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The series of benzylic-substituted 1,2,4-selenodiazolium salts were prepared via cyclization reaction between 2-pyridylselenyl chlorides and nitriles and fully characterized. Substitution of the Cl anion by weakly binding anions promoted the formation supramolecular dimers featuring four center Se 2 N 2 chalcogen bonding and two antiparallel selenium⋯π interactions. Chalcogen bonding interactions were studied using density functional theory calculations, molecular electrostatic potential (MEP) surfaces, the quantum theory of atoms-in-molecules (QTAIM), and the noncovalent interaction (NCI) plot. The investigations revealed fundamental role of the selenium⋯π contacts that are stronger than the Se⋯N interactions in supramolecular dimers. Importantly, described herein, the benzylic substitution approach can be utilized for reliable supramolecular dimerization of selenodiazolium cations in the solid state, which can be employed in supramolecular engineering.

In this study we propose to coin the term Wolfium bond (WfB) to refer to a net attractive force (noncovalent interaction) between any element of group 6 and electron donor atoms (neutral molecules or anions) and to differentiate it from a coordination bond (metal-ligand interaction). We provide evidence of the existence of this interaction by inspecting the X-ray crystal structure of proteins containing Molybdopterin and Tungstopterin cofactors from the Protein Data Bank (PDB). The plausible biological role of the interaction as well as its physical nature (antibonding Wf-Ligand orbital involved) are also analyzed by means of ab initio calculations (RI-MP2/def2-TZVP level of theory), Atoms in Molecules (AIM), Natural Bond Orbital (NBO) and Noncovalent Interactions plot (NCIplot) analyses., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Cocrystallization of a bis[1-(4-pyridyl)butane-1,3-dionato]copper(II) (1) complex and 1,4-diiodoperfluorobenzene in the presence of pyridine yields a 1 : 1 cocrystal where both the σ and π-holes of 1,4-diiodoperfluorobenzene play a role. The crystal structure shows short arene CuO 4 ⋯π-hole stacking contacts, where the {d z 2 -Cu II O 4 } moiety functions as an integrated five-center π-hole acceptor. DFT calculations combined with quantum theory of atoms-in-molecules and noncovalent interaction plot analyses corroborated the structure-defining role of the {d z 2 -Cu II O 4 }⋯π-hole contacts.

In this manuscript, three examples retrieved from the PDB are selected to demonstrate the existence and relevance of spodium bonding (SpB) in biological systems. SpB is defined as an attractive noncovalent interaction between elements of group 12 of the periodic table acting as a Lewis acid and any atom or group of atoms acting as an electron donor. The utilization of this term (SpB) is convenient to differentiate classical coordination bonds from noncovalent interactions. In the latter, the distance between the electron rich and the spodium atoms is longer than the sum of the covalent radii but shorter than the sum of the van der Waals radii. In most Zn-dependent metalloenzymes, the spodium atom is bonded to three imidazole moieties belonging to the side chains of histidine amino-acids. Herein, in addition to the investigation of the SpB in the active site of three exemplifying enzymes, theoretical models where the Zn(ii) atom is bonded either to three imidazole or triazole ligands are used in order to investigate the strength of the SpB and its competition with hydrogen bonding. A series of Lewis bases and anions have been used as SpB acceptors combined with six SpB donors (receptors) of general formula [ZnY3X]+ (Y = imidazole and triazole and X = Cl, N3 and SCH3). In addition to the investigation of the energetic and geometric features of the complexes, the SpB interactions have been further characterized using the natural bond orbital (NBO) method, quantum theory of "atoms-in-molecules" and the noncovalent interaction plot (NCI plot).

H‐selenite anions (HSeO3−) form in the solid unprecedented anionic supramolecular chains wherein single units are assembled via alternating short Se⋅⋅⋅O and H⋅⋅⋅O contacts. Crystallographic analyses and computational studies (the quantum theory of "atoms‐in‐molecules", QTAIM, and the noncovalent interaction plot, NCIPlot) consistently prove the attractive nature of these chalcogen bonds (ChBs) and hydrogen honds (HBs), the Janus‐type character of HSeO3− anions which act as both donors and acceptors of ChB and HB, and the possible stability of anion dimers in solution. The effectiveness of the ChBs herein described may lead to consider the HSeO3− moiety as a new entry in the toolbox of crystal engineering based on ChB. [ABSTRACT FROM AUTHOR]

Combining computations and X-ray structure analysis we have demonstrated that [Pt(CN4)]2− can behave as a Lewis acid inside an enzyme's cavity. The nature of a counterintuitive contact found between a catalytically active GLN residue belonging to a mitochondrial synthase and the Pt(II) center was investigated by combining molecular dynamics and quantum mechanics calculations. Results confirm the electron acceptor role of [Pt(CN4)]2−, serving as an inspiration for the design of biomolecular cages able to tweak the nucleophilic/electrophilic character of an organometallic compound. [ABSTRACT FROM AUTHOR]

Combining computations and X-ray structure analysis we have demonstrated that [Pt(CN4)]2− can behave as a Lewis acid inside an enzyme's cavity. The nature of a counterintuitive contact found between a catalytically active GLN residue belonging to a mitochondrial synthase and the Pt(II) center was investigated by combining molecular dynamics and quantum mechanics calculations. Results confirm the electron acceptor role of [Pt(CN4)]2−, serving as an inspiration for the design of biomolecular cages able to tweak the nucleophilic/electrophilic character of an organometallic compound. [ABSTRACT FROM AUTHOR]

