500 mg, 0.42 mmol) in 1,2-
dichloroethane (15 mL) was heated under reflux for 0.5 h.
The solvent was removed in vacuo. Addition of diethyl
ether to the resulting residue gave complex 5 as a pale-green
solid, which was washed with diethyl ether and dried in
vacuo. Yield: 374 mg, 75%. 1H NMR (300.1 MHz, CDCl3):
15.40 (d, 3J(PH) = 12.4 Hz, 1H, OsCH), 7.56–6.39 (m, 50 H,
other aromatic protons). 31P{1H} NMR (121.5 MHz,
2
(m, 1H, Ph2PCH), 2.66(t, J(PH) = 14 Hz, 1H, Ph2PCH),
2.90 (q, 2J(PH) = 26.5 Hz, 2J(PH) = 13.5 Hz, 1H, Ph2PCH),
3
1.53 (br, 1H, Ph2PCH), 3.72 (d, J(PH) = 7.5 Hz, 1H,
OsCHCPPh3CH), 2.16 (br, 4H, Ph2PCH2CH2CH2CH2PPh2).
31P{1H} NMR (202.47 MHz, CD2Cl2):  2.40 (s, CPPh3),
9.71 (d, 2J(PP) = 16.2 Hz, Ph2P), 2.06 (d, 2J(PP) = 16.2 Hz,
Ph2P). 13C{1H} NMR (125.77 MHz, CD2Cl2)  212.5 (br,
OsCH), 139.4–122.9 (m, other aromatic carbon atoms),
104.2 (d, 1J(PC) = 82.1 Hz, OsCHCPPh3), 87.3 (d, 2J(PC) =
32.8 Hz, OsCHCPPh3CH), 27.5 (s, Ph2PCH2CH2), 18.4 (s,
Ph2PCH2CH2). Anal. Calcd for C55H51OCl2P3Os: C, 61.05;
H, 4.75. Found: C, 61.32; H, 5.05.
2
CDCl3):  13.05 (s, CPPh3), 0.50 (d, J(PP) = 16.4 Hz,
2
OsPPh3), 7.88 (d, J(PP) = 16.4 Hz, OsPPh3). 13C{1H}
NMR (75.5 MHz, CD2Cl2):  242.6 (br, OsCH), 201.7 (d,
1
2J(PC) = 25.1 Hz, OsOCPh), 112.5 (d, J(PC) = 86.2 Hz,
OsCHCPPh3), 139.5–121.6 (m, other aromatic carbon at-
oms). Anal. Calcd for C63H51Cl2OP3Os: C, 64.23; H, 4.36.
Found: C, 64.47; H, 4.26.
2.3 Synthesis of complex 3
A red solution of complex 1 (400 mg, 0.34 mmol) in di-
chloromethane (10 mL) was stirred in CO atmosphere at
room temperature for 10 h. The solvent was removed in
vacuo. Addition of methanol to the resulting residue pro-
vided complex 3 as a pale solid, which was washed with
methanol and dried in vacuo. Yield: 280 mg, 85%. 1H NMR
2.6 X-ray crystallography
Crystals suitable for X-ray diffraction were grown from
dichloromethane (DCM) or chloroform (CHCl3) solutions
layered with diethyl ether or n-hexane for complexes 2
(DCM/Et2O), 3 (CHCl3/Et2O), 4 (CHCl3/n-hexane), and 5
(DCM/Et2O). Selected crystals were mounted on top of a
glass fiber and transferred into a cold stream of nitrogen.
Data collections were performed on an Oxford Gemini S
Ultra CCD area detector or a Bruker Apex CCD area detec-
tor using graphite-monochromated Mo Kα radiation ( =
0.71073 Å). Multiscan or empirical absorption corrections
(SADABS) were applied. All structures were solved by
direct methods, expanded by difference Fourier syntheses,
and refined by full-matrix least squares on F2 using the
Bruker SHELXTL-97 program package. All non-H atoms
were refined anisotropically. Hydrogen atoms were intro-
duced at their geometric positions and refined as riding at-
oms. CCDC-900454 (2), CCDC-900455 (3), CCDC-707874
(4), and CCDC-707875 (5) contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge from the Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/cgi-bin/catreq.cgi.
