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The isolation of silicon analogues of phenyl anions such as (C 6 H 5 ) - and (C 6 H 4 ) 2- is challenging owing to their extremely high reactivity associated with their silylene character and weak C-Si π-interaction. Herein, we report the first annulated 1,4-disilabenzene-1,4-diide compound [(ADC)Si] 2 ( 5 ) based on anionic dicarbene (ADC) scaffolds (ADC = PhC{N(Dipp)C} 2 ; Dipp = 2,6- i Pr 2 C 6 H 3 ) as a green-yellow crystalline solid. Compound 5 is prepared by KC 8 reduction of the Si(IV) chloride [(ADC)SiCl 3 ] 2 ( 3 ) or the cyclic bis-chlorosilylene [(ADC)SiCl] 2 ( 4 ), which are also prepared for the first time. 5 is a neutral molecule, and each of the two-coordinated Si(I) atoms has a lone pair and an unpaired electron. Experimental and theoretical data indicate delocalization of the silicon unpaired electrons, resulting in a 6π-electron C 4 Si 2 ring in 5 . The diradical character ( y ) for 5 amounts to 15%. At room temperature, 5 readily reacts with dihydrogen (H 2 ) to form the elusive bis-hydridosilylenes [(ADC)SiH] 2 ( Z )- 6 and ( E )- 6 . The [4 + 2]-cycloaddition of 5 and PhC≡CPh in yielding the barrelene-type bis-silylene [(ADC)SiCPh] 2 ( 7 ) emphasizes the diradical reactivity of 5 . With elemental sulfur, 5 results in the S 2 - and S 3 -bridged silathione derivatives [(ADC)Si(S)] 2 (μ-S 2 ) ( 8a ) and [(ADC)Si(S)] 2 (μ-S 3 ) ( 8b ). Moreover, the treatment of 5 with Fe 2 (CO) 9 affords the Fe(0) complex [(ADC)Si(Fe(CO) 4 )] 2 (μ-CO) ( 9 ), in which each silicon atom serves as a two-electron σ-donor ligand and shares one electron with the bridging CO unit to form two Si-C bonds. The molecular structures of all compounds have been established by X-ray diffraction, and representative compounds have been analyzed by quantum chemical calculations.

Starting from ClSbR F 2 (R F = C 2 F 5 , 3,5-(CF 3 ) 2 C 6 H 3 ) and H(E)P( t Bu) 2 (E = O, S), we prepared the oxy- and sulphanediyl-bridged adducts R F 2 Sb(Cl)-E-(H)P( t Bu) 2 , which are stable against the elimination of HCl. The different electron-withdrawing substituents and chalcogen bridging units influence the size of the Sb-E-P angle. ClSb(C 2 F 5 ) 2 and n Bu 3 SnH react to give HSb(C 2 F 5 ) 2 , which seems to interact weakly with H(O)P( t Bu) 2 in solution as observed via NMR. All products were characterised by NMR spectroscopy and all the stable ones were additionally characterised by X-ray diffraction and elemental analyses.

Although the adduct of aluminum trichloride with thionyl chloride has been reported, no thionyl chloride adduct of a main group element Lewis acid or organometallic compound has been structurally characterized. In this communication we present the synthesis and reactivity of the structurally ascertained adduct of thionyl chloride with tris(pentafluoroethyl)gallane as a representative of a main group element Lewis acid. Gallium and indium compounds with electron withdrawing groups, e.g. the pentafluoroethyl ligand, display versatile properties. While gallates and indates, [MR 4 ] - , behave as weakly coordinating anions, neutral gallanes and indanes, MR 3 , are strong Lewis acids. Salts with the tetrakis(pentafluoroethyl)gallate and -indate, [M(C 2 F 5 ) 4 ] - (M=Ga, In), have recently been studied in detail. In contrast to this, work on the syntheses of the free Lewis superacids M(C 2 F 5 ) 3 (M=Ga, In) is scarce and underdeveloped. The hydrates [M(C 2 F 5 ) 3 (OH 2 ) 2 ] proved to be suitable starting materials, particularly due to their thermal stability. Herein we report on synthesis and characterization of reactive adducts, [M(C 2 F 5 ) 3 D], with the weak donor molecules (D) SOCl 2 and Me 3 SiF. The effective Lewis acidities of Ga(C 2 F 5 ) 3 and In(C 2 F 5 ) 3 were experimentally determined by the (modified) Gutmann-Beckett method and their catalytic potential is showcased., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Cytotoxic payloads for drug conjugates suitable for directed tumor therapy need to be highly potent and require a functional group for conjugation with the homing device (antibody, peptide, or small molecule). Cryptophycins are cyclodepsipeptides that stand out from the realm of natural products due to their extraordinarily high cytotoxicity. However, the installation of a suitable conjugation handle without compromising the toxicity is highly challenging. The unit D, natively 2-hydroxyisocaproic acid (leucic acid), was envisaged as a promising attachment site based on structural information from X-ray analysis. A versatile, scalable and efficient synthetic route towards conjugable cryptophycins with modification in unit D was developed and an array of new cryptophycin analogues was synthesized. Several derivatives, especially those containing lipophilic groups with low steric demand such as alkylated amino groups, exhibit low picomolar cytotoxicity often combined with efficacy against multidrug-resistant tumor cells. The newly established cryptophycin analogues comprise a broad range of relevant functional groups used as conjugation handles, among them amino, hydroxy, carboxy, as well as sulfur-containing derivatives. X-ray crystallographic analysis of a tubulin-bound cryptophycin together with quantitative structure activity relationship manifested rationales for the synthesis of most potent cryptophycin derivatives and further confirmed the suitability of modifications in unit D., (© 2024 Wiley‐VCH GmbH.)

The alkylation of 3-/4-bromo- and -iodopyridine with methyl triflate smoothly affords the corresponding N-methylpyridinium triflate salts. An anion exchange with NaI or [PPh 4 ]Y (Y=Cl, Br, I) yields the corresponding halide salts. Most of them could be structurally characterized and their strong halogen bonds were investigated. While the halogen atom of 4-halogenopyridinium is susceptible to nucleophilic substitution, 3-halogenopyridinium ions are far more stable against nucleophilic attacks. Due to the comparable interaction strength of halogen bonds and hydrogen bonds, the latter of which is widely used in chromatography, the potential of 3-halogenopyridinium moieties for an application in chromatography is obvious and was successfully employed in affinity chromatography of different proteins., (© 2024 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

Chromatographic fractionation of CH 2 Cl 2 :MeOH (1:1) extract of Coccoloba peltata Schott cultivated in Egypt afforded four compounds, lupeol acetate ( 1 ), ent -13- epi -manoyl oxide ( 2 ), 5-methoxymethyl-7,8-dimethyltocol ( 3 ), and α -tocopherol quinone ( 4 ). The planar structures of the isolated compounds were concluded based on HRESIMS and NMR spectroscopy. X-ray crystallography of 2 is reported herein for the first time and its unambiguous absolute configuration was deduced from anomalous dispersion. To the best of our knowledge, this is the first known report on the isolation of compounds 1 - 4 from this species. Among the isolated compounds, only compound 4 showed a moderate level of cytotoxic activity against six cancer cell lines out of seven cell lines tested.

