The salt-free diamido complexes of lanthanide supported by β-diketiminate: Synthesis, characterization, and their catalytic activity for the polymerization of acrylonitrile and ε-caprolactone

Polymerization of acrylonitrile catalyzed by lanthanide-sodium alkoxide clusters Ln2(OCH2CH2NMe2)12(OH)2Na8 [Ln=Yb (1), Nd (2) and Sm (3)]

“…The tacticity of PAN was determined from the -CH 2 C(CN)H-methine resonance at 27 [31], and the results in Tables 2 and 3 indicate that all of the polymers obtained were atactic. Similar results were found for polymerization of acrylonitrile initiated by Ln-(SAr) 3 (py) 3 (La=Sm, Yb) [21], Ln(OAr) 3 (Ln=La, Y) [22] and LLn(NPh 2 ) 2 (THF) [23]. It can also be seen from Figure 2 that there is a small peak at about 14, in addition to the main-chain -CH 2 C(CN)H-resonances.…”

“…Taking the system with cluster 1 as an example, even when the molar ratio [M]/ [1] was increased to 1000, the conversion still reached 77% (Table 1). To our best knowledge, this is the most active known lanthanide catalyst [15][16][17][18][19][20]22,23]. All of the polymers obtained using the lanthanide-sodium alkoxide clusters had high molecular weight (M η >10 4 g mol −1 ).…”

“…PAN can be prepared by radical polymerization or anionic polymerization, and numerous metal complexes of alkali [5][6][7], alkaline earth [8,9] and late transition metals [10 -14] have been reported as initiators for anionic polymerization of acrylonitrile. Various lanthanide metal complexes have also been found to be single-component initiators for anionic polymerization of acrylonitrile, including [(tert-BuCp) 2 NdCH 3 ] 2 [15], (ArO) 2 Sm [16], Ind 2 LnN(i-Pr) 2 (Ln=Y, Yb) [17], SmI 2 [18], [(η 5 :η 1 -C 5 Me 4 SiMe 2 NCMe 3 )Y(CH 2 SiMe 3 )(THF)] [19], La-(C 5 Me 5 )[(CH(SiMe 3 ) 2 )] 2 (THF) [20], Ln(SAr) 3 (py) 3 (La= Sm, Yb) [21], Ln(OAr) 3 (Ln=La, Y) [22] and LLn(NPh 2 ) 2 (THF) (L=N,N′-bis(2,6-dimethylphenyl)-2,4-pentanediiminate) [Ln=Yb, Nd] [23]. However, only a few lanthanide metal complexes show the desired catalytic activity, and most of these complexes are sensitive to air and moisture.…”

Structural Elucidation of tmeda‐Solvated Alkali Metal Diphenylamide Complexes

“…Of particular interest in this study, another amido reagent, the thermally highly stable lithium diphenylamide (LiNPh 2 ), has shown promise in a range of synthetic transformations. As well as regioselective deprotonation reactions, [6][7][8][9][10] it has also been used in catalytic aldol reactions involving silyl enol ethers and aldehydes; [11,12] in elimination applications; [13,14] in metathetical reactions; [15][16][17][18][19][20][21][22][23][24][25][26][27] during the preparation of amino-containing carbenes, [28] and as an initiator in the polymerisation of methyl methacrylate. [29] utilised as the metallating agent.…”

Synthesis and structure of para‐toluene sulfonamide lanthanide complexes and their application in the polymerization of ε‐caprolactone

“…Numbers of organometallic catalysts, such as alkali metals, alkaline earth metals, transition metals and rare earth metals, have been explored for ring‐opening polymerization (ROP) of polycaprolactone. Among them, organolanthanide metal complexes have attracted more and more attention due to their high catalytic activities and capabilities of preparing polymers with high molecular weights in narrow polydispersity as well as low cytotoxicity …”