A computational insight into a metal mediated pathway for the ring-opening polymerization (ROP) of lactides by an ionic {(NHC)(2)Ag}(+)X(-) (X = halide) type N-heterocyclic carbene (NHC) complex
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Title |
A computational insight into a metal mediated pathway for the ring-opening polymerization (ROP) of lactides by an ionic {(NHC)(2)Ag}(+)X(-) (X = halide) type N-heterocyclic carbene (NHC) complex
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Creator |
STEPHEN, R
SUNOJ, RB GHOSH, P |
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Subject |
MOLECULAR-ORBITAL METHODS
AB-INITIO PSEUDOPOTENTIALS EFFECTIVE CORE POTENTIALS MIXED AQUEOUS-MEDIUM SET MODEL CHEMISTRY EPSILON-CAPROLACTONE TRIMETHYLENE CARBONATE TRANSITION-ELEMENTS GOLD(I) COMPLEXES TOTAL ENERGIES |
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Description |
A metal mediated coordination-insertion pathway for the ring-opening polymerization (ROP) of L-lactide by an ionic {(NHC)(2)Ag}(+)X(-) (X = halide) type silver complex of N-heterocyclic carbene (NHC) has been investigated using the density functional theory (DFT) method. A clear insight into the lactide insertion process could be obtained by modeling two consecutive monomer addition steps with the first one mimicking chain initiation with the second representing a propagation step. In particular, in each of the cycles, the reaction initiates with the formation of a lactide coordinated species, [1+LL] and [2+LL] that transforms into a metal bound cyclic lactide intermediate, I([1+LL] -> 2) and I([2+LL] -> 3), which subsequently ring opens to give the lactide inserted products, 2 and 3. The estimated overall activation barrier for the initiation step is 42.0 kcal mol(-1) while the same for the propagation step is 31.5 kcal mol(-1). Studies on higher monomer insertions showed a decrease in the relative product energies as anticipated for an addition polymerization pathway.
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Publisher |
ROYAL SOC CHEMISTRY
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Date |
2012-06-26T09:27:48Z
2012-06-26T09:27:48Z 2011 |
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Type |
Article
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Identifier |
DALTON TRANSACTIONS,40(39)10156-10161
1477-9226 http://dx.doi.org/10.1039/c1dt10345h http://dspace.library.iitb.ac.in/jspui/handle/100/14286 |
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Language |
English
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