Hexamer of Nitrobenzene Molecules
SHORT COMMUNICATION
1342 (sym. N–O stretch), 849.46 (C–N stretch) cm–1. UV: λmax (ε)
Cu atom is a distorted octahedron [Cu–N: 2.060(4),
2.494(4) Å; Cu–NCS: 1.965(4) Å]. Within the (4,4)-network
the ligands recognize each other through β-sheet hydrogen
bonds [N–H···O: 2.924(5) Å, 150°; 3.154(5) Å, 152°] as well
as aromatic edge-to-face interactions which form between
the phenyl spacers and also between the pyridyl groups of
adjacent ligands (Figure 3). The Cu atoms in the network
are joined together by ligand 2 with a distance of 17.272 Å
and each loop has a rhomboidal shape with diagonal-to-
diagonal distances of 33.7 and 10.5 Å. These layers stack
on each other with an interlayer separation of 5.2 Å which
suggests strong aromatic edge-to-face interactions between
the layers. The use of other solvents, such as CHCl3 or tolu-
ene, in place of nitrobenzene also resulted in single crystals
of complex 4, which indicates that the crystallization of
complex 4 does not depend on the nature of the solvents.
These reactions emphasize the fact that the host–host (aro-
matic) interactions are robust enough to allow crystal for-
mation of complex 4.
= 205.67 (816097), 260.27 (616248 dm3 mol–1 cm–1) nm.
Synthesis of Complex 4: A methanolic solution of Cu(SCN)2,
formed by addition of an MeOH (0.5 mL) solution of Cu(NO3)2
(15.2 mg, 0.063 mmol) to an MeOH (0.5 mL) solution of NaSCN
(10.2 mg, 0.126 mmol), was carefully layered onto an ethanol
(1 mL)/CHCl3 (5.0 mL) solution (6 mL) of 1,4-bis(3-pyridinecar-
boxamido)benzene (2) (40.0 mg, 0.126 mmol). Light-green crystals
formed in 20% yield (40.8 mg) after a week. C38H28CuN10O4S2
(816.36): calcd. C 55.9, H 3.4, N 17.1; found C 55.0, H 2.9, N 16.8.
IR: ν = 3326 (N–H stretch), 3066 (aromatic C–H stretch), 2068
˜
(thiocyanate, CN), 1645 (C=O stretch), 1610 (amide) cm–1. UV:
λmax (ε) = 204 (45314), 295.71 (27043 dm3 mol–1 cm–1) nm.
X-ray Structure Analysis of Complexes 3 and 4: The single-crystal
data sets were collected at room temperature for both complexes
with a Bruker-Nonius Mach3 CAD4 X-ray diffractometer using
graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å) in the
ω-scan mode. The crystals of complex 3 were immersed in oil and
covered with glue in order to prevent loss of guest molecules. The
structure was solved by direct methods and refined by least-squares
methods on F2 using SHELX-97.[7] Non-hydrogen atoms were re-
fined anisotropically and hydrogen atoms were fixed at calculated
positions and refined using a riding model. In complex 4, the S
atom of the NCS anion was disordered over two sites and hence
the occupancies were refined (61 and 39%). Crystal data for 3:
¯
Triclinic, P1, a = 9.967(2), b = 12.950(3), c = 14.945(3) Å, α =
106.90(3), β = 102.94(3), γ = 102.11, V = 1718.9(6) Å3, Z = 1,
Dcalcd. = 1.409 gcm–3, 3111 reflections out of 5858 unique reflec-
tions with I Ͼ 2σ(I), 1.50° Ͻ θ Ͻ 25.06°, final R values: R1
=
¯
0.0778, wR2 = 0.1724. Crystal data for 4: Triclinic, P1, a = 8.259(2),
b = 9.613(2), c = 12.656(3) Å, α = 85.70(3), β = 74.66(3), γ = 71.18,
V = 917.1(3) Å3, Z = 1, Dcalcd. = 1.478 gcm–3, 2292 reflections out
of 3231 unique reflections with I Ͼ 2σ(I), 1.67° Ͻ θ Ͻ 25.00°, final
R values: R1 = 0.0522, wR2 = 0.1177. CCDC-286845 (3) and
-286846 (4), contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Figure 3. (4,4)-Coordination network of crystal structure 4. Note
the intralayer β-sheet hydrogen bonds and edge-to-face aromatic
interactions between the ligands.
Supporting Information (see footnote on the first page of this arti-
cle): Preparative procedures for 1–4, TGA measurement of 3, pow-
der spectra of guest-exchanged materials of 3, ORTEP drawings of
3 and 4, and IR and UV spectra of complexes and ligands.
Experimental Section
Acknowledgments
General: FTIR spectra were recorded with an NEXUS-870 instru-
ment, Thermo Nicolet Corporation. UV/Vis spectra were recorded
with a Shimadzu UV-1601. Elemental analyses were obtained with
a Perkin Elmer instrument, series II, CHNS/O analyzer 2400. TGA
We gratefully acknowledge financial support from the Department
of Science and Technology (DST) and DST-FIST for the single-
crystal X-ray facility. M. S. thanks CSIR for a research fellowship.
data were recorded with
a Perkin Elmer instrument, Pyris
Diamond TG/DTA (air). Powder XRD data were recorded with a
Philips PW 1710 diffractometer.
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Solids, Elsevier, Amsterdam, 1989; b) G. R. Desiraju, Angew.
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L. Shimoni, N.-L. Chang, Angew. Chem. Int. Ed. Engl. 1995,
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Synthesis of Complex 3: Methanol (1.0 mL) was layered onto a
nitrobenzene (5.0 mL) solution of N,NЈ-bis(3-pyridinecarboxa-
mido)-1,2-ethane (1) (40.0 mg, 0.148 mmol). Onto this solution was
layered a Cu(SCN)2 solution, which was obtained by mixing a
methanolic solution (0.5 mL) of Cu(NO3)2 (17.8 mg, 0.074 mmol)
and
a methanolic solution (0.5 mL) of NaSCN (11.9 mg,
0.148 mmol). Green crystals formed in 70% yield (300 mg) after 3–
4 d. C66H58CuN16O16S2 (1458.94): calcd. C 54.33, H 3.97, N 15.35;
found C 53.48, H 3.71, N 15.02. IR: ν = 3317 (N–H stretch), 3071
˜
(aromatic C–H stretch), 2064 (thiocyanate CN stretch), 1632
(amide C=O stretch), 1601(amide II), 1519 (asym. N–O stretch),
[2] a) D. J. Cram, J. M. Cram, Container Molecules and Their
Guests, Royal Society of Chemistry, Cambridge, U. K., 1994;
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© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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