A series of linear trinuclear copper(II) complexes
[Cu
3
L(dmso)
5
(H
2
O)][ClO
4
]
2
·H
2
O
H
4
L = 2,6-bis[(5-substituted
salicylidene)hydrazinocarbonyl]pyridine; L = L
1
,
R = H; L = L
2
,
R = Me
3
; L = L
3
,
R = Bu
t
; L = L
4
,
R = OMe
3
; L = L
5
,
R = Cl; L = L
6
,
R = Br; dmso = dimethyl sulfoxide} have
been synthesized and characterized on the basis of infrared and electronic
spectra, electrochemical and variable-temperature (80–300 K) magnetic
measurements. The crystal and molecular structure of
[Cu
3
L
1
(dmso)
5
(H
2
O)][ClO
4
]
2
·H
2
O has been established by X-ray
diffraction. The structure consists of a
Cu
II
Cu
II
Cu
II
trinuclear cation,
unco-ordinated perchlorate anions, and a water molecule of crystallization.
Each copper ion is in a square-pyramidal environment. The compartmental
ligand L
1
co-ordinates in two different modes:
(i) as tridentate in the terminal compartment defined by
the hydrazonic carbonyl, hydrazonic nitrogen and phenolic oxygen;
(ii) tridentate in the central chamber defined by the
pyridyl nitrogen and two hydrazonic nitrogens. Cryomagnetic investigations
reveal a moderately strong antiferromagnetic spin exchange among adjacent
copper(II) ions in each complex
(J = -40 to -65 cm
-1
),
showing that the compartmental ligands of the
Cu
II
Cu
II
Cu
II
are good mediators for
spin-exchange interactions. Cyclic voltammetry of complex 1 showed
one oxidation wave attributed to
Cu
II
Cu
II
Cu
II
→&
-e
-
Cu
II
Cu
III
Cu
II
, a one-electron transfer reduction peak due to
Cu
II
Cu
II
Cu
II
→& +e
-
Cu
II
Cu
I
Cu
II
and a two-electron transfer wave established as
Cu
II
Cu
I
Cu
II
→+2e
-
Cu
I
Cu
I
Cu
I
.
一系列线性三核
铜(II)配合物[Cu 3 L(dmso) 5 (H 2 O)][ClO 4 ] 2 -H 2 O H 4 L = 2,6-双[(5-取代
水杨基)
肼羰基]
吡啶;L = L 1 ,R = H;L = L 2 ,R = Me 3 ;L = L 3 ,R = Bu t ;L = L 4 , R = OMe 3 ; L = L 5 , R = Cl; L = L 6 , R = Br; dmso =
二甲亚砜}已经合成,并根据红外光谱、电子光谱、电
化学和变温(80-300 K)磁性测量对其进行了表征。通过 X 射线衍射确定了 [Cu 3 L 1 (dmso) 5 (H 2 O)][ClO 4 ] 2 -H 2 O 的晶体和分子结构。该结构由一个 Cu II Cu II Cu II 三核阳离子、未共配的
高氯酸盐阴离子和一个结晶
水分子组成。 每个
铜离子都处于一个方阵环境中。隔室
配体 L 1 以两种不同的模式配位:(i) 在由
肼基羰基、
肼基氮和
酚氧确定的末端隔室中为三叉配位;(ii) 在由
吡啶基氮和两个
肼基氮确定的中心室中为三叉配位。低温磁性研究显示,每个配合物中相邻的
铜(II)离子之间都存在中等强度的反
铁磁自旋交换(J = -40 至 -65 cm -1 ),这表明
铜 II 的隔室
配体是自旋交换相互作用的良好媒介。复合物 1 的循环伏安法显示了一个氧化波,归因于 Cu II Cu II Cu II →& -e - Cu II Cu III Cu II,一个单电子转移还原峰,归因于 Cu II Cu II Cu II →& +e - Cu II Cu I Cu II,以及一个双电子转移波,确定为 Cu II Cu I Cu II →+2e - Cu I Cu I Cu I。