We report the crystal structure of the anhydrous form of Oxyma-B, a relevant racemization suppressor for peptide synthesis, solved by direct space methodologies with X-Ray Powder Diffraction data. The structure had remained elusive since only monohydrate crystals are readily obtained from slow crystal growth experiments. An extensive combined experimental and computational study has allowed us to obtain deeper insight into the solid-state landscape of Oxyma-B and its tendency for hydration. The singular network of H-bonds and energetically relevant O⋯π interactions formed by the two symmetrically independent molecules of anhydrous Oxyma-B has been analysed by using the quantum theory of "atoms-in-molecules" (QTAIM) and the noncovalent interaction plot (NCIplot). [ABSTRACT FROM AUTHOR]

Reactions in water between the Cu2(µ-EGTA) chelate (EGTA = ethylene-bis(oxyethyleneimino)tetraacetate(4-) ion) and Hdap in molar ratios 1:1 and 1:2 yield only blue crystals of the ternary compound [Cu4(μ-EGTA)2(μ-H(N3)dap)2(H2O)2]·7H2O (1), which has been studied via single-crystal X-ray diffraction and various physical methods (thermal stability, spectral and magnetic properties), as well as DFT theoretical calculations. In the crystal, uncoordinated water is disordered. The tetranuclear complex molecule also has some irrelevant disorder in an EGTA-ethylene moiety. In the complex molecule, both bridging organic molecules act as binucleating ligands. There are two distorted five- and two six-coordinated Cu(II) centers. Each half of EGTA acts as a tripodal tetradentate Cu(II) chelator, with a mer-NO2 + O(ether, distal) conformation. Hdap exhibits the tautomer H(N3)dap, with the dissociable H-atom on its less basic N-heterocyclic atom. These features favor the efficient cooperation between Cu-N7 or Cu-N9 bonds with appropriate O-EGTA atoms, as N6-H···O or N3-H···O interligand interactions, respectively. The bridging role of both organics determines the tetranuclear dimensionality of the complex. In this crystal, such molecules associate in zig-zag chains built by alternating π–π interactions between the five- or six-atom rings of Hdap ligands of adjacent molecules. DFT theoretical calculations (using two different theoretical models and characterized by the quantum theory of "atoms in molecules") reveal the importance of these π–π interactions between Hdap ligands, as well as those corresponding to the referred hydrogen bonds in the contributed tetranuclear molecule. [ABSTRACT FROM AUTHOR]

Thallium compounds, i.e. Tl+[S2P{OC6H3(2,5-(CH3)2)}2]− (1) and Tl+[S2P{OC6H3(3,5-(CH3)2)}2]− (2), stabilized by intra- and intermolecular triel bonds were isolated and characterized by FT-IR, NMR (31P, 1H and 13C) spectroscopy, and SC-XRD analysis. The crystal structures of 1 and 2 belong to monoclinic crystal systems with the space group C2/c and P21/n, respectively. Interestingly, the positively charged Tl atom is bonded attractively with the π-holes of the 1,1-dithioate moiety. These compounds exist in ionic form and exhibit Tl⋯S and Tl⋯π contacts (TrBs), which assist the formation of unique supramolecular polymeric architectures owing to the stereochemically active lone pair of electrons and hemi-directed coordination sphere around thallium. A differentiating feature in compound 2 is the formation of a unique Tl⋯π/π⋯π/Tl⋯π self-assembly. The attractive nature of TrB was further confirmed by DFT calculations using the quantum theory of atoms-in-molecules (QTAIM) and non-covalent interaction plot (NCIPlot) index methods. A systematic Hirshfeld surfaces analysis was also carried out to compare the intermolecular interactions. [ABSTRACT FROM AUTHOR]

In this manuscript we report the preparation of four new zinc complexes, [{(μ-CH3COO)ZnL1}2Zn]·2DMSO (1), [{(DMF)ZnL1(μ-CH3COO)ZnL1Zn(N3)}]·0.64DMSO·0.36EtOH (2), [(μ-CH3COO)2Zn2L1]n(3) and [Zn2L2Cl2] (4), and their characterization by elemental and spectral analyses, where H2L1 is 1,3-propanediylbis(iminomethylene)bis(4-chlorophenol) and H2L2 is 1,3-propanediylbis(iminomethylene)bis(6-methoxyphenol). The structures have been confirmed by single crystal X-ray diffraction analysis. The synthetic strategy for complexes 1 and 2 involves the use of drops of DMSO, which is essential to stabilize the crystals of 1 and 2, respectively, indicating the importance of DMSO in the stabilization of the complexes. A thorough DFT calculation using the quantum theory of atoms-in-molecules and the non-covalent interaction plot (NCI plot) indicates the formation of strong H-bonds, CH⋯π and ancillary SpBs in complexes 1 and 2. DMSO has not been added during the synthesis of complexes 3 and 4, where no spodium bonds have been observed. Strong self-assembled (π–π stacked or H-bonded) dimers have been found in the solid state structures of 3 and 4. [ABSTRACT FROM AUTHOR]

