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Bis(carbazolide) complexes M[3,6‐tBu2‐1,8‐(RC≡C)2Carb]2(THF)n (R=SiMe3, n=0, M=Ca, Yb; R=Ph, n=1, M=Ca, Yb; n=0, M=Yb) were synthesized through transamination reaction of M[N(SiMe3)2]2(THF)2 with two molar equivalents of carbazoles. The complexes feature M(η2‐C≡C)4 structural motif composed of M(II) ions encapsulated by four acetylene fragments due to atypical for alkaline‐ and rare‐earth metals η2‐interactions with triple C≡C bond. This interaction is evidenced experimentally by X‐ray diffraction, Raman spectroscopy in the solid state and by NMR‐spectroscopy in the solution. According to QTAIM analysis there are 4 bond critical points (3;−1) between the metal atom and each of the triple bonds, which are connected by a strongly curved, almost T‐shaped bond pathway. [ABSTRACT FROM AUTHOR]

A synthetic method for the preparation of selenoglycolurils is reported. Target compounds were obtained by two‐stage transformation of unsubstituted, 1‐substituted and 1,3‐disubstituted thioglycolurils by S‐methylation with MeI to the corresponding isothiouronium salts (Step 1) followed by selenation with NaHSe generated in situ from grey Se and NaBH4 (Step 2). Selenoglycolurils possessed potent antifungal activity against Candida albicans and Cryptococcus neoformans (MIC 0.25–0.125 μg/mL) with no discernable toxicity against mamallian cells, supporting the unique role of organoselenium compounds as novel antifungal agents. [ABSTRACT FROM AUTHOR]

Compounds with the general formula Ln3+(SeO3)(HSeO3)·2H2O, where Ln = Sm3+, Tb3+, Nd3+ and Lu3+, are characterized by orthorhombic symmetry with space group P212121 and unit‐cell parameters in the ranges a ∼ 6.473–6.999, b ∼ 6.845–7.101, c ∼ 16.242–16.426 Å. Light‐purple irregularly shaped crystals of a new monoclinic polytype of neodymium selenite Nd(SeO3)(HSeO3)·2H2O have been obtained during a mild‐condition hydrothermal synthesis. The monoclinic unit‐cell parameters are: a = 7.0815 (2), b = 6.6996 (2), c = 16.7734 (5) Å, β = 101.256 (1)°, V = 780.48 (6) Å3; space group P21/c. The crystal structures of Nd(SeO3)(HSeO3)·2H2O polymorphs show order–disorder (OD) character and can be described using the same OD groupoid family, more precisely a family of OD structures built up from two kinds of non‐polar layers (category IV). The first monoclinic maximum degree order (MDO) structure (MDO1‐polytype) with space group P21/c can be obtained when the inversion centre is active in the L2n‐type layers, while the second MDO structure (MDO2‐polytype) is orthorhombic with space group P212121 and can be obtained when the [21‐‐] operation is active in the L2n‐type layers. The structural complexity parameters and DFT calculations of both polytypes show that the polytype structures are extremely close energy‐wise and almost equally viable from the point of total energy of the structure. [ABSTRACT FROM AUTHOR]

A new class of palladium nanoparticles encapsulated in an organic crystalline salt matrix Pd@F2 (A‐2) was developed. Matrix A‐2 was readily prepared by mixing an aqueous solution of the tetrasodium salt of tetraphenylmethane‐tetrasulfonate and the PdCl4 salt of protonated tetrakis(4‐aminophenyl)under hydrogen in water. Matrix A‐2 contained 17–20 % of palladium and was not pyrophoric. The average size of the palladium metal particles was 7 nm. Matrix A‐2 could be used as an efficient heterogeneous catalyst for the reduction of acetylene derivatives and had activity similar to that of Pd/C. The catalyst could be recovered and reused several times with just one four‐hundredth of the palladium leaching after the first cycle. The reduction of diphenylacetylene could be selectively stopped at the cis‐stilbene stage after one equivalent of hydrogen was absorbed. The same selective conversion could also be accomplished with terminal acetylenes. Matrix A‐2 reduced aldehyde and epoxide groups very slowly which allowed the selective reduction of the acetylenes in the presence of aldehydes. This behavior contrasts with that of Pd/C which reduces both aldehyde and acetylene groups simultaneously. A model, suggesting the selective imbedding of the aldehyde groups in the organic F2 matrix of A‐2, isolating them from the palladium active sites, explains the observed phenomena. [ABSTRACT FROM AUTHOR]

