A new structural type of dinuclear rhodium(II) compounds: synthesis by serendipity and design; catalytic behaviour in carbene transfer reactions †
作者:Francisco Estevan、Abel García-Bernabé、Santiago García-Granda、Pascual Lahuerta、Eduardo Moreno、Julia Pérez-Prieto、Mercedes Sanaú、M. Angeles Ubeda
DOI:10.1039/a903811f
日期:——
The compound [Rh2(µ-O2CCH3)3(O2CCH3)[η2-(o-CH3OC6H4)P(C6H5)2] 1, having one phosphine acting as a chelating, equatorial (P)âaxial(O), ligand has been structurally characterized. A new family of structurally related dirhodium(II) compounds of general formula [Rh2(µ-O2CR)2(X)2η2-(o-YC6H4)P(C6H5)2}2] (R = CH3, X = CH3CO2, Y = CH3O 2; R = CF3, X = CF3CO2, Y = CH3O 3; R = CH3, X = Cl 4 or R = CH3, X = Cl, Y = CH3O 5) has been synthesized. All these compounds are structurally related; they have two orthofunctionalized phosphines acting as equatorial (P) and axial (Cl, O) donor ligands and two bridging carboxylates. The two remaining equatorial sites around the rhodium atoms are occupied by two monodentate carboxylates (2, 3) or two chlorine atoms (4, 5). Compounds 4 and 5 have been structurally characterized by X-ray methods. Compound 4, initially obtained in low yield by serendipity, was also prepared in moderate yield from rhodium acetate and P(o-ClC6H4)(C6H5)2 in the presence of a stoichiometric amount of Me3SiCl. Compounds 2 and 3 were prepared by treating the corresponding rhodium tetracarboxylate with two moles of P(o-CH3OC6H4)(C6H5)2 and 5, obtained by serendipity, was best synthesized from the reaction of 2 and two moles of Me3SiCl.
化合物[Rh2(µ-O2CCH3)3(O2CCH3)[δ-2-(o-CH3OC6H4)P(C6H5)2] 1具有一个膦作为螯合、赤道(P)â轴(O)配体的结构特征。通式为[Rh2(µ-O2CR)2(X)2δ-2-(o-YC6H4)P(C6H5)2}2](R = CH3,X = CH3CO2,Y = CH3O 2;R = CF3,X = CF3CO2,Y = CH3O 3;R = CH3,X = Cl 4 或 R = CH3,X = Cl,Y = CH3O 5)的合成。所有这些化合物在结构上都是相关的;它们有两个作为赤道(P)和轴向(Cl、O)供体配体的正官能化膦以及两个桥接羧酸盐。铑原子周围剩余的两个赤道位被两个单齿羧酸盐(2、3)或两个氯原子(4、5)占据。化合物 4 和 5 已通过 X 射线方法确定了结构特征。化合物 4 最初是偶然得到的,收率较低,后来在一定量的 Me3SiCl 存在下,由醋酸铑和 P(o-ClC6H4)(C6H5)2 制备得到,收率中等。化合物 2 和 3 是用两摩尔的 P(邻-CH3OC6H4)(C6H5)2 处理相应的四羧酸铑制备的,而通过偶然性得到的化合物 5 最好是由 2 和两摩尔的 Me3SiCl 反应合成的。