Direct synthesis and properties of binuclear copper(II) complexes

Article abstract of DOI:10.1081/SIM-100107710

At room temperature, dibenzoyl peroxide undergoes an oxidative addition reaction with metallic copper powder and the relevant ligands afford binuclear copper(II) complexes, [Cu(OOCC₆H₅)₂L]₂, L = pyridine-2,6-dicarboxylic acid (L¹), THF (L²), 3-aminopyridine (L³), 4-aminopyridine (L⁴), 2-methylpyridine (L⁵), 2,6-dimethylpyridine (L⁶) and 2-aminothiazol (L⁷). These complexes were further characterized by physico-chemical and spectroscopic methods. The structure of complex (7) has been determined by a single-crystal X-ray analysis. Each copper(II) ion is coordinated by two bridging bidentate benzoates and one L (as defined above) ligand to form dimeric binuclear molecules.

Full text of DOI:10.1081/SIM-100107710

Synthesis and Reactivity in Inorganic and Metal-Organic
Chemistry
ISSN: 0094-5714 (Print) 1532-2440 (Online) Journal homepage: http://www.tandfonline.com/loi/lsrt19
DIRECT SYNTHESIS AND PROPERTIES OF
BINUCLEAR COPPER(II) COMPLEXES
Ruina Yang , Dongmei Wang , Aiyan Kuang , Yingfan Liu & Douman Jin
To cite this article: Ruina Yang , Dongmei Wang , Aiyan Kuang , Yingfan Liu & Douman Jin
(2001) DIRECT SYNTHESIS AND PROPERTIES OF BINUCLEAR COPPER(II) COMPLEXES,
Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 31:9, 1647-1662, DOI:
10.1081/SIM-100107710
To link to this article: http://dx.doi.org/10.1081/SIM-100107710
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Date: 06 August 2017, At: 21:16

SYNTH. REACT. INORG. MET.-ORG. CHEM., 31(9), 1647±1662 (2001)
DIRECT SYNTHESIS AND PROPERTIES
OF BINUCLEAR COPPER(II) COMPLEXES
Ruina Yang,*,1 Dongmei Wang,1 Aiyan Kuang,1
Yingfan Liu,1 and Douman Jin2
1Henan Institute of Chemistry, Zhengzhou 450002,
P. R. China
2State Key Laboratory of Coordination Chemistry,
Nanjing University 210093, P. R. China
ABSTRACT
At room temperature, dibenzoyl peroxide undergoes an oxi-
dative addition reaction with metallic copper powder and the
relevant ligands a€ord binuclear copper(II) complexes,
[Cu(OOCC6H5)2L]2, L ˆ pyridine-2,6-dicarboxylic acid (L1),
THF (L2), 3-aminopyridine (L3), 4-aminopyridine (L4), 2-
methylpyridine (L5), 2,6-dimethylpyridine (L6) and 2-ami-
nothiazol (L7). These complexes were further characterized by
physico-chemical and spectroscopic methods. The structure of
complex (7) has been determined by a single-crystal X-ray
analysis. Each copper(II) ion is coordinated by two bridging
bidentate benzoates and one L(as de®ned above) ligand to
form dimeric binuclear molecules.
*Corresponding author. E-mail: yangrn@371.net
1647
Copyright # 2001 by Marcel Dekker, Inc.
www.dekker.com

