inorganic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
Zinc cyanamide, Zn(CN2)
Michael Becker and Martin Jansen*
Max-Planck-Institut f uÈ r Festk oÈ rperforschung, Heisenbergstraûe 1, D-70569 Stuttgart,
Germany
Received 20 October 2000
Accepted 10 January 2001
Figure 1
View of the crystal structure of Zn(CN
been shown as polyhedra.
2 4
). The ZnN building units have
Single crystals of the title compound have been grown by
annealing microcrystalline zinc cyanamide at 843 K in silver
crucibles. Zn(CN ) crystallizes as colourless prisms. The crystal
2
structure is composed of corner-linked ZnN tetrahedra.
/2
4
2�
Carbon and nitrogen form (CN2) dumb-bells with the C
atom on a twofold axis. Nitrogen is approximately trigonally
planar, coordinated by two Zn atoms and one C atom.
Comment
II
II
The structural characterization of M ±cyanamides (M is a
transition metal) has up until now been limited to cadmium
cyanamide (Dvoinin et al., 1982). Recently, mercury cyan-
amide has been prepared and its crystal structure determined
Figure 2
View of the staggered conformation of the anion of Zn(CN
2
) and the
cations. Displacement ellipsoids are shown at the 50% probability level.
3
3
4
[
1
Symmetry codes: (i) 1 � y, x � 1, � z; (ii) � x, y, � z; (iii) 1 � y, x � 1,
2
3
2
1
2
1
2
� z; (iv) � x, � y, + z.]
(
Becker & Jansen, 2000). In the course of further structural
investigations of crystalline metal cyanamides, we have grown
regard to zinc and nitrogen, the structure can be related to the
high pressure polymorph of Willemite (Zn SiO ±II; Marumo
single crystals of Zn(CN ), which was ®rst described by Grube
2
2
4
(
Grube & Nitsche, 1914). Nowadays, zinc cyanamide, (I), is a
component in non-polluting anticorrosive white pigments
& Syono, 1970), with nitrogen being substituted for oxygen.
The sites of the tetrahedrally coordinated Si atoms are empty
(
Nagayama et al., 1994).
in the structure of Zn(CN ). The position of carbon in zinc
2
cyanamide can be reproduced by shifting silicon in Zn SiO ±II
2
4
towards the edges of its coordination polyhedron, thus
forming dumb-bells.
Experimental
We present here the ®rst structural investigation on
Zn(CN ). In the title compound, zinc is tetrahedrally coordi-
Zn(CN
Na (CN
times with distilled water and dried in vacuo at 10 mbar (1 bar =
2
) was precipitated from aqueous solutions of ZnSO
4
and
2
2
2
) (in a 1:1 molar ratio). The precipitate was washed several
nated by N atoms, with bond lengths of 1.985 (2) and
Ê
�
3
2.035 (2) A. Nitrogen is surrounded in an approximately
trigonally planar manner by two Zn cations and one C atom.
5
1
0 Pa). The resulting powder was compacted. The pellet obtained
2
+
was placed in a silver crucible, sealed in a glass tube under argon and
heated to 843 K over a period of 70 h. It was held at this temperature
The ZnN tetrahedra share corners while the C atoms are each
4
2
�
�
1
situated between two N atoms to form slightly bent (CN2)
for 150 h. After slow cooling to room temperature (6 K h ), crystals
suitable for single-crystal investigation were obtained.
ꢀ
dumb-bells [NÐCÐN 176.3 (3) ] (Fig. 1). The cyanamide
dumb-bells are surrounded by four Zn atoms, which are
arranged in a staggered conformation (Fig. 2). Although the
corner-linked ZnN4 tetrahedra are similar to the silicon
dioxide polymorphs, there is no topological relationship to any
of them; the ZnN tetrahedra form Zn N rings which have no
Crystal data
Zn(CN
2
)
Mo Kꢀ radiation
Cell parameters from 557
re¯ections
M
r
= 105.40
Tetragonal, I42d
Ê
ꢀ
a = 8.8047 (2) A
c = 5.4329 (2) A
Ê
V = 421.17 (2) A
ꢁ = 4.41±37.55
4
4
4
Ê
� 1
ꢂ = 11.227 mm
T = 293 (2) K
precedence in SiO structures. The ZnN tetrahedra form
2
4
3
chains along the (111) direction with every second ZnN unit
4
Z = 8
� 3
x
D = 3.324 Mg m
Prism, colourless
0.06 Â 0.04 Â 0.04 mm
ꢀ
being twisted counterclockwise (rotation angle 81.5 ). With
ꢁ
Acta Cryst. (2001). C57, 347±348
# 2001 International Union of Crystallography
Printed in Great Britain ± all rights reserved 347
Becker, Michael
