Synthesis, crystal structure and magnetic properties of [{Cu(tzq)2(HCO2)}2(μ -HCO2)2]·4H2O (tzq = [1,2,3]triazolo[1,5-a]quinoline), a binuclear copper(II) complex with unusual monoatomic formate bridges
作者:Emilio Escrivà、Juan Server-Carrió、Luis Lezama、José-Vicente Folgado、José L. Pizarro、Rafael Ballesteros、Belen Abarca
DOI:10.1039/a700642j
日期:——
The compound
[Cu(tzq)
2
(HCO
2
)}
2
(µ-HCO
2
)
2
]·4H
2
O
(tzq = [1,2,3]triazolo[1,5-a]quinoline) was
obtained under mild conditions by reaction between the hydrazone of
quinoline-2-carbaldehyde and copper(II) formate in ethanolic
aqueous solution and its crystal and molecular structure have been
determined by X-ray diffraction methods: triclinic, space group
P, Z = 1,
a = 8.209(4),
b = 12.156(4),
c = 12.649(4) Å,
α = 63.21(3), β = 81.42(3),
γ = 89.12(3)°. The compound is built of
centrosymmetric neutral dimeric
[Cu(tzq)
2
(HCO
2
)}
2
(µ-HCO
2
)
2
] entities linked through hydrogen bonds
involving water molecules and carboxylate groups. The copper atom is
involved in a CuN
2
O
2
O′ chromophore and lies
in a tetrahedrally distorted square-pyramidal environment. The four
equatorial donors are two trans nitrogen atoms from two tzq
molecules and two oxygen atoms from two formate groups. One of the
oxygens acts as a bridging ligand occupying the apical position of the
symmetry-related copper atom in the dimer structure, which is viewed as
two edge-sharing distorted square pyramids. This co-ordination behaviour
(monoatomic bridging) is very unusual for the
HCO
2
-
anion. The EPR spectrum is
characteristic of a triplet state with non-negligible zero-field
splitting. Magnetic susceptibility measurements in the range
1.8–200 K showed weak antiferromagnetic exchange between the
copper(II) ions (2J = -1.05
cm
-1
). The observed behaviour is discussed on the basis
of the crystal structure and compared with those reported for related
µ-oxo carboxylate-bridged [CuO
2
Cu] dimers with
parallel-planar geometry.
该化合物
[Cu(tzq)
2
(HCO
2
)}
2
(μ-HCO
2
)
2
]·4H
2
氧
(tzq = [1,2,3]三唑并[1,5-a]喹啉)
在温和条件下通过腙之间的反应获得
乙醇中的喹啉-2-甲醛和甲酸铜(II)
水溶液及其晶体和分子结构
X射线衍射法测定:三斜晶系、空间群
P,Z = 1,
a = 8.209(4),
b = 12.156(4),
c = 12.649(4) 埃,
α = 63.21(3), β = 81.42(3),
γ = 89.12(3)°。该建筑群由
中心对称中性二聚体
[Cu(tzq)
2
(HCO
2
)}
2
(μ-HCO
2
)
2
] 通过氢键连接的实体
涉及水分子和羧酸根。铜原子是
参与CuN
2
氧
2
O′发色团和谎言
在四面体扭曲的方锥体环境中。四个
赤道供体是来自两个 tzq 的两个反式氮原子
分子和来自两个甲酸酯基团的两个氧原子。中的一个
氧作为占据顶端位置的桥配体
二聚体结构中与对称相关的铜原子,被视为
两个共享边缘的扭曲方形金字塔。这种协调行为
(单原子桥接)对于
碳酸氢根
2
-
阴离子。 EPR 谱为
具有不可忽略零场的三重态特征
分裂。范围内的磁化率测量
1.8–200 K 之间表现出微弱的反铁磁交换
铜(II)离子 (2J = -1.05
厘米
-1
)。观察到的行为是在以下基础上讨论的
晶体结构并与相关报道进行比较
µ-氧代羧酸桥联 [CuO
2
Cu]二聚体
平行平面几何。