Studies of the reaction of dimethyltin dichloride with mercaptoacetic acid in the presence of amines and crystal structure of [(n-Pr)3NH] [Me2Sn(μ2-SCH2COO)Cl]

Article abstract of DOI:10.1016/j.jorganchem.2005.04.022

A series of new five-coordinated ionic organotin(IV) complexes with general formula [Q][Me₂Sn(μ²-SCH₂COO)Cl](Q = diethylammonium, triethylammonium, di-i-propylammonium, tripropylammonium, tri-n-butylammonium, pyrimidium, 3-picolinium, methylphenylammonium, dimethylphenylammonium) were synthesized by the reaction of mercaptoacetic acid with dimethyltin dichloride in the presence of an organic base. These complexes have been characterized by elemental analyses, IR and ¹H NMR spectroscopies. The crystal structure of [(n-Pr)₃NH][Me ₂Sn(μ²-SCH₂COO)Cl] was determined by X-ray crystallography. The structure consists of an anion part, and a tri-n-propylammonium cation part as a counterion. The tin atom has a distorted cis-tbp geometry with two carbon and one sulfur atoms occupying the equatorial positions and the O atom and Cl atom occupying the axial positions. The organotin anion and its counterion are connected through a hydrogen bond between the N atom in the ammonium and the O atom of the carbonyl group with a N-O length of 2.766 A?.

Full text of DOI:10.1016/j.jorganchem.2005.04.022

Journal of Organometallic Chemistry 690 (2005) 3405–3409
www.elsevier.com/locate/jorganchem
Studies of the reaction of dimethyltin dichloride with
mercaptoacetic acid in the presence of amines and crystal structure
of [(n-Pr)3NH][Me2Sn(l2-SCH2COO)Cl]
a
a
b,
b
c
Guiyun Zhong , Qingfu Liu , Xueqing Song *, George Eng , Qinglan Xie
a
Biochemistry Department, XingTai University, Xingtai 054001, PR China
Department of Chemistry and Physics, University of the District of Columbia, 4200 Connecticut Avenue, NW, Washington, DC 20008, USA
b
c
Institute of Elemento-Organic Chemistry, NanKai University, Tianjin 300071, PR China
Received 8 April 2005; revised 11 April 2005; accepted 11 April 2005
Available online 15 June 2005
Abstract
A series of new five-coordinated ionic organotin(IV) complexes with general formula [Q][Me2Sn(l2-SCH2COO)Cl](Q = diethyl-
ammonium, triethylammonium, di-i-propylammonium, tripropylammonium, tri-n-butylammonium, pyrimidium, 3-picolinium,
methylphenylammonium, dimethylphenylammonium) were synthesized by the reaction of mercaptoacetic acid with dimethyltin
1
dichloride in the presence of an organic base. These complexes have been characterized by elemental analyses, IR and H NMR
spectroscopies. The crystal structure of [(n-Pr)3NH][Me2Sn(l2-SCH2COO)Cl] was determined by X-ray crystallography. The struc-
ture consists of an anion part, and a tri-n-propylammonium cation part as a counterion. The tin atom has a distorted cis-tbp geom-
etry with two carbon and one sulfur atoms occupying the equatorial positions and the O atom and Cl atom occupying the axial
positions. The organotin anion and its counterion are connected through a hydrogen bond between the N atom in the ammonium
˚
and the O atom of the carbonyl group with a N–O length of 2.766 A.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Five-coordinated Tin(IV) complex; Ionic organotin; Crystal structure
1. Introduction
to have stabilization properties, diorganotin sulfur com-
pounds, with the general formula R2Sn(SR0)2 are still
the mostly studied as the stabilizers [6].
