The theoretical data for the half‐lantern complexes [{Pt(trueCN^ )(μ‐trueSN^ )}2] [1–3; trueCN^ is cyclometalated 2‐Ph‐benzothiazole; trueSN^ is 2‐SH‐pyridine (1), 2‐SH‐benzoxazole (2), 2‐SH‐tetrafluorobenzothiazole (3)] indicate that the Pt⋅⋅⋅Pt orbital interaction increases the nucleophilicity of the outer dz2 orbitals to provide assembly with electrophilic species. Complexes 1–3 were co‐crystallized with bifunctional halogen bonding (XB) donors to give adducts (1–3)2⋅(1,4‐diiodotetrafluorobenzene) and infinite polymeric [1⋅1,1′‐diiodoperfluorodiphenyl]n. X‐ray crystallography revealed that the supramolecular assembly is achieved through (Aryl)I⋅⋅⋅dz2 [PtII] XBs between iodine σ‐holes and lone pairs of the positively charged (PtII)2 centers acting as nucleophilic sites. The polymer includes a curved linear chain ⋅⋅⋅Pt2⋅⋅⋅I(areneF)I⋅⋅⋅Pt2⋅⋅⋅ involving XB between iodine atoms of the perfluoroarene linkers and (PtII)2 moieties. The 195Pt NMR, UV/Vis, and CV studies indicate that XB is preserved in CH(D)2Cl2 solutions.

Platinum(II) complexes exhibiting an expressed d z 2 -nucleophilicity of the positively charged metal centers, namely, [Pt(ppy)(acac)] (1; acacH is acetylacetone; ppyH is 2-Ph-pyridine) and [Pt(ppy)(tmhd)] (2; tmhdH is 2,2,6,6-tetramethylheptanedione-3,5), were cocrystallized with the chalcogen bond donors (4-NC 5 F 4 ) 2 Ch (Ch = Se, Te) to form two isostructural cocrystals 1• 1 / 2 (4-NC 5 F 4 ) 2 Ch, and 2• 2 / 3 (4-NC 5 F 4 ) 2 Se and 2• (4-NC 5 F 4 ) 2 Te. The X-ray data for these cocrystals and appropriate theoretical DFT calculations (PBE0-D3BJ) allowed the recognition of the metal-involving chalcogen bond, namely, Ch•••d z 2 -Pt II (its energy spans from −7 to −12 kcal/ mol). In 1• 1 / 2 (4-NC 5 F 4 ) 2 Ch, Ch•••d z 2 -Pt II bonding is accompanied by the C••• d z 2 -Pt II interaction, representing a three-center bifurcate, whereas in 2•(4-NC 5 F 4 ) 2 Te the chalcogen bond Te•••d z 2 -Pt II is purely two-centered and is stronger than that in 1• 1 / 2 (4-NC 5 F 4 ) 2 Ch because of more efficient orbital overlap. The association of 2 with (4-NC 5 F 4 ) 2 Te and the structure of the formed adduct in CDCl 3 solutions was studied by using 1 H, 13 C, 19 F, 195 Pt, 125 Te NMR, 19 F− 1 H HOESY, and diffusion NMR methods. The 195 Pt and 125 Te NMR titration and the isothermal titration calorimetry results revealed a 1:1 association of 2 with (4-NC 5 F 4 ) 2 Te.

The half-lantern PdII 2 complexes trans-(O,C)-[Pd­(ppz)­(μ-O∩N)]2 (1) and trans-(E,N)-[Pd­(ppz)­(μ-E∩N)]2 (E∩N is a deprotonated 2-substituted pyridine; E = S (2), Se (3); Hppz = 1-phenylpyrazole) were cocrystallized with 1,4-diiodotetrafluorobenzene (FIB) to give cocrystals 1·(FIB) and (2−3)·2­(FIB); the parent complexes and the cocrystals were studied by X-ray crystallography. The crystal structure of trans-(O,C)-1·FIB is assembled mainly by the I···O halogen bonding (XB) to give the [@PdII 2]­O···I­(areneF)­I···O­[@PdII 2] linkage, while trans-(E,N)-(2–3)·2­(FIB) are built by the joint action of I···Pd and I···E XBs, thus furnishing the PdII 2···I­(areneF)­I···E­[@PdII 2] (E = S, Se) cluster. Detailed theoretical (DFT) studies with the application of the QTAIM, ELF, NBO, IGM, SAPT, and HSAB methods revealed several types of attractive noncovalent interactions in the cocrystals, namely, the I···Pd, I···E (E = O, S, Se), I···C, π–π-stacking, and π···F interactions. I···Pd is a rare type of XB involving the metal center as an XB acceptor, the Pd···Pd communication facilitating the I···Pd bonding. The I···Pd and I···E bonds are comparable in strength (the bond interaction energies being between −7 and −13 kcal/mol), but the former is controlled by dispersion forces, while the latter is mostly governed by an electrostatic term.

A new application for bis­(cyclometalated) iridium­(III) species containing ancillary acyclic diaminocarbene ligands, viz. for sensing of mercury­(II) ions, is disclosed. A family of bis­(cyclometalated) iridium­(III) species supported by both parent isocyanide and acyclic diaminocarbene ligands was prepared, and their electrochemical and photophysical properties were evaluated, revealing efficient blue-green phosphorescence in solution with quantum yields of up to 55%. We uncovered that the photophysical properties of these complexes are dramatically altered by the presence of metal ions and that the complex [Ir­(ppy)2(CN)­{C­(NH2)­(NHC6H4-4-X)}] with an ADC ligand reacts selectively with Hg2+ ions, enabling its use for sensing of mercury­(II) ions in solution. The limit of detection was as low as 2.63 × 10–7 M, and additional mechanistic studies indicated the formation of an unusual dinuclear iridium­(III) cyclometalated intermediate, bridged by a mercury dicyano fragment as a driving force of mercury sensing.

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