3
(400.1 MHz, CDCl3):  9.94 (d, J(PH) = 30.4 Hz, 1H,
OsCH), 7.91–6.65 (m, 35 H, other aromatic protons ), 3.49
3
(d, J(PH) = 4.4 Hz, 1H, OsCHCPPh3CH). 31P{1H} NMR
4
(162.0 MHz, CDCl3):  18.6 (d, J(PP) = 32.4 Hz, CPPh3),
4
6.4 (d, J(PP) = 32.4 Hz, OsPPh3). 13C{1H} NMR and
2
Dept 135 (100.6 MHz, CDCl3): δ 186.0 (dd, J(PC) = 85.4
2
2
Hz, J(PC) = 4.1 Hz, OsCH), 177.0 (d, J(PC) = 5.2 Hz,
CO), 175.6 (d, 2J(PC) = 5.7 Hz, CO), 141.4–122.0 (m, other
aromatic carbon atoms), 120.3 (d, 1J(PC) = 87.1 Hz,
OsCHCPPh3), 77.4 (dd, 2J(PC) = 16.6 Hz, 4J(PC) = 3.7 Hz,
OsCHCPPh3CH). Anal. Calcd for C47H38O3Cl2P2Os: C,
57.96; H, 3.93. Found: C, 57.91; H, 4.49.
2.4 Synthesis of complex 4
A red solution of complex 1 (400 mg, 0.34 mmol) in di-
chloromethane (10 mL) was treated with Cs2CO3 (554 mg,
1.7 mmol). After the mixture was stirred for 5 h at room
temperature, the suspension was filtered, and the filtrate was
evaporated. Addition of diethyl ether gave complex 4 as a
green precipitate, which was washed with diethyl ether and
dried in vacuo. Yield: 317 mg, 80%. 1H NMR (400.1 MHz,
CDCl3):  15.35 (dd, 3J(PH) = 15.0 Hz, 3J(PH) = 4.4 Hz, 1H,
3 Results and discussion
3.1 Reaction of complex 1 with DPPB
Bidentate phosphine ligand 1,4-bis(diphenylphosphino)

Liu B, et al. Sci China Chem August (2013) Vol.56 No.8
1107
butane (DPPB) is widely used in organometallic synthesis
and catalysis [8]. Treatment of complex 1 with DPPB af-
forded ligand-exchanged complex OsCl2(dppb)[CH=C(PPh3)
CHPh(OH)] (2) (Scheme 1) in 90% yield. Complex 2 was
characterized by solution NMR spectroscopy, elemental
analysis, and its structure was further confirmed by single
crystal X-ray diffraction.
(OC2H4OH)}Cl(CO)(PPh3)2 (2.180(2) Å) [11]. Clearly, only
ligand substitution occurred in this reaction, and the coor-
dinated hydroxyl ligand remained intact.
The solution NMR data of complex 2 are consistent with
its solid structure and will be discussed later together with
complexes 3–5.
The structure of complex 2 is shown in Figure 1. The
five-membered metallacycle in complex 2 is similar to
complex 1 [5b]. All bond distances and angles within the
metallacycle are comparable with those of complex 1. The
Os1–C1 (1.964(7) Å) bond distance is close to the reported
Os–C(vinyl) bonds (1.988(7)–2.195(5) Å) [9]. The C1–C2
(1.355(10) Å) bond is close to C–C double bonds and
C3–O1 (1.465(9) Å) bond is close to C–O single bonds. The
Os1–O1 (2.203(5) Å) bond length is comparable to those of
reported osmium vinyl complexes containing coordinated
hydroxyl group, such as [Os{C(Me)C(OH)PhMe}(2-O2C
CH3)(PiPr3)2]BF4 (2.188(5) Å) [10] and Os{B(OEt)
3.2 Reaction of complex 1 with CO
CO is a  acid ligand with stronger trans effect than the
oxygen atom, thus it may facilitate the cleavage of the Os–O
bond. The solution of complex 1 in dichloromethane was
stirred at room temperature under CO atmosphere for 10 h to
afford complex OsCl2(CO)2(PPh3)[CH=C(PPh3)CHPh(OH)]
(3) in 85% yield as a pale solid (Scheme 1). Complex 3 was
characterized by solution NMR spectroscopy, elemental
analysis and single crystal X-ray diffraction.