While most of the studies on organotin compounds
have been focused on the organotin carboxylates owing
to their diversified molecular structures [1,2] and wide
range of applications, such as biological activities [3–
5], organotin sulfides are another group of organotin
compounds that have drawn much current attention be-
cause of their good thermal stability and their applica-
tions as stabilizers for PVC and related plastic
materials. Although compounds of general formulae
R3Sn(SR0), RSn(SR0)3 and Sn(SR0)4 were all claimed
Recently, much interest of organotin sulfide com-
pounds has been concentrated on the syntheses and struc-
ture determinations of a series of oragnotin 1,2 dithiolate
complexes, the ligand used include aliphatic derivative,
e.g., SCH2CH2S(edt) [7], SCH2CHMeS [7], alkenyl deriv-
atives [8], e.g., SCH@CHS [9], SC(CN)@C(CN)S(mnt)
[9], aryl derivatives, SC6H4S(bdt)[10]. The key feature
of this type of organotin compounds lies in that they
are made up of two parts, an anionic unit which consists
of a cis-tbp C2SnXS2, and a cation which is an organoam-
monium. In the reaction of the mnt (mnt = (CN)2C2S2)
ligand with MeSnCl3 and PhSnCl3 in the presence of
*
Corresponding author. Tel.: +1 2022747420; fax: +1 2022746237.
E-mail address: xsong@udc.edu (X. Song).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.04.022

3406
G. Zhong et al. / Journal of Organometallic Chemistry 690 (2005) 3405–3409
tetraalkylammonium chloride, tin–carbon cleavage oc-
curred to yield [Sn(mnt)3] or [Sn(mnt)2Cl2]2ꢀ salts [11],
depending on the ligand ratio and reaction temperature.
In our previous studies, the reaction of triphenyltin chlo-
ride and mercaptoacetic acid in the presence of an or-
ganic base has been investigated [12,13], an unexpected
tin–carbon cleavage process was observed in the reaction;
while the reaction of mercaptoacetic acid with phenyltin
trichloride in the presence of an amine generated no Sn–C
cleavage products [14]. Our interest in the mechanism of
the tin–carbon cleavage of organotin induced by ligand
containing S atom has prompted us to further investigate
the reaction of some other organotin chorides. With this
in mind, the reaction of mercaptoacetic acid with dimeth-
yltin dichloride in the presence of different amines is re-
ported herein.
The mixture was stirred and refluxed for 2 h. The solid
was filtered off and the solvent and the excessive amount
of amine were removed from the filtrate under vacuum
and the white solid was obtained. The white solid was
recrystallized from ethanol by cooling for several days
to yield colorless crystals.
2.2.1. [Me2SnCl(SCH2COO)][H2NEt2] 1
Yield: 57%, m.p. >220 ꢁC. 1H NMR (CDCl3): d
0.85(6H, t, SnCH3 Æ 2, JSn–H = 73.8), 1.39(6H, t, CH3 Æ
2, J = 6.5 Hz), 3.05(4H, m, NCH2 Æ 2), 3.45(2H, t,
3
SCH2, JSn–H = 39.6 Hz) ppm. IR (KBr, cmꢀ1): 2987
m(HN+), 1574 m(OCO)asym, 1403 m(OCO)sym, 555 m(Sn–
C), 430 m(Sn–O). Anal. Calc. for C8H20ClNO2SSn: C,
27.58; H, 5.79; N, 4.02. Found: C, 27.39; H, 5.57; N,
3.89%.
2.2.2. [Me2SnCl(SCH2COO)][HNEt3] 2
1
2. Experimental
Yield: 50%, m.p. 152–154 ꢁC. H NMR (CDCl3): d
0.87(6H, t, SnCH3 Æ 2, JSn–H = 73.6), 1.32(9H, t,
CH3 Æ 3, J = 6.6 Hz), 3.05(6H, m, NCH2 Æ 3), 3.56(2H,
2.1. Materials and instrumentation
3
t, SCH2, JSn–H = 46.4 Hz) ppm. IR (KBr, cmꢀ1): 2987
Mercaptoacetic acid (HSCH2COOH), dimethyltin
dichloride and various alkyl or aromatic amines were
purchased from Alfa Aesar, Ward Hill, MA, USA were
used without further purification. Solvent evaporations
were always carried out under vacuum using a rotary
evaporator. All syntheses were carried out under a
Nitrogen atmosphere. The solvents used in the reaction
were of AR grade and dried using standard procedures.
