An unexpected carbon-oxygen bond cleavage of THF (THF = tetrahydrofuran) promoted by guanidinate titanium complex was described. Guanidinate lithium [Pr2iNC(NCy)2]Li (Cy = cyclohexyl) formed in situ reacted with TiCl4...An unexpected carbon-oxygen bond cleavage of THF (THF = tetrahydrofuran) promoted by guanidinate titanium complex was described. Guanidinate lithium [Pr2iNC(NCy)2]Li (Cy = cyclohexyl) formed in situ reacted with TiCl4(THF)2 in a 2:1 molar ratio to produce the gua- nidinate titanium chloride [Pr2iNC(NCy)2]2TiCl2 (1) in good yield. The reaction of [Pr2iNC(NCy)2]2TiCl2 with lithium diisopropylamide in THF afforded an unexpected [Pr2iNC(NCy)2]2Ti(OBun)2 (2), which was formed by the cleavage of carbon-oxygen bond of THF. Complexes 1 and 2 were fully characterized by elemental analysis, NMR and IR spectroscopies, and X-ray crystal structure determination for complex 2.展开更多
A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthe...A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthesized through the metathesis reactions of {Ln(μ-Cl)[N(Si Me3)2]2(THF)}2(Ln=Sm, Yb, Y) with lithium guanidinate {Li[(RN)2CN(CH2)2]}2(R=iPr, Cy), the latter of which was generated in situ by the reaction of carbodiimides with lithium amides. Complexes 1–5 were well characterized by elemental analyses, IR spectra, and(for Complex 3) NMR spectroscopy. The solid-state molecular structures of all of the complexes were determined by single-crystal X-ray analyses with the exception of Complex 3, which showed similar unsolvated centrosymmetric dinuclear structures. Each of the lanthanide centers is four-coordinated with two nitrogen atoms from a guanidinate ligand and two nitrogen atoms from two amido groups. The piperazidine rings adopt chair conformations in all cases. These organolanthanide complexes were found to be efficient catalysts for the hydrophosphonylation reaction of various aldehydes and unactivated ketones and to afford ?-hydroxyphosphonates in high yields under low catalyst loading(0.1 mol%) in a short reaction time.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.20472063).
文摘An unexpected carbon-oxygen bond cleavage of THF (THF = tetrahydrofuran) promoted by guanidinate titanium complex was described. Guanidinate lithium [Pr2iNC(NCy)2]Li (Cy = cyclohexyl) formed in situ reacted with TiCl4(THF)2 in a 2:1 molar ratio to produce the gua- nidinate titanium chloride [Pr2iNC(NCy)2]2TiCl2 (1) in good yield. The reaction of [Pr2iNC(NCy)2]2TiCl2 with lithium diisopropylamide in THF afforded an unexpected [Pr2iNC(NCy)2]2Ti(OBun)2 (2), which was formed by the cleavage of carbon-oxygen bond of THF. Complexes 1 and 2 were fully characterized by elemental analysis, NMR and IR spectroscopies, and X-ray crystal structure determination for complex 2.
基金supported by the National Natural Science Foundation of China(21132002,21372172,21402138)the Major Research Project of the Natural Science Foundation of the Jiangsu Higher Education Institutions(14KJA150007)the Qing Lan Project
文摘A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthesized through the metathesis reactions of {Ln(μ-Cl)[N(Si Me3)2]2(THF)}2(Ln=Sm, Yb, Y) with lithium guanidinate {Li[(RN)2CN(CH2)2]}2(R=iPr, Cy), the latter of which was generated in situ by the reaction of carbodiimides with lithium amides. Complexes 1–5 were well characterized by elemental analyses, IR spectra, and(for Complex 3) NMR spectroscopy. The solid-state molecular structures of all of the complexes were determined by single-crystal X-ray analyses with the exception of Complex 3, which showed similar unsolvated centrosymmetric dinuclear structures. Each of the lanthanide centers is four-coordinated with two nitrogen atoms from a guanidinate ligand and two nitrogen atoms from two amido groups. The piperazidine rings adopt chair conformations in all cases. These organolanthanide complexes were found to be efficient catalysts for the hydrophosphonylation reaction of various aldehydes and unactivated ketones and to afford ?-hydroxyphosphonates in high yields under low catalyst loading(0.1 mol%) in a short reaction time.