A concise seven‐step asymmetric synthesis of MSD's potent hNK1 antagonist containing a pyrrolizidinone core bearing two fluorine‐substituted aryl groups was developed. The pyrrolizidinone unit was constructed by reductive recyclization of a properly functionalized cyclic nitronate, which was assembled by stereoselective [4+2]‐cycloaddition of a nitroalkene with a vinyl ether bearing a Whitesell's chiral auxiliary group. The configuration of the hNK1 antagonist, which was previously suggested based on bioactivity data, was confirmed by X‐ray analysis. The crystal structure features multiple weak interactions involving fluorine atoms that are also found in a complex with the hNK1 receptor simulated by molecular docking. [ABSTRACT FROM AUTHOR]

We report the synthesis and structures of two base‐free alkoxide dysprosium(III) complexes of formula [Dy(L1)2(μ‐η6:η1‐Ph)2BPh2] ⋅ CH2Cl2 (1) and [Dy(L2)2(μ‐η6:η1‐Ph)2BPh2] ⋅ 3(C7H8) (2) featuring a tetraphenylborate binding (L1=2,6‐dibenzhydryl‐4‐(tert‐butyl)phenolate, L2=tri(naphtalen‐1‐yl)methanolate). Investigations of the magnetic properties for 1 in line with theoretical calculations reveal the occurrence of a field‐induced slow relaxation of the magnetization. [ABSTRACT FROM AUTHOR]

Acylation of nitroalkylmalonates was found to yield substituted isoxazoline derivatives. This redox‐neutral transformation has a wide substrate scope and produces target products with yields up to 92%. Various substituents (aryl, alkyl, and ester) at the C3 and C4 positions of the resulting isoxazolines were also tolerated. A quick assembly of the isoxazoline ring starting from nitroalkenes and malonates was successfully developed. Control experiments showed that the intramolecular ring closure is the most likely key mechanistic step. Subsequent transformations into pyrrolidine and furane derivatives demonstrated the synthetic utility of the obtained products. [ABSTRACT FROM AUTHOR]

Cyclopentadienes readily undergo fast and selective Diels–Alder reactions which can be used for conjugation of biomolecules and polymers. Herein we present a new method for the photochemical generation of cyclopentadienes by the visible light irradiation of the iron complexes [(C5H4R)Fe(arene)]+. This reaction proceeds at room temperature, in water, and in the presence of potentially interfering amino acids. Free cyclopentadiene is trapped by dienophiles to give the corresponding Diels–Alder adducts in 72–95 % yield. [ABSTRACT FROM AUTHOR]

Diene rhodium complexes are important catalysts in modern organic synthesis. Herein, we report a new approach to such complexes with the uncommon planar chirality. The synthesis is achieved by face‐selective coordination of the prochiral 2,5‐disubstituted‐1,4‐benzoquinones (R2‐Q) with rhodium precursors containing the chiral auxiliary ligand S‐salicyl‐oxazoline (S‐Salox). Such coordination leads to the formation of (R,R‐R2‐Q)Rh(S‐Salox) complexes in high yields and with exceptional diastereoselectivity (d. r.>20 : 1). Subsequent replacement of the auxiliary ligand provides various benzoquinone rhodium complexes with retention of the planar chirality. Combined theoretical and experimental studies show that due to their electron‐withdrawing nature benzoquinones bind metals stronger than the related 1,4‐cyclohexadiene, but weaker than other common diene ligands, such as cyclooctadiene. [ABSTRACT FROM AUTHOR]

A series of new tris(pyrazolyl)borate (Tp−) and tris(2‐pyridylpyrazolyl)borate (TpPy−) Eu3+, Gd3+, Tb3+ and Dy3+ complexes with the dianionic ligand 4,4′‐bis(2‐sulfonatostyryl)biphenyl (Ssp2−, a widely used fluorescent whitener) were synthesized and their luminescence properties were studied. The Gd3+, Tb3+ and Dy3+ compounds possess only ligand‐centered emission, arising from the Ssp2− ligand, with quantum yields of up to 60 %. While the emission centers in these complexes are similar, the positions of the luminescence maxima, the emission quantum yields, and the lifetimes change in the order [(Tp2Ln)2Ssp]<[(TpPyLnSsp)2]<[Ln2Ssp3]n. Among the complexes studied, Eu3+‐centered emission was observed for only [(Tp2Eu)2Ssp]. In this compound, Tp− plays the role of an antenna ligand for Eu3+‐radiation, though the quantum yield is only 5 %. [ABSTRACT FROM AUTHOR]

Spin‐crossover between high‐spin (HS) and low‐spin (LS) states of selected transition metal ions in polynuclear and polymeric compounds is behind their use as multistep switchable materials in breakthrough electronic and spintronic devices. We report the first successful attempt to observe the dynamics of a rarely found broken‐symmetry spin state in binuclear complexes, which mixes the states [HS‐LS] and [LS‐HS] on a millisecond timescale. The slow exchange between these two states, which was identified by paramagnetic NMR spectroscopy in solutions of two spin‐crossover iron(II) binuclear helicates that are amenable to molecular design, opens a path to double quantum dot cellular automata for information storage and processing. [ABSTRACT FROM AUTHOR]

