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Cocrystallization of CuI with NCNMe 2 in the presence of substituted perfluoroarenes─iodoperfluorobenzene (IFB), 4,4'-diiodoperfluorobiphenyl (4,4'-FIBP), and 4-bromoperfluorobenzonitrile (4-BrFBN)─led to the formation of three types of adducts 1 ·2(IFB), 1 ·4,4'FIBP, and 1 ·4-BrFBN ( 1 is Cu 4 I 4 (NCNMe 2 ) 4 ), all studied by X-ray crystallography. In these cocrystals, the coordinated nitrile N atom (whose electron pair is engaged in metal coordination) still acts as an electron donor, forming π-hole interactions, specifically, π-hole arene ···N nitrile , with the perfluoroarenes. These interactions were examined in the context of their occurrence alongside other interactions involving C atoms of the electron-deficient aromatic rings and nucleophilic atoms of the copper cluster. Comprehensive theoretical calculations, including MEP, QTAIM/NCI plot analysis, EDA, ELF projections, and ETS-NOCV calculations, revealed that the nitrile ligand N atom maintains significant negative potential and that π-hole interactions are energetically more favorable than σ-hole interactions in the studied systems. This nucleophilicity is based on a noticeable contribution of the heterocumulene form, Cu-N - ═C═N + Me 2 , in the resonance hybrid of Cu-bound NCNMe 2 : a phenomenon influenced by both the coordination and the conjugation between the NR 2 and CN groups The discovery of π-hole arene ···N nitrile contacts adds a new dimension to our understanding of coordinated push-pull nitriles, in particular dialkylcyanamides, revealing that the coordinated nitrile N atom can still function as a nucleophile in noncovalent binding.

In X-ray structures of the isomorphic mer-[IrX 3 (THT)(CNXyl) 2 ] (X=Cl 1, Br 2; THT=tetrahydrothiophene; Xyl=2,6-Me 2 C 6 H 3 -) complexes, we revealed short intermolecular contacts between the C-atom of an isocyanide methyl group and halide ligands of another molecule. Geometrical consideration of the X-ray data and analysis of appropriate DFT studies allowed the attribution of these contacts to C Me ⋅⋅⋅X-Ir III (X=Cl, Br) tetrel bond. Specifically, through the application of DFT calculations and various theoretical models, the presence of tetrel bonding interactions was validated, and the contribution of the C Me ⋅⋅⋅X-Ir III interaction was assessed. The reinforcement of the tetrel bond upon the isocyanide coordination to iridium(III) is substantiated by molecular electrostatic potential (MEP) surface calculations. To distinguish the tetrel bonding characteristics of CMe⋅⋅⋅X-Ir III (X=Cl, Br) interactions from conventional hydrogen bonding, we employed multiple computational methodologies, including Natural Bond Orbital (NBO) analysis and Electron Localization Function (ELF) analysis. Additionally, Energy Decomposition Analysis (EDA) was applied to selected model systems to explore the underlying physical nature of these interactions., (© 2024 Wiley-VCH GmbH.)

Cocrystallizations of trans -[PtX' 2 (NCNR 2 ) 2 ] (R 2 = Me 2 , X' = Cl 1a , Br 1b , I 1c ; R 2 = (CH 2 ) 5 , X' = I 2c ) with SbX 3 (X = Cl, Br, I) gave 1:2 cocrystals 1a ·2SbCl 3 , 1b ·2SbBr 3 , 1c ·2SbCl 3 , 1c ·2SbBr 3 , 1c ·2SbI 3 , and 2c ·2SbI 3 . In all six X-ray structures, the association of the molecular coformers is achieved mainly by Sb III ···d z 2 [Pt II ] metal-involving intermolecular pnictogen bonding. Density functional theory (DFT) calculations (based on experimentally determined geometries) using both gas-phase and solid-state approximations revealed that a σ-(Sb)-hole interacts with an area of negative potential associated with the d z 2 -orbital of the positively charged platinum(II) sites, thus forming a pnictogen bond whose energy falls in the range between -7.3 and -16.9 kcal/mol.

The structure-directing "key-to-lock" interaction of double σ-(I III )-hole donating iodonium cations with the O-flanked pseudo-lacune rims of [β-Mo 8 O 26 ] 4- gives halogen-bonded iodonium-beta-octamolybate supramolecular associates. In the occurrence of their tetragonal pyramidal motifs, deep and broad σ-(I III )-holes of a cation recognize the molybdate backbone, which provides an electronic pool localized around the two lacunae. The halogen-bonded I⋯O linkages in the structures were thoroughly studied computationally and classified as two-center, three-center bifurcated, and unconventional "orthogonal" I⋯O halogen bonds. In the latter, the O-atom approaches orthogonally the C-I III -C plane of an iodonium cation and this geometry diverge from the IUPAC criteria for the identification of the halogen bond., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

The cis - and trans -isomers of 6-(3-(3,4-dichlorophenyl)-1,2,4-oxadiazol-5-yl)cyclohex-3-ene-1-carboxylic acid ( cis - A and trans - A ) were obtained by the reaction of 3,4-dichloro- N '-hydroxybenzimidamide and cis -1,2,3,6-tetrahydrophthalic anhydride. Cocrystals of cis - A with appropriate solvents ( cis - A ‧½(1,2-DCE), cis - A ‧½(1,2-DBE), and cis - A ‧½C 6 H 14 ) were grown from 1,2-dichloroethane (1,2-DCE), 1,2-dibromoethane (1,2-DBE), and a n -hexane/CHCl 3 mixture and then characterized by X-ray crystallography. In their structures, cis - A is self-assembled to give a hybrid 2D supramolecular organic framework (SOF) formed by the cooperative action of O-H⋯O hydrogen bonding, Cl⋯O halogen bonding, and π⋯π stacking. The self-assembled cis - A divides the space between the 2D SOF layers into infinite hollow tunnels incorporating solvent molecules. The energy contribution of each noncovalent interaction to the occurrence of the 2D SOF was verified by several theoretical approaches, including MEP and combined QTAIM and NCIplot analyses. The consideration of the theoretical data proved that hydrogen bonding (approx. -15.2 kcal/mol) is the most important interaction, followed by π⋯π stacking (approx. -11.1 kcal/mol); meanwhile, the contribution of halogen bonding (approx. -3.6 kcal/mol) is the smallest among these interactions. The structure of the isomeric compound trans - A does not exhibit a 2D SOF architecture. It is assembled by the combined action of hydrogen bonding and π⋯π stacking, without the involvement of halogen bonds. A comparison of the cis - A structures with that of trans - A indicated that halogen bonding, although it has the lowest energy in cis - A -based cocrystals, plays a significant role in the crystal design of the hybrid 2D SOF. The majority of the reported porous halogen-bonded organic frameworks were assembled via iodine and bromine-based contacts, while chlorine-based systems-which, in our case, are structure-directing-were unknown before this study.