As shown in Figure 2, two CO ligands coordinate with
the central metal in a cis fashion (C4–Os1–C5 = 89.7(4)°).
The bond lengths of Os1–C1 (2.101(11) Å) is longer than
that of complex 2 (1.964(7) Å) and within the range of the
reported Os–C(vinyl) bonds [9]. The C1–C2 (1.327(14) Å)
bond distance is shorter than that of complex 2 (1.355(10) Å)
and close to the C–C double bond. The C2–C3 (1.494(14) Å)
and C3–O1 (1.418(12) Å) bond lengths are slightly shorter
than those of complex 2 (C2–C3 = 1.530(10) Å, C3–O1 =
1.465(9) Å). The bond angles of C1–C2–C3 (124.7(11)°)
and C2–C3–O1 (107.7(8)°) indicate that C2 and C3 atoms
are sp2 and sp3 hybridized, respectively.
3.3 Reaction of complex 1 with Cs2CO3
Scheme 1 Synthesis of complexes 2 and 3.
In 2009, we found that treatment of complex 1 with HBF4
gave a hydrido osmium carbyne complex [OsHCl2(PPh3)2
Figure 2 Molecular structure for complex 3 (ellipsoids at the 50% prob-
ability level). Some hydrogen atoms are omitted for clarity. Selected bond
distances (Å) and angles (deg): Os1–P1 2.429(2), Os1–Cl1 2.443(2),
Os1–Cl2 2.399(3), Os1–C1 2.101(11), Os1–C5 1.882(4), C5–O3 1.115(4),
C1–C2 1.327(14), C2–C3 1.494(14), C3–O1 1.418(12); P1–Os1–C1
173.0(3), Cl1–Os1–Cl2 90.74(9), C4–Os1–C5 89.7(4), Os1–C5–O3
174.3(9), Os1–C4–O2 178.1(8), Os1–C1–C2 136.8(9), C1–C2–C3
124.7(11), C2–C3–O1 107.7(8).
Figure 1 Molecular structure for complex 2 (ellipsoids at the 50% prob-
ability level). Some hydrogen atoms are omitted for clarity. Selected bond
distances (Å) and angles (deg): Os1–P1 2.263(2), Os1–P2 2.222(2),
Os1–Cl1 2.525(2), Os1–Cl2 2.487 (2), Os1–C1 1.964(7), Os1–O1 2.203
(5), C1–C2 1.355(10), C2–C3 1.530(10), C3–O1 1.465(9); P1–Os1–P2
93.73(7), Cl1–Os1–Cl2 86.59(6), C1–Os1–O1 77.8(2), Os1–C1–C2
120.9(5), C1–C2–C3 118.7(6), C2–C3–O1 106.9(6), C3–O1–Os1 115.0(4).

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Liu B, et al. Sci China Chem August (2013) Vol.56 No.8
{≡CC(PPh3)=CHPh}]BF4 [5b]. Herein, treatment of com-
plex 1 with Cs2CO3 in dichloromethane at room temperature
resulted in the formation of complex Os(2-OCOO)(PPh3)2
[CHC(PPh3)CPhO] (4) as a green solid in 80% yield
(Scheme 2). Complex 4 was characterized by NMR spec-
troscopy, elemental analysis and single crystal X-ray dif-
fraction.
