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The authors of this work have optimized a novel synthetic route towards glucose‐based PdII‐bis(NHC) complexes in only 4 steps with total yields up to 73 %. The synthesis route encompasses an Appel reaction towards 6‐iodo‐glucopyranosides, followed by acyl‐protection, then quaternization with imidazoles and finally the conversion of these acyl‐protected glucosyl imidazolium salts to their respective palladium(II)bis(NHC) complexes, via an intermediary silver(I) complex. Overall, 11 acyl‐protected glucosyl imidazolium iodides as NHC‐precursors and 15 complexes have been synthesized. The structure‐activity relationships of different functionalizations in these complexes and their reactivity in a model Suzuki‐Miyaura between bromobenzene and 4‐tolueneboronic acid reaction has been investigated, and a highly reactive complex leading to >99 % yield at 0.005 mol% catalytic loading has been found. [ABSTRACT FROM AUTHOR]

Ullazines and their π-expanded derivatives have gained much attention as active components in various applications, such as in organic photovoltaic cells or as photosensitizers for CO2 photoreduction. Here, we report the divergent synthesis of functionalized diazaullazines by means of two different domino-reactions consisting of either a Povarov/cycloisomerization or alkyne–carbonyl metathesis/cycloisomerization protocol. The corresponding quinolino-diazaullazine and benzoyl-diazaullazine derivatives were obtained in moderate to good yields. Their optical and electronic properties were studied and compared to related, literature-known compounds to obtain insights into the impact of nitrogen doping and π-expansion. [ABSTRACT FROM AUTHOR]

Four different isomeric azadibenzo[a,e]pyrenes (benzo[4,10]anthra[9,1‐gh]isoquinolines and benzo[4,10]anthra[1,9‐fg]isoquinolines) were prepared by combination of Pd‐catalyzed Sonogashira and Suzuki cross‐coupling, Brønsted acid mediated cycloisomerization and Pd‐catalysed CH‐activation reactions. The optical properties have been studied by steady‐state absorption and emission spectroscopy in different solvents and during acid titration. Trifluoroacetic acid protonation strongly affects absorption and emission properties, with variations depending on the position of the nitrogen atom of the specific compound. Electrochemical analysis showed distinct oxidation and reduction potentials. DFT calculations provided further insights into electronic properties. [ABSTRACT FROM AUTHOR]

Phosphorus‐centered disbiradicals, in which the radical sites exist as individual spin doublets with weak spin‐spin interaction have not been known so far. Starting from monoradicals of the type [⋅P(μ‐NTer)2P−R], we have now succeeded in linking two such monoradical phosphorus centers by appropriate choice of a linker. To this end, biradical [⋅P(μ‐NTer)2P⋅] (1) was treated with 1,6‐dibromohexane, affording the brominated species {Br[P(μ‐NTer)]2}2C6H12 (3). Subsequent reduction with KC8 led to the formation of the disbiradical {⋅[P(μ‐NTer)]2}2C6H12 (4) featuring a large distance between the radical phosphorus sites in the solid state and formally the highest biradical character observed in a P‐centered biradical so far, approaching 100 %. EPR spectroscopy revealed a three‐line signal in solution with a considerably larger exchange interaction than would be expected from the molecular structure of the single crystal. Quantum chemical calculations revealed a highly dynamic conformational space; thus, the two radical sites can approach each other with a much smaller distance in solution. Further reduction of 4 resulted in the formation of a potassium salt featuring the first structurally characterized P‐centered distonic radical anion (5−). Moreover, 4 could be used in small molecule activation. [ABSTRACT FROM AUTHOR]