Two multi-component coordination compounds of Mn(II), viz. [Mn(H2O)6](2-Mepy)2(4-NO2bz)2·2H2O (1) and [Mn(H2O)6][Mn(2,3-PDCH)3]2 (2) (where, 2-Mepy = 2-methylpyridine, 4-NO2bz = 4-nitrobenzoate, 2,3-PDC = 2,3-pyridinedicarboxylate), have been synthesized and characterized using elemental, spectroscopic (FT-IR and electronic), TGA and single-crystal X-ray diffraction analyses. Complex 1 is a co-crystal hydrate of Mn(II) involving uncoordinated 2-Mepy, 4-NO2bz and water molecules; while compound 2 is a multi-component molecular complex salt of Mn(II) comprising cationic [Mn(H2O)6]2+ and anionic [Mn(2,3-PDCH)3]−complex moieties. The uncoordinated 2-Mepy and 4-NO2bz moieties of 1 are involved in lone-pair (l.p)-π and C–H⋯π interactions which stabilize the layered assembly of the compound. The crystal structure of compound 2 has been previously reported. However, we have explored the unusual enclathration of complex cationic moieties within the supramolecular host cavities formed by the molecular assembly of complex anionic moieties. The supramolecular assemblies obtained in the crystal structure have been further studied theoretically using DFT calculations, quantum theory of atoms-in-molecules (QTAIM) and non-covalent interaction plot (NCI plot) computational tools. Theoretical studies reveal that the combination of π-staking interactions (l.p-π, π-π and C–H···π) have more structure-guiding roles compared to the H-bonds. The large binding energy of π-stacking interactions in 2 is due to the antiparallel orientation of aromatic rings and their coordination to the metal centers, thereby increasing the contribution of the dipole–dipole interactions. [ABSTRACT FROM AUTHOR]

The relevance of hydrogen‐bonding, π‐π stacking and aurophilic interactions in the solid‐state of two new heterobimetallic (AuI−MnII) complexes is analyzed in this manuscript. They are discrete complexes of formulae [Mn(bipy)2(H2O){Au(CN)2}][Au(CN)2] and [Mn(dmbipy)2{Au(CN)2}] ⋅ H2O, (bipy=2,2′‐bipyridine and dmbipy=5,5′‐dimethyl‐2,2′‐bipyridine), which are based on dicyanidoaurate(I) groups and 2,2′‐bipyridyl‐like co‐ligands. They have been synthesized in good yields and X‐ray characterized. In both compounds, aurophilic, OH⋅⋅⋅N hydrogen bonding and π‐π interactions governed the supramolecular assemblies in the solid state. These contacts with special emphasis on the aurophilic interactions have been studied using density functional theory calculations and characterized using the quantum theory of atoms‐in‐molecules and the noncovalent interaction plot. The aurophilic contacts have been also rationalized from an orbital point of view using the natural bond orbital methodology, evidencing stabilization energies up to 5.7 kcal/mol. Moreover, the interaction energies have been decomposed using the Kitaura‐Morokuma energy decomposition analysis, confirming the importance of electrostatic and orbital effects. [ABSTRACT FROM AUTHOR]

Unraveling the binding preferences involved in the formation of a supramolecular complex is key to properly understand molecular recognition and aggregation phenomena, which are of pivotal importance to biology. The halogenation of nucleic acids has been routinely carried out for decades to assist in their X-ray diffraction analysis. The incorporation of a halogen atom on a DNA/RNA base not only affected its electronic distribution, but also expanded the noncovalent interactions toolbox beyond the classical hydrogen bond (HB) by incorporating the halogen bond (HalB). In this regard, an inspection of the Protein Data Bank (PDB) revealed 187 structures involving halogenated nucleic acids (either unbound or bound to a protein) where at least 1 base pair (BP) exhibited halogenation. Herein, we were interested in disclosing the strength and binding preferences of halogenated A···U and G···C BPs, which are predominant in halogenated nucleic acids. To achieve that, computations at the RI-MP2/def2-TZVP level of theory together with state of the art theoretical modeling tools (including the computation of molecular electrostatic potential (MEP) surfaces, the quantum theory of "Atoms in Molecules" (QTAIM) and the non-covalent interactions plot (NCIplot) analyses) allowed for the characterization of the HB and HalB complexes studied herein. [ABSTRACT FROM AUTHOR]

The series of substituted 1,2,4-selenodiazolium tetraphenylborate complexes were synthesized via cyclization between 2-pyridylselenylchloride, followed by the anion metathesis, and fully characterized. The utilization of tetraphenylborate anion, a strong π-electron donor via its phenyl rings, promoted the formation of assemblies exhibiting selenium–π interactions. The chalcogen bonding (ChB) interactions involving the π-systems of the tetraphenylborate anion were studied using density functional theory (DFT) calculations, where "mutated" anions were used to estimate the strength of the Se···π chalcogen bonds. Moreover, molecular electrostatic potential (MEP) surfaces were used to investigate the electron-rich and poor regions of the ion pairs. The quantum theory of atoms-in-molecules (QTAIM) and the noncovalent interaction (NCI) plot methods based on the topology of the electron density were used and combined to characterize the ChBs. The investigation reported herein disclosed that the formation of symmetrical dimers can be broken by the introduction of a stronger π-acceptor and, consequently, forming stronger Se···π contacts with selenodiazolium cations. [ABSTRACT FROM AUTHOR]