A new method for the synthesis of chiral diene rhodium catalysts is introduced. The readily available racemic tetrafluorobenzobarrelene complexes [(R2‐TFB)RhCl]2 were separated into two enantiomers via selective coordination of one of them with the auxiliary S‐salicyl‐oxazoline ligand. One of the resulting chiral complexes with an exceptionally bulky diene ligand [(R,R‐iPr2‐TFB)RhCl]2 was an efficient catalyst for the asymmetric insertion of diazoesters into B−H and Si−H bonds giving the functionalized organoboranes and silanes with high yields (79–97 %) and enantiomeric purity (87–98 % ee). The stereoselectivity of separation via auxiliary ligand and that of the catalytic reaction was predicted by DFT calculations. [ABSTRACT FROM AUTHOR]

On the basis of the 1,2,3,4‐tetrahydrofluorenyl ligand, a simple approach was developed to new effective rhodium catalysts for the construction of C−C and C−N bonds. The halide compounds [(η5‐tetrahydrofluorenyl)RhX2]2 (2 a: X=Br; 2 b: X=I) were synthesized by treatment of the bis(ethylene) derivative (η5‐tetrahydrofluorenyl)Rh(C2H4)2 (1 a) with halogens. An analogous reaction of the cyclooctadiene complex (η5‐tetrahydrofluorenyl)Rh(cod) (1 b) with I2 is complicated by the side formation of [(cod)RhI]2. The reaction of 2 b with 2,2′‐bipyridyl leads to cation [(η5‐tetrahydrofluorenyl)Rh(2,2′‐bipyridyl)I]+ (3). The halide abstraction from 2 a,b with thallium or silver salts allowed us to prepare sandwich compounds with incoming cyclopentadienyl, dicarbollide and mesityleneligands [(η5‐tetrahydrofluorenyl)RhCp]+ (4), (η5‐tetrahydrofluorenyl)Rh(η‐7,8‐C2B9H11) (5), and [(η5‐tetrahydrofluorenyl)Rh(η‐mesitylene)]2+ (6). The structures of 1 b, 2 b ⋅ 2I2, 3PF6, 4TlI4, 5, and [(cod)RhI]2 were determined by X‐ray diffraction. Compounds 2 a,b efficiently catalyze the oxidative coupling of benzoic acids with alkynes to selectively give isocoumarins or naphthalenes, depending on the reaction temperature. Moreover, they showed moderate catalytic activity in other annulations of alkynes with aromatic compounds (such as benzamide, acetanilide, etc.) which proceed through CH activation. Compound 2 b also effectively catalyzes the reductive amination of aldehydes and ketones in the presence of carbon monoxide and water via water‐gas shift reaction, giving amines in high yields (67–99 %). [ABSTRACT FROM AUTHOR]

2,4,9‐Triazaadamantanes (TRIADs) are promising yet scarcely available, conformationally rigid platforms for potential applications in the design of functional molecules and materials. Here, we report a facile synthesis of various N‐ and C7‐substituted 2,4,9‐triazaadamantanes, starting from amines and 4‐allylhepta‐1,6‐dienes. A focus was placed on the synthesis of 2,4,9‐triazaadamantanes bearing reactive groups (NH2, propargyl, OH) on the bridge nitrogen atoms, which were then used to decorate the 3D scaffold by hydrazone, triazole, and boronate linkages. A reversible opening of the adamantane cage to the acyclic tris‐oxime form was observed for 2,4,9‐triazaadamantanes possessing hydroxy‐groups on the nitrogen atoms (TRIAD‐triols). This process could be controlled by temperature or by complexation of TRIAD‐triol with a boronic acid. The structure of 2,4,9‐triazaadamantanes and the stereodynamics at the bridge nitrogen atoms were studied by X‐ray analysis and DFT calculations. [ABSTRACT FROM AUTHOR]

The reaction of cobalt(II) and iron(III) pivalates with anions of 2‐furancarboxylic acid (pyromucic acid, Hfur) yielded trinuclear homometallic complexes with linear ([Co3(fur)6(phen)2] (1, phen=1,10‐phenanthroline)) and triangular ([Co3O(fur)6(H2O)3] (3), [Fe3O(fur)6(THF)3] ⋅ 3THF (4)) structures of the metal moiety. The hexanuclear mixed carboxylate cobalt complex [Co6(piv)8(Hpiv)4(fur)2(OH)2] (2, piv−=(CH3)3COO−) was isolated as an intermediate in the synthesis of 3. According to CVA data, complex 3 contains bivalent and trivalent cobalt ions. According to Mossbauer spectroscopy data, all the iron(III) atoms in 4, which is an isostructural analogue of 3, are solely in the high‐spin state. The antibacterial activity of compounds 1–4, K(fur) (5) and Na(fur) (6) was determined in vitro against a non‐pathogenic Mycolicibacterium smegmatis strain. The results of in vitro biological tests against Mycolicibacterium smegmatis showed a high bioactivity of complexes 1 and 4. [ABSTRACT FROM AUTHOR]

