Predominantly, carbon atoms of various species function as acceptors of noncovalent interactions when they are part of a π-system. Here, we report on the discovery of a halogen bond involving the ...isocyano carbon lone pair. The co-crystallization or mechanochemical liquid-assisted grinding of model mesityl isocyanide with four iodoperfluorobenezenes leads to a series of halogen-bonded adducts with isocyanides. The obtained adducts were characterized by single-crystal and powder X-ray diffraction, solid-state IR and
C NMR spectroscopies, and also by thermogravimetric analysis. The formation of the halogen bond with the isocyano group leads to a strong reduction of the isocyanide odor (3- to 46-fold gas phase concentration decrease). This manipulation makes isocyanides more suitable for laboratory storage and usage while preserving their reactivity, which is found to be similar between the adducts and the parent isocyanide in some common transformations, such as ligation to metal centers and the multi-component Ugi reaction.
Inspection of the X‐ray structures of the newly prepared trans‐MII(CNXyl)2(DAPT)2Cl(BF4) (M=Pd, Pt; Xyl=2,6‐Me2C6H3; DAPT=4,6‐diaminopyrimidine‐2(1H)‐thione) complexes and the appropriate Hirshfeld ...molecular surface analysis allowed the recognition of the previously unknown π‐hole⋅⋅⋅metal interactions between a ligated isocyano group (acting as a π‐hole donor) and the positively charged d8‐PtII and d8‐PdII metal centers (acting as nucleophiles); this is the first identification of π‐hole⋅⋅⋅metal interactions with triple‐bond species. Results of DFT calculations followed by the topological analysis of the electron density distribution within the framework of Bader's theory (quantum theory of atoms in molecules, QTAIM) confirmed the presence of these contacts. The electrostatic surface potential calculations indicated that π‐hole⋅⋅⋅metal contacts are formed upon interaction between the electrophilic isocyano C atom (π‐hole donor) and the nucleophilic dz2
orbital of the metal centers, which act as π‐hole acceptors. Available CCDC data were processed from the perspective of the π‐hole⋅⋅⋅metal interactions with isocyanide ligands, and their analysis disclosed the role of metal nucleophilicity in the corresponding π‐hole acceptor ability.
Noncovalent intermolecular interactions: The first recognition of π‐hole⋅⋅⋅metal (isocyano group⋅⋅⋅d8‐MII; M=Pt, Pd) interactions that involve triple‐bonded species is reported (see picture).
Non-covalent interactions are one of the key topics in coordination and organometallic chemistry. Examples of such weak interactions are hydrogen, halogen, and chalcogen bonds, stacking interactions, ...metallophilic contacts, etc. Non-covalent interactions play an important role in materials science, catalysis, and medicinal chemistry. The aim of this Special Issue of
, entitled "Non-Covalent Interactions in Coordination and Organometallic Chemistry", is to cover the most recent progress in the rapidly growing field of non-covalent interactions in coordination and organometallic chemistry. Both experimental and theoretical studies, fundamental and applied research and any types of manuscripts are welcome for consideration.
A series of
-pyridyl ureas bearing 1,2,4- (
,
, and
) and 1,3,4-oxadiazole moiety (
,
,
) was prepared and characterized by HRMS,
H and
C NMR spectroscopy, as well as X-ray diffraction. The ...inspection of the crystal structures of (
-
)
,
and the Hirshfeld surface analysis made possible the recognition of the (oxadiazole)···(pyridine) and (oxadiazole)···(oxadiazole) interactions. The presence of these interactions was confirmed theoretically by DFT calculations, including NCI analysis for experimentally determined crystal structures as well as QTAIM analysis for optimized equilibrium structures. The preformed database survey allowed the verification of additional examples of relevant (oxadiazole)···π interactions both in Cambridge Structural Database and in Protein Data Bank, including the cocrystal of commercial anti-HIV drug Raltegravir.
Non-covalent interactions are one of the key topics in modern chemical science. These inter- and intramolecular weak interactions (e.g., hydrogen, halogen, and chalcogen bonds, stacking interactions ...and metallophilic contacts) have a significant effect on the properties of polymers. In this Special Issue, "Non-covalent interactions in polymers", we tried to collect fundamental and applied research manuscripts (original research articles and comprehensive review papers) focused on non-covalent interactions in polymer chemistry and related fields. The scope of the Special Issue is very broad: we welcome all the contributions that deal with the synthesis, structure, functionality and properties of polymer systems involving non-covalent interactions.
