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Issue 2, 2018
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Rare-earth metal-mediated PhC[triple bond, length as m-dash]N insertion into N,N-bis(trimethylsilyl)naphthalene-1,8-diamido dianion – a synthetic approach to complexes coordinated by ansa-bridged amido-amidinato ligand

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Abstract

Lithium silylamides 1,8-C10H6[N(SiMe3)Li(L)]2 (L = Et2O (Image ID:c7dt03809g-t1.gif); L = TMEDA (1TMEDA)), when treated with PhC[triple bond, length as m-dash]N, formed the adducts 1,8-C10H6[N(SiMe3)Li(N[triple bond, length as m-dash]CPh)(OEt2)][N(SiMe3)Li(OEt2)] (Image ID:c7dt03809g-t2.gif) and 1,8-C10H6[N(SiMe3)Li(N[triple bond, length as m-dash]CPh)][N(SiMe3)Li(TMEDA)] (2TMEDA) containing one benzonitrile molecule coordinated to Li ion while the second molecule retains a coordinated L ligand. The salt metathesis reactions of LnCl3 (Ln = Y, Sm) with equimolar amounts of Image ID:c7dt03809g-t3.gif and 2TMEDA (THF, 4 h, 40 °C) resulted in benzonitrile insertion and formation of new dianionic amido-amidinate ligands. The reactions of Image ID:c7dt03809g-t4.gif with LnCl3 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 2TMEDA 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.

Graphical abstract: Rare-earth metal-mediated PhC [[triple bond, length as m-dash]] N insertion into N,N-bis(trimethylsilyl)naphthalene-1,8-diamido dianion – a synthetic approach to complexes coordinated by ansa-bridged amido-amidinato ligand

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Publication details

The article was received on 10 Oct 2017, accepted on 14 Nov 2017 and first published on 14 Nov 2017


Article type: Paper
DOI: 10.1039/C7DT03809G
Citation: Dalton Trans., 2018,47, 438-451
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    Rare-earth metal-mediated PhC[triple bond, length as m-dash]N insertion into N,N-bis(trimethylsilyl)naphthalene-1,8-diamido dianion – a synthetic approach to complexes coordinated by ansa-bridged amido-amidinato ligand

    D. M. Lyubov, A. V. Cherkasov, G. K. Fukin, K. A. Lyssenko, E. A. Rychagova, S. Yu. Ketkov and A. A. Trifonov, Dalton Trans., 2018, 47, 438
    DOI: 10.1039/C7DT03809G

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