The Application Of Rare-earth Metal Organic Compounds In The Transformation Of Carbodiimide

An amidato divalent ytterbium cluster[Yb3L6]·2C7H8(1)(L=C6H5CON(2,6-iPr2-C6H3))was synthesized,which was characterized by vari-ous techniques including the NMR spectroscopies and X-ray single crystal diffraction.The redox reaction of cluster 1 with carbodiimide was tested.It was also used to catalyze the guanylation reaction of carbodiimides and amines.Moreover,the catalytic activities of cluster 1 and RE[N(TMS)2]3 on the guanylation/cyclization reaction of carbodiimides and amino acid esters were investigated.The main results are as follows:1.Reaction of Yb[N(SiMe3)2]2(TMEDA)with HL in 1:2 molar ratio afforded a centrosymmetric trinuclear divalent ytterbium complex[Yb3L6]·2C7H8(1).One Yb atom is located at the center of the whole molecule,which is 6-coordinated by six oxygen atoms from each amidato ligand,and all amidato ligands are bound to the central metal Yb using ?-O:?2-amidato mode.Further studies on the reduction of iPrN=C=NiPr by complex 1 provide Yb(III)com-plex[(YbL2)2(?-NiPrCNiPr)][YbL3(THF)]C7H8(2),[(YbL3)2·2C7H8](3)and[(YbL2)2(?-NiPrCNiPr)·3C7H8](4).Complexes 1-4 were characterized by X-ray single crystal diffraction.2.The catalytic activitiy of complex 4 for the guanidination of carbodiimides and amines was tested.The reaction conditions,such as the amount of catalyst loading,solvent,temperature and so on,were screened using cluster 1 as the pre-catalyst.The results showed that cluster 1 was found to be an excellent pre-catalyst for the guanylation reaction with a high activity under mild con-ditions and with a wide scope of substrates.3.The guanylation/cyclization reaction of carbodiimides and amino acid es-ters catalyzed by cluster 1 was investigated,and it was also found that simple rare-earth metal amides RE[N(TMS)2]2 and RE[N(TMS)2]3 have high reactiv-ities in the modle reaction.So the reaction conditions were screened using simple complex RE[N(TMS)2]3 as the precatalyst.The results showed that RE[N(TMS)2]3 has great activity and performed well in relatively wide scope of substrates.In addition,a competitive reaction,the addition of alcohols with carbodiimides was observed in the system,which was also catalyzed by RE[N(TMS)2]3.