The complexes [Pt(tpp)] (H2tpp=tetraphenylporphyrin), [M(acac)2] (M=Pd, Pt, Hacac=acetylacetone), and [Pd(ba)2] (Hba=benzoylacetone) were co‐crystallized with highly electron‐deficient arene systems to form reverse arene sandwich structures built by π‐hole⋅⋅⋅[MII] (d8M=Pt, Pd) interactions. The adduct [Pt(tpp)]⋅2 C6F6 is monomeric, whereas the diketonate 1:1 adducts form columnar infinity 1D‐stack assembled by simultaneous action of both π‐hole⋅⋅⋅[MII] and C⋅⋅⋅F interactions. The reverse sandwiches are based on noncovalent interactions and calculated ESP distributions indicate that in π‐hole⋅⋅⋅[MII] contacts, [MII] plays the role of a nucleophile.

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 complexes [MII(acac)2] (M = Cu 1, Pd 2, Pt 3; Hacac = acetylacetone) and 1,4-diiodotetrafluorobenzene (FIB) were cocrystallized in CHCl3–MeOH solutions to form adducts (1–3)·FIB, whose structures were studied by X-ray diffraction. The association leads to unification of the three structures, thus demonstrating the potential of the isostructural Cu/Pd/Pt exchange for construction of supramolecular systems involving [MII(acac)2] complexes. In the crystal structures of (1–3)·FIB, the intermolecular bifurcated halogen bonding I···μ2-(O,O) and noncovalent interactions M···C were identified and then studied by density functional theory calculations and topological analysis of the electron density distribution within the framework of the QTAIM method at the M06/DZP-DKH level of theory. Apart from these unconventional interactions, two types of classic hydrogen bonding, viz. the C–H···I–C and C–H···F–C contacts between Me groups and halogen atoms of FIB, were detected. Collectively all these noncovalent structure-directing interactions provide conversion of one-dimensional arrays of the [MII(acac)2] species into three-dimensional networks.

Two phosphorescent Pt II -based cyclometalated complexes were cocrystallized with perfluorinated arenes to give 1:1 co-crystals. The X-ray study revealed that each of the complexes is embraced by arenes F to give infinite reverse sandwich structures. In four out of six structures, a d z 2 orbital of Pt II is directed to the arenes F ring via π-hole•••d z 2 [Pt II ] interactions, whereas in the other two structures, the filled d z 2 orbital is directed toward the arene C atoms. Computed molecular electrostatic potential surfaces of the arenes F and the complexes, noncovalent interaction indexes for the co-crystals, and natural bond orbital calculations indicate that π-hole•••d z 2 [Pt II ] contacts (and, generally, the stacking) are of electrostatic origin. The solid-state photophysical study revealed up to 3.5-fold luminescence quantum yield and 15-fold lifetime enhancements in the co-crystals. This increase is associated with the strength of the π-hole•••d z 2 [Pt II ] contact that is dependent on the π-acidity of the arene F and its spatial characteristics.

respectively) were cocrystallized with the metal acetylacetonates [M(acac) 2 ] (M = Pd (1), Pt (2)) to give the three adducts 1•2BNPN, 2• 2BNPN, and 1•2INPN, exhibiting reverse arene sandwich solid-state structures. The inspection of the XRD data for the adducts revealed new types of (lone pairBr) bifurcated halogen bonds (XBs) along with some other types of short contacts were recognized. The XRD experiments were supported by Hirshfeld surface analysis and DFT calculations: i.e., topological analysis of the electron density distribution within the framework of the QTAIM method at the ωB97XD/DZP-DKH level of theory. Estimated energies of all studied noncovalent contacts vary from 0.6 to 3.8 kcal/ mol. Article pubs.acs.org/crystal