Search

The catalytic activity of cyclobutadiene rhodium complexes was investigated in various transformations of alkynes. Complexes [Rh(C4Et4)Hal]n (at 1 mol% loading) were found to promote hydrosilylation of 1-octyne selectively giving 1-Z-, 1-E-, or 2-Et3Si-1-octene depending on the nature of the halide ligand and the presence of additional ligand PPh3. Complex [Rh(C4Et4)(p-xylene)]+ (1 mol%) also efficiently catalyzed the polymerization of phenylacetylene. At the same time, we found that various cyclobutadiene rhodium complexes do not catalyze the Diels–Alder reaction, alkyne hydration, and 1,4-addition of boronic acids to cyclohexanone. New complexes [Rh(C4Et4)(PPh3)2]BF4 and [Rh(C4Et4)(C10H8)]PF6 were also synthesized and their structures were established by X-ray diffraction. [ABSTRACT FROM AUTHOR]

[Display omitted] Rhodium complex based on 9-(p-methoxybenzyl)-1,2,3,4- tetrahydrofluorenyl ligand was found to be an efficient catalyst for various C–H annulation reactions such as couplings of benzoic acids with alkynes, pivaloyl hydroxamate with alkenes, or the tandem reaction of p -anisaldehyde and p-toluidine with tolane. The catalyst demonstrated higher catalytic performance than the unsubstituted analog due to the stabilization of the rhodium–tetrahydrofluorenyl bond. Tetrahydrofluorenyl rhodium complexes also effectively catalyzed the synthesis of tetramethyl thiophene-2,3,4,5- tetracarboxylate from elemental sulfur and dimethyl acetylenedicarboxylate. [ABSTRACT FROM AUTHOR]

The rhodium complex [(C5H2tBu2CH2tBu)RhCl2]2 with an asymmetric cyclopentadienyl ligand was prepared in 95% yield by the reaction of [(cod)RhCl]2 with tert-butylacetylene in the presence of AlCl3. A similar reaction in the presence of InBr3 gave the cationic fulvene complex [(C5H2tBu2 = CHtBu)Rh(cod)]InBr4 (70%), which can add alcohols ROH and produce more bulky catalysts [(C5H2tBu2CH(OR)tBu)RhCl2]2. The enantiomers of these planar-chiral complexes were separated by thin-layer chromatography in the presence of L-phenylglycinol. The complexes catalyze the reactions of arylhydroxamates with alkenes giving dihydroisoquinolones in excellent yields (80–90%), but with moderate enantioselectivity (typically 20–50% ee). [ABSTRACT FROM AUTHOR]

A rhodium(II)-catalyzed reaction of cyclic nitronates (5,6-dihydro-4H-1,2-oxazine N-oxides) with vinyl diazoacetates proceeds as a [3+3]-annulation producing bicyclic unsaturated nitroso acetals (4a,5,6,7-tetrahydro-2H-[1,2]oxazino[2,3-b][1,2]oxazines). Optimization of reaction conditions revealed the use of Rh(II) octanoate as the preferred catalyst in THF at room temperature, which allows the preparation of target products in good yields and excellent diastereoselectivity. Under basic conditions, namely, the combined action of DBU and alcohol, these nitroso acetals undergo ring contraction of an unsaturated oxazine ring into the corresponding pyrrole. Both transformations can be performed in a one-pot fashion, thus constituting a quick approach to oxazine-annulated pyrroles from available starting materials, such as nitroalkenes, olefins, and diazo compounds. [ABSTRACT FROM AUTHOR]

Piperazine (Pipz) is widely used as a building block for the self-assembly of supramolecular hydrogen-bonded crystalline networks. Here, piperazine-1,4-diol (PipzDiol) has been suggested as an analog of piperazine with an extended H-bond donor geometry. A convenient synthesis of PipzDiol has been developed and the compound has been fully characterized. Structural and stereodynamic studies showed that PipzDiol exists in solution as a dynamic mixture of conformers/invertomers. The formation of co-crystals with acids is accompanied by preferable selection of one stereoisomeric form depending on the nature of the co-former. Piperazine and PipzDiol were found to form distinct supramolecular H-bonded networks with topologically different H-bonded motifs. In crystalline adducts with sulfuric, oxalic, and para-aminobenzoic acids, piperazine forms 3D H-bonded networks, while 2D layers are assembled with PipzDiol. [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]

