Crystallization of newly prepared copper­(II) clusters [Cu4X6O­(NCNMe2)4] (X = Cl 1 or Br 2) from toluene and styrene solutions afforded crystalline adducts 1·4PhMe, 1·4PhCHCH2, 2·4PhMe, and 2·4PhCHCH2, which were characterized by physicochemical methods including single-crystal X-ray diffraction. Inspection of the X-ray structures of (1–2)·4­(arene) and the appropriate Hirshfeld molecular surface analysis allowed the recognition of the previously unreported π-hole···arene interactions involving the cyanamide ligands. The presence of these interactions and their structure-directing character was confirmed theoretically by density functional theory calculations including molecular electrostatic potential, energy decomposition, and atoms-in-molecules analyses. The observed π-hole···π interaction between coordinated cyanamide and arene moieties in the adducts exhibits a contribution of π-hole···σ­(C–Haryl) interaction. Analysis of the Cambridge Structure Database revealed that the cyanamide···arene separations in the [Cu4X6O­(NCNMe2)4]­·4­(arene) systems are among the shortest found for all reported cyanamide structures.

Luminescent, heterometallic terbium(III)–lutetium(III) terephthalate metal-organic frameworks (MOFs) were synthesized via direct reaction between aqueous solutions of disodium terephthalate and nitrates of corresponding lanthanides by using two methods: synthesis from diluted and concentrated solutions. For (TbxLu1−x)2bdc3·nH2O MOFs (bdc = 1,4-benzenedicarboxylate) containing more than 30 at. % of Tb3+, only one crystalline phase was formed: Ln2bdc3·4H2O. At lower Tb3+ concentrations, MOFs crystallized as the mixture of Ln2bdc3·4H2O and Ln2bdc3·10H2O (diluted solutions) or Ln2bdc3 (concentrated solutions). All synthesized samples that contained Tb3+ ions demonstrated bright green luminescence upon excitation into the 1ππ* excited state of terephthalate ions. The photoluminescence quantum yields (PLQY) of the compounds corresponding to the Ln2bdc3 crystalline phase were significantly larger than for Ln2bdc3·4H2O and Ln2bdc3·10H2O phases due to absence of quenching from water molecules possessing high-energy O-H vibrational modes. One of the synthesized materials, namely, (Tb0.1Lu0.9)2bdc3·1.4H2O, had one of the highest PLQY among Tb-based MOFs, 95%.

Cocrystallization of CuI with NCNMe2 in the presence of 1,4-diiodotetrafluorobenzene (1,4-FIB) and 1,4-dibromotetrafluorobenzene (1,4-FBrB) in MeCN gave cocrystals [Cu4I4(NCNMe2)4]·1,4-FIB, [Cu4I4(NCNMe2)2(NCMe)2]·1,4-FIB, and [Cu4I4(NCNMe2)4]·1,4-FBrB, whose solid-state structures were studied by X-ray diffraction. In these three cases, the perfluorinated haloarenes function as combined σ- and π-hole donors, and their crystal structures exhibit intermolecular contacts, including halogen bonding (HaB) and π-hole interactions with the iodine ligands of the copper clusters. Analysis of the theoretical calculation data indicated that the formation of (cubane)·(perfluorinated haloarene) π–hole dimer is slightly energetically more favorable than (cubane)·(perfluorinated haloarene) HaB-based σ-hole dimer. The π-hole contacts and HaBs are accompanied by additional hydrogen bonding and also π-hole­(NCN)···X (X = Br, I) contacts. Altogether, these interactions lead to the occurrence of moderately strong noncovalent binding between copper clusters and the aromatic HaB donors.

The reaction in the system CuII/sacNa(H)/NCNR2 (sacNa(H) = sodium saccharinate (saccharin); R = Me, Et) results in the formation of the complexes [Cu(sac)2(NCNR2)(H2O)2] (R = Me 1, Et 2) instead of the expected products derived from the saccharin–cyanamide coupling. Complexes 1, 2, and hydrate 1·2H2O were characterized by IR, AAS (Cu%), TGA, and also by single-crystal X-ray diffraction for 1 and 1·2H2O. An integrated computational study of model structure 1 in the gas phase demonstrates that the Cu–Ncyanamide and Cu–Nsac coordination bonds exhibited a single bond character, polarized toward the N atom and almost purely electrostatic, with the calculated vertical total energies for the Cu–Ncyanamide and Cu–Nsac of 43.6 and 156.4 kcal/mol, respectively. These data confirmed that the copper(II) completely blocks the nucleophilic centers of ligands via coordination, thus preventing the saccharin–cyanamide coupling.

Co-crystallization of the push-pull nitriles NCNR2 (R2 = Me2 1, C4H8 2, C5H10 3, C4H8O 4) with iodo-substituted perfluorobenzenes (1,4-diiodotetrafluorobenzene – 1,4-FIB and 1,3,5-triiodotrifluorobenzene – 1,3,5-FIB), gave cocrystals 1·1,3,5-FIB, 2·1,3,5-FIB, 3·½(1,4-FIB), 4·½(1,4-FIB), and 4·2(1,3,5-FIB), which were studied by single-crystal X-ray diffractometry (XRD). The structure-directing I···sp-Nnitrile halogen bond (HaB) in all cocrystals was identified based on the consideration of the XRD geometrical (bond length and angles) parameters and also by Hirshfeld surface analysis, whereupon the observed HaBs were analyzed theoretically. The HaB accepting role of the push-pulling dialkylcyanamides NCNR2 and conventional nitriles NCR (R = Alk) was examined and compared in details using, as model examples, the structures of cocrystals 3·½(1,4-FIB) (this work) and AdCN·½(1,4-FIB) (CSD refcode: KIHROL). These two cocrystals, which display similar supramolecular organization, were studied by several quantum chemistry methods including molecular electrostatic potential (MEP) surface analysis, the natural bond orbital (NBO) analysis, the quantum theory of atoms in molecules (QTAIM) combined with and NCIPlot approach, and also by the Kitaura–Morokuma energy decomposition approach. While AdCN is slightly poorer sp-N electron donor than the push-pull nitrile 3, HaBs in the cocrystals exhibit similar interaction energies. Although in the covalent chemistry, the two types of nitriles often exhibit strikingly different reactivity patterns, the -hole based I···sp-Nnitrile noncovalent interaction provided the leveling effect resulting in significant similarities between the HaB situations for both nitrile species.