Three coordination complexes {[Cu(pydco)(pz)0.5(H2O)]·H2O}n (1), [Cu(pydco)(phen)(H2O)]·2H2O (2), and [Zn2(pydco)(phen)2Cl2]·2H2O (3) have been synthesized at room temperature using a mixed-ligand system including pyridine-2,6-dicarboxylic acid N-oxide (H2pydco) as O-donor as well as pyrazine (pz) and 1,10-phenanthroline (phen) as N,N′-bidentate donors. Single-crystal X-ray diffraction (XRD) revealed that 1 forms a 1D-coordination polymer through bridging pz units while 2 and 3 form discrete complexes in which endo-bidentate phen can only connect with one metal centre via a five-membered chelate ring. Also, pydco2− can form a six-membered chelate ring around the metal ion via the N-oxide oxygen and one carboxylate oxygen. However, another carboxylate group of this ligand can also participate in the coordination and create unique structures in 1 and 3. Subsequently, 1–3 can expand their structures into 2D-supramolecular networks through π⋯π stacking or H-bonding interactions. Recurrent π⋯π stacking motifs in all compounds have been further analyzed energetically using DFT calculations and characterized using the quantum theory of "atoms-in-molecules" (QTAIM) and noncovalent interaction plot (NCIPlot) index computational tools. In compound 3, cooperativity effects in π⋯π/π⋯π/π⋯π assemblies have been also analyzed. [ABSTRACT FROM AUTHOR]

This manuscript reports the synthesis, X-ray characterization and DFT study of a series of all-cis 3a,6 : 4,5 : 7,9a-triepoxy and 3a,6 : 7,9a-diepoxybenzo[de]isoquinolines obtained by the tandem intramolecular [4 + 2]/[4 + 2] cycloaddition in bis-furans (the IMDAF reaction) between difurfurylamine derivatives and dimethyl acetylenedicarboxylate (DMAD) as a dienophile. In one compound instead of DMAD, 1-phenyl-1H-pyrrole-2,5-dione (N-phenylmaleimide) was used as a dienophile. The existence of a "through-space" alpha-effect is analyzed in these compounds, since in three of them N–H⋯O2 H-bonds are observed in the solid state promoting the formation of self-assembled dimers. That is, the close O⋯O distance between the O-bridge atoms due to the rigidity of these molecules causes a lone pair⋯lone pair (LP⋯LP) interaction that enhances the H-bond acceptor ability of the bridging atoms (through-space α-effect). This fact has been studied using DFT calculations, molecular electrostatic potential (MEP) surfaces, electron localization function (ELF), quantum theory of atoms-in-molecules (QTAIM) and noncovalent interaction plot (NCIplot) index computational tools. This is the third study of the literature where "α-effect" hydrogen bonds (AEHBs) are described. The novelty of the present work resides in the utilization of an amine linker between the furan rings that allows the incorporation of a good H-bond donor in the model system. As a result, NH⋯O2 instead of CH⋯O2 AEHBs described in previous works are established. The X-ray analyses of the synthesized di- and tri-epoxides reveal that the AEHBs are predominant in the X-ray architecture of these compounds. [ABSTRACT FROM AUTHOR]

Cocrystallization of a bis[1-(4-pyridyl)butane-1,3-dionato]copper(II) (1) complex and 1,4-diiodoperfluorobenzene in the presence of pyridine yields a 1 : 1 cocrystal where both the σ and π-holes of 1,4-diiodoperfluorobenzene play a role. The crystal structure shows short arene CuO4⋯π-hole stacking contacts, where the {dz2-CuIIO4} moiety functions as an integrated five-center π-hole acceptor. DFT calculations combined with quantum theory of atoms-in-molecules and noncovalent interaction plot analyses corroborated the structure-defining role of the {dz2-CuIIO4}⋯π-hole contacts. [ABSTRACT FROM AUTHOR]

The crystal structure of a new zonisamide cocrystal, an anticonvulsant drug used to treat the symptoms of epilepsy and Parkinson's disease, with ϵ-caprolactam is reported herein. The structure has been solved by direct space methodologies from powder X-ray diffraction data. The refinement of the structure was conducted by the Rietveld method assisted by the dispersion-corrected density-functional theory (D-DFT) calculations and periodic boundary conditions. Further analysis of the structure reveals several H-bonded synthons and self–assembled dimers that have been further analyzed by DFT calculations and other computational tools such as molecular electrostatic potential (MEP) surfaces and the quantum theory of "atom-in-molecules" (QTAIM). [ABSTRACT FROM AUTHOR]

This work reports a combined computational and experimental analysis of the crystal structure of the cancer drug tipiracil hydrochloride in the form of a methanol solvate–hydrate (4 : 1 : 3, molar ratio). The crystal structure shows a complex network of H-bonds with static discrete disorder in two out of the three symmetry-independent solvent molecules, which has been studied by means of DVS and TGA techniques. MEP surface calculations shows a region of positive potential (σ-hole) along the C–Cl bond, which induces the formation of Cl⋯O contacts that are relevant in the crystal packing. The hydrogen and halogen bonding assemblies were further analyzed using density functional theory (DFT), the quantum theory of "atom-in-molecules" (QTAIM) and the noncovalent interaction plot (NCIplot). [ABSTRACT FROM AUTHOR]