Elemental analyses (C, H, N) were determined on a
Vario EL model instrument. The 1H NMR spectra were
measured on a BRUKER AC-P 200 spectrometer at
room temperature with DCCl3 as solvent and TMS as
internal standard. IR spectra were recorded in the range
of 400–4000 cmꢀ1 on a Brucher-FT-IR-Equinqx55 as
KBr disc.
m(HN+), 1559 m(OCO)asym, 1347 m(OCO)sym, 552 m(Sn–
C), 436 m(Sn–O). Anal. Calc. for C10H24ClNO2SSn: C,
31.90; H, 6.44; N, 3.72. Found: C, 31.51; H, 6.60; N,
3.59%.
2.2.3. [Me2SnCl(SCH2COO)][H2N(i-Pr)2] 3
Yield: 57%, m.p. >220 ꢁC. 1H NMR (CDCl3): d
0.77(6H, t, SnCH3 Æ 2, JSn–H = 73.9), 1.39(12H, d,
CH3 Æ 4, J = 6.0 Hz), 3.12(2H, m, NCH Æ 2), 3.55(2H, t,
3
SCH2, JSn–H = 40.0 Hz) ppm. IR (KBr, cmꢀ1): 2987
m(HN+), 1620 m(OCO)asym, 1389 m(OCO)sym, 553 m(Sn–
C), 432 m(Sn–O). Anal. Calc. for C10H24ClNO2SSn: C,
31.90; H, 6.44; N, 3.72. Found: C, 32.10; H, 6.20; N,
3.65%.
2.2.4. [Me2SnCl(SCH2COO)][HN(n-Pr)3] 4
1
2.2. Synthesis of products
Yield: 72%, m.p. 120–122 ꢁC. H NMR (CDCl3): d
0.83(6H, t, SnCH3 Æ 2, JSn–H = 74.6), 1.02(9H, t,
CH3 Æ 3, J = 6.4 Hz), 1.69(6H, m, CH2 Æ 3), 2.95(6H, m,
The products were synthesized according to Scheme
1, and general procedure is described as following:
A solution of Me2SnCl2 (0.55 g, 2.5 mmol) in acetone
(20 ml) is added dropwise to a solution of HSCH2COOH
(0.23 g, 2.5 mmol) in 20 mL acetone under nitrogen. The
mixture was then stirred magnetically at the room tem-
perature for 0.5 h, and then an appropriate amine
(5 mmol) was added, white solid formed immediately.
3
NCH2 Æ 3), 3.42(2H, t, SCH2, JSn–H = 44.6 Hz) ppm.
IR (KBr, cmꢀ1): 2970 m(HN+), 1587 m(OCO)asym, 1359
m(OCO)sym, 548 m(Sn–C), 436 m(Sn–O). Anal. Calc. for
C13H30ClNO2SSn: C, 37.30; H, 7.24; N, 3.35. Found:
C, 37.19; H, 6.85; N, 2.97%.
2.2.5. [Me2SnCl(SCH2COO)][HN(n-Bu)3] 5
Yield: 63%, m.p. 70–72 ꢁC. 1H NMR (CDCl3): d
0.81(6H, t, SnCH3 Æ 2, JSn–H = 74.2), 0.96(9H, t,
CH3 Æ 3, J = 6.5 Hz), 1.38(6H, m, CH2 Æ 3), 1.67(6H, m,
CH23), 2.93(6H, m, NCH2 Æ 3), 3.41(2H, t, SCH2,
3JSn–H = 37.8Hz) ppm. IR (KBr, cmꢀ1): 2974 m(HN+),
1599 m(OCO)asym, 1374 m(OCO)sym, 554 m(Sn–C), 453
m(Sn–O). Anal. Calc. for C16H36ClNO2SSn: C, 41.71;
H, 7.89; N, 3.04. Found: C, 41.70; H, 7.67; N, 3.31%.
