Neodymium dihalide complexes with a tridentate amidinate phosphine oxide ligand: synthesis, structure, and catalytic activity in isoprene polymerization

• Published in: Russian chemical bulletin Vol. 68; no. 1; pp. 32 - 39
• Main Authors: Tolpygin, A. O., Linnikova, O. A., Kovylina, T. A., Cherkasov, A. V., Fukin, G. K., Trifonov, A. A.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.01.2019; Springer Nature B.V
• Subjects: AMIDINES; CATALYSIS; CATALYSTS; Catalytic activity; Chemical synthesis; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; CHLORIDES; Coordination compounds; Full Articles; Halides; Inorganic Chemistry; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ISOPRENE; LIGANDS; LITHIUM; MOLECULAR WEIGHT; NEODYMIUM; NEODYMIUM COMPLEXES; NEODYMIUM HALIDES; Organic Chemistry; Phosphine oxide; PHOSPHINE OXIDES; POLYISOPRENE; POLYMERIZATION; POTASSIUM; SYNTHESIS; TETRAHYDROFURAN; X-RAY DIFFRACTION; synthesis; isoprene polymerization; amidinate ligand; halide complexes; neodymium complexes; catalysis; structure
• DOI: 10.1007/s11172-019-2412-8
• ISSN: 1066-5285

The deprotonation of amidine 2-[Ph 2 P(O)]C 6 H 4 NHC(Bu t )=N(2,6-Me 2 C 6 H 3 ) ( 1 ) with BunLi affords lithium amidinate {2-[Ph 2 P(O)]C 6 H 4 NLiC(Bu t )=N(2,6-Me 2 C 6 H 3 )}2 ( 2 ) having a dimeric structure, as demonstrated by X-ray diffraction. New amidinate dihalide complexes {2-[Ph 2 P(O)]C 6 H 4 NC(Bu t )N(2,6-Me 2 C 6 H 3 )}NdHal 2 (THF) 2 (Hal = I ( 3 ), Cl ( 4 )) were synthesized by exchange reactions of lithium and potassium amidinates with anhydrous neodymium halides NdHal 3 (THF) n (Hal = I, n = 3.5; Cl, n = 0). The X-ray diffraction studies showed that the new compounds are monomeric and the amidinate ligand is tridentate. Chloride complex 4 involved in the three- and four-component catalyst systems 4–AlR 3 –[Ph3C] [B(C 6 F 5 ) 4 ] (1: 10: 1; AlR 3 = AlBu i 3, AlMe 3 ), 4 –AlR 3 –Pr i OH (1: 10: 10; AlR 3 = AlBu i 3 , AlMe 3 ), and 4–AlR 3 –[Ph 3 C][B(C 6 F 5 ) 4 ]–Pr i OH (1: 10: 1: 10; AlR 3 = AlBu i 3 , AlMe 3 ) exhibits activity in stereospecific isoprene polymerization and allows the preparation of high-molecular-weight polyisoprene samples with exceptionally high cis -1,4-unit content (up to 99.4%).