Received Dec. 24, 2005; Supported by the National Natural Science Foundation of China (No.20271022) and Guangdong Natural Science Foundation (No.010369)

    The content of element calculated from the results of elemental analysis was consistent with the theoretical value of CuL₂Cl₂ according to Table 1, which indicated that reaction between ligands and Cu²⁺ was complete and the CuL₂Cl₂ complexes were synthesized.

Table2 The productivity and color of the complexes

Table 3 FT-IR data of ligands and complexes (cm^-1)

    As seen in Table 3, a strong stretching peak appeared at 3450 cm^-1 which attributed to Ar-N- group in the ligands. The peaks had red shift or blue shift to a certain degree after the coordination. There were hardly change at 2850~2950cm^-1, which indicated that framework of aromatic rings had no effect on the coordinate reaction of Se and Cu. There were obvious differences about the peaks at 490~750cm^-1 attributed to N-Se-N group between the complexes and the ligands, which indicated that N-Se-N group was the coordinate site of ligand and Cu²⁺.

Table 4 Data of UV-Vis spectra for ligands and complexes

    The UV-Vis spectra of ligands and complexes were shown in Table 4, and there were obvious differences between the complexes and the ligands. Each of the characteristic peak had red shift or blue shift to a certain degree, and some of them disappeared and new peaks appeared after the coordination. Absorption peaks of BS at 240, 248nm disappeared and absorption peaks shifted from 227, 236nm to 222, 230nm respectively, while new absorption peaks appeared at 368nm after the coordination. Similarly new absorption peaks appeared at 240nm and the peak at 222nm had blue shift in NS. Absorption peaks at 233, 243nm disappeared in MB after the coordination. The coordinate effect was the reason of changes in the UV-Vis spectra.

Table 5 Data of Fluorescence spectra for the ligands and complexes

    As seen in Table 5, NS had no characteristic fluorescence and BS had intensive fluorescence peak at room temperature, as was described in the literature ^[11]. After the coordination between ligands and CuCl_2, NS still had no fluorescence spectra, while fluorescence intensity of MB and BS had great changes and the peak position had no change, which indicated that the luminescence of complex was the ligand. It seemed as if fluorescence intensity of MB increased after coordinating with CuCl₂, but actually it decreased because the ligand concentration in the complex was two times of the ligand. Fluorescence intensity obviously dropped after coordination with CuCl₂. The fluorescence data indicated that CuCl₂ could induce fluorescence quenching of complex after coordinating with ligands.
    It can be seen from the above analysis that molecular orbital energy level of the ligands had great changes after the coordination between heterocyclic aromatic selenium compounds and CuCl_2, which caused the change of intramolecular electron transition energy of the ligands and resulted in the absorption changes of the complexes.
2.2 X-ray diffraction
X-ray diffraction of ligands, CuCl₂ and complexes were shown in Fig. 1. It could be seen from Fig. 1 that X-ray diffraction of the complexes was different from the ligands and CuCl₂ obviously. The chief diffraction peaks of the reactants disappeared and new diffraction peaks appeared in the patterns of complexes, which indicated that new compound was formed.
   The crystal diffraction and the non-crystal diffraction were identified by using the multiple separation method in computer, then the crystal degree of ligands and complexes were calculated and the results were given in Table 6. As seen in Table 6, crystal degree of the ligands has descended obviously after coordinating with CuCl₂.

Table 6 Crystal degree of ligands and complexes (crystal degreeχc% )

    Three ligands all had structure of attribute. Two nitrogen atoms of the structure adopted sp³ hybridization. One hybrid orbital accommodated the lone pair on nitrogen. The bonding of the selenium atom was various and sophisticated because it had d orbital. Selenium atom could use sp² hybridization if not considering d orbital, so a pair of p electrons had a share in conjugate and lone electron pair hold one sp² hybrid orbital. Consequently, two nitrogen atoms and one selenium atom all had lone electron pair which could coordinate with CuCl₂. In addition, the electron-rich five member cycloalkane could coordinate with CuCl₂. That is to say, the site of coordination where three ligands coordinated with CuCl₂ was the five member cycloalkane. The above deduction had been proved by IR and UV-Vis. Further considering configuration and geometric of the ligands as well as lone electron pair space orientation of hetero-atom, it can be seen that the coordinated lone pair of nitrogen atom had great influences on the steric hindrance originating from the C-H bond of 4-location and 5-loaction. However, there is little probability of coordination of the five member cycloalkane. So it was most likely that the coordination site was Cu²⁺ and selenium atom. As to the complexes CuL₂Cl₂ (L= NS / MB/ BS), copper was quadridentate sp³ or sexadentate sp³d² depending on whether chloride ion formed bridge bond or not. When chloride ion coordinated through bridge bond, the complex could form chain structure. In this structure, copper ion formed sp³d² hybridization utilizing outer-shell d orbital; the four chloride ions and copper ion was in the same plane, and the two ligands were vertical to the plane and located just above and under the plane. The structural formula of the complex was shown in Fig. 2.

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硒芳香杂环-铜配合物的合成与表征
睢超霞¹ 杨芳^1,2 郑文杰^1,2 白燕¹
（暨南大学化学系， 暨南大学水生生物研究所， 广州 610632）
摘要 以硒芳香杂环化合物2,1,3-萘并[c]硒二唑(BS)、5-甲基-2,1,3-苯并[3,4-c]硒二唑（MB）和2,1,3-苯并[c]硒二唑(NS)为配体，采用液相合成法合成了CuL₂Cl₂ (L= BS、MB和NS)配合物，通过X-射线衍射(XRD)、等离子体原子发射光谱 (ICP-AES)、元素分析（EA）、红外光谱（IR）、紫外可见光谱（UV-Vis）、荧光光谱（FS）和电导率等手段对配合物进行了表征，并初步探讨了配体和Cu²⁺离子的配位机理。
关键词 硒芳香杂环、 铜配合物、 合成与表征