Cl
S
Me
Me
+
CH2
C
HNR
NR
3
3
Sn
Me2SnCl2
+
HSCH2COOH
O
O
Scheme 1. NR3 = HNEt2 (1), NEt3 (2), HN(i-Pr)2 (3), N(n-Pr)3 (4),
N(n-Bu)3 (5), pyridine (6), 3-picoline (7), HNPhMe (8), NPhMe2 (9).

G. Zhong et al. / Journal of Organometallic Chemistry 690 (2005) 3405–3409
3407
Table 1
Crystal and structure refinement data for compound 4
2.2.6. [Me2SnCl(SCH2COO)][pyridinium] 6
Yield: 56%, m.p. >220 ꢁC. 1H NMR (CDCl3): d
0.87(6H, t, SnCH3 Æ 2, JSn–H = 74.0), 3.71(2H, t, SCH2,
3JSn–H = 42.8Hz), 7.82(2H, m, o-H), 8.15(1H, m, p-H),
8.28(2H, m, m-H) ppm. IR (KBr, cmꢀ1): 3089 m(HN+),
1582m(OCO)asym, 1395 m(OCO)sym, 555 m(Sn–C), 432
m(Sn–O). Anal. Calc. for C9H14ClNO2SSn: C, 30.50;
H, 3.99; N, 3.95. Found: C, 30.78; H, 4.39; N, 4.17%.
Empirical formula
C13H30ClNO2SSn
Formula weight
Crystal system
Space group
418.58
Triclinic
ꢀ
P1
Unit cell dimensions
˚
a (A)
˚
10.497(5)
10.515(4)
10.844(5)
74.734(7)
68.943(7)
62.203(6)
981.4(8)
2
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
2.2.7. [Me2SnCl(SCH2COO)][picolinium] 7
Yield: 65%, m.p. >220 ꢁC. 1H NMR (CDCl3): d
0.87(6H, t, SnCH3 Æ 2, JSn–H = 73.8), 2.57(3H, s, CH3),
3
˚
Volume (A )
3
3.71(2H, t, SCH2, JSn–H = 2.8 Hz), 7.75-8.22(4H, m,
Z
C5H4) ppm. IR (KBr, cmꢀ1): 3093 m(HN+),
1554m(OCO)asym, 1400 m(OCO)sym, 552 m(Sn–C), 436
m(Sn–O). Anal. Calc. for C10H16ClNO2SSn: C, 32.60;
H, 4.39; N, 3.80. Found: C, 32.78; H, 3.89; N, 3.67%.
Absorption coefficient (mmꢀ1
F(000)
)
1.543
428
Crystal size (mm)
h Range for data collection
Reflections collected /
0.40 · 0.25 · 0.20
2.82–24.45ꢁ
5705
Independent reflections [Rint
Data/restraints/parameters
Goodness-of fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
]
3985 [0.0232]
3985/0/175
0.990
2.2.8. [Me2SnCl(SCH2COO)][H2NPhMe] 8
Yield: 60%, m.p. >220 ꢁC. 1H NMR (CDCl3): d
0.79(6H, t, SnCH3 Æ 2, JSn–H = 74.3), 2.97(6H, s,
R1 = 0.0327, wR2 = 0.0730
R1 = 0.0474, wR2 = 0.0786
0.991
3
NCH3), 3.47(2H, t, SCH2, JSn–H = 46.8 Hz), 7.35-
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
8.42(5H, m, C6H5) ppm. IR (KBr, cmꢀ1): 3051
m(HN+), 1571 m(OCO)asym, 1390 m(OCO)sym, 558 m(Sn–
C), 434 m(Sn–O). Anal. Calc. for C11H18ClNO2SSn: C,
34.54; H, 4.75; N, 3.66. Found: C, 34.24; H, 4.74; N,
3.56%.