A new chiral cyclopentadiene CpmyrH was synthesized from the natural terpene (R)‐myrtenal in 5 steps and about 40 % total yield. The key step was the reaction of vinyl‐dibromocyclopropane derivative with MeLi which provided the diene CpmyrH via Skattebøl rearrangement. The reaction of CpmyrH with [(cod)Rh(OAc)]2 gave the rhodium(I) complex (Cpmyr)Rh(cod) and subsequent oxidation with halogens X2 gave the rhodium(III) complexes [(Cpmyr)RhX2]2 (X = Br, I). Complex (Cpmyr)Rh(cod) in combination with benzoyl peroxide catalyzed the C–H activation of O‐pivaloyl‐phenylhydroxamic acid and its subsequent annulation with alkenes giving dihydroisoquinolones with high yield (70–90 %) but moderate enantioselectivity (16–36 % ee). [ABSTRACT FROM AUTHOR]

A new approach for the synthesis of highly pharmaceutically relevant 4‐fluoropyrazoles via oxidative annulation of α‐fluoronitroalkenes with in situ prepared hydrazones was developed. The reaction is efficiently promoted by trifluoroacetic acid while atmospheric oxygen was used as an oxidant. Broad substrate scope was demonstrated, using both electron‐rich and electron‐deficient nitroalkenes as well as different hydrazones derived from aromatic aldehydes. The mechanistic details were also outlined. [ABSTRACT FROM AUTHOR]

A novel access to isoxazolines was developed using the [4+1]‐annulation of α‐keto‐stabilized sulfur ylides with N,N‐bis(siloxy)enamines derived from aliphatic nitro compounds. The resulting 5‐keto‐substituted isoxazolines were shown to be convenient precursors of polysubstituted 3‐hydroxypyrrolidines via the one‐pot catalytic N−O hydrogenolysis/intramolecular reductive amination sequence. Application of this approach to the formal synthesis of Merck's potent NK1 receptor antagonist was demonstrated. [ABSTRACT FROM AUTHOR]

An efficient synthesis of 6,7‐dihydropyrrolo[2,1‐c][1,3]thi‐azino[3,2‐a]pyrazine‐4(11bH)‐(thi)ones from readily available 1,2‐di‐thiolo‐3‐(thi)ones and 3,4‐dihydropyrrolo[1,2‐a]pyrazine is reported. The S2 atom in both monocyclic and fused 1,2‐dithioles is selectively replaced by aminomethylene to afford fused, rigid six‐membered 1,3‐thiazines. The scope of this two‐step one‐pot reaction was investigated: 1,2‐dithiolo‐3‐ones were more reactive than the corresponding 1,2‐dithiole‐3‐thiones. Optimized reaction conditions and a mechanistic rationale for the ring transformation are presented. [ABSTRACT FROM AUTHOR]

Here we report two new ligands from a 2,6‐bis(pyrazol‐3‐yl)pyridine family often used in spin‐crossover research and their iron(II) and cobalt(II) complexes with the metal ion trapped in the high‐spin state in solids (according to magnetometry and X‐ray diffraction data). The iron(II) complexes, however, show a gradual spin‐crossover in acetonitrile solution, as probed by the popular Evans method and an analysis of temperature dependent chemical shifts, both rooted in variable‐temperature NMR spectroscopy. The observed stabilization of the high‐spin state by the electron‐withdrawing substituents mirrors the trend previously reported for spin‐crossover iron(II) complexes of isomeric 2,6‐bis(pyrazol‐1‐yl)pyridines. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation is one of the most important reactions both in academic research and industry. We explored ability of the manganese pi‐complexes to act as Shvo‐type catalysts for transfer hydrogenation of ketones. DFT calculations suggested that the transfer of hydrogen atoms from the hypothetical intermediate [(C6Me3H2OH)Mn(CO)2H] to acetone has low activation barrier of 10.9 kcal mol−1. Experimentally a number of ketones with various functional groups (OMe, NH2, Cl, CF3, pyridyl) were successfully reduced in isopropanol at 90 °C in the presence of the complex [(C6Me3H2OH)Mn(CO)3]BF4 (1 mol %) and tBuOK (75 mol %). However, further investigation revealed that the reduction was mainly promoted by base rather than the manganese complex. Isolobal analogy: Phenol manganese pi‐complexes were proposed as possible Shvo‐type catalysts for transfer hydrogenation of ketones. DFT calculations suggested the reaction can proceed via transfer of hydrogen atoms from the intermediate [(C6Me3H2OH)Mn(CO)2H] to a ketone. A number of ketones were reduced in isopropanol at 90 °C in the presence of the complex [(C6Me3H2OH)Mn(CO)3]BF4 (1 mol %) and tBuOK (75 mol %). However, further investigation revealed that the reduction was mainly promoted by base rather than the manganese complex. [ABSTRACT FROM AUTHOR]