The reaction of [Ga(C2F5)3(FSiMe3)] with chlorotrimethylsilane leads to the selective substitution of the α-fluorine atoms by chlorine atoms and thus to the formation of [Ga(CCl2CF3)3(FSiMe3)]. The corresponding chlorogallate ion, [Ga(CCl2CF3)3Cl]-, could be isolated and structurally characterized as its tetraphenylphosphonium salt. The catalytic potential of [Ga(CCl2CF3)3(FSiMe3)] was demonstrated via the chlorodefluorination of Me3SiCF3, 2,2-difluoropropane and [PPh4][Ga(C2F5)4]., (© 2024 Wiley‐VCH GmbH.)

Diradicals based on a meta-quinodimethane (m-QDM) scaffold generally have a triplet ground state and are rather scarce. Herein, m-QDM-based non-Kekulé diradicals [3,3'-(NHC) 2 BP] (3-NHC) (NHC = SIPr = C{N(Dipp)CH 2 } 2 ; IPr = C{N(Dipp)CH} 2 , Me-IPr = C{N(Dipp)CMe} 2 ; Dipp = 2,6-iPr 2 C 6 H 3 ; BP = 1,1'-C 6 H 4 C 6 H 4 ) featuring N-heterocyclic carbene (NHC) pendants are reported as crystalline solids. The EPR spectra of 3-NHC show both allowed (Δm s = 1) and forbidden (Δm s = 2; 'half-field') transitions characteristic for triplet diradicals. Variable temperature EPR studies however reveal a singlet ground state for 3-SIPr. Consistent with the EPR spectra, calculations predict a remarkably small singlet-triplet energy gap (ΔE ST ≤ 0.26 kcal/mol) for the 3-NHC compounds. The calculated singlet diradical character for the ground states of the 3-NHC compounds amounts to ~99 %., (© 2024 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

Bidentate and tetradentate chalcogen bonding host systems with SeCF 3 functions as σ-hole donors in close proximity at the alkyne functions of 1,8-diethynylanthracene and its syn -dimer were prepared in quantitative yield by tin-selenium exchange reactions of the corresponding trimethylstannyl precursors with ClSeCF 3 . The bidentate system shows chalcogen bonding interactions with THF, but does not bind halide ions. The tetradentate system cooperatively chelates chloride, bromide and iodide ions with its four CC-SeCF 3 units by rotating the four σ-holes towards the halide ion. The structures of these halide ion adducts were determined by X-ray diffraction. The hydrobromide and -iodide salts of the ethyl derivative of Schwesinger's phosphazene superbase served as halide salts with very weakly coordinating cations.

The reactions of the frustrated Lewis pair (F 5 C 2 ) 2 SbCH 2 P( t Bu) 2 with oxygen, sulphur, selenium and tellurium led to the mono-oxidation products (F 5 C 2 ) 2 SbCH 2 P(E)( t Bu) 2 (E = O, S, Se, Te). Further oxidation of these chalcogen adducts with tetrachloro- ortho -benzoquinone ( o -chloranil) gave (F 5 C 2 ) 2 Sb(CH 2 )(μ-E)P( t Bu) 2 ·Cat Cl (Cat Cl = o -O 2 C 6 Cl 4 ) with a central four-membered ring heterocycle for E = O, S, and Se. For E = Te the elimination of elemental tellurium led to an oxidation product with two equivalents of o -chloranil, (F 5 C 2 ) 2 SbCH 2 P( t Bu) 2 ·2Cat Cl , which is also accessible by reaction of (F 5 C 2 ) 2 SbCH 2 P( t Bu) 2 with o -chloranil. The synthesised compounds were characterised by NMR spectroscopy and X-ray structure analyses, and the structural properties were analysed in the light of the altered Lewis acidity due to the oxidation of the antimony atoms.

Flexible poly-Lewis acids (PLA) based on the tribenzotriquinacene (TBTQ) scaffold have been synthesised. Hydrosilylation of 4b,8b,12b-triallyltribenzotriquinacene and subsequent exchange of the chlorine substituents with weaker coordinating triflate groups afforded a novel triple silyl-functionalised PLA. By regioselective hydroboration of triallyl-TBTQ with various organoboranes, PLAs with different Lewis acidities were obtained. The synthesised PLAs were combined with neutral bases in host-guest experiments. DOSY NMR spectroscopy was performed to elucidate the complexation process in solution. These experiments revealed a highly dynamic interaction between the boron-functionalised PLA and triazine. However, the addition of one equivalent of tris(dimethylphosphino(methyl))phenylsilane led to the formation of a 1 : 1 adduct, which was confirmed by diffusion experiments.

Chalice-shaped tridentate poly-Lewis acids (PLA) based on the tribenzotriquinacene (TBTQ) scaffold have been synthesised. Stannylation of the alkyne units, attached via phenyl-spacers to the benzhydrylic positions to the TBTQ scaffold, with Me 2 NSnMe 3 afforded the trimethyltin substituted TBTQ derivative. Replacement of these tin functions with other elements resulted in rigid boron- and aluminium-functionalised PLAs. More flexible PLAs were obtained by hydrometallation reactions of the terminal alkyne groups of 4b,8b,12b-tris((ethynyl)phenyl)tribenzotriquinacene. The resulting poly-Lewis acids were tested for their acceptor abilities in host-guest experiments with suitable bases. Preliminary tests with pyridine led to the synthesis of a large tridentate base with three pyridyl groups attached to a TBTQ backbone. Complexation of this Lewis base with the PLAs resulted in the formation of aggregates, which were studied in solution in more detail by 1 H DOSY NMR experiments regarding their size. Further experiments were performed with the tridentate bases 1,4,7-trimethyl-1,4,7-triazacyclononane and tris((dimethylphosphino)methyl)phenylsilane., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The geminal Lewis pair (F 5 C 2 ) 2 SbCH 2 P( t Bu) 2 (1) was prepared by reacting (F 5 C 2 ) 2 SbCl with LiCH 2 P( t Bu) 2 . Despite its extremely electronegative pentafluoroethyl substituents, the neutral 1 exhibits a relatively soft acidic antimony function according to the HSAB concept (hard-soft acid-base). These properties lead to a reversibility in the binding of CS 2 to 1, as observed by VT-NMR spectroscopy, while no reaction with CO 2 is observed. The reaction behaviour towards heterocumulenes and the specific interaction situation in the CS 2 adduct were analysed by quantum chemical calculations. The FLP-type reactivity of 1 has also been demonstrated by reaction with a variety of small molecules (SO 2 , PhNCO, PhNCS, (MePh 2 P)AuCl). The reactions of 1 with PhNCO and PhNCS led to different types of cyclic addition products: PhNCO adds with its N[double bond, length as m-dash]C bond and PhNCS adds preferentially with its C[double bond, length as m-dash]S bond. The reaction of 1 with (MePh 2 P)AuCl gave an adduct {[(F 5 C 2 ) 2 SbCH 2 ( t Bu) 2 P] 2 Au} + with a clamp-like structure binding a chloride anion by its two antimony atoms in chelate mode. Compound 1 and its adducts have been characterised by X-ray diffraction experiments, multinuclear NMR spectroscopy, elemental analyses and computational calculations (DFT, QTAIM, IQA)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A bidentate boron Lewis acid based on 1,8-diethynylanthracene has been studied in detail with respect to its adduct formation with diamines and diphosphanes of different linker lengths between the donor functions. A clear correlation between the linker length of the bifunctional base and the formation of 1 : 1 adducts, 1 : 2 adducts or oligomers was found. The adducts were characterized in solution by NMR titration experiments and structurally by X-ray diffraction. In addition, adduct formation and competition experiments of the host system with ZR 3 (Z=N, P; R=H, Me) demonstrated the generally higher stability of alkylphosphane adducts compared to alkylamine adducts with boron functions. The results provide a general insight into the adduct formation of bidentate Lewis acids with guests of different sizes as well as the differences in stability between borane-amine and borane-phosphane adducts., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