1648
YANG ET AL.
INTRODUCTION
Binuclear copper(II) complexes are very important in coordination
chemistry and catalytic reactions. Certain copper complexes have been
shown to have unusual chemical properties of importance in such diverse
areas as oxygen transfer, oxidative addition and homogenous hydrogena-
tion1. Oxidative addition reactions are key steps in the activation of s bonds
in a great number of catalytic processes1. Copper(II) complexes are widely
used as catalysts in the decomposition of disubstituted peroxides1. To ob-
tain insight into the correlation between the structure and nature of copper
catalysts, low-molecular weight coordination compounds may be prepared2.
The electronic structure and bonding at the copper catalysts can be prof-
itably pursued by studying model complexes. These considerations
prompted e€orts to develop easy methods for the synthesis of binuclear
copper(II) complexes which would possess novel coordination chemistry.
Our aim is to investigate oxidative additions of the O-O bond in dibenzoyl
peroxide to metallic copper. Since the investigation of dinuclear compounds
of transition metals constitutes a ®eld of continuing research interest, this
report concerns an oxidative preparation method of copper(II) complexes.
In this work we ®rst prepared seven binuclear copper(II) compounds by
oxidative addition reactions. X-ray structure analysis of the binuclear
copper(II) complex [Cu(C3H4N2S)(OOCC6H5)2]2 is reported. It also
describes a detailed study of the spectroscopic properties of the title
compounds.
EXPERIMENTAL
Physical Measurements
All chemicals were of reagent grade quality obtained from commercial
sources and used without further puri®cation for the preparation of the
complexes. Elemental analyses were performed on an ERBA-1106 instru-
ment. Copper was determined using a JA96-975 ICP-AES (Inductively
Coupled Plasmas Atomic Emission Spectrometer). Molecular weight
ꢀ
determinations were made in chloroform solutions at 25 C using a COR-
ONA-117 analyser. IR spectra were recorded on a Nicolet 170SX IR
spectrophotometer in Nujol or CsI. TGA was carried out at a heating rate
ꢀ
of 5 C=min on a PE-TGS-2 thermal analyzer. Conductivity measurements
ꢀ
were carried out in acetone solutions thermostatted at 25 C using a DDS-
11A analyser. Electronic spectra were recorded with a Hitachi 330 spec-
trophotometer (chloroform solution). Magnetic measurements were carried

BINUCLEAR COPPER(II) COMPLEXES
1649
out on polycrystalline samples on a pendulum-type magnetometer equipped
with a nitrogen continuous-¯ow cryostat working in the 757300 K range.
MCD spectra were recorded on a JASCO-J20C automatic spectro-
polarimeter (magnetic ®eld: 7000 Gauss, pool length: 0.5 cm, scale:
0.002=cm).
Synthesis of the Complexes
2-Aminothiazol (1 mmol, 100 mg) was added to a mixture of
dibenzoyl peroxide (1 mmol, 242 mg) and copper powder (1 mgatom,
63.5 mg) in a mixture of methanol (30 mL) and acetone (30 mL). The
mixture was stirred for 48 h at room temperature. The resulting blue solu-
tion was ®ltered and left to yield blue crystals of compound (7). The com-
plexes (1) to (6) may be prepared by similar methods, except for complex (2)
which was obtained in a mixture of methanol and THF (1:1).
X-Ray Data Collection3
A
blue prismatic crystal of the complex (7) of dimensions
0.1060.1560.15 mm was selected and mounted on an automatic Enraf-
Nonius CAD-4 four-circle di€ractometer. Intensities were collected with a
graphite monochromator and MoKa radiation (l ˆ 0.71073 A), using the
oÀ2y scan technique. 6369 independent re¯ections were collected in the
range of 1ꢀ<y<25ꢀ; a total of 3429 observable re¯ections with [I ꢁ 3s(I)]
were used in the succeeding re®nements. Crystallographic data are as fol-
lows: monoclinic, space group P21=n, a ˆ 10:685ꢂ1† A b ˆ 19:028ꢂ6† A,
c ˆ 17:046ꢂ9† A, b ˆ 96:49ꢂ3†ꢀ, V ˆ 3443:4 A3, Z ˆ 4,
1:565 Mg=m3, R ˆ 0:046, Rw ˆ 0:053.
D
ˆ
ꢂcalcd:†
RESULTS AND DISCUSSION
Preparation of the Complexes
Dibenzoyl peroxide and the ligands [pyridine-2,6-dicarboxylic acid
(L1), THF (L2), 3-aminopyridine (L3), 4-aminopyridine (L4), 2-methylpyr-
idine (L5), 2,6-dimethylpyridine (L6), 2-aminothiazol (L7)] reacted with
metallic copper powder at room temperature giving blue solutions, the
insoluble copper powder is observed to dissolve rapidly. After a few days,

