metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
Anhydrous polymeric zinc(II)
octanoate
Fran cË oise Lacouture,* Jer oà me Peultier, Michel Fran cË ois
and Jean Steinmetz
Figure 1
Projection of the structure of (I) along [010] (ATOMS for Windows;
Dowty, 1995). Displacement ellipsoids are drawn at the 50% probability
level. H atoms have been omitted for clarity.
Laboratoire de Chimie du Solide Min e rale, UMR 7555, Universit e Henri Poincar e ,
Nancy I, Facult e des Sciences, BP 239, 54506 Vandoeuvre l e s Nancy CEDEX, France
Received 15 November 1999
Accepted 3 February 2000
chains of two adjacent layers form an angle of approximately
ꢁ
120 to one in which they are parallel. The structure of (I) (Pc)
can be deduced from that of (II) [Pbc2 , a = 4.7651 (6), b =
The structure of the title compound, poly[zinc(II)-bis(ꢀ-
0
1
octanoato-O:O )], [Zn(C H O ) ] , consists of polymeric
8
15 2 2 n
Ê
.3404 (15) and c = 37.066 (6) A] by carrying out a rotation of
180 of a layer on two around the c axis, followed by a
Ê
translation of 4.14 A along the b axis. This modi®cation in
9
sheets parallel to (100) in which tetrahedrally coordinated
2
ꢁ
+
Zn cations are connected by carboxylate bridges in a syn±
anti arrangement.
stacking involves the loss of the 2 axis parallel with the c axis
1
and of the c glide mirror perpendicular to the b axis, but
preserves the b glide mirror perpendicular to the a axis.
According to the orientation used to describe the structure of
Comment
The elucidation of the structure of the title compound, (I),
follows that already performed for zinc heptanoate, (II)
(I), the element of symmetry which is preserved is a c glide
(
Peultier et al., 1999). It was undertaken to characterize as well
mirror perpendicular to the monoclinic b axis, which for (I)
leads to a non-centrosymmetric and monoclinic structure (Pc).
as possible these metal soaps which protect zinc surfaces
against corrosion, and to understand the evolution of the
structural properties in the Zn(C H
n
O ) series according
2n� 1 2 2
to n, the number of C atoms in the aliphatic chain.
Compound (I) clearly shows the structural features of the
previously known members of the series, namely, n = 2
(
acetate; Clegg et al., 1987; Frada, 1992), n = 3 (propionate;
Clegg et al., 1986), n = 4 (butanoate; Blair et al., 1993) and n = 6
hexanoate; Segedin et al., 1999). The structure is layered, as
Figure 2
The Zn tetrahedral environment in (I) showing the orientation of the
linear octanoate chains. Displacement ellipsoids are drawn at the 50%
probability level (ATOMS for Windows; Dowty, 1995). Symmetry codes
are as given in Table 1. H atoms have been omitted for clarity.
II
(
shown in Fig. 1. Each Zn atom is tetrahedrally coordinated by
O atoms belonging to four different octanoate groups (Fig. 2).
The Zn tetrahedra are connected by syn±anti bridges of the
octanoate groups, thus forming layers parallel to (100). The
chains constituted by the C2n atoms form an angle of
approximately 60 , con®rming the tendency of these angles to
decrease when n increases (Peultier et al., 1999).
It is mainly the stacking mode of the layers which varies
according to n. For example, the addition of a C atom in going
from zinc heptanoate to zinc octanoate results in the structure
changing from one in which the planes containing the C2n
Experimental
ꢁ
Anhydrous zinc(II) octanoate was synthesized by adding a solution of
sodium octanoate in aqueous medium to a weakly acidic solution of
zinc nitrate (pH 5.5). The precipitate, (I), was washed with distilled
water and dried. Finally, compound (I) was recrystallized from
ethanol at room temperature. Colourless crystals appeared as small
plates with well developed (100) faces.
5
56 # 2000 International Union of Crystallography ꢀ Printed in Great Britain ± all rights reserved
Acta Cryst. (2000). C56, 556±557
Lacouture, Francoise