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]

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]

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]

Abstract Bis(indenyl)-rhodium and -iridium complexes [(η5-indenyl)M(η5-C 9 H 2 R 5)]PF 6 (2a : M = Rh, R = H; 2b : M = Ir, R = H; 3 : M = Rh, R = Me) were synthesized by reactions of iodides [(η5-indenyl)MI 2 ] n (1a , b) with indenes in the presence of AgPF 6. The structures of 2a SbF 6 and 2b PF 6 were determined by X-ray diffraction. They have fully eclipsed geometry, in which the bridgehead carbon atoms of the indenyl ligands are arranged close to each other. Experimental and DFT calculation data showed that the strength of the M−indenyl bond in the bis(indenyl) compounds decreases in the following row: Ir > Co > Rh. Graphical abstract Image 1 Highlights • A straightforward approach to bis(indenyl)-rhodium and -iridium complexes was developed. • X-ray diffraction suggested that they have a fully eclipsed cisoid conformation. • Correlation of 13C NMR chemical shifts with bond dissociation energy was proposed. [ABSTRACT FROM AUTHOR]

Abstract The cyclooctadiene iridium complexes [Cp*Ir(COD)X]PF 6 ([ 1a−c ]PF 6 ; X = Cl, Br, I) were synthesized by reactions of Cp*Ir(COD) with halogens followed by a counterion exchange. The cyclooctadiene in these complexes is a thermally labile ligand. Complex [ 1b ]PF 6 reacts with trimethylphosphite to give [Cp*Ir{P(OMe) 3 } 2 Br]PF 6 ([ 2 ]PF 6) as a result of the cyclooctadiene replacement. The refluxing of [ 1b ]PF 6 in 1,2-dichloroethane affords the dimeric iodide [Cp*IrI 2 ] 2. The structures of [ 1b ]PF 6 , [ 2 ]PF 6 and [Cp*IrI 2 ] 2 were determined by X-ray diffraction. The Ir–COD bonding in [ 1a−c ]+ and the related non-methylated complexes was analyzed by energy decomposition analysis. In the presence of silver salts, complexes [ 1a−c ]PF 6 (at 2.0 mol % loading) catalyze the oxidative coupling of benzoic acid with 1-phenyl-1-propyne in methanol at 60 °C to selectively give 4-methyl-3-phenylisocoumarin (3) or with diphenylacetylene in o -xylene at 160 °C to afford 1,2,3,4-tetraphenylnaphthalene (4). Graphical abstract Image 1 Highlights • A general approach to new family of cyclooctadiene iridium complexes was developed. • The complexes prepared were used as catalysts for the formation of isocoumarin or naphthalene moieties. • The selectivity of catalytic reactions strongly depends on the reaction temperature. [ABSTRACT FROM AUTHOR]

(C 4 Me 4 )Co-containing triple-decker complexes with bridging boron and phosphorus heterocyclic ligands [(C 4 Me 4 )Co(μ-η:η-L)MCp*] + ( 1 : M = Fe, L = C 5 H 5 BMe; 2 : M = Fe, L = C 4 Me 4 P; 3a : M = Fe, L =  cyclo -P 5 ; 3b : M = Ru, L =  cyclo -P 5 ) were synthesized by photochemical reaction of [(C 4 Me 4 )Co(C 6 H 6 )] + with sandwich compounds Cp*ML. They were isolated as salts with PF 6 − anion, and the structures of 1 PF 6 , 2 PF 6 , and 3a PF 6 were determined by X-ray diffraction. The μ-pentaphospholyl complex 3a was also synthesized by exchange of sandwich compounds in the μ-cyclopentadienyl triple-decker complexes [(μ-η:η-Cp){Co(C 4 Me 4 )} 2 ] + or [(C 4 Me 4 )Co(μ-η:η-Cp)FeCp] + . Complexes 1 , 2 , and 3a undergo nucleophilic degradation by acetone and acetonitrile with selective elimination of the [(C 4 Me 4 )Co] + fragment giving the starting sandwich compounds. The rate of the nucleophilic degradation depends on the nature of the bridging ligand and decreases in the following order: C 4 Me 4 P ≥ C 5 H 5 BMe >  cyclo -P 5 . The bonding in 1 , 2 , and 3a was analyzed and compared with that in the cyclopentadienyl analog [(C 4 Me 4 )Co(μ-η:η-Cp)FeCp*] + using energy decomposition analysis. [ABSTRACT FROM AUTHOR]