1650
YANG ET AL.
blue crystals were deposited in good yield. This indicates the formation of
the copper(II) compounds. The mechanism of the oxidative
Cu ‡ ꢂC6H5COO† ‡ C3H4N2S ꢂL7† ! ‰CuꢂC3H4N2S†ꢂOOCC6H5† Š
2
2 2
addition reaction is probably stepwise as the benzoyl radical reacts with Cu
to give copper(I) benzoate which then, in a subsequent reaction with a
further benzoyl radical, results in the binuclear copper(II) carboxylate
complex. These processes may be regarded as involving successive oxida-
tions of Cu, ending with the copper(II) carboxylate compounds.
According to colour changes in the process of producing the title
complexes and the obtained results, metallic copper powder has been
oxidized to form Cu(II) complexes. Therefore, the direct use of metallic
copper powder is characteristic of the present synthetic method. Molecular
weights were determined in CHCl3 solution. The compounds were soluble
enough for measurements. Results are quite reproducible and seem to be
scarcely in¯uenced by variation of concentrations. In the case of the
present complexes, molecular weight measurements give values strongly
supporting the existence of the expected binuclear species. The complexes
are stable in air at room temperature. They are easily soluble in acetone
and methanol, and sparingly soluble in benzene and hexane. Their molar
conductivities in acetone show that the title complexes are non-electrolytes.
Thus, the binuclear Cu(II) complexes with coordinated benzoate groups
may be obtained in high yields through oxidative addition reactions. The
elemental analyses of the title complexes agreed well with their formulas
(Table I).
IR and Electronic Spectra
Benzoate may coordinate to a metal ion in one of the following modes:
unidentate, bidentate or bridging. IR data (Table II) show the existence of
bridging benzoato groups by the observation of characteristic absorption
bands (160071400, 9507700, 5007600 cmÀ1)4. The IR spectra of the title
complexes are consistent with other known bridged carboxylate metal com-
plexes as determined by the position and separation between the antisym-
metric (nas) and symmetric (ns) stretches of the carboxylate group5,6. These
complexes exhibit carboxylate stretches at 157071585 Àa1nd 140071405 cmÀ1
,
respectively, where Dn (nasymÀnsym) is 1707182 cm , consistent with a
bridging mode5. In the range 9507700 and 5007600 cmÀ1, they display the
characteristic absorption bands of d(COO) and p(COO), respectively. These

BINUCLEAR COPPER(II) COMPLEXES
1651

1652
YANG ET AL.

BINUCLEAR COPPER(II) COMPLEXES
1653
are typical of a bridging coordination of benzoate7,8. They are consistent with
the results of the crystal structure of the complex.
The observed absorption band maxima in the electronic spectra
(Table II), as well as the IR spectra, agreed with those in the literature9. The
wide bands (6757685 nm) belong to d-d transitions of copper(II), while a
shoulder band (3707382 nm) is characteristic of the bridging system with
antiferromagnetic interaction9.
Thermal Analysis of the Complexes
The TG-DTA thermogram of complex (5) reveals that the pyrolitic
decomposition takes place in two steps. For example, the ®rst one corre-
sponds to a weight loss of 21.9% and is probably due to decomposition of
the ligand 2-methylpyridine (loss of weight calculated: 23.3%). The
decomposition process is con®rmed by a strong endothermic peak at
ꢀ
ꢀ
2277302 C. The second step, in the 3027680 C temperature range, cor-
responds to a pronounced weight loss due to the combustion of the organic
matter, giving CuO as ®nal residue (determined by X-ray powder patterns;
experimental weight of residue: 21.6%, calcd. 20.0%). The decomposition
pattern of complex (1) is shown in Fig. 1. The ®rst step is due to the loss of
pyridine-2,6-dicarboxylic acid (loss of weight calculated: 35.3%, found:
ꢀ
34.1%). A strong endothermic peak exists in the 2007288 C temperature
range. The second step is due to the combustion of the organic matter,
giving CuO as ®nal residue.
Magnetic Properties of the Complexes
The magnetic parameters for the compounds reveal their similarity
(Table II). Temperature-dependent magnetic susceptibility data for the se-
ven complexes have been measured from 300 K down to 100 K. The me€
values are ca. 2.0 B.M.ꢀ for these complexes at room temperature. Upon
cooling down from 25 C, the values decrease continuously for all seven
complexes, thus indicating a strong antiferromagnetic interaction between
the copper(II) atoms in the dimeric or dinuclear structures. Assuming
isotropic exchange, the exchange Hamiltonian is H ˆ À2JS1S2 with
S1 ˆ S2 ˆ 1=2, and the magnetic susceptibility per cation is given by the
following equation:
À1
wm ˆ ꢂ2Nb2g2=KT†‰3 ‡ expꢂÀ2J=KT†Š ‡ Na