As shown in Figure 3, the carbonate ion coordinated with
the osmium center using two oxygen atoms O2 and O3
(O2–Os1–O3 = 62.73(19)°). The C2–C3–O1 bond angle
(116.1(5)°) and the disappearance of the H atom on C3 at-
om indicate that C3 is sp2-hybridized. The Os1–C1 (1.920(5)
Å) and Os1–O1 (2.128(4) Å) bond lengths are shorter than
those in complex 1 (Os1–C1 = 1.997(9) Å, Os1–O1 =
2.208(6) Å). In addition, the Os1–C1 bond length is com-
parable with that of the previously reported osmafuran
OsCl2(PPh3)2{CHC(PPh3)C(O)CH2CH3} (1.904(10) Å) [2i].
The C1–C2 (1.410(8) Å) and C2–C3 (1.408(9) Å) bond
distances are between typical C–C single and double bonds.
The bond distances of Os1–O1 (2.128(4) Å) and C3–O1
(1.281(7) Å) are close to the corresponding values in osma-
furan OsCl(CO)(PiPr3)2{CHCHC(O)Ph} (Os1–O1 = 2.126(3)
Å, C3–O1 = 1.283(4) Å) [7e]. The five-membered metal-
lacycle constructed by Os1, C1, C2, C3, and O1 has good
planarity reflected by the small rms deviation (0.0426 Å)
from the least-squares plane through the five atoms. Alt-
hough complex 4 can be regarded as a chelated vinyl ketone
complex or oxametallacyclopentadiene complex, the struc-
tural data show that the metallacycle is delocalized and
complex 4 is a metallafuran.
3.4 Transformation of complex 1 at high temperature
Heating the solution of complex 1 in 1,2-dichloroethane at
reflux gave osmafuran OsCl2(PPh3)2[CHC(PPh3)CPhO] (5)
in 85% yield as a green solid (Scheme 2). Osmafuran 5 was
characterized by solution NMR spectroscopy, elemental
analysis and single crystal X-ray diffraction.
As shown in Figure 4, the two Cl atoms coordinate with
the central osmium atom in a cis fashion (Cl1–Os1–Cl2 =
85.67(9)°). Within the five-membered metallacycle, the
bond lengths are very close to those of complex 4. The pla-
narity of the metallacycle is reflected by the small rms devi-
ation (0.0528 Å). All these data show that complex 5 has a
delocalized metallacycle.
The selected NMR data for complexes 1–5 are given in
Table 1. The 1H and 13C chemical shifts in the metallacycle
of complex 2 are very close to those of complex 1, con-
sistent with the similar metallacycle structures in both com-
plexes. For complex 3, the proton signal for H1 atom shifts
Scheme 2 Synthesis of complexes 4 and 5.
Figure 4 Molecular structure for complex 5 (ellipsoids at the 50% prob-
ability level). Some hydrogen atoms are omitted for clarity. Selected bond
distances (Å) and angles (deg): Os1–P1 2.335(3), Os1–P2 2.275(2),
Os1–Cl1 2.435(2), Os1–Cl2 2.514(2), Os1–C1 1.920(9), Os1–O1 2.128(5),
C1–C2 1.413(12), C2–C3 1.424(12), C3–O1 1.254(11); P1–Os1–P2
101.45(9), Cl1–Os1–Cl2 85.67(9), C1–Os1–O1 78.0(3), Os1–C1–C2
117.3(7), C1–C2–C3 112.3(8), C2–C3–O1 117.8(8), C3–O1–Os1 113.3(6),
Cl2–Os1–C1 163.7(3), P2–Os1–O1 167.18(17).
Figure 3 Molecular structure for complex 4 (ellipsoids at the 50% prob-
ability level). Some hydrogen atoms are omitted for clarity. Selected bond
distances (Å) and angles (deg): Os1–P1 2.3019(17), Os1–P2 2.2558(17),
Os1–O2 2.219(4), Os1–O3 2.110(4), Os1–C1 1.920(5), Os1–O1 2.128(4),
C1–C2 1.410(8), C2–C3 1.408(8), C3–O1 1.281(7); P1–Os1–P2 98.77(6),
O2–Os1–O3 62.73(19), C1–Os1–O1 77.6(2), Os1–C1–C2 117.6(4),
C1–C2–C3 113.6(5), C2–C3–O1 116.1(5), C3–O1–Os1 114.2(3).