R1 = 0.0327, wR2 = 0.0730
R1 = 0.0474, wR2 = 0.0786
0.478 and ꢀ0.383
Largest diff. peak and hole (e Aꢀ3
)
isotropic temperature factors for hydrogen atoms, and
non isotropic for other atoms, gave the final
R = 0.0704 (Rw = 0.0786, S = 0.990). Final atomic coor-
dinates are listed in Table 1, selected bond lengths and
bond angles in Table 2. The structure of 1, together with
atomic numbering scheme, is depicted in Fig. 1.
2.2.9. [Me2SnCl(SCH2COO)][HNPhMe2] 9
1
Yield: 71%, m.p. 101–103 ꢁC. H NMR (CDCl3): d
0.80(6H, t, SnCH3 Æ 2, JSn–H = 74.4), 2.97(6H, s,
3
NCH3 Æ 2), 3.47(2H, t, SCH2, JSn–H = 46.8Hz), 7.35–
8.42(5H, m, C6H5) ppm. IR (KBr, cmꢀ1): 3027
m(HN+), 1569m(OCO)asym, 1380 m(OCO)sym, 560 m(Sn–
C), 436 m(Sn–O). Anal. Calc. for C12H20ClNO2SSn: C,
36.35; H, 5.09; N, 3.53. Found: C, 36.30; H, 4.79; N,
3.67%.
Table 2
Bond lengths (A) and angles (ꢁ) for[(n-Pr)3NH][Me2Sn(l2-
SCH2COO)Cl]
˚
2.3. Crystal structure determination
Sn(1)–C(4)
Sn(1)–C(3)
2.115(4)
2.116(4)
2.213(2)
2.4026(12)
2.5138(13)
1.265(4)
1.236(4)
1.802(4)
1.517(5)
1.475(5)
1.511(5)
1.502(5)
1.510(5)
1.498(5)
1.522(5)
121.89(19)
90.10(15)
89.22(15)
117.60(13)
119.65(14)
O(1)–Sn(1)–S(1)
C(4)–Sn(1)–Cl(1)
C(3)–Sn(1)–Cl(1)
O(1)–Sn(1)–Cl(1)
S(1)–Sn(1)–Cl(1)
C(11)–N(1)–C(8)
C(11)–N(1)–C(5)
C(8)–N(1)–C(5)
C(1)–O(1)–Sn(1)
C(2)–S(1)–Sn(1)
O(2)–C(1)–O(1)
O(2)–C(1)–C(2)
O(1)–C(1)–C(2)
C(1)–C(2)–S(1)
C(6)–C(5)–N(1)
C(5)–C(6)–C(7)
C(9)–C(8)–N(1)
C(8)–C(9)–C(10)
N(1)–C(11)–C(12)
C(11)–C(12)–C(13)
81.28(7)
95.71(14)
93.81(13)
170.72(7)
89.61(4)
114.1(3)
112.8(2)
110.6(2)
21.3(2)
The colorless crystals of [(n-Pr)3NH][Me2Sn(l2-
SCH2COO)Cl] suitable for X-ray crystallography study
were obtained from a dilute ethanol solution. A crystal
with approximate dimensions of 0.40 · 0.25 · 0.20 mm
was selected for data collection on a BRUKER SMART
1000 diffractometer with graphite monochromated Mo
Sn(1)–O(1)
Sn(1)–S(1)
Sn(1)–Cl(1)
O(1)–C(1)
O(2)–C(1)
S(1)–C(2)
C(1)–C(2)
˚
Ka radiation (k = 0.71073 A) at 293(2) K. The structure
C(5)–C(6)
C(6)–C(7)
C(8)–C(9)
98.45(13)
123.2(3)
117.5(3)
119.3(3)
117.1(3)
114.0(3)
111.7(3)
114.5(3)
110.4(3)
114.1(3)
111.1(3)
was solved by direct methods and refined on F2 with
anisotropic parameters for all non-hydrogen atoms.
All calculations were performed using SHELXL program
on PC computer.