1654
YANG ET AL.
Figure 1. TG-DTA curves of complex (1).
where N, g, b, K are Avogadro's constant, g factor, Bohr magneton and
Boltzman constant, respectively, Na ˆ 1:50  10À9 m2=mol. J is the ex-
change integral, if J < 0, there is ferromagnetic interaction between magnetic
metal ions, for J < 0, there is antiferromagnetic interaction between mag-
netic metal ions. Least-squares ®tting of experimental magnetic data with
the above equation gave the superexchange parameters (Table II), where F is
P
the quality factor de®ned as F ˆ ꢂwo À wc†2=wo. The value of the super-
exchange parameter for the title compounds should be considered as nor-
mal, taking into account the structural and magnetic data found in the
literature for binuclear copper(II) complexes779
.
There have been several attempts to correlate the magnitude of J with
structural parameters (related with the coordination sites and with the
bridging groups) in the [Cu2(RCOO)4] cluster and=or with the donor
properties of both carboxylate and axial ligands, but none of these e€orts
has proved successful. In this sense, it must be pointed out that the estimated
uncertainties in the J values (ca. 5710%) are of the same order of magnitude
as the variations of that parameter within a series of related compounds (i.e.
for the tetraacetatodicopper(II) adducts the J values fall in the range
2857325 cmÀ1). However, in the case of tetrabenzoate derivatives the values

BINUCLEAR COPPER(II) COMPLEXES
1655
of J span a much wider range (from 100 to 390 cmÀ1). An inspection of the
structural parameters for these compounds indicates that no magneto-
structural correlation can be established. In fact, some outstanding para-
meters involving the metal atoms such as the Cu-Cu or Cu-Obasal distances
and the C-O-Cu angle are not correlated with copper(II)-copper(II) inter-
action9,10. On the other hand, the structural di€erences in the bridging
network are substantially within the experimental error10.
Magnetic Circular Dispersion Spectra (MCD)
In general, the interaction between monocolor circular light and a
substance may be described by two absorption coecients. The di€erence
between the two absorption coecients is the circular dispersion spectrum.
The magnetic interactions between antiferromagnetic substances may be ex-
plored through the Faraday parameter of magnetic circular dispersion spec-
tra. Experimental data for (3): 4610À3 M (acetone solution), lmax ˆ 520,
280 nm, [y]M ˆ À7.14610À2, ‡4.71610À2, B ˆ ‡5.20610À5, À3.768610À4
.
Experimental data for (7): 1610À3 M (acetone solution, Fig. 2), lmax ˆ 500,
290 nm, [y]M ˆ À5.71610À2, ‡6.28610À2, B ˆ ‡5.18610À4, À1.906610À4
,
y: ovality=Gauss-mol. The Faraday parameter (B) was calculated from the
following equation:
Z
1
bandꢂ‰yŠM=n†dn ˆ À33:53ꢂB ‡ C=KT†
0
Figure 2. MCD spectrum of complex ꢂ7†.