Cocrystallization of the dimeric [Cu 2 (μ-I) 2 (CNXyl) 4 ] (Xyl = 2,6-Me 2 C 6 H 3 , 1 ) and polymeric catena -[Cu(μ-I)(CNC 6 H 3 -2-Cl-6-Me) 2 ] ( 2 ) complexes with I 2 at different molar ratios between the reactants resulted in a series of (RNC) 2 CuI-based crystal polyiodides formed along with gradual accumulation of iodine, namely the cocrystals [ 1 ·I 2 ]·[Cu(μ 1,1 -I 3 )(CNXyl) 2 ] 2 followed by the generation of [Cu(μ 1,3 -I 3 )(CNXyl) 2 ] 2 ·2I 2 ( 5 ·2I 2 ) or [Cu(μ 1,1 -I 3 )(CNC 6 H 3 -2-Cl-6-Me) 2 ] 2 and then [Cu(μ 1,3 -I 3 )(CNC 6 H 3 -2-Cl-6-Me) 2 ] n · n / 2 I 2 . The polyiodide 5 ·2I 2 exhibits a novel supramolecular motif─a purely inorganic halogen-bonded Cu 2 (μ 1,3 -I 3 ) 2 core in the chair conformation. The X-ray structure of 5 ·2I 2 featuring I···I contacts was analyzed by a set of theoretical methods and attributed to moderately strong halogen bonding (from -3.2 to -3.9 kcal/mol); these interactions determine the supramolecular architecture of 5 ·2I 2 .

Gold(III)-catalyzed annulation of electron-deficient alkynes and 2-amino-arylcarbonyls provides general modular one-step access to a broad scope of quinoline products. This highly selective reaction is a useful alternative to the classic Friedländer synthesis, which requires harsh reaction conditions. In contrast, the developed method works under relatively mild PicAuCl 2 -catalyzed conditions and exhibits a high functional group tolerance (40 examples; yields of ≤96%). Another feature of the developed approach is a versatility toward other electron-deficient alkynes. Alkynylsulfones, alkynylcarbonyls, alkynylphosphonates, propiolonitriles, and trifluoromethylated alkynes can be used as the starting materials for the preparation of quinolines diversely substituted at position 3. On the basis of experimental data, we proposed a reaction mechanism in which gold(III) functions as a strong electrophilic activator of the C≡C bond and the carbonyl group. The synthetic potential of the presented method is additionally illustrated by practical postmodifications of the obtained compounds, including a two-step synthesis of interpirdine, a potent drug candidate.

We designed 0D, 1D, and 2D supramolecular assemblies made of diaryliodonium salts (functioning as double σ-hole donors) and carboxylates (as σ-hole acceptors). The association was based on two charge-supported halogen bonds (XB), which occurred between I III sites of the iodonium cations and the carboxylate anions. The sequential introduction of the carboxylic groups in the aryl ring of the benzoic acid added a dimension to the 0D supramolecular organization of the benzoate, which furnished 1D-chained and 2D-layered structures when terephthalate and trimesate anions, correspondingly, were applied as XB acceptors. The structure-directing XB were studied using DFT calculations under periodic boundary conditions and were followed by the one-electron-potential analysis and the Bader atoms-in-molecules topological analysis of electron density. These theoretical methods confirmed the existence of the XB and verified the philicities of the interaction partners in the designed solid-state structures.

2,3,5,6-Tetramethyl-1,4-diisocyanobenzene ( 1 ), 1,4-diisocyanobenzene ( 2 ), and 1,4-dicyanobenzene ( 3 ) were co-crystallized with 1,3,5-triiodotrifluorobenzene (1,3,5-FIB) to give three cocrystals, 1 ·1,3,5-FIB, 2 ·2(1,3,5-FIB), and 3 ·2(1,3,5-FIB), which were studied by X-ray diffraction. A common feature of the three structures is the presence of I···C isocyanide or I···N nitrile halogen bonds (HaBs), which occurs between an iodine σ-hole and the isocyanide C-(or the nitrile N-) atom. The diisocyanide and dinitrile cocrystals 2 ·2(1,3,5-FIB) and 3 ·2(1,3,5-FIB) are isostructural, thus providing a basis for accurate comparison of the two types of noncovalent linkages of C≡N/N≡C groups in the composition of structurally similar entities and in one crystal environment. The bonding situation was studied by a set of theoretical methods. Diisocyanides are more nucleophilic than the dinitrile and they exhibit stronger binding to 1,3,5-FIB. In all structures, the HaBs are mostly determined by the electrostatic interactions, but the dispersion and induction components also provide a noticeable contribution and make the HaBs attractive. Charge transfer has a small contribution (<5%) to the HaB and it is higher for the diisocyanide than for the dinitrile systems. At the same time, diisocyanide and dinitrile structures exhibit typical electron-donor and π-acceptor properties in relation to the HaB donor.

We developed an atom- and reaction mass efficient strategy for the preparation of diarylselenides using iodonium salts as reactants. The developed approach allows the obtaining of diarylselenides from the corresponding trimethoxyphenyl-substituted iodonium salts via a two-step one-pot reaction sequence. The proposed metal-free methodology is based on the involvement of both iodonium aryl groups for diarylation.

The binuclear half-lantern platinum(II) complexes [Pt(pbt)(μ-S ∧ N)] 2 (pbtH = 2-phenylbenzothiazole, S ∧ N = benzo[ d ]thiazole-2-thiolate Pt1 , 6-fluorobenzo[ d ]thiazole-2-thiolate Pt2 , 6-chlorobenzo[ d ]thiazole-2-thiolate Pt3 , 6-bromobenzo[ d ]thiazole-2-thiolate Pt4 , and 6-iodobenzo[ d ]thiazole-2-thiolate Pt5 ) were synthesized by the treatment of the in situ formed [Pt(pbt)(NCMe) 2 ]NO 3 complex and appropriate benzo[ d ]thiazole-2-thiole in the presence of t BuOK; yield: 51-84%. Complexes Pt1 - 5 exhibit intense red photoluminescence originated from 3 MMLCT state reaching 22% room temperature quantum yields in a CH 2 Cl 2 solution. All complexes display excited-state decay kinetics both in solution and in the solid state; the kinetics was adequately modeled by single exponentials. The complexes display more than 10-fold higher electroluminescence brightness for the F-containing Pt2 (900 cd/m 2 ) and 2-fold higher electroluminescence brightness for the Cl-containing Pt3 (143 cd/m 2 ) compared to the H-substituted complex Pt1 (77 cd/m 2 ). It is argued that this impressive device luminance growth, occurred on formal replacement of H-to-F, is associated with the intermolecular strong hydrogen bonding H···F relevant to the H-bond found in the structure of Pt2 .

