New copper(II) complexes of the cyclic trinuclear type with 1,2,4-triazole ligands, [Cu
3(
3-OH)(aaat)
3(H
2O)
3](NO
3)
2·H
2O [Haaat = 3-acetylamino-5-amino-1,2,4-triazole]
(1) and {[Cu
3(
3-OH)(aat)
3(
3-SO
4)]·6H
2O}
n [Haat =3-acetylamino-1,2,4-triazole] (
2), have been prepared and characterized by X-ray crystallography and magneticmeasurements. Compound
1, the first reported with the ligand (H)aaat, consists of discrete trinuclear cations,associated NO
3- anions and lattice water molecules. Compound
2 consists of unusual chains of trinuclear unitswith a tridentate sulfato group linking the trimeric units and water molecules stabilizing the crystal lattice. In bothcomplexes,
1 and
2, the trinuclear [Cu
3(OH)L
3] unit contains a pyramidal Cu
3-
3OH core, and an almost flat Cu
3N
6ring formed by the N,N-bridging triazolato groups. The Cu···Cu' intratrimeric distances are 3.35-3.37-3.39 Å in
1 and 3.34-3.34-3.36 Å in
2. The copper atoms are five-coordinated with a distorted square-pyramidal geometry.Magnetic measurements have been performed in the 1.9-300 K temperature range. In the high-temperature region(
T > 90 K), experimental data could be satisfactorily reproduced by using an isotropic exchange model,
H =-
J(
S1S2 +
S2S3 +
S1S3), with
J = -194.6 cm
-1 and
g = 2.08 for
1, and
J = -185.1 cm
-1 and
g = 2.10 for
2.The magnitude of the antiferromagnetic exchange in both complexes is discussed on the basis of their structuralfeatures by comparison with reported N,N-pheripherically bridged trinuclear systems. In order to fit the experimentalmagnetic data at low temperature, an antisymmetric exchange term,
HAS =
G(
S1xS2 +
S2xS3 +
S1xS3), had to beintroduced, with
G = 27.8 (
1) and 31.0 (
2) cm
-1. Crystal data: C
12H
27Cu
3N
17O
14 (
1) (MW = 824.13) crystallizesin the triclinic space group,
P![](/images/entities/onemacr.gif)
,
Z = 2, with the cell dimensions
a = 8.852(2) Å,
b = 11.491(3) Å,
c = 15.404(3)Å,
![](/images/gifchars/alpha.gif)
= 70.43(3)
![](/images/entities/deg.gif)
,
![](/images/gifchars/beta2.gif)
= 75.11(2)
![](/images/entities/deg.gif)
,
![](/images/gifchars/gamma.gif)
= 88.43(2)
![](/images/entities/deg.gif)
, and
V = 1423.8(5) Å
3,
Dcalcd = 1.922 g cm
-3; the final agreementvalues were R1 = 0.0822 and wR2 = 0.2300 for 4989 unique reflections. C
12H
28Cu
3N
12O
14S (
2) (MW = 787.14)crystallizes in the triclinic space group,
P![](/images/entities/onemacr.gif)
,
Z = 2, with the cell dimensions
a = 7.146(6) Å,
b = 14.26(1) Å,
c =15.35(2) Å,
![](/images/gifchars/alpha.gif)
= 109.0(9)
![](/images/entities/deg.gif)
,
![](/images/gifchars/beta2.gif)
= 93.6(9)
![](/images/entities/deg.gif)
,
![](/images/gifchars/gamma.gif)
= 99.5(7)
![](/images/entities/deg.gif)
, and
V = 1448(2) Å
3,
Dcalcd = 1.806 g cm
-3; the finalagreement values were R1 = 0.0628 and wR2 = 0.1571 for 3997 "observed" reflections.