The most recyclable ionic liquid‐supported bifunctional tertiary amine–squaramide organocatalyst for the asymmetric domino reaction has been found. Over this catalyst, ortho‐aminochalcones protected with Tosyl or Nosyl groups underwent the aza‐Michael/Michael domino reaction with nitroolefins to afford corresponding 2,3,4‐trisubstituted tetrahydroquinolines as single diastereomers in nearly quantitative yield with up to 99 % ee. The catalyst was readily separated from the reaction mixture via a simple centrifugation/decantation workup and 19 times reused in the catalytic reaction without noticeable conversion or enantioselectivity reduction. The N‐nosylated products proved their synthetic value for pharmacology given their facile conversion to fused pirrolidino‐tetrahydroquinolines of high diastreomeric and enantiomeric purity via successive deprotection and reductive amination. Asymmetric aza‐Michael/Michael domino reaction of N‐Ts or N‐Nos ortho‐aminochalcones with nitroolefins has been performed in the presence of highly recyclable (19 cycles) IL‐supported tertiary amine–squaramide organocatalyst to afford trisubstituted tetrahydro‐quinolines as single diastereomers with up to 99 % ee. N‐Nosylated products were converted to fused pirrolidino‐tetrahydroquinolines. [ABSTRACT FROM AUTHOR]

Catalytic reaction of arylhydroxamic acids with alkenes represents a convenient method for preparation of biologically active dihydroisoquinolones. Here, the rhodium(III) complex [(C5H2tBu2CH2tBu)RhCl2]2, which allows one to carry out such reactions with high regioselectivity to obtain 4‐substituted dihydroisoquinolones in 72–97 % yields, is described. The regioselectivity is provided by the bulky cyclopentadienyl ligand of the catalyst, which is formed through a [2+2+1] cyclotrimerization of tert‐butylacetylene. The catalytic reaction tolerates various distant functional groups in alkenes, but is inhibited by bulky (e.g., tBu) or strongly coordinating (e.g., imidazolyl) substituents. Some of the prepared dihydroisoquinolones effectively inhibit growth of phytopathogenic fungi. Regioselective synthesis of biologically active dihydroisoquinolones was achieved by using rhodium(III) catalyst with bulky cyclopentadienyl ligand, which was formed from three tert‐butylacetylenes. [ABSTRACT FROM AUTHOR]

Abstract: The rapid development of enantioselective C−H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar‐chiral rhodium catalyst [(C5H2tBu2CH2tBu)RhI2]2 in two steps from commercially available [(cod)RhCl]2 and tert‐butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)‐proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee). [ABSTRACT FROM AUTHOR]

Pincer complexes featuring readily tunable tridentate ligand frameworks comprise one of the most actively studied classes of organometallic and metal–organic compounds and find extensive use in catalysis, organic synthesis, materials science, and other fields of chemistry and allied disciplines. Currently growing attention is devoted to non‐classical ligand scaffolds, such as functionalized carboxamides, which offer multiple options for directed structural modifications. In this study, the reactions of (methylsulfanyl)acetyl and propanoyl chlorides with 2‐(aminomethyl)pyridine, 2‐(2‐aminoethyl)pyridine, 8‐aminoquinoline and 2‐(diphenylthiophosphoryl)aniline afford a series of new pincer‐type ligands based on functionalized carboxamides. The ligands obtained readily undergo direct cyclopalladation under the action of PdCl2(NCPh)2 in dichloromethane at room temperature, resulting in Pd(II) pincer complexes with N,N,S‐ and S,N,S‐donor sets. Importantly, some of the cyclopalladated derivatives can also be produced efficiently under solvent‐free conditions according to the approach recently developed by our group. The complexes obtained have been tested for cytotoxicity against several human cancer cell lines and catalytic activity in the model Suzuki reaction. The results have been compared to those for the related Pd(II) pincer complexes to define the main structure–activity relationships and to outline the most promising structures for further investigations. [ABSTRACT FROM AUTHOR]

A new efficient synthetic route to 4-fluoro-5-aryl- 1,2,3-NH-triazoles was elaborated. The reactions of NaN3 with aryl-substituted α-fluoronitroalkenes resulted in the domino construction of the target fluorinated triazoles. Sulfamic acid is an effective promoter for this heterocyclization. The subsequent functionalization reactions of the obtained triazoles proceed highly regioselectively at the N-2 position. The observed regioselectivity was supported by DFT calculations. [ABSTRACT FROM AUTHOR]