This manuscript reports four new gold(I)--silver(I) complexes with 2-(2-pyridyl)-1,8-naphthyridine (pyNP) and terpyridine (terpy) as ancillary ligands, having formulae [Ag(pyNP)(Au(CN)2)]2 (1), [Ag2Au2(μ-CN)2(CN)2(pyNP)2] (2), [Ag2Au(μ-CN)2(terpy)2][Au(CN)2] (3) and [Ag4Au4(μ-CN)8(terpy)2( py)] (4). Complexes 1 and 2 are structural isomers obtained from different solvents. The Au(CN)2 -- anion is not coordinated and establishes intramolecular Au---Ag,Ag interactions in 1. In contrast, it is monocoordinated to silver atoms via a CN fragment in compound 2 and no metallophilic interaction is observed. In compound 3, one Au(CN)2 anion bridges two Ag(terpy) fragments. In this complex an infinite array of gold atoms is found, exhibiting aurophilic interactions of 3.415 Å. In complex 4 the 3D architecture observed in the crystal packing is driven by Au---Au and Au---Ag metallophilic interactions. All compounds have been structurally and vibrationally characterized to better understand the crystal forces. In addition, a solution chemistry study in different solvents by ESI-MS spectrometry was performed to comprehend the speciation and solvent effects. Finally, DFT calculations were carried out to analyze the Ag---Au interactions and also the π-stacking interactions that are relevant in the crystal packing of some structures. Special attention has been paid to the bifurcated nature of the Au---Ag,Ag interactions in compound 1 that has been analyzed theoretically using the quantum theory of atoms-in-molecules (QTAIM) and the Natural Bond Orbital (NBO) computational tools. [ABSTRACT FROM AUTHOR]

The vital role of triel bonding (TrB) has been highlighted in two new thallium compounds i.e. Tl+[{(4-C2H5)C6H4O}2PS2]2− (1) and Tl[{(4-CH(CH3)2)C6H4O}2PS2]2 (2). These new compounds have been characterized by elemental and spectral analyses. The crystal structures of 1 and 2 belong to the monoclinic and triclinic systems with space groups P21/c and P1¯, respectively. Interestingly, compound 1 exists in ionic form and is stabilized through intramolecular Tl⋯S (TrBs) interactions wherein the thallium atom is symmetrically positioned in the cleft of the ligand with longer Tl–S distances. In compound 2, the thallium atom is coordinated to one sulfur atom and the other sulfur atom participates in TrB interaction. Both compounds also exhibit intermolecular Tl⋯S, Tl⋯π (TrBs), and C–H⋯Tl (anagostic) interactions, which assist to form unique supramolecular architectures owing to large size as well as coordinative unsaturation on the thallium. These non-covalent TrB interactions were authenticated by Hirshfeld surface analysis (HSA) and density functional theory (DFT) calculations using the quantum theory of atoms-in-molecules (QTAIM) and non-covalent interaction plot (NCI Plot) index methods. TrBs involving Tl have been scarcely described in the literature; therefore this work provides valuable insight into the importance of these unprecedented TrBs in the solid state. [ABSTRACT FROM AUTHOR]

This manuscript reports the synthesis, X-ray characterization and DFT study of a series of all-cis 1,4:2,3:5,8:6,7-tetraepoxynaphthalenes (decahydro-2,6:3,5-diepoxynaphtho[2,3-b:6,7-b′]bis(oxirene) derivatives) obtained by the tandem [4 + 2] cycloaddition between dimethyl acetylenedicarboxylate (DMAD) and three difurans as bis-dienes (the IMDAF reaction). The "pincer"-type adduct formation is controlled by using kinetic conditions. For this work, we were only interested in the synthesis of "pincer"-type adducts to study the formation self-assembled dimers that are governed by quite short C–H⋯O H-bonds. The existence of the "through-space" alpha-effect in the "pincer"-type adducts increases their ability to establish bifurcated C–H⋯O2 H-bonds in the solid state. That is, the close distance between the O-bridge atoms provokes an interesting through space lone pair⋯lone pair (LP⋯LP) interaction that increases the H-bond acceptor ability of the O-atoms. It has been analyzed using DFT calculations, molecular electrostatic potential (MEP) surfaces, quantum theory of atoms-in-molecules (QTAIM) and noncovalent interaction plot (NCIplot) index computational tools. This is the second study of the literature where "alpha-effect" hydrogen bonds (AEHBs) are described and studied. The novelty of the present work resides in the exhaustive epoxidation of the double bonds in the resulting "pincer"-type adducts that increases the number of possible H-bond acceptors in the target vicinal tetra-epoxynaphthalenes. The X-ray analyses of the three synthesized tetra-epoxides reveal that the AEHBs are predominant in the solid phase. [ABSTRACT FROM AUTHOR]