Reaction of the thallium salt Tl[7,8-Me 2 -10-SMe 2 -7,8- nido -C 2 B 9 H 8 ] with [(cod)RhCl] 2 in THF furnishes new rhodacarborane 1,2-Me 2 -3,3-(cod)-8-SMe 2 -3,1,2 -closo -RhC 2 B 9 H 8 ( 1 ). The latter undergoes 1,2 → 1,7 carbon atom isomerization upon reflux in o -xylene for 5 h producing complex 1,8-Me 2 -2,2-(cod)-11-SMe 2 -2,1,8- closo -RhC 2 B 9 H 8 ( 2 ). Reaction of complex 2 with 1 equiv of I 2 in benzene results in a loss of the cod ligand and formation of product 3 , consisting of cationic [(1,8-Me 2 -11-SMe 2 - closo -2,1,8-RhC 2 B 9 H 8 ) 2 I 3 ] + ( 3a + ) and anionic [(1,8-Me 2 -11-SMe- closo -2,1,8-RhC 2 B 9 H 8 ) 2 I 3 ] − ( 3b – ) iodide species. In contrast, unisomerized analog 3,3-(cod)-8-SMe 2 - closo- 3,1,2-RhC 2 B 9 H 10 reacts with I 2 affording dimeric iodide [3,3-I 2 -8-SMe 2 - closo- 3,1,2-RhC 2 B 9 H 10 ] 2 ( 5 ). The structures of 2 and 5 were determined by a single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

A series of 12-vertex closo -cobaltacarboranes 1,2-Rʹ 2 -3-(C 5 R 5 )-3,1,2-CoC 2 B 9 H 9 ( 1a : R = Rʹ = H; 1b : R = Me, Rʹ = H; 2a : R = H, Rʹ = Me; 2b : R = Rʹ = Me) were synthesized by reactions of the carbonyl cobalt complexes (C 5 R 5 )Co(CO)I 2 with Tl[Tl(η-7,8-Rʹ 2 -7,8-C 2 B 9 H 9 )]. The reaction of CpCo(CO)I 2 with Tl[Tl(η-7,8-Me 2 -7,8-C 2 B 9 H 9 )] is accompanied by side formation of the novel charge-compensated nido -carborane 10-{CpCo(C 5 H 4 )}-7,8-Me 2 -7,8- nido -C 2 B 9 H 9 ( 3 ) in 19% yield. The structures of 2a , b and 3 were determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]

The vibrational smearing of electron density was studied in the crystal of complex of Cr(CO)3 with [2.2]paracyclophane. The combination of theoretical and experimental methods, including periodic calculations and screening of DFT calculated and multipole-decomposed electron densities, was utilized to reveal the vibrational smearing of electron density and its influence on the multipole-constructed electron density. The multipole model, commonly used to treat the high-resolution X-ray diffraction data, was shown to be rather inaccurate in description of electron density and its vibrational smearing in metal-π complex where the interchange between diatomic interactions can occur. Namely, some bond critical points can be hidden while analyzing multipole-decomposed electron density with proved effects of vibrational smearing even if the deconvolution problem is overcome by using the invariom approach. On the contrary, the recently proposed "clouds of critical point variation" (CCPV) approach is demonstrated as the route to gather all reasonable bonding trends and to reconstruct static electron density pattern in metal-π complexes. [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]

First examples of isomeric supraicosahedral osmacarboranes were synthesized. According to DFT study 13-vertex CAd carborane undergo low barrier cage rearrangement, which is confirmed by dynamic NMR. [Display omitted] Reaction of reduced form of 13-vertex carborane closo -1,2-(CH 2) 3 –1,2-C 2 B 11 H 11 (1) with [(ƞ6- p -cymene)OsCl 2 ] 2 in toluene solution affords two new isomeric osmacarboranes 2,3-(CH 2) 3 –1-(p -cymene)- closo -1,2,3-OsC 2 B 11 H 11 (2) and 2,8-(CH 2) 3 –1-(p -cymene)- closo -1,2,8-OsC 2 B 11 H 11 (3). The most thermodynamically stable product 3 forms due to the side redox process, which involve cage isomerization in 2. The reactions of [(ƞ6- p -cymene)OsCl 2 ] 2 with Na 2 (THF) n [ nido -1,2-CH 2 XCH 2 -1,2-C 2 B 10 H 10 ] (X = CH 2 , O) afford 12-vertex complexes 2,3-CH 2 XCH 2 -1-(p -cymene)- closo -1,2,3-OsC 2 B 10 H 10 due to the decapitation of the carborane ligand. Low temperature NMR experiments and DFT study reveal low barrier cage rearrangement in 1. [ABSTRACT FROM AUTHOR]

