Synthesis And Reactivity Of Mixed Guanidinate Alkyl Rare-Earth Matal Complexes

Recently,the synthesis and reactivity of novel rare-earth metal alkyl complexes have attracted much attention in organolanthanide chemistry.Amidinates and guanidinates stand out among many ligands,not only because of their highly tunable steric and electronic properties,but also of their easy accessibility and abundant coordination patterns.But untill now studies on synthesis and reactivity of monoguanidine rare-earth metal alkyl complexes have been almost unexplored.On the basis of our study for monoguanidinate rare-earth metal bis?o-aminobenzyl?complexes,two novel monoguanidinate rare-earth metal aminobenzyl complexes with unique structure were designed and synthesized in this paper.The reactivity of the rare-earth metal aminobenzyl enolate complexes with small molecules and their catalytic activity on the polymerization of lactide were also investigated.In addtion,some new activation patterns were also observed during the reactions of lutetium mixed methyl-aminobenzyl complex with some small molecules.The 21 new complexes were synthesized and characterized by X-ray single crystal diffraction.The results were as follows:1.Synthesis and characterization of guanidinate rare-earth metal aminobenzyl enolate complexes LRE?CH₂C₆H₄NMe₂-o??OCH=CH₂??THF??L=?PhCH₂?₂NC?NC₆H₃ⁱPr₂-2,6?₂;RE=Y?2-1a?,Lu?2-1b??,and the reactivities of 2-1a with DIC,PhNCS,PhNH₂,Ph₂NH and Ph₂PH were studied.It was found that 2-1a was treated with conjugate unsaturated DIC and PhNCS to afford insertion complexes LY[?NⁱPr₂?₂CCH₂C₆H₄NMe₂-o]?OCH=CH₂??THF??2-2?,LY[SC?CH₂C₆H₄NMe₂-o?NPh]?OCH=CH₂??THF??2-3?and dinuclear yttrium enolate complex{LY??-OCH=CH₂??OCH=CH₂?}₂?2-4?by ligands redistribution.Protonolysis of 2-1a with aromatic amines could yield LY?NHPh??OCH=CH₂??THF?₂?2-5?,LY?NHPh?₂?THF?₂?2-6?and LY?NPh₂??OCH=CH₂??THF?₂?2-7?.2-1a could react with Ph₂PH in THF solution to obtain ring-opening insertion product{LY[O?CH₂?₄PPh₂][?-O?CH₂?₄PPh₂]}₂?2-8?.Moreover,It was found that guanidinate rare-earth metal aminobenzyl enolate complexes could efficiently catalyze the controlled ring-opening polymerization of rac-lactide?PDI<1.88?without the participation of chain-transfer reagents.2.The reactivity of guanidinate lutetium methyl-aminobenzyl complex LLu?CH₂C₆H₄NMe₂-o??Me??THF??3-1??L=?PhCH₂?₂NC?NC₆H₃ⁱPr₂-2,6?₂?with DIC,CS₂,Ph₂PH,PhNH₂,Ph₂NH,PhSSPh,PhCCH and H₂ were investigated.Complex LLu[?NⁱPr₂?₂CMe]?CH₂C₆H₄NMe₂-o??3-2?was afforded from the reaction of 3-1 with DIC?1 equiv?,and DIC was inserted into Lu-Me?-bond.Complex LLu[?NⁱPr₂?₂CMe][?NⁱPr₂?₂CCH₂C₆H₄NMe₂-o]?3-3?was obtained by reaction of 3-2 with another DIC.On the contratry,3-1could react with CS₂ to yield L₂Lu₂[?-?²:?²-S₂C=CHC₆H₄NMe₂-o][?-?¹:?²-S₂C=CH C₆H₄NMe₂-o]?3-4?via tandem aminobenzyl addition and methane elimination reaction.Similarly,complex{LLu?Me?[?-O?CH₂?₄PPh₂]}₂?3-5?was obtained through tandem protonolysis-activition of Lu-C_aminobenzyl?-bond with Ph₂PH?1 equiv?.After that,complexes{LLu[O?CH₂?₄PPh₂][?-O?CH₂?₄PPh₂]}₂?3-6?and{LLu[?-O?CH₂?₄PPh₂]}₂?PPh₂??Me??3-7?were obtained with another Ph₂PH in THF or Tol solution respectively.Protonolysis of 3-1 with aromatic amines could yield lutetium amide complexes LLu?NHPh?₂?THF?₂?3-8?and LLu?NPh₂?₂?THF??3-9?.Redox reactions of 3-1 with PhSSPh in Tol or THF solution,dinuclear complex{LLu??-SPh?₂}₂?3-10?bearing four?₂-SPh ligands and mononuclear complex LLu?SPh?₂?THF??3-11?were separated respectively.Lutetium alkynyl complex[LLu??-C?CPh?]₂??-?²:?²-PhC₄Ph??3-12?with coupled butatrienediyl was obtained by protonolysis of 3-1 with PhC?CH.Futhermore,trinuclear lutetium ployhydride complex{LLu H₂}₃?THF??3-13?was given by the hydrogenolysis of 3-1 with excess H₂.