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Figure 10
Geometrical representation of X⋯X halogen bonds (X = Cl/Br/I) (a) for a single interaction (ζ1 ≃ 180°, ζ2 ≃ 90°) and (b) within a triangular X3 synthon (ζ1 ≃ 180°, ζ2 ≃ 120°). (c) Ch⋯Ch chalcogen bonds (Ch = S/Se/Te) shown within a triangular Ch3 synthon. Δζ is expected at roughly 90 and 60° in (a) and (b), whereas in (c) it is difficult to estimate due to the presence of multiple δ+/δ− sites in Chsp3 atoms [see Fig. 4[link](a)]. CSD searches for X3 and Ch3 synthons [ R33(3) motifs] involve the following criteria: distances X⋯X and Ch⋯Ch ≤ sum (vdW) + 0.4 Å, and angles ∠C—X⋯X and ∠C—Ch⋯Ch within the ranges 100–180° and 60–180°, respectively. X-atom vdW radii = 1.75, 1.85 and 1.98 Å for Cl, Br and I, respectively. Ch-atom vdW radii = 1.80, 1.90 and 2.06 Å for S, Se and Te, respectively.

IUCrJ
Volume 12| Part 3| May 2025|
ISSN: 2052-2525
https://doi.org/10.1107/S2052252525001447