Polyhedral rearrangement of iridacarborane 1,2-Me2-3,3-(cod)-4-SMe2-3,1,2-closo-IrC2B9H8 (1) proceeds in a solution at RT and affords a product of 1,2 → 1,7 isomerization 1,8-Me2-2,2-(cod)-7-SMe2-2,1,8-closo-IrC2B9H8 (2). Rhodium derivative 1,2-Me2-3,3-(cod)-4-SMe2-3,1,2-closo-RhC2B9H8 (3) is significantly more stable toward heating than iridium complex 1 and isomerizes at 110 °C by 1,2 → 1,2 and 1,2 → 1,7 reaction schemes with 1,2 → 1,2 being the predominant route forming 1,2-Me2-4,4-(cod)-8-SMe2-4,1,2-closo-RhC2B9H8 (4) and 1,8-Me2-2,2-(cod)-7-SMe2-2,1,8-closo-RhC2B9H8 (5). Complexes 4 and 5 were characterized by 11B{¹H}-11B{¹H} COSY NMR spectrometry. A mechanism of 1,2 → 1,2 isomerization of 3 to 4 was proposed on the basis of DFT calculations. Reaction of the thallium salt Tl[7,8-Me2-9-SMe2-7,8-nido-C2B9H8] (CarbTl) with [Cp*RuCl]4 in THF furnishes new ruthenacarborane 1,2-Me2-3-(Cp*)-4-SMe2-3,1,2-closo-RuC2B9H8 (6). Heating of 6 at 80 and 144 °C leads to the partial and complete decomposition, respectively. Interaction of CarbTl with [Cp*IrCl2]2 in the presence of TlPF6 provides two new Ir(III) complexes [1,2-Me2-3-(Cp*)-4-SMe2-3,1,2-closo-IrC2B9H8]PF6 (7PF6) and 1,2-Me2-3-(Cp*)-4-SMe-3,1,2-closo-IrC2B9H8 (8) both stable upon heating in boiling tetrachloroethane (146 °C). A new 10-substituted charge-compensated carborane [7,8-Me2-10-SMe2-7,8-nido-C2B9H9] (9) was synthesized via an interaction of dicarbollide dianion [7,8-Me2-7,8-nido-C2B9H9]2- with dimethyl sulfide and acetaldehyde in acidic media. Thallium salt of 9 Tl[7,8-Me2-10-SMe2-7,8-nido-C2B9H8] (10) reacts with [(cod)IrCl]2 furnishing positional isomer of 1 with a symmetrical emplacement of SMe2 substituent complex 1,2-Me2-3,3-(cod)-8-SMe2-3,1,2-closo-IrC2B9H8 (11). Iridacarborane 11 requires elevated temperatures to undergo cage isomerization and converts upon heating at 110 °C to two new compounds 1,8-Me2-2,2-(cod)-11-SMe2-2,1,8-closo-IrC2B9H8 (12) and 1,2-Me2-4,4-(cod)-9-SMe2-4,1,2-closo-IrC2B9H8 (13) as a result of 1,2 → 1,7 and 1,2 → 1,2 rearrangements respectively with 13 being the minor product. The structures of 2, 6, 7PF6, 8, 10, 12, and 13 were determined by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

According to the UV-VIS spectroscopic data, preferential solvation in binary solvents results in the formation of less stable ion pairs MQ + I – as compared to those in individual solvents. [ABSTRACT FROM AUTHOR]

Volume-based prediction of melting points and other properties of ionic liquids (ILs) relies on empirical relations with volumes of ions in these low-melting organic salts. Here we report an accurate way to ionic volumes by Bader's partitioning of electron densities from X-ray diffraction obtained via a simple database approach. For a series of 1-tetradecyl-3-methylimidazolium salts, the volumes of different anions are found to correlate linearly with melting points; larger anions giving lower-melting ILs. The volume-based concept is transferred to ionic liquid crystals (ILs that adopt liquid crystalline mesophases, ILCs) for predicting the domain of their existence from the knowledge of their constituents. For 1-alkyl-3-methylimidazolium ILCs, linear correlations of ionic volumes with the occurrence of LC mesophase and its stability are revealed, thus paving the way to rational design of ILCs by combining suitably sized ions. [ABSTRACT FROM AUTHOR]