N-Heterocyclic carbene (NHC) analogues of Wittig hydrocarbon, [(NHC)(Stil)(NHC)] (3a-c) (NHC = SIPr (1a) = C[N(Dipp)CH 2 ] 2 , Dipp = 2,6-iPr 2 C 6 H 3 ; IPr (1b) = C[N(Dipp)CH] 2 ; Me-IPr (1c) = C[N(Dipp)CMe] 2 and Stil = C 6 H 4 CHCHC 6 H 4 ) have been reported as crystalline solids. 3a-c are prepared by two-electron reductions of the corresponding bis-1,3-imidazoli(ni)um bromides [(NHC)(Stil)NHC)](Br) 2 (2a-c) with KC 8 in >94 % yields. 2a-c are accessible by the nickel catalyzed direct C-C coupling of NHCs (1a-c) with (E)-4,4'-dibromostilbene. One-electron oxidation of 3a,b yields the corresponding radical cations [(NHC)(Stil)NHC)]B(C 6 F 5 ) 4 4a,b. All compounds have been characterized by UV-Vis/NMR/EPR spectroscopy as well as 2a, 3a, and 3b by single crystal X-ray diffraction. The electronic structures of representative systems have been analyzed by quantum chemical calculations., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Four bidentate boron Lewis acids based on the 1,8-diethynylanthracene backbone have been synthesized by a tin-boron exchange reaction with various chloroboranes, yielding the products in good to excellent yields. Complexation experiments of the host compounds with pyridine, pyrimidine and TMEDA demonstrated striking differences in terms of formation and solubility of the supramolecular adducts. The host-guest complexes were investigated by multinuclear NMR spectroscopy and structurally characterized by X-ray diffraction experiments, illustrating the adaptation of the host system upon adduct formation with different neutral guest molecules.

Hexadentate poly-Lewis acids (PLA) based on the bowl-shaped tribenzotriquinacene (TBTQ) have been synthesised. The introduction of three n -propyl groups into the benzhydrylic positions of the TBTQ backbone has significantly increased the solubility of the subsequently derived compounds. Semi-flexible PLAs containing boron and aluminium were obtained by hydrometallation of the corresponding 2,3,6,7,10,11-hexaalkynyl-TBTQ. Other rigid hexadentate PLAs were synthesised by stannylation of the corresponding alkyne units with Me 3 SnNMe 2 followed by tin-element exchange reactions. The Lewis acidity of these PLAs was investigated in host-guest experiments with pyridine. Further experiments with bidentate bases showed correlations between their flexibility, their Lewis basicity and the complexation behaviour towards the synthesised PLAs. Addition of bis((dimethylphosphino)methyl)dimethylsilane (BisPhos) to solutions of the rigid alkynyl PLAs led to the formation of 3 : 1 adducts. Single crystal X-ray diffraction was used to further elucidate the host-guest connectivtiy. In addition, a sixfold pnictogen-bonding donor was synthesised by tin-antimony exchange.

Carbocyclic aluminium halides [(ADC)AlX 2 ] 2 (2-X) (X=F, Cl, and I) based on an anionic dicarbene (ADC=PhC{N(Dipp)C} 2 , Dipp = 2,6-iPr 2 C 6 H 3 ) framework are prepared as crystalline solids by dehydrohalogenations of the alane [(ADC)AlH 2 ] 2 (1). KC 8 reduction of 2-I affords the peri-annulated Al(III) compound [(ADC H )AlH] 2 (4) (ADC H= PhC{N(Dipp)C 2 (Dipp H )N}, Dipp H =2-iPr,6-(Me 2 C)C 6 H 3 )) as a colorless crystalline solid in 76 % yield. The formation of 4 suggests intramolecular insertion of the putative bis-aluminylene species [(ADC)Al] 2 (3) into the methine C-H bond of HCMe 2 group. Calculations predict singlet ground state for 3, while the conversion of 3 into 4 is thermodynamically favored by 61 kcal/mol. Compounds 2-F, 2-Cl, 2-I, and 4 have been characterized by NMR spectroscopy and their solid-state molecular structures have been established by single crystal X-ray diffraction., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Herein, reactivity studies of a cyclic bis-hydridostannylene [(ADC)SnH] 2 (1-H 2 ) (ADC=PhC{(NDipp)C} 2 ; Dipp=2,6-iPr 2 C 6 H 3 ) with various unsaturated organic substrates are reported. Reactions of terminal alkynes (RC≡CH) with 1-H 2 afford mixed acetylide-vinyl-functionalized bis-stannylenes via dehydrogenation and hydrostannylation. Treatment of 1-H 2 with PhC≡CCH 3 gives a unique distannabarrelene via dehydrogenative C (sp3) -H stannylation and hydrostannylation of the C≡CCH 3 moiety. 1-H 2 undergoes dehydrogenative [2+2]-cycloaddition reactions with diphenylacetylene, azobenzene, acetone, benzophenone, and benzaldehyde to form the 1,4-distannabarrelene derivatives. The elimination of H 2 in these reactions suggests the masked-diradical property of 1-H 2 . In fact, these [2+2]-cycloaddition products are also accessible on treatments of the Sn(I) diradicaloid [(ADC)Sn] 2 (1) with appropriate reagents. All compounds have been characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction. Moreover, the catalytic activity of 1-H 2 has been shown for the hydroboration of unsaturated substrates., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