The demethylation reactions of the cyclohexadienyl complexes [(η-X-SMe2-7,8-C2B9H10)Fe(η5-C6H7)] {X = 9 ( 1a), 10 ( 1b); X is the number of the substituent position} with PhCH2SNa in N, N-dimethylformamide (DMF) and subsequent protonation by acetic acid lead to the iron-benzene complexes [(η-X-SMe-7,8-C2B9H10)Fe(η-C6H6)] ( 2a and 2b). The visible-light irradiation of 2a in the presence of tBuNC or [Cp*Fe(η- cyclo-P5)] (Cp* = pentamethylcyclopentadienyl) affords the neutral half-sandwich complex [(η-9-SMe-7,8-C2B9H10)Fe( tBuNC)3] ( 3) or the triple-decker complex [(η-9-SMe-7,8-C2B9H10)Fe(µ-η:η- cyclo-P5)FeCp*] ( 4). The reaction of 2b with (THF)W(CO)5 (THF = tetrahydrofuran) selectively gives the iron-tungsten dinuclear complex [(η-10-SMe{W(CO)5}-7,8-C2B9H10)Fe(η-C6H6)] ( 5). The structures of 2a, 4, and 5 were determined by X-ray diffraction. Electrochemistry revealed that the redox processes of the SMe-substituted ferracarboranes are cathodically shifted (by ca. 350 mV) with respect to the corresponding redox changes of the SMe2 analogs. The Fe-C6H6 bonding in 2a and the related benzene complexes [(η-9-SMe2-7,8-C2B9H10)Fe(η-C6H6)]+ and [(η-7,8-C2B9H11)Fe(η-C6H6)] was analyzed by energy-decomposition analysis. [ABSTRACT FROM AUTHOR]

The reactions of thallium salt Tl[7-SMe2-7,8-C2B9H10] with [(cod)RhCl]2 and [Cp*RuCl]4 are accompanied by room-temperature polyhedral rearrangement, giving rhoda- and ruthenacarboranes 1-cod-8-SMe2-1,2,8-RhC2B9H10 ( 2) and 1-Cp*-8-SMe2-1,2,8-RuC2B9H10 ( 3), respectively. According to DFT calculations, the rearrangement could be attributed to the triangular face rotation mechanism. The reaction of iridium derivative 1-cod-8-SMe2-1,2,8-IrC2B9H10 ( 1) with anhydrous hydrohalic acids HX (X = Cl, Br, I) results in the dimeric halide iridacarboranes [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2 [ 4a- c; X = Cl ( a), Br ( b), I ( c)]. Bromide 4b reacts with Tl[Tl(η-7,8-C2B9H11)] and TlCp giving iridacarboranes 8′-SMe2-1,1′-Ir(2,3-C2B9H11)(2′,8′-C2B9H10) ( 5) and 1-Cp-8-SMe-1,2,8-IrC2B9H10 ( 6). The formation of the latter compound is accompanied by demethylation of the SMe2 substituent. The structures of 2, 3, 5 and 6 were determined by single-crystal X-ray diffraction. Iridacarboranes 4b and [1,1-Br2-4-SMe2-1,2,3-IrC2B9H10]2 ( 7) catalyze the dimerization of diphenylacetylene, giving 1,2,3-triphenylnaphthalene in 20-24 % yields. Compounds 4b and 7 also effectively catalyze the reductive amination reaction between aldehydes (or ketones) and primary (or secondary) amines in the presence of carbon monoxide, giving the corresponding secondary and tertiary amines in high yields (60-85 %). [ABSTRACT FROM AUTHOR]

The undesirable side-processes responsible for the fast deactivation of primary amino acid derived organocatalysts in asymmetric aldol reactions are identified. A new ionic-liquid-supported ( S)-valine-/( S)-α,α-diphenylserinol-derived catalyst ( 9) is designed on the basis of these results and exhibits much better recyclability in asymmetric syn-aldol reactions between hydroxyacetone and aldehydes. Furthermore, this catalyst appeared to be useful for the stereoselective synthesis of the naturally occurring 1( 3H)-isobenzofuran-1-one scaffold through an asymmetric syn-aldol/lactonization cascade reaction. [ABSTRACT FROM AUTHOR]

