| 摘要: | 我們合成了一系列由鐵二價及鈷二價為中心金屬的雙配位基錯合物，鐵雙配位基錯合物不管改變配位基立體障礙大小，皆為六配位的構型。相對的，鈷雙配位基錯合物當配位基的立體障礙較小時，如 (CztBu(PyrH)2)2Co(II) (Co(II)H) 及 (CztBu(PyrMe)2)2Co(II) (Co(II)Me) 為六配位的構型，而當配位基的立體障礙較大時，如 (CztBu(PyriPr)2)2Co(II) (Co(II)iPr) 及 (CztBu(PyrPh)2)2Co(II) (Co(II)Ph) 為四配位構型。當加入一當量 AgPF6 嘗試將錯合物氧化時，發現 (CztBu(PyrR)2)2Co(II) (Co(II)R, R = Me, iPr, Ph) 將會形成鈷銀的雙金屬雙配位基錯合物，其他錯合物則是被氧化成三價金屬。設計兩種不同途徑，合成出比銀一價錯合物更具反應性的銅一價錯合物，分別為四配位鈷金屬及三配位銅金屬的雙金屬錯合物 (Co(II)CuBrR, R = Me, iPr) 及四配位鈷金屬及二配位銅金屬的雙金屬錯合物 (Co(II)CuR, R = iPr, Ph)，且這四種銅一價錯合物皆可在空氣中穩定存在。使用非金屬氧化劑 NOPF6 成功將多電子氧化還原錯合物 Co(II)Ph 氧化，改變氧化劑當量數可成功單離了氧化一次及氧化兩次的產物，並透過晶體結構、磁矩及電子順磁共振光譜來判斷其氧化的位置。;We have synthesized a series of bis-ligand complexes featuring Fe(II) and Co(II) as the central metals. Regardless of the steric bulk of the ligands, the iron bis-ligand complexes all adopt a six-coordinate geometry. In contrast, the cobalt bis-ligand complexes exhibit geometry dependent on ligand sterics: complexes with less sterically demanding ligands, such as (CztBu(PyrH)2)2Co(II) (Co(II)H) and (CztBu(PyrMe)2)2Co(II) (Co(II)Me), adopt a six-coordinate geometry, while those with more sterically hindered ligands, such as (CztBu(PyriPr)2)2Co(II) (Co(II)iPr) and (CztBu(PyrPh)2)2Co(II) (Co(II)Ph), adopt a four-coordinate geometry. Addition of one equivalent of AgPF₆ for oxidation led to the formation of heterobimetallic Co–Ag bis-ligand complexes in the cases of Co(II)R (R = Me, iPr, Ph), whereas other complexes were oxidized to the corresponding trivalent metal species. Two different synthetic routes were designed to access Cu(I) complexes that are more reactive than their Ag(I) analogues, resulting in four heterobimetallic Co–Cu complexes: one set comprising four-coordinate cobalt and three-coordinate copper centers (Co(II)Cu(I)BrR, R = Me, iPr), and the other comprising four-coordinate cobalt and two-coordinate copper centers (Co(II)Cu(I)R, R = iPr, Ph). All four Cu(I) complexes are air-stable. Using the non-metallic oxidant NOPF₆, we successfully oxidized the multi-electron redox-active Co(II)Ph complex. By varying the equivalents of the oxidant, we were able to isolate both singly and doubly oxidized products. The oxidation states and oxidation sites were elucidated through crystallographic analysis, magnetic susceptibility measurements, and electron paramagnetic resonance (EPR) spectroscopy. |
