Synthesis and characterisation of unsymmetrical Zr(<scp>iv</scp>) amine tris(phenolate) complexes and their application in ROP of rac-LA

Forder, Thomas R.; Mahon, Mary F.; Davidson, Matthew G.; Woodman, Timothy J.; Jones, Matthew D.

doi:10.1039/c4dt01260g

Cited by 26 publications

(10 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…54 55 and without the addition of any further solvents 56 was previously reported. 57 MALDI-TOF mass spectrometry (see Fig. 53 The corresponding ligand was reacted with one equivalent of di(n-butyl)magnesium in toluene at −78°C to afford complexes 1 and 2 (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Magnesium amino-bis(phenolato) complexes for the ring-opening polymerization of rac-lactide

et al. 2015

View full text Add to dashboard Cite

Magnesium compounds of tetradentate amino-bis(phenolato) ligands, Mg[L1] (1) and Mg[L2] (2) (where [L1] = 2-pyridyl-N,N-bis(2-methylene-4-methoxy-6-tert-butylphenolato), and [L2] = dimethylaminoethylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenolato)) were prepared. The proligands, H2[L1] and H2[L2] were reacted with di(n-butyl)magnesium in toluene to give the desired compounds in high yields. Compounds 1 and 2 exhibit dimeric structures in solutions of non-coordinating solvents as observed by NMR spectroscopy and in the solid state as shown by the single crystal X-ray structure of 2. These compounds exhibit good activity for rac-lactide polymerization in solution and in molten lactide.

show abstract

Section: Resultsmentioning

confidence: 99%

“…Similar isomerism has been observed in zirconium amine-tris( phenolates). 57 MALDI-TOF mass spectrometry (see Fig. S1 and S2 in ESI †) showed complexes 1 and 2 exhibit dimeric structures in the gas phase as well as in solution and the solid state.…”

Section: Synthesis and Characterization Of Proligands And Magnesium C...mentioning

confidence: 99%

Magnesium amino-bis(phenolato) complexes for the ring-opening polymerization of rac-lactide

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The methodology is analogous to that we used to prepare B for M = Ni, X = OSiMe 3 (Chart 1), which is referred to here as Me 3 SiOU(OAr P ) 3 Ni 4. 13 The homoleptic uranium complex U(OAr P ) 4 3 is prepared from the reaction of UI 4 (Et 2 O) 2 with four molar equivalents of KOAr P in THF.…”

Section: Synthesismentioning

confidence: 99%

“…Importantly, the design principles that guide how a ligand will govern tacticity are still not clear. 4 One ligand family of particular interest are the C 3 tris( phenolate) trianions; stereoselective initiators based on Zr IV have generated highly heterotactic polymers, 5 while we have previously shown that a chiral, racemic heterobidentate alkoxide can selectively assemble to form homochiral, C 3 symmetric complexes that are active initiators for the formation of isotactic PLA (P i = 0.75, 298 K). 6 Although often overlooked due to misconceptions of scarcity and excessive oxophilicity, the f-block cations possess a unique capability to tune the ROP performance due to the available range of size and Lewis acidity.…”

Section: Introductionmentioning

confidence: 99%

Ring opening polymerisation of lactide with uranium(iv) and cerium(iv) phosphinoaryloxide complexes

et al. 2017

View full text Add to dashboard Cite

The C-symmetric uranium(iv) and cerium(iv) complexes MeSiOM(OAr), M = U (1), Ce (2), OAr = OCH-6-Bu-4-Me-2-PPh, have been prepared and the difference between these 4f and 5f congeners as initiators for the ring opening polymerisation (ROP) of l-lactide is compared. The poorly controlled reactivity of the homoleptic analogue U(OAr) (3) demonstrates the importance of the M-OSiMe initiating group. The incorporation of a nickel atom in 1 to form the U-Ni heterobimetallic complex MeSiOU(OAr)Ni (4) may be the first example of the use of the inverse trans influence to switch the reactivity of a complex. This would imply the formation of the U-Ni bond strengthens the U-OSiMe bond to such an extent that the ROP catalysis is switched off. Changing the conditions to immortal polymerisation dramatically increases polymerisation rates, and switches the order, with the Ce complex now faster than the U analogue, suggesting ligand protonolysis to afford a more open coordination sphere. For the ROP of rac-lactide, uranium complex 1 promotes heterotacticity at the highest levels of stereocontrol yet reported for an actinide complex.

show abstract

“…The Ti-O-Ti bond angles for the double oxo-bridge are narrower than the literature examples at 111.56(6) • , due to the shape of the overall structure forcing Zr1 and Zr3, closer together [43]. To the best of our knowledge, complex 8 is the first example of a trimetallic Zr cluster with amine bis/tris(phenolate) ligands where the Zr centres are bridged by only oxo-bridges [23,43,44,46]. The ester groups were not hydrolysed during the synthesis.…”

Section: Synthesis Of Ti and Zr Clustersmentioning

confidence: 73%

Polymetallic Group 4 Complexes: Catalysts for the Ring Opening Polymerisation of rac-Lactide

et al. 2021

View full text Add to dashboard Cite

Five novel air- and moisture-stable polymetallic Ti and Zr amino acid-derived amine bis(phenolate) (ABP) complexes were synthesised and fully characterised, including X-ray crystallographic studies. The reaction of the ABP proligands with Ti or Zr alkoxides has resulted in the formation of polymetallic aggregates of different nuclearity. The steric bulk on the pendant arm of the ligand was found to play a critical role in establishing the nuclearity of the aggregated complex. Sterically, less-demanding groups, such as H or Me, facilitated the formation of tetrametallic Ti clusters, bridged by carboxylate groups, while increased steric bulk (tBu) led to the formation of binuclear μ-oxo-bridged species. The isolated complexes were employed as catalysts for the ring opening polymerisation (ROP) of rac-lactide. Overall, the Ti catalysts were all active with the smaller, bimetallic Ti aggregates exhibiting relatively faster rates. A monometallic, bis(ABP) Zr complex was found to exert remarkable ROP activity, albeit with limited control over the tacticity and molecular weight distribution of the polymer. A further oxo-bridged Zr cluster was shown to display a previously unprecedented trimetallic structure and achieved a moderate rate in the ROP of rac-lactide.

show abstract

Synthesis and characterisation of unsymmetrical Zr(iv) amine tris(phenolate) complexes and their application in ROP of rac-LA

Cited by 26 publications

References 31 publications

Magnesium amino-bis(phenolato) complexes for the ring-opening polymerization of rac-lactide

Magnesium amino-bis(phenolato) complexes for the ring-opening polymerization of rac-lactide

Ring opening polymerisation of lactide with uranium(iv) and cerium(iv) phosphinoaryloxide complexes

Polymetallic Group 4 Complexes: Catalysts for the Ring Opening Polymerisation of rac-Lactide

Contact Info

Product

Resources

About