Metallacarborane [1,8-Me2-2,2-(C 2 H 4 )2-7-SMe2-2,1,8-IrC 2 B 9 H 8 ] (1) was obtained by an interaction of [(C 2 H 4 )2IrCl] 2 with Tl[9-SMe 2 -7,8-Me2-7,8-C 2 B 9 H 8 ]. Reaction proceeds with a low temperature “1,2 → 1,7” polyhedral rearrangement. Ethene complex 1 reacts with iodine in toluene with the formation of ionic compound 3, consisting of cationic [(1,8-Me2-7-SMe2-2,1,8-IrC 2 B 9 H 8 )2I 3 ]+ (3a+) and anionic [(1,8-Me 2 -7-SMe-2,1,8-IrC 2 B 9 H 8 )2I 3 ]− (3b–) iodide species. The structures of 1 and 3 were determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Room temperature reactions of the rhodium and iridium bromides (η-9-SMe 2 -7,8-Me 2 -7,8-C 2 B 9 H 8 )MBr 2 (M = Rh ( 1a ), Ir ( 1b )) with CpTl give the dicarbollide thioether complexes (η-9-SMe-7,8-Me 2 -7,8-C 2 B 9 H 8 )MCp ( 2a,b ), as a result of demethylation of the SMe 2 substituent. These reactions are accompanied by transformation of cage structure from pseudocloso to closo . Refluxing of the sulfonium derivatives [(η-9-SMe 2 -7,8-Me 2 -7,8-C 2 B 9 H 8 )MCp] + ( 3a , b ) with [Bu 4 N]Br also affords 2a , b . In the same manner ruthenacarboranes [(η-9-SMe 2 -7,8-C 2 B 9 H 10 )Ru(η-C 6 H 6 )] + ( 4a ) and [(η-10-SMe 2 -7,8-C 2 B 9 H 10 )Ru(η-C 6 H 6 )] + ( 4b ) react with halide ions giving the thioether complexes (η-9-SMe-7,8-C 2 B 9 H 10 )Ru(η-C 6 H 6 ) ( 5a ) and (η-10-SMe-7,8-C 2 B 9 H 10 )Ru(η-C 6 H 6 ) ( 5b ). Dependence of the demethylation rate on the nature of halide ion and solvent was studied both experimentally and theoretically. The structures of 2a and 3a PF 6 were determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]

A general and highly effective protocol for the direct synthesis of mono- and dithioglycolurils containing various substituents at the 1,3-nitrogen atoms has been developed based on the condensation of easily accessible dihydroxyimidazolidin-2-ones with HSCN under mild reactions conditions. [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]

The reaction of copper acetate with phosphoryl-substituted salicylaldimines 2a , b and template assembling of the imines on different sources of the copper(II) ion have been studied. The length of the pendant phosphoryl arm and reaction conditions were found to strongly affect the reaction course, selectively resulting in four- ( 3 ), five- ( 4 , 6 ), or six-coordinate ( 5 ) Cu(II) complexes. In the case of the derivatives with the elongated phosphoryl arm, the product structure is dictated by the nature of a solvent system used for recrystallization. In the case of the derivatives with the P O group directly attached to the central benzene ring, the reaction result depends on the nature of the reagents. An unusual example of a mixed aldehydate–iminate complex (compound 6 ) has been detected that can be used to obtain unsymmetrical bis(iminate) complexes ( e.g. , compound 7 ). The structures of all the complexes obtained were unambiguously confirmed based on the IR spectral data as well as single-crystal and powder X-ray diffraction. [ABSTRACT FROM AUTHOR]

The modeling of experimental electron density in a twinned crystal of 1,10-phenanthroline hydrate within an invariom approach revealed its another advantage for charge density studies, which is assessing the reliability of chemically relevant information provided by a conventional multipole refinement against high-resolution X-ray diffraction data. [ABSTRACT FROM AUTHOR]