Five new copper(I) complexes─composed of the paired dibenzohalolium and [CuL 2 ] - (L = 1,2,4-oxadiazolate) counterions in which O,O-atoms of the anion are simultaneously linked to the halogen atom─were generated and isolated as the solid via the three-component reaction between [Cu(MeCN) 4 ](BF 4 ), sodium 1,2,4-oxadiazolates, and dibenzohalolium triflates (or trifluoroacetates). This reaction is different from the previously reported Cu I -catalyzed arylation of 1,2,4-oxadiazolones by diaryliodonium salts. Inspection of the solid-state X-ray structures of the complexes revealed the strong three-center X···O,O (X = Br, I) halogen bonding occurred between the oxadiazolate moieties and dibenzohalolium cation. According to performed theoretical calculations, this noncovalent interaction (or noncovalent chelation) was recognized as the main force in the stabilization of the copper(I) complexes. An explanation for the different behavior of complexes, which provide either chelate or nonchelate binding, is based on the occurrence of additional -CH 3 ···π interactions, which were also quantified.

Co-crystallization of 180°-orienting σ-hole-accepting tectons, namely, 1,4-diisocyanobenzene (1) and 1,4-diisocyanotetramethylbenzene (2), with such homoditopic halogen bond donors as 1,4-diiodotetrafluorobenzene (1,4-FIB) and 4,4'-diiodoperfluorobiphenyl (4,4'-FIBP) afforded co-crystals 1 ⋅ 1,4-FIB, 1 ⋅ 4,4'-FIBP, and 2 ⋅ 1,4-FIB. Their solid-state structures exhibit 1D-supramolecular arrangements, which are based on poorly explored I⋅⋅⋅C halogen bonding; this study is the first in which the supramolecular assembly utilizing halogen bonding with a terminal C atom was performed. The use of the potentially tetrafunctional σ-hole accepting tetraiodoethylene (TIE) leads to supramolecular architecture of a higher dimension, 3D-framework, observed in the structure of 1 ⋅ TIE. DFT calculations, used to characterize the halogen bonding situation, revealed that the I⋅⋅⋅C non-covalent interactions are moderately strong, ranging from -4.07 in 1 ⋅ TIE to -5.45 kcal/mol in 2 ⋅ 1,4-FIB. The NBO analysis disclosed that LP(C)→σ* charge transfer effects are relevant in all co-crystals., (© 2023 Wiley-VCH GmbH.)

The co-crystallization of tetracyanobenzene (TCB) with haloarenes ArX provided six new co-crystals TCB ⋅ ArX (ArX=PhCl, PhBr, 4-MeC 6 H 4 Cl, 4-MeC 6 H 4 Br, 4-MeOC 6 H 4 Cl, 1,2-Br 2 C 6 H 4 ) which were studied by X-ray diffraction. In these systems, the strong collective effect of π⋅⋅⋅π stacking interactions and lone pair-(X)⋅⋅⋅π-hole-(C) bondings between TCB and ArX promote the strength of X⋅⋅⋅N cyano halogen bonding (HaB). Theoretical studies showed that the stacking interactions affect the σ-hole depth of the haloarenes, thus significantly boosting their ability to function as HaB donors. According to the molecular electrostatic potential calculations, the σ- hole-(Cl) value (1.5 kcal/mol) in the haloarene 4-MeOC 6 H 4 Cl (featuring an electron-rich arene moiety and exhibiting very poor σ-hole-(Cl) ability) increases significantly in the stacked trimer (TCB) 2  ⋅ 4-MeOC 6 H 4 Cl (12.5 kcal/mol). Theoretical DFT calculations demonstrate the dramatic increase of X⋅⋅⋅N cyano HaB strength for stacked trimers in comparison with parent unstacked haloarenes., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The co-crystallization of the lead(II) complex [Pb(S 2 CNEt 2 ) 2 ] with tetraiodoethylene (C 2 I 4 ) gave the co-crystal, [Pb(S 2 CNEt 2 ) 2 ]∙½C 2 I 4 , whose X-ray structure exhibits only a small change of the crystal parameters than those in the parent [Pb(S 2 CNEt 2 ) 2 ]. The supramolecular organization of the co-crystal is largely determined by an interplay between Pb⋯S tetrel bonding (TeB) and I⋯S halogen bonding (HaB) with comparable contributions from these non-covalent contacts; the TeBs observed in the parent complex, [Pb(S 2 CNEt 2 ) 2 ], remain unchanged in the co-crystal. An analysis of the theoretical calculation data, performed for the crystal and cluster models of [Pb(S 2 CNEt 2 ) 2 ]∙½C 2 I 4 , revealed the non-covalent nature of the Pb⋯S TeB (-5.41 and -7.78 kcal/mol) and I⋯S HaB (-7.26 and -11.37 kcal/mol) interactions and indicate that in the co-crystal these non-covalent forces are similar in energy.

A single-crystal X-ray diffraction (XRD) study of diaryliodonium tetrachloroaurates (or, in the recent terminology, tetrachloridoaurates), [( p -XC 6 H 4 ) 2 I][AuCl 4 ] (X = Cl, 1 ; Br, 2 ), was performed for 1 (the structure is denoted as 1a to show similarity with the isomorphic structure 2a ) and two polymorphs─ 2a (obtained from MeOH) and 2b (from 1,2-C 2 H 4 Cl 2 ). Examination of the XRD data for these three structures revealed 2-center C-X···Au III (X = Cl and Br) and 3-center bifurcated C-Br···( Cl - Au ) halogen bonding (abbreviated as XB) between the p -Cl or p -Br atoms of the diaryliodonium cations and the gold(III) atom of [AuCl 4 ] - . The noncovalent nature of Au III -involving interactions, the nucleophilicity of the gold(III) atoms, and the electrophilic role of p -X atoms of the diaryliodonium cations in the XBs were studied by a set of complementary computational methods. Combined experimental and theoretical studies allowed the recognition of the d-nucleophilicity of the [d 8 Au III ] atom which, regardless of its rather substantial formal 3+ charge, can function as a d-nucleophilic partner of XB. This conclusion was also supported by theoretical calculations performed for the structures' refcodes BINXOM and ICSD 62511; the obtained data verified the nucleophilicity of Au III toward a K + ions or a σ-(Cl)-hole, respectively. All our results, together with consideration of relevant literature, indicate that gold atoms in the three oxidation states (0, I, and even III) exhibit nucleophilicity in XBs.