1656
YANG ET AL.
MCD data of the complexes (3) and (7) show a positive peak at ꢃ 290 nm in
the UV region and a negative peak at ꢃ 500 nm in the visible region. The
1
former is attributed to the A1g ! B2u transition of a benzenoid structure.
The negative MCD peak ( ꢃ 500 nm) results from dxy ! dx2Ày2 transitions.
The blending of 3d and 4p orbitals give rise to non-zero rotation strength
with magnetic ®eld. MCD of the complexes only bring about the Faraday
parameter (B). Faraday parameters (A) are absent. The Faraday parameter
(A) is related to the magnetic moment. The absence of A showed anti-
ferromagnetic interaction between the copper atoms11. The results con®rm
the formation of binuclear complexes.
Crystal Structure
Figure 3 illustrates the conformation of the molecule. Selected bond
distances and angles of complex (7) are listed in Table III, supplementary
data are collected in Table IV.
There have been many structural reports concerning bridged binuclear
copper(II) compounds that are similar to the present complexes779. The
carboxylate bridged Cu Á Á Á Cu distance of the present compound is found
to be 2.678(1) A, which is comparable to that in tetrakis
(benzoate)bis(triphenylphosphine oxide)dicopper(II), 2.657(1) A12. The
average C-O distances in the complex are not signi®cantly di€erent,
1.254 A, and possess values comparable to those in other benzoate-bridging
dicopper complexes6. All other bond distances and angles are within normal
ranges.
In the binuclear copper(II) complexes, the Cu atom is coordinated by
®ve atoms: four oxygens belonging to bridging carboxyl groups, and one N
atom of 2-aminothiazol. Two benzoate groups and two 2-aminothiazol li-
gands are, respectively, located on the opposite sides to minimise repulsion
between the ligands.
Complex (7) has the expected dimeric form bridged via carboxylate
groups. Each copper(II) shows a ®ve-fold coordination in the form of a
distorted square pyramid with the four O atoms of the bridging carboxyl
groups in the basal plane and the N atom of a 2-aminothiazol molecule at
the apex. The sums of angles around each copper center, of <† O(1)-Cu(1)-
O(7) (88.1ꢀ), <† O(7)-Cu(1)-O(3) (88.5ꢀ), <† O(3)-Cu(1)-O(5) (89.6ꢀ),
<† O(5)-Cu(1)-O(1) (91.0ꢀ) and <† O(2)-Cu(2)-O(8) (89.4ꢀ), <† O(8)-Cu(2)-
O(4) (91.3ꢀ), <† O(4)-Cu(2)-O(6) (88.6ꢀ), <† O(6)-Cu(2)-O(2) (87.9ꢀ) is
357.2ꢀ (near 360ꢀ). Four oxygen atoms lie in the basal plane with average
interatomic distances of Cu-O of 1.974 A, and similar values have been
observed in tetrakis(benzoate)bis(triphenylphosphine oxide)dicopper(II)

BINUCLEAR COPPER(II) COMPLEXES
1657
Figure 3. Molecular structure of [Cu(C3H4N2S)(OOCC6H5)2]2.

1658
YANG ET AL.
Table III. Selected Bond Lengths (A) and Angles (ꢀ) for Complex (7)
Bond distances
Cu(1)-Cu(2)
Cu(1)-O(5)
Cu(2)-O(2)
Cu(2)-O(8)
2.678(1) Cu(1)-O(1)
1.961(6) Cu(1)-O(7)
1.945(5) Cu(2)-O(4)
2.024(5) Cu(2)-N(2)
2.011(5)
1.956(5)
1.952(5)
2.135(6)
Cu(1)-O(3)
Cu(1)-N(4)
Cu(2)-O(6)
1.967(5)
2.162(6)
1.978(5)
Bond angles
Cu(2)-Cu(1)-O(1)
80.2(1)
80.9(2)
170.4(2)
91.0(2)
100.0(2)
90.1(2)
86.9(1)
85.8(2)
168.1(2)
87.9(2)
97.5(2)
91.3(2)
Cu(2)-Cu(1)-O(3)
Cu(2)-Cu(1)-O(7)
O(1)-Cu(1)-O(3)
O(1)-Cu(1)-O(7)
O(5)-Cu(1)-O(7)
O(7)-Cu(1)-N(4)
Cu(1)-Cu(2)-O(4)
Cu(1)-Cu(2)-O(8)
O(2)-Cu(2)-O(4)
O(2)-Cu(2)-O(8)
O(4)-Cu(2)-O(6)
O(4)-Cu(2)-N(2)
83.2(2)
89.6(2)
163.1(2)
88.1(2)
170.4(2)
99.5(2)
83.6(1)
77.4(4)
170.1(2)
89.4(2)
88.6(2)
91.6(2)
Cu(2)-Cu(1)-O(5)
Cu(2)-Cu(1)-N(4)
O(1)-Cu(1)-O(5)
O(3)-Cu(1)-N(4)
O(5)-Cu(1)-N(4)
Cu(1)-Cu(2)-O(2)
Cu(1)-Cu(2)-O(6)
Cu(1)-Cu(2)-N(2)
O(2)-Cu(2)-O(6)
O(2)-Cu(2)-N(2)
O(4)-Cu(2)-O(8)
(av. 1.968 A)12. The nearest neighbours of the copper atom are the four
oxygen atoms of the bridging benzoate ligands in a square-planar ar-
rangement. A square-based pyramidal arrangement about the copper atom
is completed by the nitrogen of the 2-aminothiazol ligand at
2.135(6)72.162(6) A from the copper atom. The apical N atom is slightly
displaced from the regular position and the N-Cu-O angles are between
90.1ꢀ and 100.0ꢀ [See also the Cu(2)-Cu(1)-N(4) and Cu(1)-Cu(2)-N(2)
angles in Table III]. The Cu(1) and Cu(2) atoms lie 0.164(5) A and
0.168(5) A, respectively, out of the least-squares plane de®ned by the four
oxygen atoms. The eight-membered ring of Cu(1) O(1) C(1) O(2) Cu(2)
O(4) C(8) O(3) (the sum of angles is 1078.7ꢀ) and Cu(1) O(5) C(15) O(6)
Cu(2) O(8) C(22) O(7) (the sum of angles is 1079.6ꢀ) are in the basal plane
conformation. The dihedral angle is 89.9ꢀ.
There are intramolecular hydrogen bonds in complex (7). The
lengths and angles of hydrogen bonds are O(4)-H(01) (3.06 A), O(1)-H(03)
(2.95 A), N(3)-H(03)-O(1) (138.2ꢀ) and N(1)-H(01)-O(4) (125.6ꢀ). The
bond distances of C(1)-O(1) (1.272 A) and C(8)-O(4) (1.270 A) are longer
than other C-O bonds (1.22971.267 A) because of formation of hydrogen
bonds.