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Reactions of a masked N‐heterocyclic phosphinidene (mNHP, 1), a four‐membered heterocycle with a divalent P atom, with various isonitriles (tBu−NC, Dmp−NC) and carbonyls (CO, Fe(CO)5, and benzalacetone) have been studied. The isonitriles (tBu−NC and Dmp−NC) insert into a P−N bond of the four‐membered ring of 1, leading to the formation of a five‐membered heterocycle (2tBu, 2Dmp), indicating carbene‐like reactivity of the isonitriles. In exactly this way, CO, which is isolobal to isonitriles, reacts to form a five‐membered ring (3) with an exocyclic C=O double bond. If, on the other hand, Fe(CO)5 is used as a CO source, a CO molecule is inserted analogously, however, the remaining Fe(CO)4 fragment is bound via a phosphorus‐iron dative bond to the five‐membered heterocycle. When mNHP 1 reacts with the α,β‐unsaturated ketone benzalacetone, phosphinidene reactivity is observed for 1. This means that the four‐membered ring opens and the P atom reacts with the benzalacetone in a cyclization reaction to form a 1,2‐oxaphospha‐cyclopentene. Theoretical studies of the five‐membered heterocycles 2 and 3 carrying eight π electrons show that zwitterionic Lewis representations dominate in the resonance scheme and only a very low biradical character (<5 %) is found. [ABSTRACT FROM AUTHOR]

2‐(1‐Hydroxyethylidene)malononitrile (4) is commercially sold as the keto isomer and is described in the literature as either a keto (4 b) or enol (4 a) species. Using NMR techniques and single crystal X‐ray diffraction, we were able to show that 4 exists exclusively as the enol isomer (4 a) in solution as well as in the solid state, which agrees with quantum chemical calculations. By adding one or two equivalents of the Lewis acid B(C6F5)3, the mono‐ or diadducts are formed in exergonic reactions, in which the enol form is further thermodynamically stabilized. The structure and acidity of enol 4 a and its borane adducts are discussed based on experimental and theoretical results. [ABSTRACT FROM AUTHOR]

This report describes a one‐pot multi‐step procedure to obtain double azahelicenes via nucleophilic fluorine substitution of 2,2‐di(2‐bromophenyl)‐1,1‐difluoroalkenes and palladium‐catalysed ring closing reaction. The developed synthesis approach allows easy diversification of substituents at all four fragments of the obtained X‐shaped aza[4,6]helicene entity. Yields range from 20 % to 60 % among 12 product examples. X‐ray single crystal analysis reveals formation of (P,P) and (M,M) enantiomer mixture of products. Optical and electrochemical properties of selected products were studied by performing UV/Vis absorption, photoluminescence and cyclic voltammetry measurements. Experimental results are supported by (TD)‐DFT, NICS and NICS2BC calculations. [ABSTRACT FROM AUTHOR]

The incorporation of heteroatoms into polycyclic aromatic hydrocarbons (PAHs) has been recognized as valuable tool to alter their inherent optical and electrochemical properties and are thought as promising next‐generation semiconductor materials. We herein report the synthesis of diindenopyrene, a fragment of C70 and two of its nitrogen‐doped aza‐analogs. The developed synthetic procedure is based on Brønsted‐acid‐mediated cycloisomerization followed by Pd‐catalyzed C−H‐activation as key‐steps. The impact of N‐doping on the optical and electrochemical properties has been studied and the experimental results are supported by DFT calculations. [ABSTRACT FROM AUTHOR]

C10a‐Acetoxylated perhydroazepino[1,2‐a]‐indoles, accessible via visible light‐mediated sensitized photooxygenation of cyclo‐hepta[b]indoles, are precursors to structurally elaborate carbon‐centered radicals. Their photoredox‐catalyzed SET reduction by phenothiazine or phenoxazine photocatalysts, followed by fragmentation and C−O bond cleavage, liberates tricyclic α‐amino‐α‐carbonyl radicals that readily engage in radical addition reactions with silyl enol ethers and silyl ketene acetals. The C−C functionalized azepinoindole[1,2‐a]indoles are useful building blocks for the synthesis of polycyclic indole derivatives as shown by the controlled borohydride reduction of a C10a‐methylenecarboxylate derivative, which leads stereoselectively to tetracyclic azepino[1,2‐a]furo[3,2‐b]indoles. The photocatalytic method developed herein is also suitable for the radical functionalization of simple α‐acetoxy acetophenones. [ABSTRACT FROM AUTHOR]

A series of N‐doped Benzo[b]fluoranthenes was synthesized. Specifically varying the position of the Nitrogen atom in all four positions of the bottom ring. In the last reaction step the five‐membered ring of the unsubstituted core structure is formed by palladium catalyzed CH‐activation. This synthetic approach allows for the selective introduction of heteroatoms into the core structure and leads to four regioisomeric products. Subsequently the optical and electrochemical properties of these polyaromatic heterocycles were compared. DFT/TD‐DFT and NICS calculations were performed to further analyze, how the position of Nitrogen impacts the overall characteristics of the molecules. This composes a thorough study on the chemical behavior of N‐doped Benzo[b]fluoranthenes. [ABSTRACT FROM AUTHOR]