The important role of spodium bonding (SpB) in Zn(II) and Cd(II) complexes is highlighted in this feature article. SpB has been recommended to distinguish coordination bonds (high covalent character) from non-covalent contacts. Here, two new d10-metal dithiophosphate complexes, [M(L)2]2 {where M = Zn (1) and Cd (2); L = O,O′-bis(4-tert-butylphenyl) phosphorodithioate} have been synthesized in purely aqueous media and characterized by elemental and spectral analyses. The X-ray crystallography analyses indicate that both complexes are dinuclear, in which each metal atom is coordinated with four sulfur atoms in a distorted tetrahedral environment containing two four-membered chelate rings joined to a central eight-membered ring through metal (Zn/Cd) atoms. In complex 1 the eight-membered ring possesses a "saddle" conformation located on a two-fold axis of symmetry, C2, while in complex 2 it possesses a centrosymmetric "twisted chair" conformation, Ci. In addition, the oxygen and sulfur atoms belonging to the bridging ligands form intramolecular SpBs with Zn(II) in 1 and Cd(II) in 2. The existence of intramolecular SpBs in both complexes is evidenced by DFT calculations by using the Bader's Quantum Theory of Atoms-in-Molecules (QTAIM) combined with the non-covalent interaction plot (NCI plot) index that is based on the reduced density gradient (NCI-RDG) method. A Hirshfeld surface study has been carried out to understand the intermolecular contacts in the crystal lattice. [ABSTRACT FROM AUTHOR]

• Theoretical and CSD study of Sb•••Te noncovalent bonds. • Pnictogen-Chalcogen bonding competition at both ends of the Te–Sb bond. • QTAIM, NCIPlot and ELF characterization of Sb•••Te interactions. In this manuscript a curious behavior observed in the solid state of several X-ray structures retrieved from the Cambridge structural database (CSD) is described and analyzed. These structures have in common the presence of a metalloid–metalloid pnictogen (Pn)–chalcogen (Ch) covalent bond (i.e., Sb–Te bond) in the structure. The Sb–Te bond presents different σ-holes at both ends of the bond in terms of size and intensity. These compounds have a tendency to form short intermolecular Sb•••Te interactions in the solid state. The aim of this work is to investigate, by using dispersion-corrected density functional theory (DFT-D3) calculations, whether the Sb•••Te contacts observed in the solid state correspond to PnB (Sb is the Lewis acid) or ChB (Te is the Lewis acid). Moreover, using two model stibanyl telluranes, the interaction energies with a series of Lewis bases and anions using both ends of the Sb–Te covalent bond have been computed to investigate which side (PnB or ChB donor) is able to establish stronger interactions with common electron rich atoms. Finally, several computational tools such as the quantum theory of atoms-in-molecules (QTAIM), noncovalent interaction plot (NCIPlot) index and electron localization (ELF) function (2D and 3D maps) have been used to further characterize the physical nature of the Sb•••Te interactions. The results reported herein suggest that in the Sb•••Te contacts the Te atom acts as σ-hole donor and the Sb as electron density donor. [Display omitted]. [ABSTRACT FROM AUTHOR]

The role of thiocyanate/azide moiety as multiple hydrogen bond acceptors (CH•••S,N and NH•••S,N) in the solid state structures of two new zinc(II) complexes with N 2 O 2 donor 'reduced Schiff bases' been analyzed by DFT calculations. [Display omitted] • The synthesis of two new zinc(II) complexes. • Characterization by single crystal X-ray diffraction analysis. • Formation of 1D supramoelcular assemblies utilizing the multiple H-bond acceptor behavior of pseudo halides. • Analysis of supramolecular assemblies theoretically using DFT calculations. • Estimation of the energy associated to each contact using the quantum theory of atoms-in-molecules. • Emphasis on the importance of long-range van der Waals interactions. In this manuscript we report the synthesis of two new zinc(II) complexes, [(DMSO) 2 ZnL1Zn(NCS) 2 ] (1), and [{(N 3)ZnL2} 2 Zn(DMSO) 2 ] (2) that were characterized by elemental and spectral analyses {H 2 L1 is 2,2-dimethyl-1,3-propanediylbis(iminomethylene)bis(phenol), and H 2 L2 is 1,2-propanediylbis(iminomethylene)bis(4-chlorophenol)}. The structures have been confirmed by single crystal X-ray diffraction analysis. Both complexes form 1D supramoelcular assemblies where the pseudohalides act as multiple H-bond acceptors (CH•••S,N and NH•••S,N). These assemblies have been analyzed theoretically using DFT calculations, and the energy associated to each contact has been estimated using the quantum theory of atoms-in-molecules. The importance of long-range van der Waals interactions is emphasized. This manuscript, where two new complexes are synthesized and the H-bonding contacts individually estimated, is expected to attract the attention not only of synthetic inorganic chemists, but also theoreticians and chemists working in crystal engineering and supramolecular chemistry. [ABSTRACT FROM AUTHOR]

