貴金屬 (銅、銀) 嵌入第六族 (鉬、鎢) 與碲羰基團簇化合物之合成、結構、反應性及半導體性質之探討

Abstract

由 Te 粉末、M(CO)6 (M = Mo, W) 和 Et4NBr 在 KOH/MeCN/MeOH 溶液下以不同比例反應可合成一系列新穎的多核含碲之第六族過渡金屬羰基化合物，[Te7Mo6(CO)20]4- (1)、[Te6Mo6(CO)15]4- (2) 與 [Te6W5(CO)12]4- (3)。X 光單晶結構分析顯示，化合物 1 為籠狀團簇物，而化合物 2 與 3 則以過渡金屬為中心連接外圍 Te 與過渡金屬羰基片段形成籃型與碗型化合物。當高負價化合物 1 與 1 當量的 [Cu(MeCN)4]+ 反應時，可成功獲得銅引入之籠狀化合物 [Cu@Te7Mo6(CO)20]3- (Cu@1)。若化合物 1 與 2 當量 [Ag(MeCN)4]+ 反應時，可獲得車輪型結構之氧化產物 [Te8Mo6(CO)18]2- (4)。此外，化合物 2 或 3 與 1 當量 [M'(MeCN)4]+ (M' = Cu, Ag) 反應時，皆可獲得雙銅或銀橋接兩個 Te6M5(CO)12 (M = Mo, W) 片段之高負價啞鈴型化合物 [M'2{Te6M5(CO)12}2]6- (M'= Cu, M = Mo, 5-Cu, W, 6-Cu; M'= Ag, M = Mo, 5-Ag, W, 6-Ag)。再者，當提高 [M'(MeCN)4]+ (M' = Cu, Ag) 之當量為 3與化合物 2 或 3反應，則可獲得一貴金屬橋接兩 Te6M5(CO)12 (M = Mo, W) 片段之化合物 [M'{Te6M5(CO)12}2]3- (M'= Cu, M = Mo, 7-Cu, W, 8-Cu; M'= Ag, M = Mo, 7-Ag, W, 8-Ag)，其中化合物 7-M' 及 8-M' (M' = Cu, Ag) 之外圍兩 Te6M5(CO)12 片段皆具額外的 M‒M 鍵。從 X 光電子能譜 (XPS) 與 X-ray 吸收近邊緣光譜 (XANES) 得知化合物 5-M', 6-M', 7-M' 及 8-M' (M' = Cu, Ag) 中貴金屬 (銅、銀) 原子的氧化態趨近於 0 價。重要的是，固態反射式 UV-vis 光譜顯示此系列含碲之多核鉬及鎢羰基團簇物具有低能隙 (0.75‒1.10 eV)，指出貴金屬引入後可有效調節其能隙，並表現出良好的半導體性質A novel series of tellurium-containing polynuclear group 6 transition metal (Mo, W) carbonyl clusters, the cage-like [Te7Mo6(CO)20]4- (1), the basket-like [Te6Mo6(CO)15]4- (2), and the bowl-like [Te6W5(CO)12]4- (3), were synthesized from the reactions of different ratios of Te powder, M(CO)6 (M = Mo, W), and Et4NBr in concentrated KOH/MeCN/MeOH solutions, respectively. When 1 reacted with 1 mole of [Cu(MeCN)4]+, the Cu-encapsulated cage complex [Cu@Te7Mo6(CO)20]3- (Cu@1) was obtained in high yield. If 1 was treated with 2 moles of [Ag(MeCN)4]+, the paddle wheel-like complex [Te8Mo6(CO)18]2- (4) was obtained. In addition, if 2 or 3 was treated with 1 mole of [M’(MeCN)4]+ (M’ = Cu, Ag), the di-Cu- or di-Ag-bridged coupling products [M’2{Te6M5(CO)12}2]6- (M’ = Cu, M = Mo, 5-Cu, W, 6-Cu; M’ = Ag, M = Mo, 5-Ag, W, 6-Ag), were formed, respectively. Besides, as the moles of [M’(MeCN)4]+ (M’ = Cu, Ag) was increased to 3, the reactions produced the Cu or Ag-bridged dumbbell-like products [M’{Te6M5(CO)12}2]3- (M’ = Cu, M = Mo, 7-Cu, W, 8-Cu; M’ = Ag, M = Mo, 7-Ag, W, 8-Ag), respectively. The X-ray photoelectron spectra (XPS) and X-ray absorption near-edge structures (XANES) showed that the physical oxidation state of the nobel metal (Cu, Ag) atoms was closed to 0. Diffuse reflectance spectra of these synthesized complexes possessed low-energy-gap characteristics in the range of 0.75‒1.10 eV, in which varied, controllable, and fine-tuned energy gaps were revealed by the noble metal-introduced process.