We report the room temperature dimerization of carbon monoxide mediated by C4/C5-vicinal anionic dicarbenes Li(ADC) (ADC = ArC{(Dipp)NC} 2 ; Dipp = 2,6-iPr 2 C 6 H 3 ; Ar = Ph, DMP (4-Me 2 NC 6 H 4 ), Bp (4-PhC 6 H 4 )) to yield (E)-ethene-1,2-bis(olate) (i.e. - O-C=C-O - = CO en ) bridged mesoionic carbene (iMIC) lithium compounds CO en -[(iMIC)Li] 2 (CO en -[iMIC] 2 = [ArC{(Dipp)NC} 2 (CO)] 2 ) in quantitative yields. CO en -[(iMIC)Li] 2 are highly colored stable solids, exhibit a strikingly small HOMO-LUMO energy gap, and readily undergo 2e-oxidations with selenium, CuCl (or CuCl 2 ), and AgCl to afford the dinuclear compounds CO on -[(iMIC)E] 2 (E = Se, CuCl, AgCl) featuring a 1,2-dione bridged neutral bis-iMIC (i.e. CO on -[iMIC] 2 = [ArC{(Dipp)NC} 2 (C=O)] 2 ). CO en -[(iMIC)Li] 2 undergo redox-neutral salt metathesis reactions with LiAlH 4 and (Et 2 O) 2 BeBr 2 and afford CO en -[(iMIC)AlH 2 ] 2 and CO en -[(iMIC)BeBr] 2 , in which the dianionic CO en -moiety remains intact. All compounds have been characterized by NMR spectroscopy, mass spectrometry, and X-ray diffraction. Stereoelectronic properties of CO on -[iMIC] 2 are quantified by experimental and theoretical methods., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Di- tert -butyldiphosphatetrahedrane ( t BuCP) 2 (1) is a mixed carbon- and phosphorus-based tetrahedral molecule, isolobal to white phosphorus (P 4 ). However, despite the fundamental significance and well-explored reactivity of the latter molecule, the precise structure of the free ( t BuCP) 2 molecule (1) and a detailed analysis of its electronic properties have remained elusive. Here, single-crystal X-ray structure determination of 1 at low temperature confirms the tetrahedral structure. Furthermore, quantum chemical calculations confirm that 1 is isolobal to P 4 and shows a strong largely isotropic diamagnetic response in the magnetic field and thus pronounced spherical aromaticity. A spectroscopic and computational study on the photochemical reactivity reveals that diphosphatetrahedrane 1 readily dimerises to the ladderane-type phosphaalkyne tetramer ( t BuCP) 4 (2) under irradiation with UV light. With sufficient thermal activation energy, the dimerisation proceeds also in the dark. In both cases, an isomerisation to a 1,2-diphosphacyclobutadiene 1' is the first step. This intermediate subsequently undergoes a [2 + 2] cycloaddition with a second 1,2-diphosphacyclobutadiene molecule to form 2. The 1,2-diphosphacyclobutadiene intermediate 1' can be trapped chemically by N -methylmaleimide as an alternative [2 + 2] cycloaddition partner., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Decarbonylation of a cyclic bis-phosphaethynolatostannylene [(ADC)Sn(PCO)] 2 based on an anionic dicarbene framework (ADC = PhC{N(Dipp)C} 2 ; Dipp = 2,6-iPr 2 C 6 H 3 ) under UV light results in the formation of a Sn 2 P 2 cluster compound [(ADC)SnP] 2 as a green crystalline solid. The electronic structure of [(ADC)SnP] 2 is analyzed by quantum-chemical calculations. At room temperature, [(ADC)SnP] 2 reversibly binds with CO 2 and forms [(ADC) 2 {SnOC(O)P}SnP]. [(ADC)SnP] 2 enables catalytic hydroboration of CO 2 and reacts with elemental selenium and Fe 2 (CO) 9 to afford [(ADC) 2 {Sn(Se)P 2 }SnSe] and [(ADC)Sn{Fe(CO) 4 }P] 2 , respectively. All compounds are characterized by multinuclear NMR spectroscopy and their solid-state molecular structures are determined by single-crystal X-ray diffraction., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Herein, ring-opening of mesoionic carbenes (iMICs) (iMIC=[ArC{N(Dipp)} 2 C(SiMe 3 )C:) (Dipp=2,6-iPr 2 C 6 H 3 , Ar=Ph, 4-Me 2 NC 6 H 4 or 4-PhC 6 H 4 ) based on an 1,3-imidazole scaffold to yield N-ethynylformimidamide (eFIM) derivatives as crystalline solids (eFIM={(Dipp)N=C(Ar)N(Dipp)}C≡CSiMe 3 ) is reported. eFIMs are thermally stable under inert gas atmosphere and show moderate air stability (t 1/2= 3 h for Ar=Ph). eFIMs are excellent surrogates of iMICs, which generally have a limited shelf-life, and readily undergo ring-closing click reactions with a variety of main-group as well as transition metal Lewis acids to form hitherto challenging iMIC-compounds in good to excellent yields. In addition to the relevance of eFIMs in the synthesis of iMIC-compounds, quantification of the stereoelectronic properties of a representative iMIC (Ar=Ph) by experimental and theoretical methods suggests remarkably σ-donor property and steric profile of these new ligand sets., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

A bidentate pnictogen bonding host-system based on 1,8-diethynylanthracene was synthesized by a selective tin-antimony exchange reaction and investigated regarding its ability to act as a Lewis acidic host component for the complexation of Lewis basic or anionic guests. In this work, the novel C≡C-Sb(C 2 F 5 ) 2 unit was established to study the potential of antimony(III) sites as representatives for the scarcely explored pnictogen bonding donors. The capability of this partly fluorinated host system was investigated towards halide anions (Cl - , Br - , I - ), dimethyl chalcogenides Me 2 Y (Y=O, S, Se, Te), and nitrogen heterocycles (pyridine, pyrimidine). Insights into the adduct formation behavior as well as the bonding situation of such E⋅⋅⋅Sb-C F moieties were obtained in solution by means of NMR spectroscopy, in the solid state by X-ray diffraction, by elemental analyses, and by computational methods (DFT, QTAIM, IQA), respectively., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A highly halide affine, tetradentate pnictogen-bonding host-system based on the syn -photodimer of 1,8-diethynylanthracene was synthesized by a selective tin-antimony exchange reaction. The host carries four C[triple bond, length as m-dash]C-Sb(C 2 F 5 ) 2 units and has been investigated regarding its ability to act as a Lewis acidic host component for the cooperative trapping of halide ions (F - , Cl - , Br - , I - ). The chelating effect makes this host-system superior to its bidentate derivative in competition experiments. It represents a charge-reversed crown-4 and has the ability to dissolve otherwise poorly soluble salts like tetra-methyl-ammonium chloride. Its NMR-spectroscopic properties make it a potential probe for halide ions in solution. Insights into the structural properties of the halide adducts by X-ray diffraction and computational methods (DFT, QTAIM, IQA) reveal a complex interplay of attractive pnictogen bonding interactions and Coulomb repulsion., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Cyclic organoalane compounds [(ADC Ar )AlH 2 ] 2 (ADC Ar = ArC{(DippN)C} 2 ; Dipp = 2,6-iPr 2 C 6 H 3 ; Ar = Ph or 4-PhC 6 H 4 (Bp)) based on anionic dicarbene (ADC) frameworks have been reported as crystalline solids. Treatments of Li(ADC Ar ) with LiAlH 4 at room temperature afford [(ADC Ar )AlH 2 ] 2 with the concomitant release of LiH. Compounds [(ADC Ar )AlH 2 ] 2 are stable crystalline solids and are freely soluble in common organic solvents. They are annulated tricyclic compounds with an almost planar central C 4 Al 2 -core embedded between two peripheral 1,3-imidazole (C 3 N 2 ) rings. At room temperature, [(ADC Ph )AlH 2 ] 2 readily reacts with CO 2 to form two- and four-fold hydroalumination products [(ADC Ph )AlH(OCHO)] 2 and [(ADC Ph )Al(OCHO) 2 ] 2 , respectively. Further hydroalumination reactivity of [(ADC Ph )AlH 2 ] 2 has been shown with isocyanate (RNCO) and isothiocyanate (RNCS) species (R=alkyl or aryl group). All compounds have been characterized by NMR spectroscopy, mass spectrometry, and single-crystal X-ray diffraction., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Phosphoranides comprising three phosphorus carbon bonds are scarcely represented in the literature. We now utilized tris(pentafluoroethyl)phosphane, P(C 2 F 5 ) 3 , and cyanobis(pentafluoroethyl)phosphane, P(C 2 F 5 ) 2 (CN), featuring electron withdrawing pentafluoroethyl groups, to synthesize such compounds. Metal fluorides MF (M=Ag, Cs) add to P(C 2 F 5 ) 3 yielding respective M[P(C 2 F 5 ) 3 F] salts. Those M[P(C 2 F 5 ) 3 F] subsequently suffer a loss of C 2 F 4 , furnishing M[P(C 2 F 5 ) 2 F 2 ]. The cesium salt decomposes instantaneously when warmed to rt, whereas the silver salt decomposes slowly over several days at rt. Treatment of Ag[P(C 2 F 5 ) 3 F] with 2,2'-bipyridine facilitated the isolation and structural characterization of [Ag(bipy){P(C 2 F 5 ) 3 F}]. With P(C 2 F 5 ) 2 (CN), AgF reacts under substitution of the cyano group yielding P(C 2 F 5 ) 2 F, rather than phosphoranide formation. However, [K(18-crown-6)]F adds to P(C 2 F 5 ) 2 (CN) furnishing [K(18-crown-6)][P(C 2 F 5 ) 2 (CN)F]. Its structural characterization was successful, despite its tendency to undergo an exchange of substituents, yielding [K(18-crown-6)][P(C 2 F 5 ) 2 F 2 ] and presumably [K(18-crown-6)][P(C 2 F 5 ) 2 (CN) 2 ]. The latter forms an equilibrium with [K(18-crown-6)]CN and P(C 2 F 5 ) 2 (CN) which lies well on side of the phosphane and cyanide salt., (© 2023 The Authors. ChemPlusChem published by Wiley-VCH GmbH.)

