含十六族元素(硫、硒、碲)與過渡金屬(鉻、錳、鐵)之團簇化合物的合成與反應探討以及化性與物性研究

Abstract

E–Cr (E = S, Se)系統 取硫粉末或是 SeO2 與 Cr(CO)6 於80 ~ 85 oC 下以2：3的比例在鹼性甲醇溶液中，加熱反應可得雙三角錐結構的 [HE2Cr3(CO)9]3– (E = S, 1a; Se, 1b)，有趣的是當 1a 或 1b 在 – 40oC 低溫且充滿 CO 的環境下，加入兩當量的醋酸，可分別得到 [E2Cr3(CO)10]2– (E = S, 1a; Se, 1b) 伴隨著氫氣的產生。進一步我們將 2a 和 2b 分別與兩當量的 KOH 溶於MeCN/MeOH中並加熱至80 oC ，可逆反應生成 1a 和 1b。另一方面Na2S 和Cr(CO)6 於90 oC下以莫耳比2: 3在甲醇溶液中反應36小時，可得化合物 2a，並有效的提生產率由20 %至54 %。 此外我們將1a 分別與有機鹵化物 RX (R = PhCH2，X = Br；R = Ph，X = I) 反應可得到化合物 [S4Cr5(CO)14]3– (3)，並伴隨著 Toluene 以及 Benzene的生成，相同地，1b 和 PhCH2Br 反應也可得到有機產物 Toluene，但與 PhI卻無反應發生。同時藉由理論計算對一系列化合物之電子結構、電化學進行分析與討論。

E–Mn–Fe (E = Se, Te)系統 取適量 E (E = Se、Te) powder 與 Mn2(CO)10 和 Fe(CO)5 及 [PPN]Cl 於75 oC下以莫耳比2: 1: 1: 1在1.66M KOH 甲醇溶液中反應，可得混和 Mn─Fe 的四角錐金屬團簇物 [E2Mn2Fe(CO)9]2– (E = Se, 1; Te, 2)，有鑑於 X-ray 上無法分辨錳和鐵原子，因此利用密度泛函數理論 (Density Fuctional Theory) 進行分子的紅外線光譜模擬，證實此四角錐之底部四邊形是由 E2Mn2 以對位的形式構成，頂端蓋接 Fe(CO)3 片段。 再者，將四角錐錯合物1 分別與一當量 Fe(CO)5 和 Mn2(CO)10與適量 KOH 溶於 CH2Cl2/MeOH 下進行擴核反應，可得到不同金屬比例的八面體形結構化合物 [Se2Fe2Mn2(CO)11]2– (3) 和 [Se2FeMn3(CO)11]2– (4) 。化合物4亦可由 [Se2Mn3(CO)9]– 於冰浴下與一當量 [HFe(CO)4]– 進行擴核反應得到。進一步藉由理論計算對一系列混和錳鐵化合物之電子結構以及電化學進行分析與討論。

E–Cr–Fe (E =S, Se, Te)系統 取適量 S powder與 Cr(CO)6 和 Fe(CO)5 及 [PPN]Cl 於85 oC下以莫耳比1: 1: 1: 2 於2 M KOH 的甲醇溶液中反應，可得到主族為硫且混和鉻和鐵的八面體結構化合物 [S2Cr2Fe2(CO)12]2– (1)。將主族改變為硒，並將莫耳比改為1: 1: 1: 2，可得到一混和鉻鐵團簇化合物 [Se2CrFe3(CO)11]2– (2)，根據 X-ray 單晶繞射分析顯示1和2均為八面體構形且E (E = S, Se) 原子分別蓋接在 M4 (M = Cr or Fe) 金屬環上方以及下方，但若將主族改變為碲，而莫耳比改為2: 1: 2: 2，卻得 arachano 錯合物 [Te2CrFe2(CO)10]2– (3)，X-ray 單晶繞射分析顯示結構 3 底部為一蝴蝶構形的Te2Fe2(CO)9，再由一Cr(CO)4 片段橋接在Te2 上。進一步我們將化合物 2 於80 oC 1 M KOH的甲醇及乙氰溶液中反應可得到雙三角錐化合物 [Se2Cr2Fe(CO)9]2– (4). 並藉由理論計算對一系列混和鉻鐵化合物之電子結構以及電化學進行分析與討論。