Cyclometalated platinum(II) complexes [Pt(ppy)Cl(CNAr)] (ppy = 2-phenylpyridinato-C 2 , N ; Ar = C 6 H 4 -2-I 1 , C 6 H 4 -4-I 2 , C 6 H 3 -2-F-4-I 3 , and C 6 H 3 -2,4-I 2 4 ) bearing ancillary isocyanide ligands were obtained by the bridge-splitting reaction between the dimer [Pt(ppy)(μ-Cl)] 2 and 2 equiv any one of the corresponding CNAr. Complex 2 was crystallized in two polymorphic forms, namely, 2 I and 2 II , exhibiting green (emission quantum yield of 0.5%) and orange (emission quantum yield of 12%) phosphorescence, respectively. Structure-directing non-covalent contacts in these polymorphs were verified by a combination of experimental (X-ray diffraction) and theoretical methods (NCIplot analysis, combined electron localization function (ELF), and Bader quantum theory of atoms in molecules (QTAIM analysis)). A noticeable difference in the spectrum of non-covalent interactions of 2 I and 2 II is seen in the Pt···Pt interactions in 2 II and absence of these metallophilic contacts in 2 I . The other solid luminophores, namely, 1 , 3 I-II , 4 , and 4 ·CHCl 3 , exhibit green luminescence; their structures include intermolecular C-I···Cl-Pt halogen bonds as the structure-directing interactions. Crystals of 1 , 2 I , 3 I , 3 II , 4 , and 4 ·CHCl 3 demonstrated a reversible mechanochromic color change achieved by mechanical grinding (green to orange) and solvent adsorption (orange to green)., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Imidoylamidinate-based heteroleptic bis(2-phenylbenzothiazole)iridium(III) and -rhodium(III) complexes [( bt ) 2 M(N ∩ N)] ( bt = 2-phenylbenzothiazole, N ∩ N = N '-(benzo[ d ]thiazol-2-yl)acetimidamidyl ( Ir1 and Rh1 ), N '-(6-fluorobenzo[ d ]thiazol-2-yl)acetimidamidyl ( Ir2 ), N '-(benzo[ d ]oxazol-2-yl)acetimidamidyl ( Ir3 ), N '-(1-methyl-1 H -benzo[ d ]imidazol-2-yl)acetimidamidyl ( Ir4 ); yields 70-84%) were obtained by the reaction of the in situ-generated solvento-complex [( bt ) 2 M(NCMe) 2 ]NO 3 and benzo[ d ]thia/oxa/ N -methylimidozol-2-amines in the presence of NaOMe. Complexes Ir1 - 4 exhibited intense orange photoluminescence, reaching 37% at room temperature quantum yields, being immobilized in a poly(methyl methacrylate) matrix. A photophysical study of these species in a CH 2 Cl 2 solution, neat powder, and frozen (77 K) MeOC 2 H 4 OH-EtOH glass matrix─along with density-functional theory (DFT), ab initio methods, and spin-orbit coupling time-dependent DFT calculations─verified the effects of substitution in the imidoylamidinate ligands on the excited-state properties. Electrochemical (cyclic voltammetry and differential pulse voltammetry) and theoretical DFT studies demonstrated noninnocent behavior of the imidoylamidinate ligands in Ir1 - 4 and Rh1 complexes due to the significant contribution coming from these ligands in the HOMO of the complexes. The iridium(III) species exhibit a ligand (L, 2-phenylbenzothiazole)-centered ( 3 LC), metal-to-ligand (L', imidoylamidinate) charge-transfer ( 3 ML'CT, 3 MLCT) character of their emission. The imidoylamidinate-based iridium(III) species were proved to be effective as the emissive dopant in an organic light-emitting diode device, fabricated in the framework of this study.

Porous architectures characterized by parallel channels arranged in honeycomb or rectangular patterns are identified in two polymorphic crystals of a zwitterionic 4-(aryliodonio)-benzenesulfonate. The channels are filled with disordered water molecules which can be reversibly removed on heating. Consistent with the remarkable strength and directionality of the halogen bonds (XBs) driving the crystal packing formation, the porous structure is stable and fully preserved on almost quantitative removal and readsorption of water. The porous systems described here are the first reported cases of one-component 3D organic frameworks whose assembly is driven by XB only (XOFs). These systems are a proof of concept for the ability of zwitterionic aryliodonium tectons in affording robust one-component 3D XOFs. The high directionality and strength of the XBs formed by these zwitterions and the geometrical constraints resulting from the tendency of their hypervalent iodine atoms to act as bidentate XB donors might be key factors in determining this ability., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Three isomorphic cocrystals were obtained via the crystallization of [PPN][AuCl 2 ] ( 1 ) from CHBr 3 ( 1 ·CHBr 3 ), or CHCl 3 /1,2-C 2 F 4 Br 2 ( 1 ·CHCl 3 ) and CH 2 Cl 2 /Et 2 O ( 1 ·CH 2 Cl 2 ) mixtures. Analysis of the single-crystal X-ray diffraction data for these cocrystals revealed a gold(I)-involving two-center C-X···Au halogen bond (abbreviated as XB; X = Cl, Br) and a three-center bifurcated C-Br···( Cl - Au ) XB; in the latter, the gold(I)-chloride linkage functions as an integrated XB acceptor. The noncovalent nature and energies [spanning from -1.58 to -5.52 kcal/mol for C-X···Au and -6.37 kcal/mol for C-Br···( Cl - Au ) XBs] of these noncovalent interactions were studied by density functional theory calculations and topological analysis of the electron density distribution in the framework of the quantum theory of atoms-in-molecules (QTAIM) followed by noncovalent interaction (NCI) analysis at the B3LYP-D3/jorge-TZP-DKH level of theory. The nucleophilicity of the gold(I) centers toward halogens of halomethanes was verified by a set of independent methods including electrostatic potential surfaces, electron localization function projection, natural bond orbital charge transfer, electron density/electrostatic potential profile, Wiberg bond indexes, natural population analysis, and atoms-in-molecules charge analyses.

Gold(I)-catalyzed [4 + 2] cycloaddition of indolylynamides and cyanamides (aminonitriles) is an efficient redox-neutral and atom-economic route to diversely substituted 1,3-diamino-β-carbolines. The protocol operates under mild conditions (Ph 3 PAuNTf 2 5 mol %, DCE, 60 °C) with a good tolerance to functional groups (23 examples and yields up to 98%). The obtained β-carboline systems represent a versatile synthetic platform with modifiable substituents for successive functionalizations. Control experiments indicate the crucial role of both the nature of reactants and the identity of employed catalysts in the developed cycloaddition.

The architecture of transparent contacts is of utmost importance for creation of efficient flexible light-emitting devices (LEDs) and other deformable electronic devices. We successfully combined the newly synthesized transparent and durable silicone rubbers and the semiconductor materials with original fabrication methods to design LEDs and demonstrate their significant flexibility. We developed electrodes based on a composite GaP nanowire-phenylethyl-functionalized silicone rubber membrane, improved with single-walled carbon nanotube films for a hybrid poly(ethylene oxide)-metal-halide perovskite (CsPbBr 3 ) flexible green LED. The proposed approach provides a novel platform for fabrication of flexible hybrid optoelectronic devices.