New multidentate ligands have been synthesized by the condensation of 2-(methylsulfanyl)benzoyl chloride with a range of amines bearing ancillary N or S donors. In reactions with PdCl2(NCPh)2, the ligands smoothly underwent direct cyclopalladation to give pincer complexes with 5,6- or 6,6-membered fused metallocycles. The oxidation of the sulfide ligands with H2O2 afforded the corresponding sulfoxide derivatives, which readily formed analogous pincer complexes with the PdII ions. The realization of κ3- S, N, X coordination (X = N or S) was confirmed by multinuclear NMR and IR spectroscopic data and, in some cases, X-ray crystallography. An unusual dynamic behavior of the 6,6-membered S, N, S complex with an organophosphorus ligand was additionally studied by the ROESY technique. All of the palladocycles obtained were tested as precatalysts for the Suzuki cross-coupling of aryl bromides with arylboronic acids, which allowed us to evaluate the main structure-activity relationships. [ABSTRACT FROM AUTHOR]

Silyl nitronates undergo rhodium-catalyzed formal [3+3]-cycloaddition with enol diazoacetates to form N-silyloxy-3,6-dihydro-2 H-1,2-oxazines. The scope of the reaction and the extent of the major side process were evaluated. A mechanistic scheme was proposed. The nitrogen inversion barrier in the obtained nitroso acetals was estimated based on both quantum calculations and kinetic measurements. [ABSTRACT FROM AUTHOR]

Cyclobutadiene rhodium complexes bear high potential for applications in organometallic synthesis and catalysis. We have found that the cyclobutadiene complexes with substitutionally labile p-xylene ligands [(C4R4)Rh( p-xylene)]+ can be synthesized in one step from the commercially available bis(ethylene) complex [{(C2H4)2RhCl}2], p-xylene, and internal alkynes. The replacement of p-xylene by various ligands provides a general access to other [(C4R4)Rh] compounds, such as [(C4R4)RhCl] x, [(C4R4)RhL3]+, [(C4R4)Rh(C5H5)], and [(C4R4)Rh(arene)]+. Complex [(C4Et4)Rh( p-xylene)]+ also catalyzes an unusual cycloisomerization of a 1,11-dien-6-yne into a bicyclic diene. [ABSTRACT FROM AUTHOR]

A series of new ( E)-1,3-dialkyl-4-((hetarylmethylidene)amino)-5-thioxohexahydroimidazo[4,5- d]imidazole-2(1 H)-ones (thioglycolurils) was synthesized via tandem hydrazone formation-ring contraction reaction of 5,7-dialkyl-3-thioxoperhydroimidazo[4,5- e]-1,2,4-triazin-6-ones with heteroaromatic aldehydes. [ABSTRACT FROM AUTHOR]

A novel recyclable prolinamide-derived ionic-liquid-supported organocatalyst of asymmetric cross-aldol reactions in aqueous medium has been developed. In its presence, aromatic aldehydes react with cyclic or linear ketones to afford chiral aldol adducts in moderate to high yields and with excellent dr ( anti/ syn up to 96:4) and ee (81-99 %) values that do not tend to decline over ten recycles of the catalyst. Furthermore, it allows a highly enantioselective catalytic synthesis of linear bis-aldols in aqueous medium. [ABSTRACT FROM AUTHOR]

Previously unknown 3,4-diamino-1,2,5-selenadiazole ( 6) was prepared by hydrolysis of [1,2,5]selenadiazolo[3,4- c][1,2,5]selenadiazole ( 7b) and used in synthesis of novel 1,2,5-selenadiazolo[3,4- b]pyrazines by the Koerner-Hinsberg reaction covering the parent compound 4 and its substituted derivatives 5a- g. The compounds synthesized were characterized by solution and solid-state 77Se NMR, and 6, 5-Ph and 5,6-Me2[1,2,5]selenadiazolo[3,4- b]pyrazines ( 5a, g, respectively) by X-ray diffraction. Electrochemical reduction of 5,6-R2[1,2,5]selenadiazolo[3,4- b]pyrazines 5c, g (R = Ph, Me) into novel persistent radical anions (RAs) was studied by cyclic voltammetry and the RAs [ 5c]- and [ 5g]- were characterized by EPR spectroscopy combined with DFT calculations. [ABSTRACT FROM AUTHOR]

A comparative study of two guanidinium salts, chloride and carbonate, is carried out to test the performance of the invariom approach for ionic crystals. Although treating them as formed by isolated ions with no charge transfer between them, the invariom approach provides features of interionic contacts that are amazingly similar to those obtained from conventional charge density analysis of high-resolution X-ray diffraction data, thus emerging as an easy way towards reliable description of chemical bonding peculiarities in ionic crystals. [ABSTRACT FROM AUTHOR]

In the original article, Scheme 5 describes the reaction of O-Boc-phenylhydroxamic acid with a mixture of alkenes, Scheme 6 describes the reaction of O-Boc- and O-Piv-phenylhydroxamic acid with styrene. For example, reaction of B 1 a b with an equimolar mixture of allyl alcohol, styrene and myrcene proceed selectively in the presence of the catalyst B 5 b to give 4-CH SB 2 sb OH-substituted product B 4 e b in 89 % yield (Scheme 5). Indeed, we observed that the reaction of O-Boc-phenylhydroxamic acid B 1 a b with styrene in the presence of the classical catalyst [Cp*RhCl SB 2 sb ] SB 2 sb gives only the 3-benzylisoindolin-1-one B 4 p b , while similar reaction of O-pivaloyl-phenylhydroxamic acid B 1 b b produced the 3-substituted structural isomer B 3 p b (Scheme 6). [Extracted from the article]

