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J. Cho et al. / Inorganica Chimica Acta 342 (2003) 305Á310
/
luted with BaSO4 were recorded with a Shimadzu 2401
PC UVÁVis recording spectrophotometer. Elemental
analyses were performed by the Korea Research In-
stitute of Chemical Technology, Taejon, Korea. The
precursor complex [Cu(L)Cl2] was prepared by a
template method according to the literature procedures
previously reported [15].
used to collect sufficient data. The data frames were
integrated and scaled using the DENZO-SMN package
[16]. The structures were solved and refined, using the
/
SHELXTL\PC V5.1 package [17]. Refinement was by full-
matrix least-squares on F2, using all data (negative
intensities included). Hydrogen atoms were included in
calculated positions, except for those involving hydro-
gen bonding specifically for the hydrogen atoms of the
carboxyl groups, hydroxyl groups and those bonded to
the nitrogen atoms, which were refined with isotropic
2.2. Synthesis of 1
thermal parameters. In 2 the hydrogen atom on the ꢀ
OH group of ꢀCH2ꢀCH2ꢀOH is disordered over two
OH
/
To an aqueous solution (10 ml) of [Cu(L)Cl2] (217 mg,
0.5 mmol) was added a methanol solution (10 ml) of btc
(254 mg, 1.0 mmol) in an open beaker. Reddish purple
crystals 1 were obtained in a day. Suitable crystals of 1
for X-ray diffraction studies and subsequent spectro-
scopic measurements were manually collected under the
microscope. Anal. Calc. for C32H40N6O18Cu (1): C,
44.64; H, 4.65; N, 9.76. Found: C, 45.01; H, 4.88; N,
9.97%.
/
/
/
sites to facilitate hydrogen bonding to two other ꢀ
/
groups on symmetry related molecules.
3. Results and discussion
3.1. Description of structures for 1 and 2
2.3. Synthesis of 2
The molecular structure of 1 shows a monomeric
copper(II) complex [Cu(L)(btcꢂ)2] as illustrated in Fig.
1. The coordination environment around the central
copper(II) ion shows an axially elongated octahedron
To an aqueous solution (20 ml) of [Cu(L)Cl2] (217 mg,
0.5 mmol) was added a methanol solution (20 ml) of btc
(127 mg, 0.5 mmol) and two drops of pyridine in an
open beaker. Purple crystals 2 were obtained in 2 weeks.
Double deprotonation of btc occurred regardless of the
ratio of acid to base. However, the longer crystallization
times and more dilute reaction conditions are requisite
for the isolation of the compound 2. Suitable crystals of
2 for X-ray diffraction studies and subsequent spectro-
scopic measurements were manually collected under the
microscope. Anal. Calc. for C22H34N6O10Cu (2): C,
43.56; H, 5.61; N, 13.86. Found: C, 44.04; H, 5.90; N,
14.11%.
with four Cuꢀ
contacts. The Cu atom is located on an inversion center.
The four CuꢀN distances are in the range 2.0026(12)Á
/
N bonds and two Cuꢀ/O (carbonyl)
/
/
˚
2.0189(13) A and shorter than the Cuꢀ
/
O distance
˚
of 2.4814(11) A. These values fall within the range
of comparable reports for such
([Cu(L1)(CH3CN)2]×2PF6; Cuꢀ
2.0481(18) A, [Cu(L1)(terephthalato)]n ×
a
Nꢀ
2nH2O; Cuꢀ
3,14-dimethyl-
geometry
2.0188(18),
/
/
/
˚
/
/
˚
Nꢀ
/
2.0225(16), 2.0294(16) A) (L1ꢀ
/
2,6,13,17-tetraazatricyclo[14.4.01.18.07.12]docosane)
[18,19]. Selected interatomic distances and angles for 1
are listed in Table 2. As is usual, the macrocyclic ligand
skeleton in 1 adopts the trans III (R,R,S,S) conforma-
tion. Two structurally interesting features are found in
complex 1. Only one of the four COOH groups in the
btc is deprotonated under the reaction conditions
described in the Section 2, resulting in the formation
of a rare btcꢂ anion. The most common are the btc4ꢂ
and the btc2ꢂ anions [11,20]. The deprotonated COOꢂ
2.4. X-ray crystallography
A summary of selected crystallographic data for 1 and
2 is given in Table 1. X-ray data were collected on a
Nonius KappaCCD diffractometer, using graphite
˚
0.71073 A). A
monochromated Mo Ka radiation (lꢀ
/
combination of 18 f and V (with k offsets) scans were
Cho, Jaeheung