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 3-Iodo-1-nitrosonaphthalene-2-ol (I-NON) was obtained by the copper(II)-mediated iodination of 1-nitroso-2-naphthol (NON). The suitable reactants and optimized reaction conditions, providing 94% NMR yield of I-NON, included the usage of Cu(OAc) 2 ·H 2 O and 1:2:8 Cu II /NON/I 2 molar ratio between the reactants. The obtained I-NON was characterized by elemental analyses (C, H, N), high-resolution ESI + -MS, 1 H and 13 C{ 1 H} NMR, FTIR, UV-vis spectroscopy, TGA, and X-ray crystallography (XRD). The copper(II) complexes bearing deprotonated I-NON were prepared as follows: cis -[Cu(I-NON-H)(I-NON)](I 3 ) ( 1 ) was obtained by the reaction between Cu(NON-H) 2 and I 2 in CHCl 3 /MeOH, while trans -[Cu(I-NON-H) 2 ] ( 2 ) was synthesized from I-NON and Cu(OAc) 2 in MeOH. Crystals of trans -[Cu(I-NON-H) 2 (THF) 2 ] ( 3 ) and trans -[Cu(I-NON-H) 2 (Py) 2 ] ( 4 ) were precipitated from solutions of 2 in CHCl 3 /THF and Py/CHCl 3 /MeOH mixtures, respectively. The structures of 1 and 3 - 4 were additionally verified by X-ray crystallography. The characteristic feature of the structures of 1 and 3 is the presence of intermolecular halogen bonds with the involvement of the iodine center of the metal-bound deprotonated I-NON. The nature of the I···I and I···O contacts in the structures of 1 and 3 , correspondingly, were studied theoretically at the DFT (PBE0-D3BJ) level using the QTAIM, ESP, ELF, NBO, and IGM methods.

The gold-catalyzed reaction between benzofuroxans, functioning as nitrene transfer reagents, and N -allylynamides leads to 3-azabicyclo[3.1.0]hexan-2-imines. This highly selective annulation proceeds smoothly under mild conditions (5 mol % Ph 3 PAuNTf 2 , PhCl, 60 °C) and exhibits high functional group tolerance (21 examples, ≤96% yields). The obtained cyclopropanated products represent a useful synthetic platform with an easily modulated substitution pattern as illustrated by their postmodifications. Intramolecular cyclopropanation of gold α-imino carbene intermediates is suggested as a key step of the catalytic cycle.

An interplay between 4-bromo- and 4-iodo-5-nitrophthalonitriles (XNPN, X=Br or I) and any one of the azines (pyridine 1, 4-dimethylaminopyridine 2, isoquinoline 3, 4-cyanopyridine 4, 2-methylpyridine 5, 2-aminopyridine 6, quinoline 7, 1-methylisoquinoline 8, and 2,2'-bipyridine 9) proceeds differently depending on steric and electronic effects of the heterocycles. Sterically unhindered azines 1-3 underwent N-arylation to give the corresponding azinium salts (characterized by 1 H and 13 C{H} NMR and high-resolution ESI-MS). In contrast, azines 4-9 with sterically hindered N atoms or bearing an electron-withdrawing substituent, form stable co-crystals with XNPN, where two interacting molecules are bound by halogen bonding. In all obtained co-crystals, X⋅⋅⋅N structure-directed halogen bonds were recognized and theoretically evaluated including DFT calculations (PBE0-D3/def2-TZVP level of theory), QTAIM analysis, molecular electrostatic potential surfaces, and noncovalent interaction plot index. Estimated energies of halogen bonding vary from -7.6 kcal/mol (for 6 ⋅ INPN) to -11.4 kcal/mol (5 ⋅ INPN)., (© 2021 Wiley-VCH GmbH.)

Triflic acid (10 mol%) catalyzes the highly regioselective [2 + 2 + 2] cycloaddition between two cyanamides and one ynamide to grant the 2,4,6-triaminopyrimidine core. The developed synthetic method is effective for the preparation of a family of the diversely substituted heterocyclic products (30 examples; yields up to 94%). The synthesis can be easily scaled up and conducted in gram quantities. As demonstrated by the post-functionalizations involving the amino-substituents, the obtained heterocycles represent a useful platform for the construction of miscellaneous pyrimidine-based frameworks. The performed density functional theory calculations verified a particular role of H+, functioning as an electrophilic activator, in the regioselectivity of the cycloaddition.

Gold(I)-catalyzed hetero-tetradehydro-Diels-Alder cycloaddition of enynamides and cyanamides comprises an efficient route to diversely substituted 2,6-diaminopyridines (28 examples; yields up to 99%). The reaction proceeds under very mild conditions (DCM, rt) with high functional group tolerance. The obtained 2,6-diaminopyridines represent a useful synthetic platform with an easily modulated substitution pattern for subsequent functionalizations of both the pyridine core and the N -substituents.

The complexes [RhX(COD)] 2 (X = Cl, Br; COD = 1,5-cyclooctadiene) form cocrystals with σ-hole iodine donors. X-ray diffraction studies and extensive theoretical considerations indicate that the d z 2 -orbitals of two positively charged rhodium(I) centers provide sufficient nucleophilicity to form a three-center halogen bond (XB) with the σ-hole donors. The two metal centers function as an integrated XB acceptor, providing assembly via a metal-involving XB., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

We report on gold(I)-catalyzed oxidative annulation involving ynamides, nitriles, and 2,3-dichloropyridine N -oxide. The application of 2,3-dichloropyridine N -oxide as an oxygen atom transfer reagent reverses the regioselectivity to give 5-amino -1,3-oxazoles, in comparison with the previously reported syntheses of aminooxazoles based on gold-catalyzed nitrene transfers to ynamides to furnish 4-amino -1,3-oxazoles. The developed oxygen atom transfer approach allows the generation of 1,3-oxazoles containing a variety of sulfonyl-protected alkylamino groups in the fifth position of the oxazole ring (29 examples; up to 88% yields). In addition, the use of N -substituted nitriles, namely cyanamides, leads to the facile generation of difficult-to-obtain 2,5-diaminooxazoles. The process is feasible for wide ranges of ynamides or nitriles, and it can be conducted in gram scale.

Hydrosilylation catalyzed by the rhodium(I) complex [Rh(acac)(CO) 2 ] or platinum(0)-based Karstedt's catalyst was employed to combine hydrophilic propargylated hydroxyethyl cellulose and hydrophobic hydride-terminated polydimethylsiloxane to give polymer hybrid structures. The final polymers were characterized by FTIR, solid state 1 H, 13 C and 29 Si NMR, contact angle, microcalorimetry and thermogravimetry measurements. The grafting degree was controlled by the catalyst choice and by the reagent load variations; an increase of the polysiloxane load and a change from Karstedt's to the rhodium catalyst led to a higher (from 2 to 7%) silicon content in the glycosilicones. The glycosilicones were insoluble in water, but swelled in organic solvents (DMSO, DMF, and chloroform). The hydrophilicity of the glycosilicones decreased with incrementing silicon content: the contact angles increased from 30 (cellulose) to 103-131° in the hybrids. The glycosilicones obtained via the hydrosilylation are less toxic toward algae Chlorella vulgaris and infusoria Paramecium caudatum than those obtained with CuAAC., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Two phosphorescent Pt II -based cyclometalated complexes were co-crystallized 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.

The theoretical data for the half-lantern complexes [{Pt( C N ^ )(μ- S N ^ )} 2 ] [1-3; C N ^ is cyclometalated 2-Ph-benzothiazole; S N ^ 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 d z 2 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⋅⋅⋅d z 2 [Pt II ] XBs between iodine σ-holes and lone pairs of the positively charged (Pt II ) 2 centers acting as nucleophilic sites. The polymer includes a curved linear chain ⋅⋅⋅Pt 2 ⋅⋅⋅I(arene F )I⋅⋅⋅Pt 2 ⋅⋅⋅ involving XB between iodine atoms of the perfluoroarene linkers and (Pt II ) 2 moieties. The 195 Pt NMR, UV/Vis, and CV studies indicate that XB is preserved in CH(D) 2 Cl 2 solutions., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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 13 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.

