Iodopentafluorobenzene (IPFB or Ph^FI) was co-crystallized with tetra(n-butyl)ammonium tetraiodo-μ,μ′-diiododiplatinate(II), [n-Bu₄N]₂[Pt₂(μ-I₂)I₄] (1), to give the adduct 1·2IPFB. The XRD experiment revealed that 1·2IPFB displays previously unreported C⋯I–Pt anion–π interactions formed along with the expected Ph^F–I⋯I–Pt^II halogen bond (XB); these two interactions join two complexes and two IPFBs in a heterotetrameric cluster. Processing of the available CSD data revealed only one structure (CSD code: IKIYAE) with a heterotetrameric cluster bearing simultaneous two Ph^F–I⋯X (X = I–Pt^IV, N) XBs and C⋯I lp(I)–π contacts between the two IPFBs. Results of the DFT calculations (M06/DZP-DKH level of theory) followed by the topological analysis of the electron density distribution within the framework of Bader's approach (QTAIM) for both 1·2IPFB and IKIYAE confirmed the availability of these (anion/lp)–π weak interactions. The estimated energies of the observed (anion/lp)–π and XBs contacts are in the 0.9–1.3 kcal mol⁻¹ and 1.3–5.3 kcal mol⁻¹ ranges, respectively. π-Hole donor ability of IPFB was additionally confirmed by theoretical calculations of the molecular surface electrostatic potential for the optimized equilibrium structure of IPFB.

By performing combined XRD and theoretical studies, we established the modes of R^EWGI⋯I–Pt XBs with [Pt₂(μ-I)₂I₄]²⁻acting as an XB acceptor.

Co-crystallization of dithiocarbamate complexes [M^II(S₂CNEt₂)₂] (M = Cu 1, Ni 2, Pd 3, Pt 4) and 1,3,5-triiodotrifluorobenzene (FIB) gives an isomorphic series of (1–4)·2FIB co-crystals exhibiting quadruple Cu/Ni/Pd/Pt isostructural exchange. In the structures of (1–4)·2FIB, the halogen-bonded C–I⋯M (Ni, Pd, Pt) and semicoordination M⋯I–C (Cu) metal-involving contacts were identified by X-ray diffractometry and their nature was verified theoretically. The directionality of the I_σ-hole⋯d² _zM^II and M^II⋯I_{electron belt} interactions depends on the identity of a metal center: on going from a rather electrophilic Cu^II to substantially more nucleophilic Ni^II, Pd^II, and Pt^II centers, we observed the electron belt-to-σ-hole switch of a noncovalently bound iodine(I) of FIB and, correspondingly, its shift from semicoordination to halogen bonding. The negative values of the electrostatic potentials (given in parentheses) were estimated for all metal centers and they decrease in the order Cu^II (−8.8) > Ni^II (−24.5) > Pd^II (−28.6) > Pt^II (−33.3 kcal mol⁻¹). Despite the negative potentials at all M^IIs, the semicoordinative contact Cu⋯I was established by the recognition of the LP(I) → LP*(Cu) charge transfer using natural bond orbital (NBO) analysis and the comparison of electron density (ED) and electrostatic potential (ESP) minima positions along the I⋯Cu bond paths. In the case of the rather nucleophilic (although positively charged) Pd^II and Pt^II centers, the contacts C–I⋯d² _z[Pd] and C–I⋯d² _z[Pt] can be attributed to the unconventional metal-involving halogen bonding; these contacts are among the strongest (4.30 and 5.42 kcal mol⁻¹, correspondingly) between any metal center and iodine(I)-based σ-hole donors.

The complexes [RhX(COD)]₂ (X = Cl, Br; COD = 1,5-cyclooctadiene) form cocrystals with σ-hole iodine donors. X-ray diffraction studies and extensive theoretical considerations indicate that the d_z²-orbitals of two positively charged rhodium(I) centers provide sufficient nucleophilicity to form a three-center halogen bond (XB) with the σ-hole donors. The two metal centers function as an integrated XB acceptor, providing assembly via a metal-involving XB.

In the X-ray structures of the 1 : 1 adduct of [Ph₃PNPPh₃]₂[PtCl₄] with 1,4-diiodotetrafluorobenzene (1·FIB) and the salt [Ph₃PCH₂I]₂[PtCl₄] (2), the tetrachloroplatinate(II) anion behaves as a halogen bond (XB)-accepting tecton toward σ-hole-donating organohalogen species to form either C–I⋯Cl–PtCl₂–Cl⋯I–C or C–I⋯Cl–PtCl₃ moieties, respectively. All XB contacts are clearly observed on the Hirshfeld surfaces; in addition, intermolecular contacts are visualized using noncovalent interactions (NCI) analysis. The steric factor and the number of XB donor centers play important roles in the supramolecular organization of compounds 1·FIB and 2: the bifunctional FIB with two σ-hole donor centers forms an extended structure, including the bridging [PtCl₄]²⁻, whereas the [Ph₃PCH₂I]⁺ cation with a σ-hole donor center in a sterically encumbered environment forms only one terminal XB with [PtCl₄]²⁻. The results of DFT calculations followed by topological analysis of the electron density distribution within the framework of the QTAIM method at the ωB97XD/DZP-DKH level of theory reveal that the energies of the attractive intermolecular noncovalent interactions are 6.3–6.4 kcal mol⁻¹ for compound 1·FIB and 2.6–2.9 kcal mol⁻¹ for compound 2.