C(9)–C(10)
C(11)–C(12)
C(12)–C(13)
C(4)–Sn(1)–C(3)
C(4)–Sn(1)–O(1)
C(3)–Sn(1)–O(1)
C(4)–Sn(1)–S(1)
C(3)–Sn(1)–S(1)
Of the 5705 reflections measured (max = 26.52ꢁ),
3985 were independent, of which 3185 had I > 2r (I).
The positions of the non-hydrogen atoms were found
from the three-dimensional Patterson and Fourier
synthesis. Block-diagonal least squares refinement with

3408
G. Zhong et al. / Journal of Organometallic Chemistry 690 (2005) 3405–3409
cause the weak signals to disappear. Methyl protons
are in the region of 0.77–0.87 ppm. The chemical shifts
of the protons in SCH2 exhibit signals at 3.41–
3.71 ppm as a triplet which is caused by the long
distance (119Sn–1H) coupling. The spin–spin coupling
constant 3J(119Sn–1H) is in the range 37.4–46.8 Hz. Pro-
tons on the carbon atoms of the ammonium ions have
observed in their normal positions.
3.3. Crystal structure
The molecular structure and molecular packing of 4,
[(n-Pr)3NH][Me2Sn(l2-SCH2COO)Cl], are shown in
Figs. 1 and 2, respectively. The crystal data are listed
in Table 1. Selected bond lengths and bond angles are
in Table 2.
The Fig. 1 shows that the tin atom in anion is coor-
dinated by five atoms with O(1) and Cl(1) at axial posi-
tions and C(3),C(4),S(1) forming the equatorial plane.
The anion has a slightly-distorted cis-trigonal bipyrami-
dal geometry around tin atom with the Sn–S–C–C–O
metallocycle having envelope conformation. Few exam-
ples of cis-tbp geometries are found in the structural lit-
erature of triorganotin carboxylate compounds. The
structure of the [Me2SnCl(mercaptoacetato)] anion in
the present stannate is similar to that in literature in that
both compounds possess a five-membered chelate ring.
The axial skeleton is a little bent, (Cl–Sn–O angle of
170.72ꢁ). In such a structure, the sum of the angles be-
tween the tin atom and the equatorial ligating atoms
(i.e. two C atoms and one S atom) is the 359.1(2)ꢁ com-
pared to the ideal octahedral value of 360ꢁC. The distri-
bution of these 360ꢁ, which should normally be 120ꢁ for
each angle, is almost equal with C(4)–Sn(1)–C(3), C(4)–
Sn(1)–S(1) and C(3)–Sn(1)–S(1) being 121.89(19)ꢁ,
117.60(13)ꢁ and 119.65(14)ꢁ, respectively. This indicates
that the Sn atom is almost exactly on the equatorial
Fig. 1. Molecular structure of [(n-Pr)3NH][Me2Sn(l2-SCH2COO)Cl],
H-atoms omitted for clarity.
3. Results and discussion
3.1. IR
In the spectrum of the ligand, the strong, well-devel-
oped band at 1600 cmꢀ1 is assigned to m(S–H). However,
the absence of the characteristic absorption of m(S–H)
indicates the S involving in the coordination to tin atom.
Medium to weak bands in the region 430–453 cmꢀ1 are
assigned to Sn–O, those in the region 548–560 cmꢀ1
indicate the presence of Sn–C bands [15]. The absorp-
tion frequencies of asymmetry ðmCOa2sÞ and symmetry
(mCOOs) of carbonyl groups are in the region 1554–
1620 and 1347–1403 cmꢀ1, respectively. The difference
between the two frequencies (DmCO2) is 154–171 cmꢀ1
.
This is much lower than the DmCOO value for a monod-
entate carboxylate. This can be ascribed to the fact that
there exists a strong hydrogen bonding between N atom
in the ammonium ion and the O atom in the carbonyl
group. The carbonyl oxygen donates part of its electrons
to the hydrogen bonding, which makes the difference be-
tween the absorption frequencies of asymmetry
(mCOOas) and symmetry (mCOOs) of carbonyl groups
decrease.
