metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
Aqua(4,40-oxydibenzoato-jO)-
cadmium(II)
Figure 1
ORTEPII plot (Johnson, 1976) of the title compound at the 50%
probability level, illustrating the ®ve-coordinate geometry of the Cd
atom. H atoms are drawn as small spheres of arbitrary radii.
Mao-Lin Hu,a Peng Gaob and Seik Weng Ngc*
aDepartment of Chemistry, Wenzhou Normal College, Wenzhou 325027, People's
Republic of China, bEnvironmental Monitoring and Supervising Center Station of
Wenzhou, Wenzhou 325000, People's Republic of China, and cInstitute of
Postgraduate Studies, University of Malaya, 50603 Kuala Lumpur, Malaysia
Correspondence e-mail: h1nswen@umcsd.um.edu.my
tions as a bichelate in the cobalt complex, which adopts a
chain structure (Skakle et al., 2001). In the copper complex,
both carboxyl ends are monodentate to Cu atoms; the double-
bonded O atoms are engaged in hydrogen bonding with the
lattice methanol molecules (Burger et al., 1995). As no
cadmium derivative of the parent acid appears to have been
synthesized, the structure of (I) can only be compared with
related structures, such as, for example, the malonate analog.
The CdÐO distances are similar to distances found in these
carboxylates. On the other hand, the CdÐOwater distance
Received 3 April 2002
Accepted 9 April 2002
Online 11 May 2002
The Cd atom in the polymeric title compound, [Cd-
(C14H8O5)(H2O)]n, is linked to four carboxyl O atoms and a
water molecule in a ®ve-coordinate coordination polyhedron
that is midway between a square pyramid and a trigonal
bipyramid. The Cd atom and the water molecules both lie on
the same twofold axis and the central O atom of the 4,40-
oxydibenzoate moiety lies on another twofold axis. Covalent
CdÐO bonds lead to the formation of a layer architecture
perpendicular to the twofold axis, the layers being held
together by hydrogen bonds in the third direction.
Ê
compares well with the distances in the trigonal [2.277 (7) A;
Post & Trotter, 1974] and rhombohedral modi®cations
Ê
[2.283 (3) A; Naumov et al., 2001] of cadmium malonate.
The d10 electron con®guration of cadmium(II) allows the
ion to exist in a variety of stereochemical environments, with
the six-coordinate geometry accounting for 56% of examples;
the ®ve-coordinate geometry is found in only 8% of examples
(Siegel & Martin, 1994). The geometry of the Cd atom in (I),
as calculated by PLATON (Spek, 1990), is approximately
midway between a square pyramid and a trigonal bipyramid.
Ê
Comment
Additionally, two somewhat long interactions of 2.824 (2) A
The study of diaqua[4,40-(ethylenedioxy)dibenzoato]cadmium
has documented the chelating mode of the two carboxyl ends
indicate a trigonal-prismatic geometry whose rectangular face
is capped (Fig. 2). A ®ve-coordinate geometry is found in the
anionic complexes [{(C2H5)2NCS2}CdX] (X = NCS, Cl or Br).
The geometry of the X = Cl derivative also lies midway along
the Berry pseudorotation pathway. However, there are no
important contacts (Baggio et al., 1996) that could raise the
coordination number. The unambiguous seven-coordinate
of the dicarboxylate group [CdÐO
= 2.241 (3) and
Ê
2.537 (3) A], which links the six-coordinate Cd atoms into a
zigzag chain (Liu et al., 2001). The omission of the ¯exible
±CH2CH2O± linkage in the dicarboxylate unit furnishes the
more tightly packed title compound, (I) (Fig. 1). The Cd atom
and the water molecules both lie on the same twofold axis and
the central O atom (O3) lies on another twofold axis. Both
carboxyl O atoms are engaged in bonding to one metal atom
Ê
[CdÐO = 2.198 (2) and 2.394 (2) A] to furnish a layer struc-
ture. The layers are held together by hydrogen bonds
Ê
[OwaterÁ Á ÁO = 2.690 (3) A]. The ®ve-coordinate geometry is
Ê
completed by the water ligand [CdÐO = 2.231 (3) A].
Figure 2
A search using the Cambridge Structural Database (Allen
et al., 1983) did not locate the parent carboxylic acid; only two
metal complexes have been documented, namely a cobalt(II)
and a copper(II) derivative. The dicarboxylate group func-
ORTEPII plot (Johnson, 1976) showing the ®ve-coordinate square-
pyramidal/trigonal-bipryamidal intermediate geometry distorted to a
seven-coordinate geometry, in which one rectangular face of the trigonal
prism is capped. Symmetry-related atoms are not labeled.
Acta Cryst. (2002). C58, m323±m324
DOI: 10.1107/S0108270102006352
# 2002 International Union of Crystallography m323
Hu, Mao-Lin
