Metalloligands containing aminofulvene-aldiminate (AFA) ligands and their bimetallic complexes
作者:Philip J. Bailey、Mahmudur Rahman、Simon Parsons、Muhammad R. Azhar、Fraser J. White
DOI:10.1039/c2dt32804f
日期:——
A simple and convenient route to η5-coordinated Ru and Rh aminofulvene-aldiminate (AFA) complexes is described. The metalloligands [Cp*Ruη5-(Ph2AFAH)}][BF4] (3), [Cp*Ruη5-(benzyl2AFAH)}][OTf] (7), [Cp*Rhη5-(Cy2AFA)H}][BF4]2 (8) and [Cp*Rhη5-(Cy2AFA)}][BF4] (9) have been synthesised and characterised. The basicity of 9 has been found to be significantly less than its neutral analogue and thus eliminates the need for a deprotonation step to ligate to a second metal in the κ2-N,N′-coordination mode. The reaction of 9 with a palladium precursor provides a mixed-metal complex [Cp*Rh(η5/κ2-Cy2AFA)PdCl2][BF4] (12). Cyclic voltammetry studies of the Ph2AFAH ligand shows an irreversible one electron oxidation peak at +1.0 V (vs. Fc/Fc+). Complex 3 shows an irreversible oxidation at +1.5 V and a reduction peak at −1.0 V. The oxidation of 3 occurs on the AFA ligand backbone whereas the structurally analogous neutral 1,2-bis(imidoyl)pentamethyl-ruthenocene shows reversible oxidation at the Ru center.
本文描述了一种简单方便的方法来制备 η5 配位的 Ru 和 Rh 氨基乙醛酸盐 (AFA) 复合物。合成并表征了金属配体 [Cp*Ruη5-(Ph2AFAH)}][BF4] (3)、[Cp*Ruη5-(苄基 2AFAH)}][OTf](7)、[Cp*Rhη5-(Cy2AFA)H}][BF4]2 (8) 和 [Cp*Rhη5-(Cy2AFA)}][BF4] (9)。研究发现,9 的碱性明显低于其中性类似物,因此无需去质子化步骤就能以κ2-N,N′配位模式与第二种金属连接。9 与钯前体反应生成了一种混合金属复合物 [Cp*Rh(η5/κ2-Cy2AFA)PdCl2][BF4](12)。Ph2AFAH 配体的循环伏安研究显示,在 +1.0 V 处有一个不可逆的单电子氧化峰(对 Fc/Fc+)。配合物 3 在 +1.5 V 处出现不可逆氧化,在 -1.0 V 处出现还原峰。络合物 3 的氧化发生在 AFA 配体骨架上,而结构类似的中性 1,2-双(亚胺酰)五甲基钌则显示出 Ru 中心的可逆氧化。