The coupling of cis-PdCl2(CNXyl)2 (Xyl = 2,6-Me2C6H3) with 4-phenylthiazol-2-amine in molar ratio 2:3 at RT in CH2Cl2 leads to binuclear (diaminocarbene)PdII complex 3c. The complex was characterized ...by HRESI+-MS, 1H NMR spectroscopy, and its structure was elucidated by single-crystal XRD. Inspection of the XRD data for 3c and for three relevant earlier obtained thiazole/thiadiazole derived binuclear diaminocarbene complexes (3a EYOVIZ; 3b: EYOWAS; 3d: EYOVOF) suggests that the structures of all these species exhibit intra-/intermolecular bifurcated chalcogen bonding (BCB). The obtained data indicate the presence of intramolecular S•••Cl chalcogen bonds in all of the structures, whereas varying of substituent in the 4th and 5th positions of the thiazaheterocyclic fragment leads to changes of the intermolecular chalcogen bonding type, viz. S•••π in 3a,b, S•••S in 3c, and S•••O in 3d. At the same time, the change of heterocyclic system (from 1,3-thiazole to 1,3,4-thiadiazole) does not affect the pattern of non-covalent interactions. Presence of such intermolecular chalcogen bonding leads to the formation of one-dimensional (1D) polymeric chains (for 3a,b), dimeric associates (for 3c), or the fixation of an acetone molecule in the hollow between two diaminocarbene complexes (for 3d) in the solid state. The Hirshfeld surface analysis for the studied X-ray structures estimated the contributions of intermolecular chalcogen bonds in crystal packing of 3a–d: S•••π (3a: 2.4%; 3b: 2.4%), S•••S (3c: less 1%), S•••O (3d: less 1%). The additionally performed DFT calculations, followed by the topological analysis of the electron density distribution within the framework of Bader’s theory (AIM method), confirm the presence of intra-/intermolecular BCB S•••Cl/S•••S in dimer of 3c taken as a model system (solid state geometry). The AIM analysis demonstrates the presence of appropriate bond critical points for these interactions and defines their strength from 0.9 to 2.8 kcal/mol indicating their attractive nature.
The structure, fundamental properties, and reactivity of chemical systems at various hierarchical levels of organization of matter is the paradigm of chemistry. A qualitative and quantitative ...description of various intermolecular and intramolecular non-covalent interactions in chemical systems is the main tool for supramolecular design and the driving force of smart prediction of kinetic and thermodynamic parameters of chemical reactions. This perspective is dedicated to highlighting the recent progress of our research group in the investigation of various non-covalent contacts in organic, organometallic, and inorganic chemical systems relevant for medicine, materials science, and catalysis. This research is interdisciplinary in nature and lies at the intersection of computer modeling with such natural science disciplines as chemistry, physics, crystallography, biology, and medicine, as well as directly related to materials science and nanotechnology.
The existence of X⋯Au non-covalent contacts was confirmed by using QTAIM analysis of the theoretical electron density distribution in model associates Au(CN)2−·CH2Cl2 and AuBr2−·(C2I4)4 obtained from ...the published X-ray structures.
Display omitted
•Existence of X⋯Au non-covalent contacts confirmed by using QTAIM analysis.•Energies for appropriate weak interactions are within the range 1.9–4.7 kcal/mol.•Relativistic approach gives higher estimates for strength of these contacts.
The supramolecular assembly based on various intermolecular interactions involving metal centers currently is cutting edge topic in coordination chemistry community. Meanwhile, there are several reports whose authors simply did not pay any attention to the phenomenon of metal-involving X⋯Au (X = I, Cl) non-covalent contacts. We have proved the existence of such non-covalent interactions in model structures for the solvates Au(CN)2−·CH2Cl2 and AuBr2−·(C2I4)4 using DFT calculations followed by the topological analysis of the electron density distribution within the formalism of Bader’s theory (QTAIM method) based on the experimental geometrical parameters. The appropriate bond critical points (3, −1) were located and energies for these weak contacts (2–5 kcal/mol) were estimated.
Self-Healing Polymers Novikov, Alexander S
Polymers,
05/2022, Volume:
14, Issue:
11
Journal Article
Peer reviewed
Open access
Self-healing polymers are synthetic or artificially-created substances that have the built-in ability to automatically repair damages to themselves without any external diagnosis of the problem or ...human intervention ....
PDF
