含鉍之 (鉻、鐵) 金屬團簇化合物的合成、轉換關係、化性、物性與理論計算之探討

Abstract

當開放型四面體化合物 [Bi{Cr(CO)5}4]3– 與 2 當量的 [Cu(MeCN)4][BF4] 試劑於 MeCN 中反應，可生成平面三角形化合物 [Bi{Cr(CO)5}3]– (1)；反之，1 可藉由與 2 當量 [HCr(CO)5]– 逆反應得 [Bi{Cr(CO)5}4]3–。X-ray 結構解析發現化合物 1 為以鉍原子為中心鍵結三個 [Cr(CO)5] 片斷的平面三角形之構型；特別的是，化合物 1 具有不飽和之  電子系統。有鑑於此，將 1 分別與 KX (X = Cl, Br, I, OH) 於 MeCN 或 THF 中反應，可生成鹵素或羥基加成之四面體化合物 [XBi{Cr(CO)5}3]2– (X = Cl, 2-Cl; Br, 2-Br; I, 2-I; OH, 3)；其中，當 2-I 與 AgNO3 反應時，可逆反應形成 1。若進一步將 1 與 Fe(CO)5 於鹼性甲醇溶液反應，可生成罕見混合鉻與鐵之四面體化合物 [Bi{Cr(CO)5}3{Fe(CO)4}]3– (4)。特別的是，化合物 1 具有溶劑化顯色 (Solvatochromism) 之特性，當其分別溶於 DMF、MeCN、Acetone、MeOH、THF、EtOH 與 CH2Cl2 時，溶液所呈現的顏色依序為紅、橘紅、橘黃、黃、草綠、碧綠與孔雀綠。本研究藉由偵測此一系列化合物之電化學、液態紫外/可見光光譜與反射式固態紫外光譜來探討引入不同鹵素與異核金屬的效應，並搭配理論計算來佐證。When the tetrahedral complex [Bi{Cr(CO)5}4]3– reacted with 2 equiv of [Cu(MeCN)4][BF4] in MeCN solution, the trigonal-planar complex [Bi{Cr(CO)5}3]– (1) was obtained, which could be reconverted to [Bi{Cr(CO)5}4]3– by treatment with 2 equiv of [HCr(CO)5]–. X-ray analysis showed that 1 possessed a central bismuth atom trigonally coordinated to three [Cr(CO)5] groups. Notably, 1 exhibited an unsaturated  system in three Bi─Cr bonds. Hence, when 1 reacted with KX (X = Cl, Br, I, OH) in MeCN or THF solutions, the halide- or hydroxyl-addition tetrahedral complexes [XBi{Cr(CO)5}3]2– (X = Cl, 2-Cl; Br, 2-Br; I, 2-I; OH, 3) were produced, complex 2-I could convert to 1 upon treatment with AgNO3. Moreover, when 1 reacted with Fe(CO)5 in KOH/MeOH solutions, the rare mixed chromium─iron tetrahedral complex [Bi{Cr(CO)5}3{Fe(CO)4}]3– (4) was formed. It was noted that complex 1 exhibited solvatochromic properties with the color changing from red to green upon dissolving in DMF, MeCN, Acetone, MeOH, THF, EtOH, or CH2Cl2. Furthermore, the nature, formation, and electrochemical and physical properties of complexes 1─4 were systematically discussed in terms of the effects of halide and heterometallic interaction with the aid of molecular calculations at MPW1PW91 and BP86 level of density functional theory .