BINUCLEAR COPPER(II) COMPLEXES
1659
Table IV. Positional Parameters and Their Estimated Standard Deviations of
Complex (7)
Atom
x
y
z
B(A2)
Cu(1)
Cu(2)
O(1)
O(2)
O(3)
O(4)
O(5)
O(6)
O(7)
O(8)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
0.09523(9)
0.00027(9)
0.0227(5)
À0.0493(5)
0.1372(5)
0.0690(5)
0.2451(5)
0.1671(5)
À0.0670(5)
À0.1476(5)
À0.0274(7)
À0.0648(8)
À0.0587(9)
À0.088(1)
À0.125(1)
À0.137(1)
À0.104(1)
0.1178(7)
0.1571(7)
0.1438(9)
0.178(1)
0.06990(5)
0.16995(5)
0.1347(3)
0.2189(3)
0.0245(3)
0.1114(3)
0.1295(3)
0.2155(3)
0.0213(3)
0.1040(3)
0.1942(4)
0.2369(4)
0.3080(4)
0.3483(6)
0.3168(6)
0.2457(7)
0.2053(5)
0.0513(4)
0.0117(4)
0.0412(4)
0.0034(6)
À0.0643(5)
À0.0927(5)
À0.0554(4)
0.1876(4)
0.2227(4)
0.1881(5)
0.2198(6)
0.2899(6)
0.3263(5)
0.2932(5)
0.0467(4)
0.0090(4)
À0.0614(4)
À0.0967(5)
À0.0651(5)
0.0048(5)
0.0406(5)
0.2997(2)
0.2849(7)
0.2486(5)
0.32622(5)
0.22615(5)
0.4026(3)
0.3180(3)
0.2289(3)
0.1473(3)
0.3266(3)
0.2474(3)
0.3123(3)
0.2296(3)
0.3854(4)
0.4530(4)
0.4467(5)
0.5172(5)
0.5778(6)
0.5799(5)
0.5174(5)
0.1617(4)
0.0921(4)
0.0178(5)
À0.0450(5)
À0.0334(5)
0.0395(6)
0.1030(5)
0.2911(4)
0.3037(4)
0.3335(5)
0.3447(6)
0.3281(6)
0.3004(6)
0.2867(5)
0.2663(4)
0.2530(4)
0.2739(5)
0.2599(6)
0.2261(6)
0.2048(7)
0.2185(5)
0.0154(2)
0.0891(8)
0.1438(6)
3.17(2)
3.08(2)
4.4(1)
4.0(1)
4.1(1)
4.2(1)
4.7(1)
4.2(1)
4.0(1)
4.0(1)
3.6(2)
4.1(2)
5.6(2)
8.1(3)
8.1(3)
7.7(3)
6.1(2)
3.4(2)
3.5(2)
5.1(2)
6.5(3)
6.6(2)
6.3(2)
4.7(2)
3.6(2)
3.9(2)
5.2(2)
6.5(3)
6.4(2)
6.6(3)
5.4(2)
3.4(2)
3.3(2)
4.6(2)
5.8(2)
6.1(2)
6.8(3)
5.1(2)
9.00(9)
8.9(4)
7.3(3)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
S(1)
0.223(1)
0.234(1)
0.2008(8)
0.2521(7)
0.3779(7)
0.4851(8)
0.5999(9)
0.6070(9)
0.504(1)
0.3860(9)
À0.1544(7)
À0.2764(7)
À0.2834(8)
À0.3941(9)
À0.4990(9)
À0.4933(9)
À0.3822(8)
À0.1943(4)
À0.287(1)
À0.226(1)
C(29)
C(30)
(continued)

