Synthesis, characterisation and reactivity of water-soluble ferrocenylimine-Rh(I) complexes as aqueous-biphasic hydroformylation catalyst precursors

Water-soluble complexes based on monosodium 5-sulfonato salicylaldimine (3) and 3-tbutyl-5-<br>sulfonatosalicylaldimine have been synthesised via sulfonation and Schiff base condensation reactions.<br>The ligand (3) and the new water-soluble mononuclear 5-sulfonatosalicylaldimine-ferrocenylimine<br>complexes (4 and 5) have been synthesised and characterised fully using 1H NMR, 13C{1H} NMR, and FTIR<br>spectroscopy, elemental analysis as well as mass spectrometry. Subsequently, the Rh(I) heterobimetallic<br>complexes (6 and 7) were synthesised from [RhCl(COD)]2 (COD ¼ 1,5-cyclooctadiene) and the<br>ferrocenylimine metalloligands (4 and 5) and characterised using various analytical and spectroscopic<br>techniques. These complexes were applied as catalyst precursors in aqueous biphasic hydroformylation<br>reactions. Optimal conditions were established at 95 ?C (40 bar), showing the best chemoselectivity for<br>aldehydes. The mononuclear ferrocenyl pre-catalysts (4 and 5) were inactive in the aqueous-biphasic<br>hydroformylation of 1-octene. The heterobimetallic catalyst precursors (6 and 7) displayed good activity<br>and could be recycled for at least 4 runs under the investigated conditions for the aqueous biphasic<br>hydroformylation of 1-octene.

以5-磺基水杨醛亚胺单钠盐（3）与3-叔丁基-5-磺基水杨醛亚胺为配体的水溶性配合物，通过磺化反应及席夫碱（Schiff base）缩合反应合成得到。
配体（3）以及新型水溶性单核5-磺基水杨醛亚胺-二茂铁亚胺配合物（4和5）已成功合成，并通过1H核磁共振波谱（1H NMR）、13C{1H}核磁共振波谱（13C{1H} NMR）、傅里叶变换红外光谱（FTIR）、元素分析以及质谱分析完成了全面表征。
随后，以二(μ-氯)双(1,5-环辛二烯)二铑(I)（[RhCl(COD)]2，其中COD为1,5-环辛二烯（1,5-cyclooctadiene））与二茂铁亚胺金属配体（4和5）为原料，合成了铑(I)（Rh(I)）异双金属配合物（6和7），并通过多种分析与光谱技术完成了表征。
上述配合物均作为催化剂前驱体应用于水相双相氢甲酰化反应中。
最优反应条件设定为95℃（40 bar），此时对醛类产物的化学选择性最佳。
单核二茂铁基预催化剂（4和5）在1-辛烯的水相双相氢甲酰化反应中无催化活性。
异双金属催化剂前驱体（6和7）表现出良好的催化活性，且在所考察的1-辛烯水相双相氢甲酰化反应条件下，至少可循环使用4次。