New lanthanoid biphenolate complexes, their further reactivity with trimethylaluminium and catalytic activity for the polymerisation of rac-lactide

Shephard, Angus C.G., Ali, Safaa H., Wang, Jun, Guo, Zhifang, Davies, Murray S., Deacon, Glen B., and Junk, Peter C. (2021) New lanthanoid biphenolate complexes, their further reactivity with trimethylaluminium and catalytic activity for the polymerisation of rac-lactide. Dalton Transactions, 50 (41). pp. 14653-14661.

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Abstract

A series of rare earth biphenolate complexes of the general form [Ln(mbmp)(mbmpH)(thf)3] (Ln = Y (1), Nd (2), Gd (3), Dy (4), Er (5), Tm (6) and Lu (7)) have been synthesised by redox transmetallation/protolysis (RTP) from the free rare earth metal, Hg(C6F5)2 and 2,2′-methylenebis(6-tert-butyl-4-methylphenol) (mbmpH2). The rare earth metal is six coordinate with one chelating biphenolate mbmp2- ligand and one unidentate monophenolate mbmpH- ligand. The yttrium complex, when crystallised from hot toluene or deuterated benzene, loses a coordinated thf and exhibits coordination through all three phenolate oxygen atoms, as well as the oxygen of the phenol, yielding two solvates [Y(mbmp)(mbmpH)(thf)2]·nsolv (solv = PhMe, n = 1 (8a) or C6D6, n = 2 (8b)). Of these rare earth complexes, the yttrium derivative (1) yielded the heterobimetallic complex [AlMe2Y(mbmp)2(thf)2] (9) when treated with trimethylaluminium, whereas all other complexes produced the transmetallation product [AlMe(mbmp)(thf)] (11). The dinuclear dysprosium complex [Dy2(mbmp)3(thf)3] (10) was isolated alongside 11 from the reaction of 4 with trimethylaluminium, suggesting trimethylaluminium instigates a redistribution reaction. The ROP activity of the mononuclear neodymium, dysprosium, lutetium, and aluminium complexes towards rac-lactide in toluene at 70 °C was found to be poor compared to rare earth complexes of monodentate aryloxides, but increased with increased rare earth ion size.

Item ID: 70484
Item Type: Article (Research - C1)
ISSN: 1477-9234
Copyright Information: © The Royal Society of Chemistry 2021
Funders: Australian Research Council (ARC)
Projects and Grants: ARC DP19010079
Date Deposited: 30 Nov 2021 02:04
FoR Codes: 34 CHEMICAL SCIENCES > 3402 Inorganic chemistry > 340203 F-block chemistry @ 100%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280105 Expanding knowledge in the chemical sciences @ 100%
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