Highly Active and Iso-selective Catalysts for ROP of Cyclic Esters Using Group 2 Metal Initiators

Panda, Tarun K and Bhattacharjee, J and Harinath, A and Nayek, H P and Sarkar, A (2017) Highly Active and Iso-selective Catalysts for ROP of Cyclic Esters Using Group 2 Metal Initiators. Chemistry - A European Journal. ISSN 0947-6539

Full text not available from this repository. (Request a copy)


A series of alkali and alkaline earth (Ae) metal complexes bearing 1,2 phenylene(bis-diphenylphosphinothioic/selenoic amide) [{Ph2P(E)NH}2C6H4] (E = S (1-H2); Se (2-H2) ligands are reported. Alkali metal complexes [{Ph2P(S)N}2C6H4]Na(THF)4 (3a) [{Ph2P(Se)N}2C6H4]Na(THF)4 (3b), and [{Ph2P(Se)N}2C6H4]K(THF)5 (4b) were obtained in good yield by treating protic ligand 1-H2 or 2-H2 with corresponding metal hexamethyldisilazides [MN(SiMe3)2] (M = Na and K) at ambient temperature. The Ae metal complexes formulated as [{Ph2P(E)N}2C6H4]M(THF)3 [E = S, M = Ca (5a), Sr (6a), Ba (7a); E = Se, M = Ca (5b), Sr (6b), Ba (7b)] can be synthesized using two routes. The molecular structures of the free ligand 1-H2 and metal complexes 5a,b-7a,b in their solid states were established. Complexes 3a and 3b are isostructural; however, in complex 4b, an attachment different from ligand 2 was observed. The complexes 5a,b-7a,b are isostructural and each metal ion exhibits a distorted pentagonal bipyramidal geometry around it. All Ae metal complexes 5a,b-7a,b were tested for the ring-opening polymerization (ROP) of racemic lactide (rac-LA) and - caprolactone (-CL) at room temperature. Calcium complexes 5a and 5b show excellent iso-selectivity, with a Pi value of 0.78-0.87 at 298 K with a high degree of polymerization control, whereas the corresponding strontium complexes 6a and 6b exhibit moderate iso-selectivity, and barium complexes 7a and 7b yield only atactic polylactides (PLAs).

[error in script]
IITH Creators:
IITH CreatorsORCiD
Panda, Tarun Khttp://orcid.org/0000-0003-0975-0118
Item Type: Article
Uncontrolled Keywords: Bis-diphenylphosphino-chalcogen amide; Alkali metal; Alkaline earth metal; Lactide polymerization; isotactic PLA
Subjects: Chemistry
Divisions: Department of Chemical Engineering
Depositing User: Team Library
Date Deposited: 12 Jun 2017 06:32
Last Modified: 07 Sep 2017 11:34
URI: http://raiith.iith.ac.in/id/eprint/3211
Publisher URL: https://doi.org/10.1002/chem.201700672
OA policy: http://www.sherpa.ac.uk/romeo/issn/0947-6539/
Related URLs:

Actions (login required)

View Item View Item
Statistics for RAIITH ePrint 3211 Statistics for this ePrint Item