The reaction of Li[[Mes.sup.*]NH] (1, [Mes.sup.*] = 2,4,6-tri-tert-butylphenyl) with aminoarsane [Mes.sup.*]N(H)As[Cl.sub.2] (2, [Mes.sup.*] = 2,4,6-t-[Bu.sub.3][C.sub.6][H.sub.2]) at -80 [degrees]C resulted in the formation of bisamino(chloro)arsane [([Mes.sup.*]NH).sub.2]AsCl (3Cl) by elimination of LiCl. 3Cl reacted with the Lewis acids such as Al[Cl.sub.3], Ga[Cl.sub.3], and Ag[X] (X = As[F.sub.6.sup.-], OT[f.sup.-], B[F.sub.4.sup.-]; OTf = trifluoromethanesulfonate = OS[O.sub.2]C[F.sub.3.sup.-]) upon chloride ion abstraction to give salts bearing the cation [[[([Mes.sup.*]NH).sub.2]As].sup.+] (3[X]; X = As[F.sub.6.sup.-], OT[f.sup.-], B[F.sub.4.sup.-], E[Cl.sub.4]; E = Al, Ga). [3.sup.+] represents the first NH-functionalized acyclic bis(amino)arsenium cation. The formation of the salts bearing [3.sup.+] could also be observed in the reaction of cyclo-1, 3-diarsa-2, 4-diazane [[ClAs([mu]-N[Mes.sup.*])].sub.2] (4) with Lewis acids (Al[Cl.sub.3], Ga[Cl.sub.3]) in the presence of proton sources in solution. All presented salts 3[X] were stable at room temperature and fully characterized. Key words: arsenic, cation, bis(amino)arsenium cation, crystal structure. La réaction du Li[[Mes.sup.*]NH] (1, [Mes.sup.*] = 2,4,6-tri-tert-butylphényl) avec l'aminoarsane [Mes.sup.*]N(H)As[Cl.sub.2] (2, [Mes.sup.*] = 2,4,6-t-[Bu.sub.3][C.sub.6][H.sub.2]) à -80 [degrees]C a donné lieu à la formation du bisamino(chloro)arsane [([Mes.sup.*]NH).sub.2]AsCl (3Cl) par élimination du LiCl. Le 3Cl a réagi avec des acides de Lewis tels que l'Al[Cl.sub.3], le Ga[Cl.sub.3] et l'Ag[X] (X = As[F.sub.6.sup.-], OT[f.sup.-], B[F.sub.4.sup.-]; OTf = trifluorométhanesulfonate = OS[O.sub.2]C[F.sub.3.sup.-]) par abstraction de l'ion chlorure pour former des sels comportant le cation [[[([Mes.sup.*]NH).sub.2]As].sup.+] (3[X]; X = As[F.sub.6.sup.-], OT[f.sup.-], B[F.sub.4.sup.-], E[Cl.sub.4]; E = Al, Ga). L'ion [3.sup.+] représente le premier cation bis(amino)arsénium cyclique fonctionnalisé par un groupe NH. Nous avons pu également observer la formation de sels comportant l'ion [3.sup.+] lors de la réaction du cyclo-1,3-diarsa-2,4-diazane [[ClAs([mu]-N[Mes.sup.*])].sub.2] (4) avec des acides de Lewis (Al[Cl.sub.3], Ga[Cl.sub.3]) en solution en présence d'une source de protons. Tous les sels 3[X] présentés se sont révélés stables à température ambiante et ont été soumis à une caractérisation complète. [Traduit par la Rédaction] Mots-clés: arsenic, cation, cation bis(amino)arsénium, structure cristalline., Introduction In the last decades, the possibility to generate dicoordinate nitrogen bound arsenic compounds was shown not only for a series of amino(imino)arsanes (I, Scheme 1), but also for non-cyclic [...]

