Study On The Organic Reactions Catalyzed By Lanthanide-Sodium Alkoxide Bimetallic Clusters

Nine lanthanide-sodium alkoxide clusters were synthesized in high yield with -OCH₂CH₂NMe₂ and -OtBu as ligand according to the methods presented in the thesis of Doc. Hongting Sheng. The catalytic activity of clusters Ln₂(OCH₂CH₂NMe₂)₁₂(OH)₂Na₈(Ln = Pr 1 ; Nd 2 ; Sm 3 ; Yb 4 ;Y 5) for the Tishchenko reaction was studied. Besides, The catalytic activity of cluster LnNa₈(O^tBu)₁₀(OH) for the acylation of nitriles and amidation of aldehydes and amines were examined. The main results obtained are as follows:1. The lanthanide-sodium alkoxide clusters Ln₂Na₈ (OCH₂CH₂NMe₂)₁₂(OH)₂(Ln = Pr 1 ; Nd 2 ; Sm 3 ; Yb 4 ;Y 5) were synthesized in moderate to high yields by the reaction of NaOCH2CH2NMe2 with LnCl3 in 6:1 molar ratio in the presence of one equiv of NaOH.2. Using the reaction of NaOtBu with LnCl3 in 10:1 molar ratio in the presence of two equiv of NaOH, we synthesized the lanthanide-sodium tert-butoxide clusters LnNa8(OtBu)10(OH) (Ln = Nd, Sm, Eu, Yb) as crystals upon crystallization.3. The catalytic activity of clusters Ln₂Na₈ (OCH₂CH₂NMe₂)₁₂(OH)₂(Ln = Pr 1 ; Nd 2 ; Sm 3 ; Yb 4 ;Y 5) for the Tishchenko reaction was tested. The clusters catalyzed the Tishchenko reaction of aldehydes with high activity and good tolerance to functional groups. The activity was found to be much higher than those lanthanide alkoxides reported previously. The catalytic mechanism was also investigated.4. The acylation of nitriles and esters with clusters LnNa₈(O^tBu)₁₀(OH)(Ln = Nd, Sm, Yb) as catalysts was studied. The preliminary results demonstrated that the clusters are efficient catalysts for the acylation with both enolizable and nonenolizable esters to provide the correspondingβ-ketonitriles. To our best knowledge , this is the first example of catalytic acylation of nitriles with esters. The reaction mechanism was proposed.5. Clusters LnNa₈(O^tBu)₁₀(OH)(Ln = Nd, Sm, Eu, Yb) are found to be high active catalysts for amidation of aldehydes and amines . The present systems proceed smoothly with low loading of catalyst and mild reaction conditions. Moreover, the systems have the advantage of tolerance to various substrates.