4
X.-S. Gao, J.-T. Wang / Inorganica Chimica Acta 386 (2012) 1–7
Fig. 3. (a) Molecular structure of 2 (uncoordinated H2O molecule and all H-atoms omitted for clarity) and (b) the monocapped tetragonal antiprism coordination geometry of
Eu3+ ion (viewed along the direction of Eu1–N2 bond).
(0.36 mmol) KSCN in 20 mL absolute ethanol and stirred. The pre-
cipitated KNO3 was removed by filtration, then a solution of
0.4994 g (1.25 mmol) DAPBH in 25 mL 95% ethanol was added
dropwisely. This mixture was stirred at 55 °C for 3 h to yield a yel-
lowish solids, which were separated via filtration, washed with
10 mL absolute ethanol and dried in air yielding 0.79 g (ꢃ80%
and calculation based on the reactant DAPBH) of 2. Anal. Calc. for
of \O(1)Eu(1)O(4) = 130.2° and \O(2)Eu(1)O(3) = 129.1°. Two N
atoms, labeled as N(3) and N(8), are respectively capped on two
tetragonal faces, and the N(3), Eu(1) and N(8) atoms show almost
linear arrangement with an angle of \N(3)Eu(1)N(8) = 175.7°.
Each DAPBH ligand is hydrogen bonded to three uncoordinated
nitrates as well as one of two co-crystallized water molecules. Three
crystallographically inequivalent nitrates exhibit distinct hydrogen
C
28H29EuN8O4S3: C, 42.6; H, 3.70; N, 14.2. Found: C, 42.2; H,
3.43; N, 13.9%. The main vibration bands in IR spectrum (KBr disc,
cmꢂ1): 1600s contributed from
(C@O), 1576s assigned to (C@N),
1541s arose from (C@C), 2053s given from
(SCNꢂ).
bonding models. The nitrate with N(12) atom acts as a l2-bridge
linking two DAPBH ligands via N atoms of @NANHA groups and O
atoms of the nitrate with dO(8)ꢀꢀꢀN(5) = 2.991 Å, \N(5)–H(5A)ꢀꢀꢀO(8) =
125.4° and dO(10)ꢀꢀꢀN(6) = 2.805 Å, \N(6)–H(6A)ꢀꢀꢀO(10) = 149.3°. The
m
m
m
m
Single crystals of 2, Eu(DAPBH)(SCN)3ꢀH2O, suitable for X-ray
nitrate with N(11) exhibits another l2-bridge model. O(7) is linked
analysis were obtained by slowly cooling the hot filtrate.
to N(5) of @NANHA group with dO(7)ꢀꢀꢀN(5) = 2.991 Å, \N(5)–H
(5A)ꢀꢀꢀO(7) = 123.1° and the O(6) atom is connected to Ow(2) with
dO(6)ꢀꢀꢀOw(2) = 3.038 Å, \Ow(2)–Hw(2B)ꢀꢀꢀO(6) = 107.1°. The nitrate
with N(13) is attached to the DAPBH ligand via H-bonding interac-
tion between its O atom and the N atom of @NANHA group with
dO(12)ꢀꢀꢀN(1) = 2.763 Å, \N(1)–H(1A)ꢀꢀꢀO(12) = 123.7°.
2.6. X-ray crystallography
Single crystal X-ray diffraction data of 1 and 2 were collected on
a Siemens SMART-CCD and Enraf–Nonius CAD-4 diffractometer
As illustrated in Fig. 2, two neighboring coordination cations of
Eu3+, four lattice water molecules together with two nitrates form
supramolecular ring architecture through intermolecular H-
bonding interactions. And the neighboring supramolecular rings
further link into a supramolecular H-bonding chain through two
Ow(1)-type water molecules along the b-axis direction, and the
supramolecular H-bonding chains are held together by means of
weak van der Waals forces. The intermolecular H-bond geometric
parameters are summarized in Table 3.
Complex 2 crystallizes in the monoclinic space group P2(1)/c,
and the asymmetric unit consists of one neutral mononuclear
Eu3+ complex together with one lattice water molecule. The Eu3+
ion is coordinated by six N atoms and three O atoms from one
pentadentate DAPBH ligand, three SCNꢂ ions and one ethanol mol-
ecule (Ref. Fig. 3a) and shows the coordination geometry with a
distorted monocapped tetragonal antiprism (Fig. 3b). The Eu–N
bond lengths between Eu3+ ion and the pentadentate DAPBH ligand
range from 2.601 to 2.646 Å with an average value of 2.619 Å,
which are comparable to the corresponding values in 1; the
Eu–N bond lengths between Eu3+ ion and three SCNꢂ anions are
in the range of 2.413–2.482 Å, obviously shorter than those
between Eu3+ and pentadentate DAPBH ligand, indicating the exis-
tence of stronger Eu–N coordinated bonds between the Eu3+ ion
and the negatively-charged SCNꢂ ions than the neutral N atoms.
The DAPBH Eu–O distances are 2.419 and 2.431 Å while the
ethanol Eu–O distance is 2.426 Å (see Table 4). Two deformed
tetragonal faces in the monocapped tetragonal antiprism, com-
prised respectively of N(4)N(7)O(3)O(2) (the bottom of the tetrag-
onal antiprism) and N(1)N(8)O(1)N(6) (the top of the tetragonal
with graphite monochromatic MoK
a radiation (k = 0.71073 Å) at
293(2) K, respectively. The structures were solved by direct
methods and refined on F2 using full matrix least-squares methods
with SHELXTL version 97 [29]. All non-hydrogen atoms were refined
anisotropically, and hydrogen atoms were theoretically added,
riding on their parent atoms. During the structural refinement of
1, the geometric constraints were applied to two of three nitrates,
N(11)O(5)O(6)O(7) and N(13)O(11)O(12)O(13), respectively. Crys-
tallographic and structural refinement data of 1 and 2 are summa-
rized in Table 1.
3. Results and discussion
3.1. Description of the structures
ꢀ
Complex 1 crystallized in triclinic space group P1, and an asym-
metric unit contains one Eu3+ ion, two DAPBH ligands and three
uncoordinated nitrates together with two lattice water molecules.
As shown in Fig. 1a, the Eu3+ ion in the coordination cation is sur-
rounded by two pentadentate DAPBH ligands and coordinated by
six N atoms and four O atoms; the bond lengths and angles in
the coordination sphere, listed in Table 2, are normal. The coordi-
nation geometry of the Eu3+ ion can be described as a distorted bi-
capped tetragonal antiprism (Ref. Fig. 1b). Two deformed
tetragonal faces of the bicapped tetragonal antiprism, comprised
respectively of O(1)N(7)O(4)N(9) and O(2)N(2)O(3)N(4), make a
dihedral angle of 2.3° and are nearly parallel to each other. Two
O atoms in each tetragonal face occupy trans-sites with the angles