1660
YANG ET AL.
Table IV. Continued
Atom
x
y
z
B(A2)
C(31)
N(1)
S(2)
C(32)
C(33)
N(4)
À0.0760(9)
0.033(1)
0.3209(4)
0.293(1)
0.367(1)
0.1958(7)
0.2010(9)
0.121(1)
0.0975
0.0477
0.0540
0.1350
À0.1716
À0.1081
0.1093
0.1723
0.2446
0.2687
0.2068
0.4786
0.6760
0.6880
0.5108
0.3103
À0.2082
À0.3975
À0.5779
À0.5692
À0.3780
À0.3745
À0.2669
À0.4399
À0.3046
À0.0369
À0.0802
À0.1440
0.2546(5)
0.2450(5)
À0.0455(2)
À0.0363(6)
À0.0668(7)
0.0019(3)
0.0013(5)
0.0384(5)
0.2194
0.2624
0.0668
0.0404
0.2222
0.1536
0.0887
0.0258
À0.0928
À0.1397
À0.0768
0.1390
0.1934
0.3138
0.3764
0.3200
À0.0858
À0.1461
À0.0909
0.0286
0.0896
0.3020
0.2313
À0.0963
À0.0402
0.3305
0.3980
0.3438
0.0714(5)
0.0474(6)
0.5384(2)
0.3925(6)
0.4510(8)
0.4133(4)
0.4889(5)
0.5305(5)
0.0786
5.5(2)
10.3(3)
9.49(9)
8.4(3)
10.0(4)
4.3(2)
5.4(2)
7.9(3)
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
5*
C(34)
N(3)
H(01)
H(02)
H(03)
H(04)
H(6)
À0.0027
0.5045
0.5871
0.6252
0.5193
0.0107
À0.0976
À0.0773
0.0480
0.1552
0.3475
0.3644
0.3363
0.2882
0.2651
0.2984
0.2741
0.2159
0.1809
0.2016
0.0893
H(7)
H(10)
H(11)
H(12)
H(13)
H(14)
H(17)
H(18)
H(19)
H(20)
H(21)
H(24)
H(25)
H(26)
H(27)
H(28)
H(29)
H(30)
H(32)
H(33)
H(3)
0.1891
0.4424
0.3380
0.4003
0.5175
0.6217
H(4)
H(5)
Starred atoms were re®ned isotropically. Anisotropically re®ned atoms are given in
the form of the isotropic equivalent thermal parameter de®ned as: (4=3)[a2 B(1,1)‡b2
B(2,2)‡c2 B(3,3)‡ab cos gB(1,2)‡ac cos b B(1,3)‡bc cos aB(2,3)].

BINUCLEAR COPPER(II) COMPLEXES
1661
Therefore, the oxidative addition reaction is an easy and available
method for the synthesis of binuclear copper(II) complexes.
ACKNOWLEDGMENTS
We thank NSFC (No. 29871009), the Henan Province Outstanding
Youth Science Foundation (No. 9910) and the Henan Province Natural
Science Foundation for the ®nancial support to this research.
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Received April 3, 2001
Accepted August 18, 2001
Referee I: R. D. Pike
Referee II: D. Rabinovich