A series of thienoindolizine structural isomers have been synthesized in a one‐pot, two‐step procedure starting from easily accessible gem‐difluoroalkene functionalized bromothiophenes. The developed method gives easy access to a range of thienoindolizine products containing thieno[3,2‐g]‐, thieno[3,4‐g]‐ and thieno[2,3‐g]indolizine core structures. The described synthesis strategy consists of a base mediated, transition metal free nucleophilic substitution of fluorine atoms by nitrogen containing heterocycles followed by a Pd catalyzed intramolecular cyclization. A series of 22 final product examples has been obtained with yields ranging from 29 % to 95 %. UV/Vis absorption, fluorescence spectroscopy, fluorescence lifetime measurements and cyclic voltammetry were carried out with selected final products to evaluate structural effects on photophysical and electrochemical properties. (TD)DFT and NICS calculations were performed to provide insight into the electronic properties of the four core molecular structures. [ABSTRACT FROM AUTHOR]

Differently substituted phenyl isonitriles (with C−H bonds in ortho‐position) and naphthyl isonitriles were reacted with the cyclic biradical [⋅P(μ‐N‐Ter)2P⋅] (1). Insertion of the isonitrile formed a cyclic five‐membered biradical [⋅P(NTer)2C(R)P⋅] (2R, R=phenyl, naphthyl) in the first step, followed by C−H activation at the aryl substituent, resulting in novel azaphospholes (5R), which could be isolated and fully characterized. The formation of the azaphospholes can be prevented by the addition of a second equivalent of isonitrile, which causes the blocking of the radical centers in 2R by adduct formation (3R). Quantum mechanical calculations showed that a significant increase in the aromaticity of the benzo‐ and naphtho‐azaphospholes is one of the driving forces for the activation process leading to the formation of thermodynamically favored azaphospholes. Targeted activation of C−H bonds using biradical systems represents a new synthetic approach to generate benzo‐ and naphtho‐azaphospholes. [ABSTRACT FROM AUTHOR]

A new synthetic route to 1H-1,2,3-triazole-4,5-dithiols (tazdtH2) as ligands for the coordination of NiII, PdII, PtII and CoIII via the dithiolate unit is presented. Different N-protective groups were introduced with the corresponding azide via a click-like copper-catalyzed azide-alkyne [3 + 2] cycloaddition (CuAAC) and fully characterized by NMR spectroscopy. Possible isomers were isolated and an alternative synthetic route was investigated and discussed. After removal of the benzyl protective groups on sulfur by in situ-generated sodium naphthalide, complexes at the [(dppe)M] (M = Ni, Pd, Pt), [(PPh3)2Pt] and [(η5-C5H5)Co] moieties were prepared and structurally characterized by XRD analysis. In this process, the by-products 11 and 12 as monothiolate derivatives were isolated and structurally characterized as well. With regioselective coordination via the dithiolate unit, the electronic influence of different metals or protective groups at N was investigated and compared spectroscopically by means of UV/Vis spectroscopy and cyclic voltammetry. Complex [(η5-C5H5)Co(5c)] (10), is subject to a dimerization equilibrium, which was investigated by temperature-dependent NMR and UV/Vis spectroscopy (solution and solid-state). The thermodynamic parameters of the monomer/dimer equilibrium were derived. [ABSTRACT FROM AUTHOR]

We present the extension of Pacman ligands to bidentate phosphane ligands enabling them to bind metals in their sterically protected cavity. The coordination of coinage metals shows the ability of the ligand to adopt different coordination modes by distortion, of which some additionally include the imine nitrogen atoms. Besides the coordinated metal, the substitution on the phosphorus atoms influences the type of coordination. [ABSTRACT FROM AUTHOR]

The chlorination of 1,2‐diphosphinobenzene with PCl5 to 1,2‐bis(dichlorophosphino)benzene was performed with high yields (93 %) despite the high number of P−H functions. The method was further applied to other phosphanes, enabling the first synthesis and complete characterization of 1,2,4‐tris(dichlorophosphino)benzene (89 % yield) and 1,2,4,5‐tetrakis(dichlorophosphino)benzene (91 % yield), valuable precursors for example for binuclear complexes, coordination polymers, organic wires, or metal–organic frameworks. The application of the chlorophosphanes in base induced ring closure reactions with primary amines is demonstrated. [ABSTRACT FROM AUTHOR]