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.