DFT calculations have been performed to study the mixed valence nature of three linear trinuclear cobalt complexes with tetradentate N 2 O 2 donor reduced Schiff base ligands, and acetate or bezoate as anionic co-ligands. The structure directing role of several noncovalent interactions in the solid state of the complexes has been investigated. [Display omitted] Three linear mixed valence trinuclear cobalt(III)-cobalt(II)-cobalt(III) complexes, [CoII{(μ-L1)(μ-OOCCH 3)CoIII(OOCCH 3)} 2 ]⋅4H 2 O (1), [CoII{(μ-L2)(μ-OOCCH 3)CoIII(OOCCH 3)} 2 ]⋅4H 2 O (2) and [CoII{(μ-L1)(μ-OOCPh)CoIII(OOCPh)} 2 ] (3) , have been synthesized using two N 2 O 2 donor 'reduced Schiff base' ligands, H 2 L1 (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol) and H 2 L2 (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-bromophenol), and acetate or bezoate as anionic co-ligands. The complexes have been characterized by spectroscopic measurements and their solid state structures have been determined by single crystal X-ray diffraction analysis. DFT calculations have been performed to study the mixed valence nature of the complexes. Moreover, the structure directing role of several noncovalent interactions in the solid state of the complexes has been investigated. The interactions have been characterized by a combination of two computational tools based on the topological analysis of the electron density, which are the quantum theory of atoms-in-molecules (QTAIM) and the noncovalent interaction plot, since they are useful to reveal noncovalent interactions in the solid state. [ABSTRACT FROM AUTHOR]

Unconventional supramolecular assemblies involving inclusion of complex cationic moieties within the supramolecular host cavities of metal–organic multi-component compounds of Mn(II) and Zn(II). [Display omitted] In the present study, we have reported the synthesis of two new dinuclear Mn(II) and Zn(II) metal–organic compounds, [Mn(2,5-PDC)(phen) 2 ][Mn(phen) 2 (H 2 O) 2 ]2Cl·10H 2 O (1) and [Zn(phen) 3 ][Zn(2,6-PDC) 2 ]·11.5H 2 O (2) (where, 2,5-PDC = 2,5-pyridinedicarboxylate, 2,6-PDC = 2,6-pyridinedicarboxylate, phen = 1,10-phenanthroline) at room temperature which have been characterized by elemental analysis, TGA, spectroscopic (FTIR, electronic) and single crystal X-ray diffraction techniques. A fascinating chloride-water supramolecular cluster in 1 and (H 2 O) 13 H-bonded cluster in 2 along with π-stacked assemblies stabilize the solid state structures. The most interesting aspect of the crystal structure of 1 is the inclusion of complex cationic moieties within the infinite self-assembled chloride-water cluster. Similarly the inclusion of cationic complex moieties in compound 2 inside the supramolecular cavity formed by the anionic complex provides rigidity to the crystal structure. DFT calculations, molecular electrostatic potential (MEP) surface analysis, quantum theory of atoms-in-molecules (QTAIM) and the non-covalent index plot (NCI plot) analysis were performed to investigate the supramolecular assemblies of the compounds. The studies reveal that the antiparallel π-stacking interactions are energetically significant synthons for the assemblies. However, the assemblies in 2 have been dominated mostly by Columbic attraction of the cationic and anionic complex moieties. [ABSTRACT FROM AUTHOR]

• Nutraceutical cocrystals. • Hirshfeld surface analyses. • DFT calculations in combination with MEP surface/NCI plot/QTAIM analysis. The SCXRD structure of the natural dietary compound pterostilbene (trans-3,5-dimethoxy-4-hydroxystilbene) and phenanthroline (1,10-phenanthroline) cocrystal is reported herein. In the solid state the cocrystal forms several H-bonded and C H···π supramolecular synthons that have been analyzed by DFT calculations, with a particular focus on the parallel face-to-face stacking of the phenanthroline rings, a relevant and quite unusual feature (antiparallel displaced mode is more common). Cooperativity effects between H-bonding and aromatic interactions have been studied to rationalize the formation of this unusual π-stacking mode and the supramolecular assemblies have been further analyzed using several computational techniques, i.e., molecular electrostatic potential (MEP) surfaces and the quantum theory of "atom-in-molecules" (QTAIM) combined with reduced density gradient (RDG) plots. [ABSTRACT FROM AUTHOR]

[Display omitted] • [Pb 2 L 2 (CH 3 CN)(ClO 4) 2 ]·2H 2 O (1 ·∙2H 2 O) was obtained from a thiosemicarbazide derivative (HL). • The supramolecular structure of 1 ·∙2H 2 O exhibits Pb∙∙∙N and Pb∙∙∙S tetrel bonds. • In the crystal structure of 1 ·∙2H 2 O tetrel bonds produce a 1D polymeric chain. • The structure of 1 ·∙2H 2 O was validated using a combination of QTAIM and NCIplot tools. In this work, we report on a new lead(II) coordination complex [Pb 2 L 2 (CH 3 CN)(ClO 4) 2 ]·2H 2 O (1 ·2H 2 O), which was readily synthesized from a mixture of Pb(ClO 4) 2 ·3H 2 O and 1-(pyridine-2-yl)benzylidene-4-phenylthiosemicarbazide (HL). The crystal structure analysis of 1 ·2H 2 O evidenced that the lead(II) cation is N , N' , S -chelated by the tridentate pincer type L with formation of a [PbL]+ coordination species, which dimerizes through a couple of reciprocal bridging Pb–S bonds, yielding the [Pb 2 L 2 ]2+ complex cation. The metal centers within this cation are linked by two Pb∙∙∙N tetrel bonds through the bridging acetonitrile molecule with the formation of a [Pb 2 L 2 (CH 3 CN)]2+ building unit. These units are glued by reciprocal Pb∙∙∙S tetrel bonds, yielding a 1D supramolecular polymeric chain. The lead(II) cations interact also with disordered oxygen atoms of both the minor and major occupancies of the perchlorate anions either through covalent Pb–O bonds or Pb∙∙∙O tetrel bonds, respectively. 1D polymeric chains resemble an expanded hexagonal projection and span along the a axis, yielding a grid-like crystal packing, where the cavities are filled by lattice water molecules. The interactions have been studied using DFT calculations and characterized by using the quantum theory of atoms-in-molecules (QTAIM) and the non-covalent interaction plot (NCIplot) computational tools. [ABSTRACT FROM AUTHOR]

