Monoanionic triketiminate ligands: Peculiarity of coordination mode to lithium and rare earth ions.
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| Title: | Monoanionic triketiminate ligands: Peculiarity of coordination mode to lithium and rare earth ions. |
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| Authors: | Skvortsov, Grigorii G.1 (AUTHOR), Fukin, Georgy K.1 (AUTHOR), Cherkasov, Anton V.1 (AUTHOR), Kovylina, Tatyana A.1 (AUTHOR), Trifonov, Alexander A.1,2 (AUTHOR) trif@iomc.ras.ru |
| Source: | Inorganica Chimica Acta. Aug2020, Vol. 508, pN.PAG-N.PAG. 1p. |
| Subjects: | Rare earth ions, Rare earth metals, Ligands (Chemistry), Ternary system, Molecular weights |
| Abstract: | • Monoanionic β-triketiminate ligands feature bidentate coordination mode and are coordinated to a metal center only through two nitrogen atoms. • The ternary systems based on these complexes exhibit catalytic activity in isoprene polymerization. • The ternary systems provide very high content of cis -1,4 units (98.9%). Deprotonation of β-triketimines (2,6-Me 2 C 6 H 3 N = CMe) 3 CH (1), (2,6-Me 2 C 6 H 3 N = CMe) 2 CH(2-MeOC 6 H 4 N = C t Bu) (2), (2,6-Me 2 C 6 H 3 N = CMe) 2 CH(2,6-Me 2 C 6 H 3 N = C t Bu) (3) by equimolar amount of n -BuLi afforded lithium triketiminate complexes [(2,6-Me 2 C 6 H 3 N = CMe) 3 C]Li(THF) (4), [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]Li(THF) 2 (5), [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]Li(THF) 2 (6) in 70–80% yields. The salt metathesis reactions of LnCl 3 (Ln = Y, Nd) with 6 lead to the formation of neutral triketiminate dichloro complexes [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]LnCl 2 (THF) 2 (Ln = Y (7), Nd (8)) in 78 and 70% yields, while the analogous reaction of YCl 3 with 5 resulted in triketiminate yttrium chloro ate complex [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]Y(THF)Cl(µ2-Cl) 2 Li(THF) 2 (9). The reactions of the potassium derivatives of the related triketimines 2 , 3 with YbI 2 (THF) 2 resulted in the formation of mononuclear triketiminate iodo Yb(II) complexes [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]YbI(THF) 2 (10) and [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]YbI(TMEDA) (11). X-ray analysis revealed that in 4 and rare-earth metals complexes 7 – 11 the monoanionic β-triketiminate ligands [(2,6-Me 2 C 6 H 3 N = CMe) 3 C]−, [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]−, [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]− feature bidentate coordination mode and are coordinated to a metal center only through two nitrogen atoms. The ternary systems 7–9 /Al i Bu 3 /[CPh 3 [B(C 6 F 5) 4 exhibit catalytic activity in isoprene polymerization, allowing to carry out polymerization of 1000 equivalents in 2 h with 91–100% conversion. The obtained polyisoprenes feature high molecular weights (M n = 12.8 × 104–20.2 × 104) and moderate polydispersities (M w / M n = 2.7–3.6), however excellent control of regio- and stereoselectivities (up to 9.9% cis -1,4 units) was observed. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
| Abstract: | • Monoanionic β-triketiminate ligands feature bidentate coordination mode and are coordinated to a metal center only through two nitrogen atoms. • The ternary systems based on these complexes exhibit catalytic activity in isoprene polymerization. • The ternary systems provide very high content of cis -1,4 units (98.9%). Deprotonation of β-triketimines (2,6-Me 2 C 6 H 3 N = CMe) 3 CH (1), (2,6-Me 2 C 6 H 3 N = CMe) 2 CH(2-MeOC 6 H 4 N = C t Bu) (2), (2,6-Me 2 C 6 H 3 N = CMe) 2 CH(2,6-Me 2 C 6 H 3 N = C t Bu) (3) by equimolar amount of n -BuLi afforded lithium triketiminate complexes [(2,6-Me 2 C 6 H 3 N = CMe) 3 C]Li(THF) (4), [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]Li(THF) 2 (5), [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]Li(THF) 2 (6) in 70–80% yields. The salt metathesis reactions of LnCl 3 (Ln = Y, Nd) with 6 lead to the formation of neutral triketiminate dichloro complexes [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]LnCl 2 (THF) 2 (Ln = Y (7), Nd (8)) in 78 and 70% yields, while the analogous reaction of YCl 3 with 5 resulted in triketiminate yttrium chloro ate complex [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]Y(THF)Cl(µ2-Cl) 2 Li(THF) 2 (9). The reactions of the potassium derivatives of the related triketimines 2 , 3 with YbI 2 (THF) 2 resulted in the formation of mononuclear triketiminate iodo Yb(II) complexes [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]YbI(THF) 2 (10) and [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]YbI(TMEDA) (11). X-ray analysis revealed that in 4 and rare-earth metals complexes 7 – 11 the monoanionic β-triketiminate ligands [(2,6-Me 2 C 6 H 3 N = CMe) 3 C]−, [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2-MeOC 6 H 4 N = C t Bu)]−, [(2,6-Me 2 C 6 H 3 N = CMe) 2 C(2,6-Me 2 C 6 H 3 N = C t Bu)]− feature bidentate coordination mode and are coordinated to a metal center only through two nitrogen atoms. The ternary systems 7–9 /Al i Bu 3 /[CPh 3 [B(C 6 F 5) 4 exhibit catalytic activity in isoprene polymerization, allowing to carry out polymerization of 1000 equivalents in 2 h with 91–100% conversion. The obtained polyisoprenes feature high molecular weights (M n = 12.8 × 104–20.2 × 104) and moderate polydispersities (M w / M n = 2.7–3.6), however excellent control of regio- and stereoselectivities (up to 9.9% cis -1,4 units) was observed. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00201693 |
| DOI: | 10.1016/j.ica.2020.119623 |
