3.1.1 | Geometries
In the work reported in ref. [29], trans isomers were
obtained for all systems but one: acetal 7, for which a mixture ofcis (7a) and trans (7b) derivatives were formed in the
synthetic process. Therefore, there are in total nine monomers reported
on in this study. All of their geometries were optimized at the
B3LYP-D3/6-311++G(d,p) and B3LYP-D3/def2-TZVP levels of theory. Figure 2
shows the nine 1,2-diiodoolefin structures optimized at the
B3LYP-D3/6-311++G(d,p) level of theory. The C=C bond lengths (the common
part in the nine 1,2-diiodoolefin structures) in both the optimized and
crystal structures are listed in Table 1. It can be seen that the bond
lengths of the C=C in the nine monomers calculated at the
B3LYP-D3/6-311++G(d,p) and B3LYP-D3/def2-TZVP levels of theory are all
in good agreement with the values seen in the crystal structures. Also,
there is only a marginal difference between the C=C bond lengths
optimized at the two levels of theory. Therefore, considering the
computational cost, the B3LYP-D3/6-311++G(d,p) level of theory was
applied to carry out all molecular electrostatic potential (Vs,max)
calculations.