The phytochemical investigation of the MeOH and CH 2 Cl 2 -MeOH (1:1) extracts from the flowers and twigs of Helichrysumfoetidum (L.) Moench (Asteraceae), which showed antileishmanial and antiplasmodial activities during the preliminary screening, led to the isolation of four undescribed compounds, including two ent-beyer-15-ene-type diterpenoids, foetidumins A (1) and B (2), one flavonoid, foetidumin C (3) and one chalcopyrone, foetidumin D (4). Additionally, fourteen known compounds comprising, two ent-beyer-15-ene-type diterpenoids (5-6), six flavonoids (7-12), two steroids (13-14), three triterpenoids (15-17), and one glyceryl monostearate (18) were also isolated. The chemical structures of foetidumins A-D were fully elucidated by analyses of their spectroscopic data. The structure and the stereochemistry of foetidumin A (1) were confirmed by SC-XRD analyses. Among the tested compounds, foetidumin C (3), erythroxylol A (6), and kaempferol (7) displayed the highest antileishmanial potency with IC 50 values of 13.0, 11.8, and 11.1 μM, respectively. Foetidumin C (3) had no cytotoxicity toward Vero cells with the selectivity index > 3.59. Meanwhile, extracts of flowers and twigs had higher activity against Plasmodium falciparum chloroquine-sensitive (Pf3D7) strain with IC 50 values of 3.66 and 10.52 μg/mL, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The bio guided fractionation of the dichloromethane/methanol (1:1) crude extract of the air-dried whole plant of C. aegyptiaca led to the isolation of one new flavone derivative designated conyflavone ( 1 ) and one new clerodane diterpene type designated conyclerodane ( 2 ) along with five known compounds including two flavonoids Gardenin C ( 3 ), chrysosplenetin ( 4 ) and two steroids glucoside of β -sitosterol ( 5 ), the mixture of stigmasterol ( 6 ) and β -sitosterol ( 6' ) and ent-2b,18,19trihydroxycleroda-3,13-dien-16,15-olide ( 7 ). The structures were established by spectroscopic methods including IR, 1D and 2D NMR in conjunction with mass spectroscopy and by comparison to data of related compounds described in literature. The stereocentres in compound 2 were determined by SC-XRD analysis. Crude extract as well as fractions and pure compounds were evaluated in vitro for their antibacterial activities against four pathogenic and two clinical isolate strains using microdilution methods. Extracts and compounds displayed a moderate antibacterial activity with MIC values ranging from 125 to 500 µg/mL.

The first 1,4-distibabenzene-1,4-diide compound [(ADC)Sb] 2 (5) based on an anionic dicarbene (ADC) (ADC=PhC{N(Dipp)C} 2 , Dipp=2,6-iPr 2 C 6 H 3 ) is reported as a bordeaux-red solid. Compound 5, featuring a central six-membered C 4 Sb 2 ring with formally Sb I atoms may be regarded as a base-stabilized cyclic bis-stibinidene in which each of the Sb atoms bears two lone-pairs of electrons. 5 undergoes 2 e-oxidation with Ph 3 C[B(C 6 F 5 ) 4 ] to afford [(ADC)Sb] 2 [B(C 6 F 5 ) 4 ] 2 (6) as a brick-red solid. Each of the Sb atoms of 6 has an unpaired electron and a lone-pair. The broken-symmetry open-shell singlet diradical solution for (6) 2+ is calculated to be 2.13 kcal mol -1 more stable than the closed-shell singlet. The diradical character of (6) 2+ according to SS-CASSCF (state-specific complete active space self-consistent field) and UHF (unrestricted Hartree-Fock) methods amounts to 36 % and 39 %, respectively. Treatments of 6 with (PhE) 2 yield [(ADC)Sb(EPh)] 2 [B(C 6 F 5 ) 4 ] 2 (7-E) (E=S or Se). Reaction of 5 with (cod)Mo(CO) 4 affords [(ADC)Sb] 2 Mo(CO) 4 (8)., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The molecular structure of acenaphthene has been determined experimentally in the gas phase using gas electron diffraction intensities and literature-available rotational constants. Supplementary high-level quantum-chemical calculations were utilized in refinements of the semi-empirical equilibrium structure. In this work we investigate on how different schemes of GED data averaging and weighting can be used for obtaining the most accurate and precise structural parameters. Single-crystal X-ray diffraction experiments at different temperatures have been performed and the solid-state structure of acenaphthene has been determined. Both gas and solid-state acenaphthene molecules are planar and possess a non-twisted ethylene bridge. The aliphatic C-C bond in the ethylene fragment is elongated to 1.560(4) Å in the gas phase and 1.5640(4) Å in the solid phase. Based on the experimental data several theoretical approximations have been calibrated and predictions for other molecules were made, taking into account dispersion and electrostatic interactions. Particular derivatives of acenaphthene may potentially have significantly elongated C-C bonds up to 1.725 Å. However, among the experimental gas-phase structures available to date probably the longest C-C bond ( r e , (av) = 1.750(28) Å at w = 0.93) was determined in a carbaborane derivative 1,2-(SeH) 2 - closo -1,2-C 2 B 10 H 10 .