Liu B, et al. Sci China Chem August (2013) Vol.56 No.8
1109
Table 1 Selected NMR data for complexes 1–5
(1H) (ppm)
(13C) (ppm)
(31P) (ppm)
H1
H3
C1
C2
C3
80.9
OsP
CP
1
2
3
4
5
12.22
11.70
9.94
3.21
3.72
3.49

204.9
212.5
186.0
247.6
242.6
98.1
7.74, 3.72
9.71, 2.06
6.4
8.90, 4.47
0.50, 7.88
0.99
2.40
104.2
120.3
109.5
112.5
87.3
77.4
18.6
15.35
15.40
199.2
201.7
14.98
13.05



This work was supported by the National Natural Science Foundation of
China (21174115 and 21202054), the National Basic Research Program of
China (973 Program, 2012CB821600) and the Program for Changjiang
Scholars and Innovative Research Team in University.
upfield in comparison to complexes 1 and 2, presumably
due to the change of the coordination environment around
the metal center. The same trend is observed for C1 and C3,
but the signals of C2 and CPPh3 shift downfield. In com-
plexes 4 and 5, the 1H and 13C chemical shifts in the metal-
lacycle shift downfield considerably compared with com-
plexes 1 and 2, clearly showing their aromaticity. In com-
plex 5, the 31P chemical shifts of OsPPh3 shift upfield sig-
nificantly in comparison to complex 4, indicating the coor-
dination environment of the metal is changed.
A mechanism for the formation of complex 5 is proposed
in Scheme 3. Complex 1 eliminates HCl from the proton of
the hydroxyl group and a Cl ligand, affording intermediate
A (step i). The H3 atom attached to C3 atom shifts to os-
mium atom to give intermediate B (step ii). The HCl mole-
cule formed in step i reacts with the hydride ligand in in-
termediate B to give complex 5 and H2 (step iii). It is clear
that the relative position of the ligands around metal center
changed during the reaction. A similar mechanism has been
proposed by Esteruelas and Oro et al in 1994 [7e]. In the
presence of Cs2CO3, the two Cl ligands in complex 5 can
be substituted, giving complex 4 and CsCl.
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Scheme 3 Proposed mechanism for the formation of complex 5.
4 Conclusions
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1111
LIU Bin obtained his master degree in Zhengzhou University in 2006, and his Ph.D. in Xiamen Uni-
versity in 2009 under the supervision of Prof. Haiping Xia. His thesis focused on the synthesis and char-
acterization of transition metal containing aromatics and he has synthesized a series of these compounds
such as metallapyridinium, metallapyridine, metallanaphthalene, and metallanaphthalyne. Then he went
to the Hong Kong University of Science and Technology as a research associate. From 2010, he started
his independent career in the Central China normal University.
CAO Xiao-Yu obtained his B.S. in chemistry from Peking University in 2003. He has been worked
with Prof. Yufen Zhao, Zhenfeng Xi and Jian Pei. From 2004 to 2011, he worked with Prof. Jean-Marie
Lehn in Université de Strasbourg in France for his Ph.D., and with Prof. E. W. (Bert) Meijer in Eindho-
ven University of Technology, the Netherlands, as a postdoc. In 2011, he joined Xiamen University as an
associate professor. His research focuses on design, synthesis, self-assembly and applications of novel
aromatic molecules.
XIA Haiping obtained his B.S. in chemistry in 1983, his M.S. in 1986, and his Ph.D. in 2002 from
Xiamen University. He started to work at Xiamen University in 1986, and was promoted to associate
professor in 1991, professor in 1999. From 1995 to 1997 he went to the Hong Kong University of Sci-
ence and Technology as a research associate. In 2009, he received the National Natural Science Funds for
Distinguished Young Scholar of China. His research focuses on the synthesis, reactivity and applications
of metalla-aromatics.