˚
plane. It is displaced only 0.0443 A out of the plane de-
fined by C(3), C(4), S(1), which well agrees with the ideal
1
3.2. H NMR
1H NMR spectra of the compounds are mainly com-
posed of three parts: methyl protons (SnCH3), methy-
lene protons in SCH2 moiety and amine protons. The
existence of the hydrogen bonding between protons in
R3HN+ and carbonyl (C@O) oxygens cause the ammo-
nium protons to appear in a much lower field range
from 10 to 11 ppm as a weak signal than those in the ori-
ginal amines. In some cases, the rapid exchange of
ammonium protons with deuterated solvent would
Fig. 2. Cell packing of [(n-Pr)3NH][Me2Sn(l2-SCH2COO)Cl].

G. Zhong et al. / Journal of Organometallic Chemistry 690 (2005) 3405–3409
3409
TBP. The Fig. 2 shows that there is existence of mutual
interaction through the hydrogen-bonding between the
cation and the anion moities; the distance of N–O is
(fax: +44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk
or www: http://www.ccdc.cam.ac.uk). Supplementary
data associated with this article can be found, in the on-
line version at doi:10.1016/j.jorganchem.2005.04.022.
˚
2.766 A, which is much shorter than the sum of Van
˚
der Waals radii for N and O of 3.2 A. The hydrogen
bonding greatly affects the distribution of the electrons
on the carbonyl group, this is observed by the two iden-
˚
tical C–O bond distances at 1.237(4) A (O(1)-C(23)) and
References
˚
1.261(4) A (O(2)–C(23)). This is in agreement with the
[1] E.R.T. Tiekink, Trends Organomet. Chem. 1 (1994) 71.
[2] E.R.T. Tiekink, Appl. Organomet. Chem. 5 (1991) 1.
[3] R. Willem, M. Biesemans, M. Boualam, Appl. Organomet. Chem.
7 (1993) 311.
lowering value of the difference between the absorption
frequencies of asymmetry ðmCOa2sÞ and symmetry ðmCO2s Þ
of carbonyl groups.
[4] S.W. Ng, V.G. Kumar Das, J. Holecek, A. Lycka, M. Gielen,
M.G.B. Drew, Appl. Organomet. Chem. 11 (1997) 39.
[5] R. Willem, M. Biesemans, F. Kayser, Inorg. Chim. Acta 197
(1992) 25.
Acknowledgements
[6] E.W. Abel, D.A. Armitage, Adv. Organomet. Chem. 6 (1965)
49.
Financial support from the National Natural Science
Foundation of China and the State Commission of Edu-
cation of China are gratefully acknowledged.
[7] G. Bandoli, U. Casellato, V. Peruzzo, G. plazzogna, J. Organo-
met. Chem. 352 (1988) 283.
[8] E.W. Abel, S.K. Bhargava, K.g. Orrell, V. Ski, J. Chem. Soc.
Dalton Trans. (1982) 2073.
[9] E.W. Abel, C.R. Jenkins, J. Chem. Soc. A (1967) 1344.
[10] Z.H. Zahid, R.A. Howie, J.L. Wardell, J. Organomet. Chem., 577
(1999) 140.
Appendix A. Supplementary data
[11] E.S. Bretschneider, C.W. Allen, J. Organomet. Chem. 38 (1972)
43.
Crystallographic data for the structures reported in
this paper have been deposited with Cambridge Crystal-
lographic Data Center and allocated the deposition
number CCDC 264151 for 4. Copies of this information
may be obtained free of charge from the Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
[12] X. Song, Q. Xie, X. Fang, Chin. Chem. Lett. 9 (1998) 977.
[13] L.J. Sun., X.Q. Song, J.X. Chen, G.Y. Zhong, Q.L. Xie, Chem. J.
Chinese Universities 4 (2004) 646.
[14] G.Y. Zhong, H.B. Song, L.J. Sun, Q.L. Xie, Chem. Res. Chinese
Universities 3 (2004) 274.
[15] R. Okawara, K. Yasuda, J. Organomet. Chem. 1 (1964) 356.