The two oxygen-bridged geminal frustrated Lewis pairs (FLP) tBu 2 P-O-AlBis 2 (Bis=CH(SiMe 3 ) 2 ; 1) and tBu 2 P-O-Si(C 2 F 5 ) 3 (2) were reacted with the heterocumulenes PhNCO, PhOCN, PhNCS, CS 2 and PhNSO as well as SO 2 . With isocyanate and cyanate, both 1 and 2, form addition products under formation of five-membered rings. With CS 2 , isothiocyanate and sulfinylaniline, only 1 forms stable adducts, whereas 2 shows reactivity towards sulfinylaniline, but the product decomposed after a few minutes. The reaction of 1 with SO 2 led to partial cleavage of the P-O-Al and Al-C units, as confirmed by X-ray diffraction studies of a complex aggregate. The reaction of 2 with SO 2 affords the 1,2-addition product. All adducts were characterized by means of multinuclear NMR spectroscopy, X-ray crystallography and CHN analyses., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

In the rising field of organoindium chemistry little is known about the perfluoroorganyl-substituted indium compounds. The increasing use of indium reagents is explained by their high stability and tolerance towards water and functional groups. Here we report on the synthesis of the novel tetrakis(pentafluoroethyl)indate, [In(C 2 F 5 ) 4 ] - , and its characterization in salts with the cations [Li(thf) 3 ] + , Cs + , [PPh 4 ] + and [H 14 O 6 ] 2+ (thf=tetrahydrofuran). To the best of our knowledge, these salts constitute the first perfluoroalkylindates and, in general, the first isolated perfluoroalkylindium compounds which are fully characterized by NMR spectroscopy, mass spectrometry, elemental analysis and X-ray diffraction analysis., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Phenyl and pentafluorophenyl trifluorothioacetate, CF 3 C(O)SC 6 H 5 and CF 3 C(O)SC 6 F 5 , were prepared by condensation of CF 3 C(O)Cl and the corresponding mercaptan RSH under vacuum conditions. The compounds were isolated and properly characterized by using infrared spectroscopy, UV-Vis, multinuclear NMR spectroscopy techniques and by mass spectrometry. The crystal structures have been determined for both CF 3 C(O)SC 6 H 5 and according to the best of our knowledge the not yet reported in the literature CF 3 C(O)SC 6 F 5 species. The conformational preferences of the three title species were also determined by means of FTIR spectroscopy. In the case of CF 3 C(O)OC 6 F 5 , the FTIR spectrum was also measured in an Ar-matrix and a subsequent photochemical study was performed. The main stable photoproduct found, beside CO, was the ether C 6 F 5 OCF 3 . Quantum-chemical calculations were used to determine the conformational preferences and complement the experimental structure parameters as well as to interpret the UV-Vis spectra determined for the three species under study. As a result of all these experimental determinations complemented with computational calculations, it can be affirmed that the title compounds present a single syn conformation in the analyzed phases ( syn with respect to the CO double bond and the opposite C-chalcogen single bond). This finding reconfirms the syn conformational transferability found so far for both thioesters and esters, a result that is closely related to the properties of these families in biological processes.

The reaction of the oxygen-bridged frustrated Lewis pairs (FLPs) tBu 2 P-O-Si(C 2 F 5 ) 3 (1) and tBu 2 P-O-AlBis 2 (2) with azobenzene, promoted by UV irradiation, led to a selective complexation of the cis-isomer. The addition product of 2 is stable, while the adduct of 1 isomerizes in solution in an ortho-benzidine-like [3,3]-rearrangement by cleavage of the N-N bond, saturation of the nitrogen atoms with hydrogen atoms and formation of a new bond between two phenyl ortho-carbon atoms. Similar rearrangements take place with different para-substituted azobenzenes (R=Me, OMe, Cl) and di(2-naphthyl)diazene, while ortho-methylated azo compounds do not form adducts with 1. All adducts were characterized by multinuclear NMR spectroscopy and elemental analyses and the mechanism of the rearrangement was explored by quantum-chemical calculations., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Ten previously undescribed metabolites were isolated from Peperomia incana (Haw.) A. Dietr. (Piperaceae), among which four contained a chromene moiety, two were identified as meroterpene lactones, and four were cannabinoid-like compounds. While the chemical structures of the compounds were assigned based on HRESIMS and 1D and 2D-NMR spectra analyses, the relative and absolute configurations were assigned from NOE correlations and a combination of ECD data and X-ray single crystal analyses, respectively. In a cytotoxic assay against a panel of seven human cancer cell lines (A549, MDA-MB-231, HeLa, DU 145, 5637, Hep G2, and MIA PaCa-2, which represent non-small cell lung cancer, as well as breast, cervical, prostate, bladder, liver, and pancreas carcinomas, respectively) most of the isolated compounds showed promising cytotoxic activities. The incanachromenes B, and incanabinoids A and C exhibited the highest cytotoxicity toward all tested cancer cell lines with IC 50 values in the range of 5.0-10.0 μM, whereas incanolides A, B, and incanabinoid B showed the lowest cytotoxic activity. In addition, incanachromene C and incanabinoid C produced a significant antibacterial effect toward planktonic cells and biofilms of multidrug-resistant Staphylococcus aureus strains., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A series of five ortho -phenylene-bridged phosphorus-silicon Lewis pairs was synthesized, with phosphorus bearing isopropyl groups while the substituents at the silicon atom vary (-CH 3 , -Cl, -F). Possible interactions between Lewis acid and base were investigated both experimentally (NMR, XRD) and theoretically to determine the influence of the different substituents. Calculated ortho -interaction energies (OIEs) show a stabilizing interactions between the acidic and basic units which were also found for the meta - and para -interaction energies (MIEs and PIEs, respectively), indicating stabilization resulting not from direct acid-base interaction but from electronic interactions through the ring. Further spectroscopic (NMR, XRD) and theoretical (NBO, QTAIM, SAPT) investigations confirmed the absence of direct interactions between silicon and phoshorus.

The chemical investigation of the EtOH extract from the stem bark of Trichilia monadelpha (Thonn.) J. J. De Wilde afforded two new limonoids ( 1 and 2 ): 24-acetoxy-21,25-dihydroxy-21,23-epoxytirucall-7-en-3-one ( 1 ) and (6 R )-1- O -deacetylkhayanolide E ( 2 ), together with eleven known compounds ( 3 - 13 ), including additional limonoids, flavonoids, triterpenoids, steroids, and fatty acid. Their structures were determined using 1D- and 2D-NMR experiments, ESI mass spectrometry, and single crystal X-ray diffraction analysis. The antibacterial and antiplasmodial activities of the extracts, sub-extracts, fractions, and some of the isolated compounds were evaluated in known pathogenic strains, including Staphylococcus aureus and Plasmodium falciparum . Fraction E ( n -Hex/EtOAc 30:70, v / v ) showed significant activity against S . aureus ATCC 25923 with a MIC value of 3.90 µg/mL, while one of its constituents (epicatechin ( 9 )) exhibited significant activity with MIC values of 7.80 µg/mL. Interestingly, grandifotane A ( 6 ) (IC 50 = 1.37 µM) and khayanolide D ( 5 ) (IC 50 = 1.68 µM) were highly active against the chloroquine-sensitive/sulfadoxine-resistant plasmodium falciparum 3D7 strain, unlike their corresponding plant extract and fractions.