Five mononuclear nickel(II) complexes containing nitrogen heteroaromatic ligands and pseudohalides were synthesized to explore the role of different heteroaromatic ligands and pseudohalides in the crystal packing. [Display omitted] • Structures of five mononuclear nickel(II) complexes. • Influence of nitro-heteroaromatic and pseudohalide ligands on non-covalent interactions. • Energetics of the π–stacking dimers in the solid state. • Hirshfeld surface analysis. Five mononuclear nickel(II) complexes, [Ni(NCS) 2 (imz) 4 ] (1) and [Ni(NCS) 2 (pyz) 4 ] (2), [Ni(NCS) 2 (3-OHpy) 4 ] (3), [Ni(NCS) 2 (3-Clpy) 4 ] (4) and [Ni(NCO) 2 (3-Clpy) 2 (H 2 O) 2 ] (5), where imz, pyz, 3-OHpy and 3-Clpy are imidazole, pyrazole, 3-hydroxypyridine and 3-chloropyridine, respectively, have been synthesized and characterized by X-ray crystallographic studies to explore the role of different heteroaromatic ligands and pseudohalides in the crystal packing. The noncovalent interactions witnessed in the crystal packing of these complexes have been well-defined focusing on the recurrent π–stacking motifs, leading to the π–stacked dimeric assemblies. Besides, noncovalent interactions such as, N H(C H)···π, lone pair···π, along with both conventional and nonconventional hydrogen bonding interactions play important roles in the stabilization of these complexes in the solid state. The energetic features of the π–stacking and the importance of additional noncovalent interactions towards cooperatively formed π–stacking dimers were investigated using DFT calculations in combination with the quantum theory of atoms-in-molecules (QTAIM) and noncovalent interaction plot (NCI plot) index computational tools. Remarkably, the aromatic ligands (imidazole, pyridine) through coordination generate favourable antiparallel orientation of the dipoles (180°) in the dimeric form of complexes 1 , 3 , 4 and 5 , and thus exhibit strong π–stacking interaction in comparison to complex 2 (pyrazole) in its dimeric form with the perpendicular orientation of dipoles. This study may provide further insight into elucidating the role of weak noncovalent interactions in the supramolecular assemblies of metal-containing compounds. [ABSTRACT FROM AUTHOR]

• Three new CPs of La(III), Pr(III) and Nd(III), decorated with Succinate linker have been reported. • All Ln(III) centres in Ln-succinates 1-3 exhibit ten coordinated bicapped square antiprismatic geometry which is not known in the previously reported Ln(III)–succinates without auxillary coligands. • DFT studies reveal that compound 3 forms interesting water channels in the solid state. • Artificial water channels [10.1016/j.coche.2019.06.007] are synthetic molecules that aim to mimic the structural and functional features of biological water channels (aquaporins). • The CP 3 reported herein can be considered as a potential new class of artificial water channel. Three new coordination polymers have been assembled by self-assembly of lanthanide(III) ions and succinic acid in dimethylformamide–water (DMF-H 2 O) mixed solvent having formulae; {[Ln(suc) 1.5 (H 2 O) 2 ]•xH 2 O} n ; (1) , (2) and (3) [Where Ln = La (1), Pr (2) and Nd (3), suc = succinate dianion; x = 2 for CP 1 , x = 1 for CP 2 and x = 4 for CP 3 ]. In all three coordination polymers (CPs) 1-3, the Ln(III) centres are ten coordinated with bicapped square antiprismatic geometry (SAPRS-10). Crystallographic analysis reveals that CPs 1-3 crystallize in triclinic system P ¯1 space group. The linker succinic acid displays two different bonding modes: (μ 2 - κ 4, η 2: η 2) and (μ 4 - κ 6, η 1: η 2: η 2: η 1). All CPs 1-3 are isostructural and isomorphous. The two Ln centres in CPs 1-3 are bridged together through succinate anions via (μ 4 - κ 6, η 1: η 2: η 2: η 1) mode forming dinuclear (Ln 2 O 18) Secondary building unit (SBU) which are extended infinitely to generate one-dimensional chains. These 1D chains are further extended along the b -axis to form two-dimensional layered structures via (μ 2 - κ 4, η 2: η 2) mode and finally three-dimensional network. In case of Nd, the quality of the crystal allows to locate a major number of lattice water molecules (x = 4) than in the other two complexes and, remarkably, the formation of water channels can be realized and studied. It has been analyzed using DFT calculations combined with the molecular electrostatic potential (MEP) surfaces, the quantum theory of "atoms-in-molecules" QTAIM and non–covalent interaction index (NCIplot) analyses. [Display omitted] [ABSTRACT FROM AUTHOR]