2 research outputs found
Molecules with High Bond Orders and Ultrashort Bond Lengths: CrU, MoU, and WU
The
structural and energetic parameters of MU heterobimetallic dimers
(M = Cr, Mo, W) have been computed using the complete active space
self-consistent-field method followed by second-order perturbation
theory. Our results show that the effective bond order (EBO) of the
MoU dimer (5.5) is higher than that for the tungsten dimer (5.2),
known to date as the molecule with the highest EBO. These heterodimers
present also ultrashort bond distances and remarkably large dissociation
energies, which make these molecules suitable and interesting potential
candidates in synthetic bimetallic organometallic chemistry
Experimental Evidence Shedding Light on the Origin of the Reduction of Branching of Acrylates in ATRP
Intramolecular chain transfer to
polymer and subsequent propagation
of tertiary radicals cause extensive branching in radical polymerization
of acrylic monomers. Studies in the literature have shown that under
controlled radical polymerization conditions the extent of branching
is significantly reduced. There are two competing theories to explain
this effect. In one, the cause of reduced branching is attributed
to a reduction in the number of backbiting events, and in the other
that has been specifically applied to atom-transfer radical polymerization
(ATRP), the cause is due to trapping of the tertiary radical by a
fast deactivation step. In this article we show that trapping of the
tertiary radical is not the cause for the reduction in branching fraction.
This is shown by the absence of the corresponding patched midchain
bromide structure as revealed by quantitative <sup>13</sup>C NMR and
by the ability to chain extend from a polyĀ(butyl acrylate-<i>co</i>-butyl 2-bromoacrylate) copolymer by ATRP. These results
are complemented by quantum mechanical computations