Novel phosphorus-containing ligands have been synthesized by the condensation of 2-(thio)phosphorylated anilines with 2,6-dichloro- and 4-chloropyridine-2-carbonyl chlorides in the presence of Et3N and unsubstituted pyridine-2-carboxylic acid using P(OPh)3as a coupling agent. The compounds derived readily form complexes with a range of transition metals (M=Re(I), Pd(II), and Cu(II)), serving as bi- or tridentate monoanionic ligands. The composition and structure of the resulting metallocycles depend both on the presence/amount of the Cl atoms in the pyridine ring and on the nature of the donor atom X in the P=X moiety. The novel compounds were characterized by multinuclear NMR and IR spectroscopy as well as X-ray crystallography. [ABSTRACT FROM PUBLISHER]

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 reactivity of nido -carboranes in acid-induced nucleophilic substitution reaction and unique behavior of carborane with covalently binded cage carbon atoms are presented. [Display omitted] Reactions of the nido -carborane salts Me 4 N[7,8-R,R-7,8- nido -C 2 B 9 H 10 ] (R,R = Me 2 ; R,R = o-C 6 H 4 (CH 2) 2) with Me 2 S in the presence of triflic acid give a mixture of isomeric carboranes 9-Me 2 S-7,8-R,R-7,8- nido -C 2 B 9 H 9 and 10-Me 2 S-7,8-R,R-7,8- nido -C 2 B 9 H 9. In contrast, Me 4 N[7,8-(CH 2) 3 –7,8- nido -C 2 B 9 H 10 ] affords the only isomer 10-Me 2 S-7,8-(CH 2) 3 –7,8- nido -C 2 B 9 H 9. Interaction of Me 4 N[7,8-(CH 2) 3 –7,8- nido -C 2 B 9 H 10 ] and dimethyl sulfoxide in acidic conditions leads to the formation of a product 10-Me 2 SO-7,8-(CH 2) 3 –7,8- nido -C 2 B 9 H 9 in which, according to the SC-XRD, dimethyl sulfoxide molecule attaches to nido -carborane cage through an oxygen atom. The half-peak potential of the first oxidation wave of nido -carboranes correlates well with their ability to undergo acid-assisted nucleophilic substitution reactions. Thermal isomerization of 10-Me 2 S substituted nido -carboranes to 9-Me 2 S isomers was observed at higher temperatures than acid-assisted nucleophilic substitution and could proceed with the formation of 11-vertex closo -carboranes as intermediates according to the DFT study. [ABSTRACT FROM AUTHOR]

This work demonstrates the influence of the catalyst and alkyne nature on the regioselectivity of rhodium-catalyzed annulation of alkoxy-substituted benzoic acids (such as 3-methoxybenzoic, 3,4-dimethoxybenzoic, and piperonylic acids) with alkynes. Here, X-ray diffraction and DFT calculation data gave evidence that the observed regioselectivity is provided by both steric and coordination effects of methoxy groups. The latter is the result of weak non-covalent C–H⋯O interactions with the supporting ligand rather than with the rhodium atom. We believe that these results are also valid for other reactions of the C-H activation of methoxy-substituted arene compounds. [ABSTRACT FROM AUTHOR]

Pharmacology-relevant compounds bearing structural fragments of racetam nootropics, wound-healing acyclic isoprenoids and neurotropic GABA analogues, were enantioselectively (up to 94% ee ) synthesized from available and inexpensive precursors. [ABSTRACT FROM AUTHOR]

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]

Chemical binding in a mixed copper sodium carbonate Na2Cu(CO3)2, a layered material showing ferromagnetic intralayer exchange and weak antiferromagnetic interlayer coupling, was examined within the topological analysis of experimental (from high-resolution X-ray diffraction) and theoretical (from periodic quantum chemical calculations) electron density functions in its crystal. Together with modeling of a superexchange pathway within the LSDA and DFT+U approach, the results obtained reveal a very weak Cu···O interaction (0.5 kcal/mol worth) between the copper-carbonate layers that is nevertheless stabilizing (bonding) and may serve as a possible pathway for antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]

Stereoelectronic interaction lp(O1)→ σ*(N1–O2)in a O–N–O unit was analyzed by means of R. Bader’sAtoms in Molecule theory on the basis of X-ray diffraction data fordimethyl-(2R,4aR,5S,7R)-2,5,7-triphenylhexahydro-4H-[1,2]oxazino[2,3-b][1,2]oxazine-4,4-dicarboxylate. Atomic energiesobtained by applying this approach to both the experimental and theoreticalelectron densities were used to probe the energy of this strong stereoelectronicinteraction, giving consistent results with the NBO analysis, althoughshowing its destabilizing character. [ABSTRACT FROM AUTHOR]