關鍵字: 16 族元素、團簇化合物、錳、鉻、鐵、氫氣、電化學。E–Cr (E = S, Se) System The reaction of sulfur powder or SeO2 with Cr(CO)6 in molar ratio of 2: 3 in KOH/MeOH/hexanes solutions at 80 oC formed a selenium-capping trichromium closo-trigonal-bipyramidal (TBP) carbonyl hydride clusters [HE2Cr3(CO)9]3– (E = S, 1a; Se, 1b). Interestingly, the deprotonation of 1a and 1b using acetic acid under CO atmosphere at –40oC rapidly released H2 and afforded selenium-capping trichromium TBP dianionic clusters [E2Cr3(CO)10]2– (E = S , 2a; Se, 2b), respectively. Conversely, clusters 2a and 2b could be reconverted to 1a and 1b by the treatment with two equivalents of KOH in MeCN/MeOH solutions at 80 oC. On the other hand, when Na2S reacted with Cr(CO)6 in molar ratio of 2: 3 in MeOH solutions at 90 oC, cluster 2 was formed, efficiently increasing the yield from 20 % to 54 %. Additionally, when cluster 1a reacted with organic halides RX (R = PhCH2，X = Br；R = Ph，X = I), the Cr-linked S2Cr2(CO)-based cluster [S4Cr5(CO)14]3– (3) was obtained along with the formation of toluene and benzene, respectively. Likewise, the reaction of 1b with PhCH2Br gave 3 and toluene. However, no reaction was observed for the reaction of 1b with PhI. Furthermore, the nature and electrochemical studies of the resultant clusters were studied and elucidated with the aid of molecular calculations of the density functional theory.

E–Mn–Fe (E = Se, Te) System When E powder, Fe(CO)5, Mn2(CO)10, and [PPN]Cl were mixed in concentrated KOH methanolic solutions in molar ratio of 2: 1: 1: 1 at 75 oC , the mixed Fe–Mn square-pyramidal clusters [E2FeMn2(CO)9]2– (E = Se, 1; Te, 2) were obtained, respectively. X-ray analysis revealed that clusters 1 and 2 were isostructural, in which the trans-E2Mn2 square was capped by an apical Fe(CO)3 fragment. Further studies showed that 1 can undergo cluster-growth reactions by the treatments of Fe(CO)5 and Mn2(CO)10 in KOH/MeOH solution to form mixed Fe–Mn octahedral complexes [Se2Fe2Mn2(CO)11]2– (3) and [Se2FeMn3(CO)11]2– (4), respectively. Clusters 2 and 3 were isostructures, and the M4 (M = Mn or Fe) ring was capped above and below by the Se atoms. Cluster 4 could was also obtained from the reaction of homometallic trigonal-bipyramidal cluster [Se2Mn3(CO)9]– with [HFe(CO)4]– under controlled conditions. The electrochemical studies showed two series of mixed Mn–Fe clusters possessed rich redox capabilities. Further, the nature, formation, and electrochemistry of these mixed Fe–Mn carbonyl clusters were studied and elucidated with the aid of molecular calculations of the density functional theory.

E–Cr–Fe (E = Se, Te) System When S powder, Cr(CO)6, Fe(CO)5, and [PPN]Cl were mixed in concentrated KOH methanolic solutions in molar ratio of 1: 1: 1: 2 at 80 oC , a mixed Cr–Fe octeahedral cluster [S2Cr2Fe2(CO)12]2– (1) was obtained. On the other hand, Se powder could reacted with Cr(CO)6, Fe(CO)5, and [PPN]Cl in concentrated KOH methanolic solutions in molar ratio of 2: 1: 3: 2 at 80 oC to give a new mixed Cr–Fe cluster [Se2CrFe3(CO)11]2– (2). X-ray analysis showed that clusters 1 and 2 each consisted of an octahedral core, where the M4 (M = Cr or Fe) ring was capped above and below by the E atoms (E = S, Se). Besides, when Te powder was used as the chalcogen source under the similar condition, a new arachno-cluster [Te2CrFe2(CO)10]2– (3) was formed. Cluster 3 comprised of a Te2Fe2 butterfly with the “wintip” Te atoms linked by a Cr(CO)4 fragment. Furthermore,the reaction of compound 2 with 1 M KOH/MeOH/MeCN solution at 80 oC produced the trigonal-bipyramidal complex [HSe2CrFe2(CO)9]2– (4). Moreover, the nature, formation, and electrochemistry of these mixed Cr–Fe carbonyl clusters were studied and elucidated with the aid of molecular calculations of the density functional theory.

Keywords: chalcogens, cluster compounds, manganese, chromium, iron, hydrogen, electrochemistry.