Synthesis,Characterization,and Catalytic Performance Of Aluminum And Tin(Ⅱ) Compounds Supported By β-diketiminato Ligands

This paper mainly synthesized five aluminum and tin（II）compounds containing N-donor ligands.All compounds were characterized by NMR spectroscopy and single crystal X-ray structural analysis.The five new compounds can act as good catalysts for the hydroboration reactions.Herein,the catalytic behaviour of the five new compounds in hydroboration reactions was investigated.The loadings of catalysts,the reaction temperature and the reaction time of the hydroboration reaction were also investigated.1.L¹Al（SCH₂Ph）₂（1）and[CH{（Me）CN-2,6-ⁱPr₂C₆H₄}₂Al Cl₂]（2）,supported byβ-diketiminato ligands L¹H[CH{（Me）CN-2,4,6-Me₃C₆H₂}₂H]and L²H[CH{（Me）CN-2-ⁱPr C₆H₄}₂H]were obtained in good yield respectively.A solution of L¹Al H₂ in toluene was added drop by drop to a solution of benzyl mercaptan in toluene at0°C.Colorless crystals of 1 were obtained.Compound 2 was prepared by the similar procedure described for 3,using L²H in THF and Al Cl₃ in THF to afford colorless crystals.The aluminum atoms in the compound 2 connected with two chlorine atoms and two nitrogen atoms of the ligand alchlor skeleton respectively.Aluminum atoms center adopt a distorted tetrahedral geometry.2.n-Bu Li was added to a precooled solution of L²H in THF.The mixture was stirred and warmed to room temperature.A solution of Sn Cl₂ was added to the L²Li solution.The ligand L³H was reacted with equimolar n-butyl lithium to obtain lithium salt L³Li,then reacted with Sn Cl₂,to obtain L³Sn Cl was added to Li SCH₂Ph₃ solution to obtain organotin compound 4,and compound 5 was accidentally obtained.3.The catalytic behaviour of five new compounds in the hydroboration reactions was studied.The hydroboration of aldehydes and ketones catalyzed by compounds 1-5 generate a series of organoboron complexes under mild conditions and at low catalyst loadings.In comparison,the hydroboration of benzaldehyde showed less reactivity in the absence of any catalyst.Compound 2 exhibits the highest catalytic activity among the three complexes.The higher catalytic activity of 2 might be caused by the decreased steric hindrance and the stronger Lewis acidity in aluminum center.Moreover,the main group metallic compounds display non-toxic and environmentally friendly properties.