An efficient protocol has been developed for the synthesis of larger condensed arenes from aromatic hydrocarbons and internal alkynes. This protocol uses readily available [CpRhI2 ]n as a catalyst and Cu(OAc)2 as an oxidant and proceeds smoothly through undirected double C–H activation. The addition of trifluoroacetic acid has a crucial positive impact on the reaction selectivity and the yields of the target products. In contrast to the previously reported catalytic systems, the new conditions allow the use of both dialkyl- and diarylacetylenes with the same high efficiency. [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]

A ruthenium complex with a chiral arene ligand [(camphor–arene)RuCl2 ]2 was synthesized by the reaction of RuCl3 ·nH2 O with a chiral diene which was obtained from natural camphor in three steps. This complex catalyzed the asymmetric hydrogenation of acetophenone (64–85% ee), but decomposed in catalytic reactions involving C–H activation of 2-phenylpyridine or benzoic acid derivatives. [ABSTRACT FROM AUTHOR]

• General procedures to a family of half-sandwich complexes with N,Nʹ-ligands was developed. • The complexes efficiently catalyze the CF 3 -carbenoid alkylation of N-(pyrimidin-2-yl)indole. • The alkylation exclusively proceeds to C3 position of indole moiety. • 2,2′-Bipyridyl, 1,10-phenanthroline, and tris(pyrazolyl)borate anion were used as N,Nʹ-ligands. The complexes [CpM(N,Nʹ-ligand)Br]PF 6 (M = Rh, Ir; N,Nʹ-ligand = 2,2′-bipyridyl, 1,10-phenanthroline) were synthesized by reactions of bromides [CpMBr 2 ] n with 2,2′-bipyridyl or 1,10-phenanthroline followed by a counterion exchange. The replacement of cyclooctadiene in [CpIr(cod)I]I 3 with N,Nʹ-ligands leads to complexes [CpIr(N,Nʹ-ligand)I]I 3 (N,Nʹ-ligand = 2,2′-bipyridyl, 1,10-phenanthroline). The structures of [CpRh(2,2′-bipyridyl)Br]PF 6 , [CpIr(2,2′-bipyridyl)I]I 3 , and [CpIr(1,10-phenanthroline)Br]PF 6 were determined by X-ray diffraction. The compounds prepared as well as the related the tris(pyrazolyl)borate derivatives [CpCoTp]PF 6 and [Cp*MTp]PF 6 (M = Rh, Ir) efficiently catalyze the alkylation of N-(pyrimidin-2-yl)indole with methyl 3,3,3-trifluoro-2-diazopropionate to selectively introduce the CF 3 and carboxylate functions at the C3 position of the indole moiety. In contrast, the tris(pyrazolyl)borate cobalt complex [Cp*CoTp]PF 6 predominantly provides the alkylation at the C2 position. [Display omitted] [ABSTRACT FROM AUTHOR]

Chemical bonding peculiarities in the crystalline dihydrate of sodium iodide were examined by means of Bader's "Atoms in Molecule" theory and the energies of cation-anion, cation-water and anion-water contacts were estimated on the basis of the experimental data that were shown to provide insight into the tendency of NaI to form co-crystals with the majority of solvents. [ABSTRACT FROM AUTHOR]

Reaction of two molecules of o‐diphenylphosphino‐tolane with RhCl(PPh3)3 produces the metallacycle complex with C4Rh(P3)Cl core. Further addition of tolane leads to 2+2+2‐cycloaddition and gives the cationic complex [Rh(Ph2P−C6H4−C6Ph4−C6H4−PPh2)]Cl, in which the metal is coordinated to C6Ph4 aromatic ring as well to two chelating PPh2 groups. The resulting bulky terphenyl‐diphosphine ligand with phosphorous atoms locked in cis‐position can be decoordinated from rhodium by a strong and non‐hindered ligand tBuNC. Peculiar structures of all the compounds were studied by the X‐ray diffraction. [ABSTRACT FROM AUTHOR]

