F. Katzsch et al. / Journal of Molecular Structure 1064 (2014) 122–129
125
involving the whole range of alcohols from methanol to 1-pentanol
as secondary coordinated species. However, using the present
experimental conditions, this could not be realized in all cases
(Table 1).
like in the case of 1-propanol, while the other one is bent at the
alcoholic oxygen. By way of contrast, the asymmetric part of the
unit cell of 5 consists of only a half paddle wheel with an elongated
1-pentanol molecule at the copper showing again a twofold disor-
der (sof = 0.83) (Fig. 3c). Moreover, the paddle wheel frameworks
of 4 and 5 are disordered by torsion of the carboxylate group
regarding the connection to the copper atoms. This differs from
the regular structure 3 containing nearly rectangular OACuAO an-
gles (Table 3). The site occupancy factors for each carboxylate dis-
order are 0.51 (O1A, O3A), 0.50 (O2A, O4A), 0.53 (O6A, O8A), 0.52
(O7A, O9A) and 0.52 (O1A, O3A), 0.50 (O2A, O4A) for 4 and 5,
respectively. As a result, during the structure refinement of 3, 4
and 5 it was necessary to use DELU, SIMU, ISOR and EADP restrains
to conform the anisotropic displacement parameters of the carbox-
ylate oxygens O1A, O4B, O7A, O7B, O8B (4) and O1A, O2B, O4A (5)
as well as of the alcohol carbons C32A, C32B (4) and C15B, C16B,
C18B, C19B (5).
Comparison of the CuACu distances within the paddle wheels
shows a slight decrease with growing size of the alcohol (Table 4).
Considering the literature known copper(II) benzoate paddle
wheels, though being predominantly coordinated by nitrogen con-
taining ligands, it is obvious that the present structures 3–5 as well
as the ethanol coordinated paddle wheel of 2 [33] feature shorter
CuACu distances. Only in a structure having coordinated 1,4-diox-
ane, the CuACu distance is somewhat shorter (2.569 Å) [41]. On
the other site, the longest CuACu distance (d = 2.694 Å) is found
in the copper(II) benzoate with 6-methylquinoline as ligands
[42]. Moreover, the CuAO distances at the open metal sites of
3–5 are shorter than in the literature structures, excepting the
pyridine N-oxide coordinated copper(II) benzoate which is
comparable in this property (d = 2.134 Å) [43].
Unlike the expectation, the blue green crystalls of 1 obtained
from slow evaporation of the methanol–water phase were found
to contain dimeric copper(II) benzoate units having benzoic acid
molecules coordinated to the open metal sites of copper(II) instead
of two methanols. The respective crystal structure is a known one
and has already been described by Kawata et al. [34]. Following an
analogous experimental procedure with a mixture of ethanol and
water, the desired coordination of ethanol molecules is formed,
giving rise to a compound (2) the crystal structure of which is also
known from recent literature [33]. Crystallization of copper(II)
benzoate from 1-propanol-water results in the formation of a com-
plex 3 composed of two different copper(II) benzoate paddle wheel
units. One, as expected, being secondarily coordinated to two
1-propanol molecules while the other one includes two molecules
of water at the open metal sites. Finally, in the cases of 1-butanol
and 1-pentanol, complexes 4 and 5 containing only the respective
alcohols coordinated to the copper(II) ions were obtained. Hence,
though a rather uniform method of preparation was used, com-
plexes of different composition (1–5) have been isolated.
3.2. X-ray single crystal structure analysis
As mentioned above, structures of two of the isolated com-
plexes (1 and 2) have already been reported in the literature and
can directly serve for structural comparison, while the complexes
3–5 and thus also their X-ray crystal structures are new. These
are described and comparatively discussed including relevant data
of the known structures in the following.
Crystal data and details of the structure determinations involv-
ing the new compounds are given in Table 2. Compounds 3 and 4
crystallize in the triclinic space group P-1, crystals of 5 are mono-
clinic P21/n. The asymmetric part of the unit cell of 3 contains two
half paddle wheels with a water molecule and a 1-propanol mole-
cule at the open metal sites, respectively. The 1-propanol shows
In the packing structures of the paddle wheel units of 3–5,
hydrogen bonding interactions (Table 5) are dominant. In a more
detailed description, in the structure of 3, the paddle wheels
Table 4
CuACu and CuAO distances of 3, 4 and 5.
Distances (Å)
twofold disorder with
a site occupancy factor (sof) of 0.71
3
4
5
(Fig. 3a). Also in the structure of 4, two half molecules are found
in the asymmetric part of the unit cell, however with two 1-buta-
nol molecules positioned at the free copper sites with different ori-
entations (Fig. 3b). One of the solvent molecules is elongated away
from the paddle wheel and is also twofold disordered (sof = 0.51),
Cu1ACu1
Cu2ACu2
Cu1AO5
Cu2AO10
2.589
2.597
2.126 (1-PrOH)
2.173 (H2O)
2.572
2.579
2.133 (1-BuOH)
2.131 (1-BuOH)
2.571
2.126 (1-PentOH)
Table 3
OACuAO bond angles of 3, 4 and 5.
Angles (°), (atoms)
3
4
5
Molecule 1 Disorder site A
Molecule 1 Disorder site B
Molecule 2 Disorder site A
Molecule 2 Disorder site B
89.82 (O1ACu1AO2)
90.11 (O2ACu1AO3)
87.52 (O3ACu1AO4)
90.67 (O4ACu1AO1)
88.26 (O1AACu1AO2A)
75.43 (O2AACu1AO3A)
89.84 (O3AACu1AO4A)
104.31 (O4AACu1AO1A)
102.69 (O1AACu1AO2A)
90.81 (O2AACu1AO3A)
72.90 (O3AACu1AO4A)
91.31 (O4AACu1AO1A)
89.49 (O1BACu1AO2B)
104.30 (O2BACu1AO3B
90.77 (O3BACu1AO4B)
72.76 (O4BACu1AO1B)
75.19 (O1BACu1AO2B)
85.98 (O2BACu1AO3B)
109.01 (O3BACu1AO4B)
87.72 (O4BACu1AO1B)
89.78 (O6ACu2AO7)
89.63 (O7ACu2AO8)
90.53 (O8ACu2AO9)
88.18 (O9ACu2AO6)
73.67 (O6AACu2AO7A)
88.43 (O7AACu2AO8A)
106.84 (O8AACu2AO9A)
88.21 (O9AACu2AO6A)
105.97 (O6BACu2AO7B)
90.89 (O7BACu2AO8B)
69.83 (O8BACu2AO9B)
90.64 (O9BACu2AO6B)
Katzsch, Felix
