Rare-earth metal mediated PhCN insertion into N,N-bis(trimethylsilyl)naphthalene-1,8-diamido dianion – a synthetic approach to complexes coordinated by ansa-bridged amido-amidinato ligand. Synthesis, structures and catalytic activityстатья
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Аннотация:Lithium silylamides 1,8-C10H6[N(SiMe3)Li(L)](2) (L = Et2O (1(Et2O)); L = TMEDA (1(TMEDA))), when treated with PhC N, formed the adducts 1,8-C10H6[N(SiMe3)Li(N CPh)(OEt2)][N(SiMe3) Li(OEt2)] (2(Et2O)) and 1,8-C10H6[N(SiMe3)Li(N CPh)][N(SiMe3)Li(TMEDA)] (2(TMEDA)) containing one benzonitrile molecule coordinated to Li ion while the second molecule retains a coordinated L ligand. The salt metathesis reactions of LnCl(3) (Ln = Y, Sm) with equimolar amounts of 2(Et2O) and 2(TMEDA) (THF, 4 h, 40 degrees C) resulted in benzonitrile insertion and formation of new dianionic amido-amidinate ligands. The reactions of 2(Et2O) with LnCl(3) afforded ionic chloro complexes [{1,8-C10H6[NSiMe3][NC(Ph) NSiMe3]}{1,8-C10H6[N(H) SiMe3][NC(Ph) NSiMe3]} LnCl][Li(L)(n)] (Ln = Y, L = THF, n = 4 (3Y), Ln = Sm, L = DME, n = 3 (3Sm)), while the reaction of 2(TMEDA) and YCl3 leds to the formation of the neutral salt-free yttrium chloro complex {1,8-C10H6[NSiMe3][NC(Ph) NSiMe3]}YCl(TMEDA) (4). The treatment of 3Y and 4 with tBuOK enabled the synthesis of tert-butoxides [{1,8-C10H6[NSiMe3][NC(Ph)NSiMe3]}{1,8-C10H6[N(H)SiMe3][NC(Ph)NSiMe3]} YOtBu][Li(THF)(4)] (7) and {1,8-C10H6[NSiMe3][NC(Ph)NSiMe3]}YOtBu(TMEDA) (8). Complexes 7 and 8 were evaluated as initiators for the ring opening polymerization of rac-lactide. Neutral tert-butoxide complex 8 demonstrated significantly higher activity compared to that of ionic 7.