The tetrahedral clusters [(C 4 Me 4)CoRh 3 Cpʹ 3 (μ 3 -CO) 3 ]+ (2 ; Cpʹ = C 5 H 4 Me) and [(Ph 3 P)AuRh 3 Cpʹ 3 (μ 2 -CO) 3 ]+ (3) were synthesized by reactions of Rh 3 Cpʹ 3 (μ 2 -CO) 3 (1b) with metalloelectrophiles [(C 4 Me 4)Co]+ (generated from [(C 4 Me 4)Co(C 6 H 6)]+ under visible-light irradiation) and [(Ph 3 P)Au]+ (generated from (Ph 3 P)AuCl/Tl+). They were isolated as salts with PF 6 − anion, and the structures of 2 PF 6 and 3 PF 6 were determined by X-ray diffraction. The structural data gave evidence that the coordination of [(C 4 Me 4)Co]+ occurs to the face of 1b with the CO ligands, while the [(Ph 3 P)Au]+ species reacts with the opposite face of 1b. The latter interaction is accompanied by elongation of the Rh–Rh bonds within the rhodium triangle by 0.1 Å. DFT calculations (at the BP86/TZP level) revealed that the selectivity of the metalloelectrophile coordination is determined by orbital control. Image 1 • New heteronuclear tetrahedral CoRh 3 and AuRh 3 clusters were synthesized. • The triangular rhodium cluster showed dual reactivity towards metalloelectrophiles [(C 4 Me 4)Co]+ and [(Ph 3 P)Au]+. • The [(C 4 Me 4)Co]+ and [(Ph 3 P)Au]+ species prefer π- and σ-bonding, respectively. • The selectivity of the metalloelectrophile coordination is determined by orbital control. [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]

Abstract: The first example of the formation of a 1,2-heteroaromatic diketone from a 1,3-diketone by air oxidation mediated by lanthanides is described. The structures of the products are confirmed by X-ray single crystal diffraction and NMR spectroscopy. A possible reaction mechanism is proposed. [Copyright &y& Elsevier]

[Display omitted] The reactions of aryllithium reagents o -LiC 6 H 4 CH 2 NR 2 with (MeO) 2 CO afford two new tris(aryl)carbinols bearing pendant-NR 2 donor groups in the side chain [ o -R NCH C H ] COH [R = Me, R + R = (CH) ]. These alcohols feature helical chirality due to differently inclined aromatic fragments and are presented in a crystalline cell as two M and P enantiomers. Carbinol (R = Me) readily reacts with (Me3SiCH2)3Sc(THF)2 to give a scandium bis(alkyl) complex [(o -C 6 H 4 CH 2 NMe 2) 3 CO]Sc(CH 2 SiMe 3) 2 featuring rigid binding of the alkoxy anion through a κ1-O, κ2-N chelating coordination mode [ABSTRACT FROM AUTHOR]

The mechanism of the hypercoordination of the iodine atom and its role in the crystal packing of iodic acid were examined within the topological analysis of the experimental electron density function. [ABSTRACT FROM AUTHOR]

Abstract: The zirconocene alkyne complex rac-(ebthi)Zr(η 2-Me3SiC2SiMe3) (1) reacts with 1,4-bis-tert-butyl-buta-1,3-diyne to yield the novel five-membered metallacyclocumulene rac-(ebthi)Zr(η 4-t-Bu-C4-t-Bu) (2) (ebthi=1,2-ethylene-1,1′-bis(η 5-tetrahydroindenyl)), t-Bu= tert-butyl). The structure of 2 was confirmed by X-ray studies. [Copyright &y& Elsevier]

Condensation of 1,3-dimethyl-3a,9a-diphenyl-3,3a,9,9a-tetrahydroimidazo[4,5-e]-1,3-thiazolo[3,2-b]-1,2,4-triazine-2,7(1H,6H)-dione with isatins afforded 6-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-3,3a,9,9a-tetrahydro-1,3-dimethyl-3a,9a-diphenylimidazo-[4,5-e]thiazolo[3,2-b]-1,2,4-triazine-2,7(1H,6H)-diones; a new conglomerate (space group P212121) was found by an X-ray diffraction study. [ABSTRACT FROM AUTHOR]

An unexpected mechanism of halogen bonding that cannot be rationalized within the accepted σ-hole model was found in the co-crystal of N-methylpyrazine iodide with molecular iodine viathe topological analysis of the electron density distribution derived from the high-resolution X-ray diffraction data. [ABSTRACT FROM AUTHOR]