Keywords: chirality; diene ligands; quinones; rhodium EN chirality diene ligands quinones rhodium 1 1 1 03/31/22 20220328 NES 220328 B Chiral rhodium complexes b are widely used in asymmetric catalysis. Cover Feature: Planar Chiral Rhodium Complexes of 1,4-Benzoquinones (Chem. Eur. J. 18/2022) Chirality, diene ligands, quinones, rhodium. [Extracted from the article]

A comparative study of chemical bonding peculiarities in 1,2,4,5-tetrazine was carried out to test the performance of a recently developed invariom approach against a conventional charge density analysis of high-resolution X-ray diffraction data and quantum chemical calculations within the plane-wave functional theory. The amazing similarity between the intermolecular features thus obtained for this van der Waals crystal showed the invariom approximation to now emerge as a fast and convenient way towards reliable description of weak intermolecular interactions. [ABSTRACT FROM AUTHOR]

A combined investigation of the structural, electronic, and optical properties of three crystalline nonaaqualanthanoid(III) triflates, [Ln(H2O)9(CF3SO3)3], has provided unambiguous experimental evidence for charge redistribution in the first coordination sphere of a lanthanide ion as a result of hydrogen bonds with outer-sphere anions. As well as resulting in charge transfer from the noncoordinated anions to the coordinated water molecules, these hydrogen bonds give rise to a new excited state, an hydrogen-bond-induced charge-transfer state, which is observed experimentally for the first time. This state was shown to be responsible for the previously unknown negative aspect of hydrogen bonds with a lanthanide-bound water molecule: rather than increasing the luminescence efficiency of the complex, they can lead to additional quenching that is unfavorable for the task-specific design of optical materials. [ABSTRACT FROM AUTHOR]

Frontispiz: Unravelling of a [High Spin - Low Spin] <-> [Low Spin - High Spin] Equilibrium in Spin-Crossover Iron(II) Dinuclear Helicates Using Paramagnetic NMR Spectroscopy Keywords: broken symmetry; helicates; paramagnetic NMR; spin crossover EN broken symmetry helicates paramagnetic NMR spin crossover 1 1 1 01/12/22 20220117 NES 220117 B Spin-Crossover b . Broken symmetry, helicates, paramagnetic NMR, spin crossover. [Extracted from the article]

Replacement of the naphthalene ligand in ruthenium complex [CpRu(C10H8)]+ ( 1) by halide anions readily proceeds at room temperature to give insoluble oligomeric species [CpRuX] n (X = Cl, Br, I). Similar reactions in the presence of mono- or bidentate ligands afford complexes [CpRuL2X] where L = CO, P(OMe)3, tBuNC; L2 = dppm, dppe, dppp, bipy, phen, cod, nbd, or 1,4-diphenylbutadiene. Useful catalysts [CpRu(cod)X] were obtained by this method in 70-90 % yields. The structure of [CpRu(cod)I] was determined by X-ray diffraction. Reaction of 1 with Br- and allyl bromide afforded RuIV complex [CpRu(η3-C3H5)]Br2. Cation 1 also was found to react with azide anion in the presence of bidentate phosphanes to afford [CpRuL2N3] (L2 = dppm, dppe). Reaction of 1 with neutral ligands in the absence of nucleophilic anions proceeded under visible-light irradiation to give cationic complexes [CpRuL3]+ [L = CO, P(OMe)3, P(OEt)3, tBuNC] in 80-90 % yields. Complex 1 (2 mol-%) catalyzed cyclotrimerization of dipropargyl Meldrum's acid with various alkynes RC≡CH [R = H, Bu, Hex, Ph, SiMe3, (CH2)4C≡CH, (CH2)3OH, (CH2)2Br, CH2OMe, CH2OAc, CH2NMeBoc] producing benzene derivatives in 50-85 % yields. According to DFT calculations, the attack of the first ligand (Cl- or L) is a rate-determining step in the naphthalene replacement in 1. The activation barrier for attack of the Cl- anion is ca. 10 kcal mol-1 lower in energy than that of the neutral ligands L = CO, MeNC, MeCN, thus providing a rationale for the faster reaction in the presence of halide anions. The barriers for naphthalene replacement in 1 were also found to be ca. 10-15 kcal mol-1 lower in energy than those for the benzene replacement in [CpRu(C6H6)]+. [ABSTRACT FROM AUTHOR]