The abundance and geometric features of nonbonding contacts between metal centers and `soft' sulfur atoms bound to a non-metal substituent R were analyzed by processing data from the Cambridge Structural Database. The angular arrangement of M, S and R atoms with ∠(R-S...M) down to 150° was a common feature of the late transition metal complexes exhibiting shortened R-S...M contacts. Several model nickel(II), palladium(II), platinum(II) and gold(I) complexes were chosen for a theoretical analysis of R-S...M interactions using the DFT method applied to (equilibrium) isolated systems. A combination of the real-space approaches, such as Quantum Theory of Atoms in Molecules (QTAIM), noncovalent interaction index (NCI), electron localization function (ELF) and Interacting Quantum Atoms (IQA), and orbital (Natural Bond Orbitals, NBO) methods was used to provide insights into the nature and energetics of R-S...M interactions with respect to the metal atom identity and its coordination environment. The explored features of the R-S...M interactions support the trends observed by inspecting the CSD statistics, and indicate a predominant contribution of semicoordination bonds between nucleophilic sites of the sulfur atom and electrophilic sites of the metal. A contribution of chalcogen bonding (that is formally opposite to semicoordination) was also recognized, although it was significantly smaller in magnitude. The analysis of R-S...M interaction strengths was performed and the structure-directing role of the intramolecular R-S...M interactions in stabilizing certain conformations of metal complexes was revealed.

Reinvestigation of ( o -benzoquinonedioximate) 2 Ni/I 2 systems demonstrated that the reaction itself and also the crystallization conditions dramatically affect the identity of generated species. Crystallization (CHCl 3 , 20-25 °C) of the nickel(II) dioximate complex [Ni(bqoxH) 2 ] (bqoxH 2 = o -benzoquinonedioxime) with I 2 in the 1:(1-10) molar ratios of the reactants led to several ( o -benzoquinonedioximate) 2 Ni derivatives and/or iodine adducts [Ni(I)(bqoxH)(bqoxH 2 )]· 3 / 2 I 2 , [Ni(I 3 )(bqoxH)(bqoxH 2 )]·[Ni(bqoxH) 2 ], and [Ni(I 3 )(bqox •- )(bqoxH 2 )]·I 2 ; the latter one, featuring the anion-radical bqox •- ligand, is derived from the formal (-2H + /1 e - )-oxidation of bqoxH 2 . In these three adducts, various types of noncovalent interactions were identified experimentally and their existence was supported theoretically. The [Ni(I 3 )(bqox •- )(bqoxH 2 )]·I 2 adduct exhibits simultaneous semicoordination and coordination patterns of the triiodide ligand; this is the first recognition of the semicoordination of any polyiodide ligand to a metal center. The semicoordination noncovalent contact Ni···I 3 (3.7011(10) Å) is substantially longer that the Ni-I 3 coordination bond (2.8476(9) Å), and the difference in energies between these two types of linkages is 8-12 kcal/mol.

2,3-Dichloropyridine N -oxide, a novel oxygen transfer reagent, allows the conductance of the gold(I)-catalyzed oxidation of alkynes to 1,2-dicarbonyls in the absence of any acid additives and under mild conditions to furnish the target species, including those derivatized by highly acid-sensitive groups. The developed strategy is effective for a wide range of alkyne substrates such as terminal- and internal alkynes, ynamides, alkynyl ethers/thioethers, and even unsubstituted acetylene (40 examples; yields up to 99%). The oxidation was successfully integrated into the trapping of reactive dicarbonyls by one-pot heterocyclization and into the synthesis of six-membered azaheterocycles. This synthetic acid-free route was also successfully applied for the total synthesis of a natural 1,2-diketone.

Hexaiododiplatinates(ii) bearing ammonium and phosphonium cations, [R4N]2[Pt2(μ-I)2I4] {R = Et (1) and n-Bu (2)} and [R3PR1]2[Pt2(μ-I)2I4] {R = n-Bu and R1 = n-Bu (3); R = Ph and R1 = Ph (4); R = Ph and R1 = CH2Ph (5)}, were synthesized and characterized by high resolution ESI-MS, 1H, 13C{1H}, 31P{1H}, and 195Pt NMR spectroscopy, Fourier transform infrared and Raman spectroscopy, X-ray diffraction (XRD), X-ray powder diffraction, and also electrostatic surface potential calculations. Complexes 1-3 were cocrystallized with halogen bond (XB) donors based on organic iodides featuring electron withdrawing groups {REWGIs: 1,3,5-triiodotrifluorobenzene (1,3,5-FIB), iodopentafluorobenzene (IPFB), 1,4-diiodotetrafluorobenzene (1,4-FIB), and tetraiodoethylene (C2I4)} to give crystalline adducts 1·2(1,3,5-FIB), 1·2IPFB, 2·2(1,4-FIB), and 3·C2I4. Inspection of the XRD data of the obtained adducts revealed the presence, in all four structures, of intermolecular REWGII-Pt XBs between the iodine centers of REWGIs and the terminal iodide ligands of [Pt2(μ-I)2I4]2- anions, where the latter act as rectangular XB-accepting synthons forming XBs with two, three, and even four Pt-Iterminal ligands. The results of Hirshfeld molecular surface analysis and density functional theory (DFT) calculations (the M06/DZP-DKH level of theory) followed by topological analysis of the electron density distribution within the framework of Bader's approach (QTAIM) confirmed the existence of the detected XBs, and their estimated energies vary from 2.2 to 4.7 kcal mol-1.

