*3.2. Lone-Pair*···π *Interactions in ASZ*·*1.5(1,4-FIB)*

*d*(C···I)/(RvdW(I) + RvdW(C)).

iodofluorobenzenes [60,79,80].

Besides the expected C–I· · · N halogen bonding, the C· · ·I–C contacts (Table 2) were identified between **ASZ** and **1,4-FIB** molecules in **ASZ**·1.5 (**1,4-FIB**) (Figure 4). According to the ∠(C· · ·I–C) angle, which is close to 90◦ (Table 2), this interaction can be interpreted as lp(I)· · · π(C) interaction [60]. *Crystals* Their theoretically estimated strength is 1.6 kcal **2020**, *10*, 371 /mol. 5 of 13

**Figure 4.** The lp(I)···π(C) interaction between **ASZ** and **1,4-FIB** molecules in **ASZ**·1.5(**1,4-FIB**). **Figure 4.** The lp(I)· · · π(C) interaction between **ASZ** and **1,4-FIB** molecules in **ASZ**·1.5(**1,4-FIB**).


*Comparison a 3.68 1.00 90*  a Comparison is the vdW radii sum [42] for distances and classic XB acceptor angle. b R*CI* = <sup>a</sup> Comparison is the vdW radii sum [42] for distances and classic XB acceptor angle. <sup>b</sup> R*CI* = *d*(C· · ·I)/(RvdW(I) + RvdW(C)).

Previously, the lp(I)···π(C) interactions including 1,2,4-triazole moiety were discussed only for five 1,2,4-triazolium iodides [61,62], where these interactions are interionic. We analyzed the CCDC data and identified 23 more structures with the C···I interactions including 1,2,4-triazoles. 1,2,4-triazolium iodides [20,63–70] were also found in 15 structures. The C···I–M interactions [71–76] in 1,2,4-triazole-containing MOFs were detected in 6 structures. Structure XIWGOC contains the C···I– interactions between the cationic IrIII complex and iodide counterion [77]. Only in the IDIFEH structure was another example of the C···I–C interactions between neutral isolated molecules [78] identified. The C···I distances vary from 3.4363(2) to 3.670 (3) Å (for details see Table S2), and the C9···I1S distance (3.528 (8) Å) in **ASZ**·1.5(**1,4-FIB**) is within this range. Previously, the lp(I)· · · π(C) interactions including 1,2,4-triazole moiety were discussed only for five 1,2,4-triazolium iodides [61,62], where these interactions are interionic. We analyzed the CCDC data and identified 23 more structures with the C· · ·I interactions including 1,2,4-triazoles. 1,2,4-triazolium iodides [20,63–70] were also found in 15 structures. The C· · ·I–M interactions [71–76] in 1,2,4-triazole-containing MOFs were detected in 6 structures. Structure XIWGOC contains the C· · ·I <sup>−</sup> interactions between the cationic IrIII complex and iodide counterion [77]. Only in the IDIFEH structure was another example of the C· · ·I–C interactions between neutral isolated molecules [78] identified. The C· · ·I distances vary from 3.4363(2) to 3.670 (3) Å (for details see Table S2), and the C9· · ·I1S distance (3.528 (8) Å) in **ASZ**·1.5(**1,4-FIB**) is within this range.

Besides, possible lp(I)···π(C) interaction between **1,4-FIB** molecules was found (Figure 5). Although the C···I distance is around the vdW sum (3.686 (8) vs 3.68 Å), further theoretical calculations performed on experimentally determined atomic coordinates (see next section) confirmed the existence of the interaction and its noncovalent nature (estimated energy is 0.9–1.1 kcal/mol). Notably, the same interactions were found by us for **1,4-FIB** and other Besides, possible lp(I)· · · π(C) interaction between **1,4-FIB** molecules was found (Figure 5). Although the C· · · I distance is around the vdW sum (3.686 (8) vs 3.68 Å), further theoretical calculations performed on experimentally determined atomic coordinates (see next section) confirmed the existence of the interaction and its noncovalent nature (estimated energy is 0.9–1.1 kcal/mol). Notably, the same interactions were found by us for **1,4-FIB** and other iodofluorobenzenes [60,79,80].