The new oxygen-bridged geminal Si/P Frustrated Lewis Pair (FLP) tBu 2 P-O-Si(C 2 F 5 ) 3 (2) is able to reversibly bind carbon dioxide at ambient temperature. We compared its reactivity towards benzil, but-3-en-2-one, nitriles and phenylacetylene to that of the Al/P FLP tBu 2 P-O-AlBis 2 (Bis=-CH(SiMe 3 ) 2 ) (1). When reacted with benzil, both, 1 and 2, form the 1,2-addition product, but in the Si/P FLP 2, the second carbonyl function additionally binds to the silicon atom. With but-3-en-2-one 2 forms the 1,2-addition product, while 1 binds in 1,4-position. The reaction with acetonitrile yielded an unexpected etheneimine adduct for both systems, while only 1 reacted with tert-butylnitrile. With benzonitrile and acrylonitrile, 2 showed reversible addition to the C≡N bond and 1 forms a stable adduct with benzonitrile. Solely 1 shows reactivity towards phenylacetylene affording a mixture of the CH deprotonation adduct tBu 2 P(H)-O-AlBis 2 (CCPh) and the FLP -C≡C 1,2-addition adduct under ring formation. All compounds were characterized by multinuclear NMR spectroscopy, XRD and elemental analysis., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Room temperature ionic liquids of cyclic sulfonimide anions n cPFSI (ring size: n = 4-6) with the cations [EMIm] + (1-ethyl-3-methylimidazolium), [BMIm] + (1-butyl-3-methylimidazolium) and [BMPL] + (BMPL = 1-butyl-1-methylpyrrolidinium) have been synthesized. Their solid-state structures have been elucidated by single-crystal X-ray diffraction and their physicochemical properties (thermal behaviour and stability, dynamic viscosity and specific conductivity) have been assessed. In addition, the ion diffusion was studied by pulsed field gradient stimulated echo (PFGSTE) NMR spectroscopy. The decisive influence of the ring size of the cyclic sulfonimide anions on the physicochemical properties of the ILs has been revealed. All ILs show different properties compared to those of the non-cyclic TFSI anion. While these differences are especially distinct for ILs with the very rigid 6cPFSI anion, the 5-membered ring anion 5cPFSI was found to result in ILs with relatively similar properties. The difference between the properties of the TFSI anion and the cyclic sulfonimide anions has been rationalized by the rigidity (conformational lock) of the cyclic sulfonimide anions. The comparison of selected IL properties was augmented by MD simulations. These highlight the importance of π + -π + interactions between pairs of [EMIm] + cations in the liquid phase. The π + -π + interactions are evident for the solid state from the molecular structures of the [EMIm] + -ILs with the three cyclic imide anions determined by single-crystal X-ray diffraction., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Herein, the first stable anions K[SIPr Bp ] (4 a-K) and K[IPr Bp ] (4 b-K) (SIPr Bp =BpC{N(Dipp)CH 2 } 2 , IPr Bp =BpC{N(Dipp)CH} 2 ; Bp=4-PhC 6 H 4 ; Dipp=2,6-iPr 2 C 6 H 3 ) derived from classical N-heterocyclic carbenes (NHCs) (i.e. SIPr and IPr) have been isolated as violet crystalline solids. 4 a-K and 4 b-K are prepared by KC 8 reduction of the neutral radicals [SIPr Bp ] (3 a) and [IPr Bp ] (3 b), respectively. The radicals 3 a and 3 b as well as [Me-IPr Bp ] 3 c (Me-IPr Bp =BpC{N(Dipp)CMe} 2 ) are accessible as crystalline solids on treatment of the respective 1,3-imidazoli(ni)um bromides (SIPr Bp )Br (2 a), (IPr Bp )Br (2 b), and (Me-IPr Bp )Br (2 c) with KC 8 . The cyclic voltammograms of 2 a-2 c exhibit two one-electron reversible redox processes in -0.5 to -2.5 V region that correspond to the radicals 3 a-3 c and the anions (4 a-4 c) - . Computational calculations suggest a closed-shell singlet ground state for (4 a-4 c) - with the singlet-triplet energy gap of 17-24 kcal mol -1 ., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A new α -pyrone, asperpyrone ( 1 ) and two known compounds, stigmasterol ( 2 ) and 7-hydroxy-3-(2,3-dihydroxybutyl)-1(3 H )-Isobenzofuranone ( 3 ) were isolated from the solid rice culture of the endophytic fungus Aspergillus sp., an endophytic fungus isolated from the fresh inner tissue of the barks of Garicinia smeathmannii . Their structures were determined by extensive spectral analysis including 1 D and 2 D NMR, HRESIMS and single-crystal X-ray crystallographic analysis. Asperpyrone ( 1 ) was tested against an axenic culture of Entamoeba moshkovskii , but did not exhibit any significant amoebicidal activity.

In this work, an enantioselective biocatalytic synthesis of chiral thiomorpholines using imine reductases (IREDs) is described. As substrates, four prochiral and one chiral 3,6-dihydro-2 H -1,4-thiazines were synthesized in a modified Asinger reaction and subsequently reduced using imine reductases as a biocatalyst, NADPH as a cofactor, and a glucose dehydrogenase (GDH)-glucose cofactor regeneration system. As a result, chiral thiomorpholines with a stereogenic center created in 3-position were obtained under mild process conditions with high conversions and excellent enantioselectivities of up to 99%. Furthermore, as a proof of concept, a sequential one-pot process combining both individual reaction steps was achieved.

Photo-dimers of 1,5-diethynylanthracene and 1,5-bis[(trimethylsilyl)ethynyl]anthracene, obtained by UV radiation of the monomers, were treated with the bulky aluminium hydride [(SiMe 3 ) 2 HC] 2 AlH in hydroalumination reactions. Hydroalumination of the tetraethynyl-substituted anthracene photo-dimers ( syn and anti ) led to fourfold aluminium-functionalized Janus-like products with two aluminium functions on each side oriented towards the same direction. The reactions of the monomeric anthracene derivatives with [(SiMe 3 ) 2 HC] 2 AlH afforded semi-flexible bidentate Lewis acids, which are interesting building blocks for molecular chains bearing multiple Lewis-acidic functions. The aluminium-functionalized anti -photo-dimer was treated with various donor molecules to gain insight into its host-guest chemistry. All poly-Lewis acids and their adducts were characterized by X-ray diffraction experiments, multinuclear NMR spectroscopy and by elemental analyses.