The dihalomethanes CH 2 X 2 (X=Cl, Br, I) were co-crystallized with the isocyanide complexes trans-[MX M 2 (CNC 6 H 4 -4-X C ) 2 ] (M=Pd, Pt; X M =Br, I; X C =F, Cl, Br) to give an extended series comprising 15 X-ray structures of isostructural adducts featuring 1D metal-involving hexagon-like arrays. In these structures, CH 2 X 2 behave as bent bifunctional XB/XB-donating building blocks, whereas trans-[MX M 2 (CNC 6 H 4 -4-X C ) 2 ] act as a linear XB/XB acceptors. Results of DFT calculations indicate that all XCH 2 -X⋅⋅⋅X M -M contacts are typical noncovalent interactions with estimated strengths in the range of 1.3-3.2 kcal mol -1 . A CCDC search reveals that hexagon-like arrays are rather common but previously overlooked structural motives for adducts of trans-bis(halide) complexes and halomethanes., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Inspection of the X-ray structures of the newly prepared trans-[M II (CNXyl) 2 (DAPT) 2 ]Cl(BF 4 ) (M=Pd, Pt; Xyl=2,6-Me 2 C 6 H 3 ; 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 d 8 -Pt II and d 8 -Pd II 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 d z 2 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., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reaction of [Ir(μ-Cl)(ppy) 2 ] 2 (1) with 4 equivs of CNC 6 H 4 X (X = F 2a, Cl 2b, Br 2c, I 2d) in the presence of 2 equivs of AgOTf in dichloromethane at 20-25 °C furnished the bisisocyanide complexes [Ir(ppy) 2 (CNC 6 H 4 X) 2 ](OTf) ([3a-d](OTf); 72-87%). Reaction of [3a-d](OTf) with an excess of gaseous ammonia at room temperature gave the bisdiaminocarbene species [Ir(ppy) 2 {C(NH 2 )NHC 6 H 4 X} 2 ](OTf) [5a-d](OTf) (73-83%); the two-step addition proceeds through an intermediate formation of appropriate monocarbene complexes [4a-d](OTf). Further reaction of [5a-d](OTf) with an excess of gaseous ammonia at 50 °C led to the cleavage of one diaminocarbene ligand to the cyanide ligand in [Ir(ppy) 2 (CN){C(NH 2 )NHC 6 H 4 X}] (6a-d) and this transformation is accompanied with the elimination of a substituted aniline. Treatment of [5a-d](OTf) with N(CH 2 CH 2 OH) 3 at 50 °C resulted in the cleavage of the diaminocarbene ligand to the isocyanide and uncomplexed NH 3 ; isocyanide remains bound to the iridium(iii) center in [Ir(ppy) 2 {C(NH 2 )NHC 6 H 4 X}(CNC 6 H 4 X)](OTf) (4a-d). All isolated compounds were characterized by elemental analyses (C, H, N), molar conductivity measurements, TG/DTA, HRESI +/- -MS, FTIR, 1D ( 1 H, 13 C{ 1 H}, 19 F{ 1 H}) and 2D ( 1 H, 1 H-COSY, 1 H, 13 C-HMQC/ 1 H, 13 C-HSQC, 1 H, 13 C-HMBC) NMR, and also by X-ray diffraction (for the bisisocyanide 3, the diaminocarbene/isocyanide 4, the bisdiaminocarbene 5, and the diaminocarbene/cyanide 6 type complexes).

Efficient gold(I)-catalyzed oxidation of COR 2 -functionalized internal alkynes to vicinal tricarbonyl compounds by 2,6-dichloropyridine N-oxide proceeds under mild conditions (DCM, rt). This catalytic reaction provides a good to excellent yielding route to diverse tricarbonyls such as α,β-diketoesters, 1,2,3-triketones, and α,β-diketoamides. The utility of these compounds was also demonstrated by facile one-pot synthesis of important azaheterocyclic systems.

The complexes [Pt(tpp)] (H 2 tpp=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⋅⋅⋅[M II ] (d 8 M=Pt, Pd) interactions. The adduct [Pt(tpp)]⋅2 C 6 F 6 is monomeric, whereas the diketonate 1:1 adducts form columnar infinity 1D-stack assembled by simultaneous action of both π-hole⋅⋅⋅[M II ] and C⋅⋅⋅F interactions. The reverse sandwiches are based on noncovalent interactions and calculated ESP distributions indicate that in π-hole⋅⋅⋅[M II ] contacts, [M II ] plays the role of a nucleophile., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The mechanism of the addition of indazole (Ind)-a bifunctional aromatic N,NH-nucleophile-to cyclohexyl isocyanide coordinated to the palladium(II) center in the model complex cis -[PdCl₂(CNMe)(CNCy)] ( 1 ) to give the corresponding aminocarbene ligand was investigated in detail by theoretical (DFT) methods. The most plausible mechanism of this reaction is that of the associative type involving nucleophilic attack of Ind by its unprotonated N atom at the isocyanide carbon atom followed by the stepwise proton transfer from the nucleophile molecule to the isocyanide N atom via deprotonation/protonation steps. Two reaction channels based on two tautomeric forms of indazole were found. The channel leading to the experimentally isolated aminocarbene product is based on the less stable tautomeric form. Another channel based on the more stable tautomer of Ind is slightly kinetically more favorable but it is endergonic. Thus, the regioselectivity of this reaction is thermodynamically rather than kinetically driven. The bonding situation in key species was analyzed.

In the current study, we evaluated the solubility of a number of organometallic species and showed that it is noticeably improved in diiodomethane when compared to other haloalkane solvents. The better solvation properties of CH 2 I 2 were associated with the substantially better σ-hole-donating ability of this solvent, which results in the formation of uniquely strong solvent-(metal complex) halogen bonding. The strength of the halogen bonding is attenuated by the introduction of additional halogen atoms in the organometallic species owing to the competitive formation of more favourable intermolecular complex-complex halogen bonding. The exceptional solvation properties of diiodomethane and its inertness towards organometallic species make this solvent a good candidate for NMR studies, in particular, for the acquisition of spectra of insensitive spins., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Facile gold-catalyzed hydrohydrazidation of alkynes with various hydrazides R 2 CONHNH 2 (R = Alk or Ar; including those with an additional nucleophilic moiety) in the presence of Ph 3 PAuNTf 2 (6 mol %) leading to a wide range of substituted keto- N-acylhydrazones (18 examples) in excellent to good yields (99-66%) is reported. This novel metal-catalyzed coupling proceeds under mild conditions (chlorobenzene, 60 °C), exhibits high functional group tolerance, and is insensitive to the electronic and steric effects of the substituents in the reactants.

Zinc(II)-catalyzed (10 mol % ZnCl 2 ) coupling of acyl hydrazides and dialkylcyanamides in ethanol leads to 3-dialkylamino-1,2,4-triazoles (76-99%; 17 examples). This reaction represents a novel, straightforward, and high-yielding approach to practically important 3-NR 2 -1,2,4-triazoles, which utilizes commercially available and/or easily generated substrates. Seventeen new 3-NR 2 -1,2,4-triazoles were characterized by HRESI + -MS and IR, 1 H, and 13 C{ 1 H} NMR spectroscopies and five species additionally by single-crystal X-ray diffraction (XRD). The Zn II -catalyzed reaction proceeds via initial generation of the [Zn{RC(=O)NHNH 2 } 3 ](ZnCl 4 ) complexes (exemplified by isolation of the complex with R = Ph, 76%; characterized by HRESI + -MS, IR, CP-MAS TOSS 13 C{ 1 H} NMR, and XRD). Electronic effects of substituents at the acyl hydrazide moiety do not significantly affect the reaction rate and the yield of the target triazoles, whereas the steric hindrances reduce the reaction rate without affecting the yield of the heterocycles., Competing Interests: The authors declare no competing financial interest.