**Figure 5.** The lp(I)···π(C) interaction between **1,4-FIB** molecules in **ASZ**·1.5(**1,4-FIB**).

iodofluorobenzenes [60,79,80].

*d*(C···I)/(RvdW(I) + RvdW(C)).

C9···I1S distance (3.528 (8) Å) in **ASZ**·1.5(**1,4-FIB**) is within this range.

**Figure 4.** The lp(I)···π(C) interaction between **ASZ** and **1,4-FIB** molecules in **ASZ**·1.5(**1,4-FIB**).

**Table 2.** Parameters of the lp(I)···π(C) interactions in **ASZ**·1.5(**1,4-FIB**).

**C···I–C** *d***(C···I), Å R***CI***<sup>b</sup>** ∠**(C···I–C),°**  C9···I1S–C1S 3.528 (8) 0.96 86.6(3) C9S···I2S–C4S 3.686 (8) 1.00 92.9(3) *Comparison a 3.68 1.00 90*  a Comparison is the vdW radii sum [42] for distances and classic XB acceptor angle. b R*CI* =

Previously, the lp(I)···π(C) interactions including 1,2,4-triazole moiety were discussed only for five 1,2,4-triazolium iodides [61,62], where these interactions are interionic. We analyzed the CCDC data and identified 23 more structures with the C···I interactions including 1,2,4-triazoles. 1,2,4-triazolium iodides [20,63–70] were also found in 15 structures. The C···I–M interactions [71–76] in 1,2,4-triazole-containing MOFs were detected in 6 structures. Structure XIWGOC contains the C···I– interactions between the cationic IrIII complex and iodide counterion [77]. Only in the IDIFEH structure was another example of the C···I–C interactions between neutral isolated molecules [78] identified. The C···I distances vary from 3.4363(2) to 3.670 (3) Å (for details see Table S2), and the

Besides, possible lp(I)···π(C) interaction between **1,4-FIB** molecules was found (Figure 5). Although the C···I distance is around the vdW sum (3.686 (8) vs 3.68 Å), further theoretical calculations performed on experimentally determined atomic coordinates (see next section) confirmed the existence of the interaction and its noncovalent nature (estimated energy is 0.9–1.1

**Figure 5.** The lp(I)···π(C) interaction between **1,4-FIB** molecules in **ASZ**·1.5(**1,4-FIB**). **Figure 5.** The lp(I)· · · π(C) interaction between **1,4-FIB** molecules in **ASZ**·1.5(**1,4-FIB**). *Crystals* **2020**, *10*, 371 6 of 13

*3.3. Hydrogen Bonding in ASZ*·*1.5(1,4-FIB) 3.3. Hydrogen Bonding in ASZ·1.5(1,4-FIB)* 

As well as in the structure of free **ASZ**, cyano N atoms are involved in weak hydrogen bonding (theoretically estimated strength of appropriate contacts vary from 0.9 to 1.9 kcal/mol) (Figure 6 and Table 3). Apart from methyl H atoms, the hydrogen atom in the methylene group is also an HB donor, which was not observed in the **ASZ** structure previously. As well as in the structure of free **ASZ**, cyano N atoms are involved in weak hydrogen bonding (theoretically estimated strength of appropriate contacts vary from 0.9 to 1.9 kcal/mol) (Figure 6 and Table 3). Apart from methyl H atoms, the hydrogen atom in the methylene group is also an HB donor, which was not observed in the **ASZ** structure previously.

**Figure 6.** The C–H···N HBs in **ASZ**·1.5(**1,4-FIB**). **Figure 6.** The C–H· · · N HBs in **ASZ**·1.5(**1,4-FIB**).


**Table 3.** Parameters of the C–H· · · N HBs in **ASZ**·1.5(**1,4-FIB**).

*Comparison a 2.75 1.00 3.25 110.0*  a Comparison is the vdW radii sum [42] for distances and minimal HB angle. b R*HN* = <sup>a</sup> Comparison is the vdW radii sum [42] for distances and minimal HB angle. <sup>b</sup> R*HN* = *d*(H· · · N)/(RvdW(H) + RvdW(N)).