Herein, we report on the synthesis, characterization, and reactivity studies of the first cyclic C 2 As 2 -diradicaloid {(IPr)CAs} 2 (6) (IPr = C{N(Dipp)CH} 2 ; Dipp = 2,6-iPr 2 C 6 H 3 ). Treatment of (IPr)CH 2 (1) with AsCl 3 affords the Lewis adduct {(IPr)CH 2 }AsCl 3 (2). Compound 2 undergoes stepwise dehydrochlorination to yield {(IPr)CH}AsCl 2 (3) and {(IPr)CAsCl} 2 (5 a) or [{(IPr)CAs} 2 Cl]OTf (5 b). Reduction of 5 a (or 5 b) with magnesium turnings gives 6 as a red crystalline solid in 90% yield. Compound 6 featuring a planar C 2 As 2 ring is diamagnetic and exhibits well resolved NMR signals. DFT calculations reveal a singlet ground state for 6 with a small singlet-triplet energy gap of 8.7 kcal mol -1 . The diradical character of 6 amounts to 20% (CASSCF, complete active space self consistent field) and 28% (DFT). Treatments of 6 with (PhSe) 2 and Fe 2 (CO) 9 give rise to {(IPr)CAs(SePh)} 2 (7) and {(IPr)CAs} 2 Fe(CO) 4 (8), respectively., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Bis(dimethylphosphino)methane (dmpm) was used as a ligand to synthesize four semi-supported dinuclear gold(I) complexes, dmpm(AuR) 2 (R = Cl, C 6 H 5 , C 6 Cl 5 , and C 6 F 5 ), which were studied concerning the synergistic effects of two weak noncovalent interactions: aurophilic and aryl-aryl stacking interactions. The chloro-substituted complex was synthesized by the ligand substitution of (tht)AuCl with dmpm and further functionalized by the reaction with PhMgBr or in situ- generated C 6 Cl 5 Li to afford the phenyl- and pentachlorophenyl-substituted compounds, respectively. The pentafluorophenyl-substituted gold complex was generated by the ligand substitution of (tht)Au(C 6 F 5 ) with dmpm. All complexes were characterized by multinuclear NMR spectroscopy, CHN analyses, and X-ray diffraction experiments. Additionally, the basic photoluminescence properties of dmpm(AuCl) 2 , dmpm(AuC 6 Cl 5 ) 2 , and dmpm(AuC 6 F 5 ) 2 were examined. The aggregation behavior of dmpm(AuC 6 F 5 ) 2 was further investigated by variable-temperature diffusion-ordered NMR spectroscopy experiments.

In this contribution, we report on the "free" [P(C 2 F 5 ) 2 F 2 ] - ion and its ligand properties in transition metal complex chemistry. For this purpose, Ag[P(C 2 F 5 ) 2 F 2 ] was treated with [{(Et 2 N) 3 P═N} 3 P═NHC(CH 3 ) 3 ]Cl ([EtP 4 H]Cl) to yield [EtP 4 H][P(C 2 F 5 ) 2 F 2 ], featuring a weakly coordinating phosphazenium cation. Due to the weak interaction between the cation and anion, the [P(C 2 F 5 ) 2 F 2 ] - ion meets the so-called pseudo-gas-phase conditions. To determine the Tolman electronic parameter, [EtP 4 H][Ni(CO) 3 {P(C 2 F 5 ) 2 F 2 }] was prepared from [EtP 4 H][P(C 2 F 5 ) 2 F 2 ] and [Ni(CO) 4 ], facilitating the classification of the P(C 2 F 5 ) 2 F 2 moiety as a moderately π-acidic ligand. By treatment of [EtP 4 H][P(C 2 F 5 ) 2 F 2 ] with [AuCl(tht)], the neutral tetrahydrothiophene ligand was substituted by the phosphoranide ion, yielding [EtP 4 H][AuCl{P(C 2 F 5 ) 2 F 2 }]. When Ag[P(C 2 F 5 ) 2 F 2 ] was treated with [AuCl(tht)], on the other hand, the chloride was substituted. Transmetalation reactions of this type proved to be an efficient transfer method of the P(C 2 F 5 ) 2 F 2 moiety, as further demonstrated by the reactions of Ag[P(C 2 F 5 ) 2 F 2 ] with [FeCl(CO) 2 Cp], [FeCl(CO) 2 Cp*], and [PdCl 2 (NCMe) 2 ]. Surprisingly, P(C 2 F 5 ) 2 F demonstrated fluorinating abilities toward [FeCl(CO) 2 Cp], [FeCl(CO) 2 Cp*], [AuCl(tht)], and [PdCl 2 (NCMe) 2 ]. Apparently, fluorido transition metal complexes were generated in situ under the formation of P(C 2 F 5 ) 2 Cl. The fluorido iron and palladium complexes transfer their fluoride ions onto P(C 2 F 5 ) 2 F, yielding the respective phosphoranido complexes, featuring the P(C 2 F 5 ) 2 F 2 moiety.

The reaction of t Bu 2 P(O)H with Bis 2 AlH (Bis = CH(SiMe 3 ) 2 ) afforded the adduct t Bu 2 P(H)-O-Al(H)Bis 2 (3). It slowly releases H 2 to form the first oxygen-bridged geminal Al/P frustrated Lewis pair t Bu 2 P-O-AlBis 2 . It is capable of reversibly binding molecular hydrogen to afford 3, shown by NMR and H/D scrambling experiments, and forms a 1,2-adduct with CO 2 . Importantly, the H 2 adduct 3 reduces CO 2 in a stoichiometric reaction leading to the formic acid adduct t Bu 2 P(H)-O-Al(CO 2 H)Bis 2 . The formation of the different species was explored by density functional theory calculations which provide support for the experimental results. All products were characterized by NMR spectroscopy as well as X-ray diffraction experiments and elemental analyses., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Mesoionic dithiolates [(MIDt Ar )Li(LiBr) 2 (THF) 3 ] (MIDt Ar ={SC(NDipp)} 2 CAr; Dipp=2,6-iPr 2 C 6 H 3 ; Ar=Ph 3 a, 3-MeC 6 H 4 (3-Tol) 3 b, 4-Me 2 NC 6 H 4 (DMP) 3 c) and [(MIDt Ph )Li(THF) 2 ] (4) are readily accessible (in≥90 % yields) as crystalline solids on treatments of anionic dicarbenes Li(ADC Ar ) (2 a-c) (ADC Ar ={C(NDipp) 2 } 2 CAr) with elemental sulfur. 3 a-c and 4 are monoanionic ditopic ligands with both the sulfur atoms formally negatively charged, while the 1,3-imidazole unit bears a formal positive charge. Treatment of 4 with (L)GeCl 2 (L=1,4-dioxane) affords the germylene (MIDt Ph )GeCl (5) featuring a three-coordinated Ge atom. 5 reacts with (L)GeCl 2 to give the Ge-Ge catenation product (MIDt Ph )GeGeCl 3 (6). KC 8 reduction of 5 yields the homoleptic germylene (MIDt Ph ) 2 Ge (7). Compounds 3 a-c and 4-7 have been characterized by spectroscopic studies and single-crystal X-ray diffraction. The electronic structures of 4-7 have been analyzed by DFT calculations., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Phosphino-functionalized mesoionic olefins (p-MIOs), (iMIC)CHR (iMIC = PhC{N(Dipp)} 2 C(PPh 2 )C, Dipp = 2,6-iPr 2 C 6 H 3 ; R = H 4a or Ph 4b), derived from a 1,3-imidazole-based mesoionic carbene (iMIC) are reported. The p-MIOs 4a (blue) and 4b (green) are crystalline solids and have been characterized by NMR spectroscopy and X-ray diffraction as well as DFT calculations. The calculated proton affinities of 4a (291.3 kcal mol -1 ) and 4b (288.1 kcal mol -1 ) support their remarkable basicity that exceeds that of classical NHCs. Treatment of 4a with (Me 2 S)AuCl (and AgOTf) affords the dinuclear gold compounds [(4a)Au](X) 2 (5-X) (X = Cl or OTf) with a short Au⋯Au distance of 3.130(2) Å for 5-Cl. The reaction of 4a with the main-group reagent PhBCl 2 yields the boronium cation [(4a)BPhCl]Cl (6).