The reaction of cis-[PdCl 2 (CNXyl) 2 ] (Xyl = 2,6-Me 2 C 6 H 3 ) with the aminoazoles [1 H-imidazol-2-amine (1), 4 H-1,2,4-triazol-3-amine (2), 1 H-tetrazol-5-amine (3), 1 H-benzimidazol-2-amine (4), 1-alkyl-1 H-benzimidazol-2-amines, where alkyl = Me (5), Et (6)] in a 2:1 ratio in the presence of a base in CHCl 3 at RT proceeds regioselectively and leads to the binuclear diaminocarbene complexes [(ClPdCNXyl) 2 {μ-C(N-azolyl)N(Xyl)C═NXyl}] (7-12; 73-91%). Compounds 7-12 were characterized by C, H, N elemental analyses, high-resolution ESI + -MS, Fourier transform infrared spectroscopy, 1D ( 1 H, 13 C) and 2D ( 1 H, 1 H-COSY, 1 H, 1 H-NOESY, 1 H, 13 C-HSQC, 1 H, 13 C-HMBC) NMR spectroscopies, and X-ray diffraction (XRDn). Inspection of the XRDn data and results of the Hirshfeld surface analysis suggest the presence in all six structures of intramolecular π-hole isocyanide ···π arene interactions between the electrophilic C atom of the isocyanide moiety and the neighboring arene ring. These interactions also result in distortion of the Pd-C≡N-Xyl fragment from the linearity. Results of density functional theory calculations [M06/MWB28 (Pd) and 6-31G* (other atoms) level of theory] for model structures of 7-9 followed by the topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method) reveal the presence of these weak interactions also in a CHCl 3 solution, and their calculated strength is 1.9-2.2 kcal/mol. The natural bond orbital analysis of 7-9 revealed that π(C-C)Xyl → π*(C-N)isocyanide charge transfer (CT) takes place along with the intramolecular π-hole isocyanide ···π arene interactions. The observed π(C-C) Xyl → π*(C-N) isocyanide CT is due to ligation of the isocyanide to the metal center, whereas in the cases of the uncomplexed p-CNC 6 H 4 NC and CNXyl species, the effects of CT are negligible. Available CCDC data were processed from the perspective of isocyanide-involving π-hole···π interactions, disclosed the role of metal coordination in the π-hole donor ability of isocyanides, and verified the π-hole isocyanide ···π arene interaction effect on the stabilization of the in-conformation in metal-bound acyclic diaminocarbenes.

The reaction of cis-[PdCl 2 (CNCy) 2 ] (1) with thiazol-2-amines (2-10) leads to the C,N-chelated diaminocarbene-like complexes [PdCl{ C(N(H)4,5-R 2 -thiazol-2-yl)NHCy}(CNCy)] (11-14; 82-91%) in the case of 4,5-R 2 -thiazol-2-amines (R, R = H, H (2), Me, Me (3), -(CH 2 ) 4 - (4)) and benzothiazol-2-amine (5) or gives the diaminocarbene species cis-[PdCl 2 {C(N(H)Cy)N(H)4-R-thiazol-2-yl}(CNCy)] (15-19; 73-93%) for the reaction with 4-aryl-substituted thiazol-2-amines (R = Ph (6), 4-MeC 6 H 4 (7), 4-FC 6 H 4 (8), 4-ClC 6 H 4 (9), 3,4-F 2 C 6 H 3 (10)). Inspection of the single-crystal X-ray diffraction data for 15-17 and 19 suggests that the structures of all these species exhibit previously unrecognized bifurcated chalcogen-hydrogen bonding μ (S,N-H) Cl and also Pd II ···Pd II metallophilic interactions. These noncovalent interactions collectively connect two symmetrically located molecules of 15-17 and 19, resulting in their solid-state dimerization. The existence of the μ (S,N-H) Cl system and its strength (6-9 kcal/mol) were additionally verified/estimated by a Hirshfeld surface analysis and DFT calculations combined with a topological analysis of the electron density distribution within the formalism of Bader's theory (AIM method) and NBO analysis. The observed noncovalent interactions are jointly responsible for the dimerization of 15-19 not only in the solid phase but also in CHCl 3 solutions, as predicted theoretically by DFT calculations and confirmed experimentally by FTIR, HRESI-MS, 1 H NMR, and diffusion coefficient NMR measurements. Available CCDC data were processed under the new moiety angle, and the observed μ (S,E-H) Cl systems were classified accordingly to E (E = N, O, C) type atoms.

This work describes the preparation of a series of platinum-aminocarbene complexes [PtCl{C(N=C a (C 6 R 2 R 3 R 4 R 5 CON b ))=N(H)R 1 }(CNR 1 )] a-b ( 8 - 19 , 65-75% isolated yield) via the reaction of cis -[PtCl 2 (CNR 1 ) 2 ] (R 1 = Cy 1 , t -Bu 2 , Xyl 3 , 2-Cl-6-MeC 6 H 3 4 ) with 3-iminoisoindolin-1-ones HN=C a (C 6 R 2 R 3 R 4 R 5 CON b H) (R 2 -R 5 = H 5 ; R 3 = Me, R 2 , R 4 , R 5 = H 6 ; R 3 , R 4 = Cl, R 2 , R 5 = H 7 ). New complexes 17 - 19 were characterized by elemental analyses (C, H, N), ESI + -MS, Fourier transform infrared spectroscopy (FT-IR), one-dimensional ( 1 H, 13 C{ 1 H}), and two-dimensional ( 1 H, 1 H correlation spectroscopy (COSY), 1 H, 13 C heteronuclear multiple quantum correlation (HMQC)/ 1 H, 13 C heteronuclear single quantum coherence (HSQC), 1 H, 13 C heteronuclear multiple bond correlation (HMBC)) NMR spectroscopy, and authenticity of known species 8 - 16 was confirmed by FT-IR and 1 H and 13 C{ 1 H} NMR. Complexes 8 - 19 were assessed as catalysts for hydrosilylation of terminal alkynes with hydrosilanes to give vinyl silanes, and complex [PtCl{C(N=C a (C 6 H 3 (5-Me)CON b ))=N(H)(2-Cl-6-MeC 6 H 3 )}{CN(2-Cl-6-MeC 6 H 3 )}] a - b ( 18 ) showed the highest catalytic activity. The catalytic system proposed operates at 80-100 °C for 4-6 h in toluene and with catalyst loading of 0.1 mol %, enabling the reaction of a number of terminal alkynes (PhC≡CH, t -BuC≡CH, and 4-( t -Bu)C 6 H 4 C≡CH) with hydrosilanes (Et 3 SiH, Pr 3 SiH, i -Pr 3 SiH, and PhMe 2 SiH). Target vinyl silanes were prepared in 48-95% yields (as a mixture of α/β isomers) and with maximum turnover number of 8.4 × 10 3 . Hydrosilylation of internal alkynes (PhC≡CPh, Me(CH 2 ) 2 C≡C(CH 2 ) 2 Me, and PhC≡CMe) with hydrosilanes (Et 3 SiH, PhMe 2 SiH) led to the corresponding trisubstituted silylated alkenes in 86-94% yields. Initial observations on the mechanism of the catalytic action of platinum-ADC catalysts 8 - 19 suggested a molecular catalytic cycle., Competing Interests: The authors declare no competing financial interest.