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Variation of a single ligand in the W(ii) alkyne complexes of bis(diphenylphosphino)acetylene leads to W(ii)/W(iii) redox potentials spanning a window of 850 mV. The corresponding dinuclear complexes with PdCl2 show differing catalytic activity.

Dibenzoacridines were prepared by alkyne–carbonyl-metathesis and the optical properties of the products were studied.

A new way to play “Pac-Man™”: We have synthesized two different Pacman phosphanes as a new kind of multidentate phosphane ligands and used them to complex coinage metals.

Photocatalytic dehydrogenative [2 + 2] cycloadditions between amines and alkenes were developed that allow for the stereoselective and high-yielding synthesis of functionalized azetidines. The oxidative formal Aza Paternò-Büchi reactions are induced by photoredox-catalyzed aerobic oxidation of dihydroquinoxalinones

Lewis acid-catalysed oxa Diels–Alder reactions of unsaturated azepino[1,2-a]indole diones with enol ethers lead to tetracyclic azepane-fused pyrano[3,2-b]indoles, with high stereoselectivity and under mild reaction conditions.

Spirocyclic diindenothiophenes were prepared by cyclization of tosylhydrazones, readily available from ketones, with 3,4-dibromo-2,5-bis(2-bromphenyl)thiophene. For bicyclic ketones, the bis-spirocycles were formed with very good diastereoselectivity.

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.

Naphthothiophenes were prepared from commercially available 2,3-dibromothiophenes in two steps by one-pot Suzuki/Sonogashira or Sonogashira/Suzuki coupling reactions, followed by intramolecular alkyne-carbonyl-metathesis reactions. The final cyclization reaction proceeds in the presence of

1,2,3-Triazole dithiol derivatives, which are straightforwardly accessible by 1,3-dipolar addition of azides with sulfide substituted alkynes, show dithiolene-type coordination behaviour.

Imidazo[1,2-a]benzoazepines were prepared in good yields by combination of Pd catalyzed cross coupling reactions with alkyne-carbonyl metathesis (ACM).

The cycloaddition of aldehydes to the singlet biradical [P(μ-NTer)]2 is demonstrated experimentally. High-level ab initio calculations reveal a minimal electronic activation barrier.

Reaction of [(μ-NR)P˙]2 with CSCl2 and Mg gives a deep blue, highly labile cyclic thioketone with singlet biradical character. It can be converted to a housane-type isomer by light and to bicyclic cage compounds by addition of CS2 and benzaldehyde.

The tricyclic azepino[1,2-a]indole acetates 7, readily accessible by visible-light-driven catalytic photooxygenation of cyclohepta[b]indoles 1, are convenient precursors to novel and uncommon cyclic C,N-diacyliminium ions 3. We report here the first Lewis acid-catalyzed C-C bond forming reactions of these species with TMSCN and silyl enol ethers as nucleophiles and utilizing TIPSOTf as well as Sc(OTf)3 as catalysts. Employing Sc(OTf)3/pybox complexes as a chiral catalyst system, regio- and enantioselective asymmetric alkylations with silyl enol ethers were achieved.

Imidazo[1,2

New complexes of trivalent cobalt with substituted thiosemicarbazone ligands having an NNS donor system {HL1 = 4-(4-nitrophenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide and HL2 = 4-(2,5-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} were synthesized via the in situ oxidation of divalent cobalt chloride accompanying its addition to the ligands. The complexes C1 and C2 were characterized via elemental (CHNS) analysis and 1H NMR, FT-IR and UV-Vis. spectroscopic data. Further, conductometric studies on the DMF solutions of the complexes indicated their 1:1 nature, and their diamagnetism revealed the low-spin trivalent oxidation state of the cobalt in the complexes. The X-ray diffraction analysis of complex C1 indicated that it crystallizes in the triclinic space group P-1. The metal exhibits an octahedral environment built by two anionic ligands bound via pyridine nitrogen, imine nitrogen and thiol sulfur atoms. The complex is counterbalanced by a chloride ion. In addition, two lattice water molecules were detected in the asymmetric unit of the unit cell. The ligand HL2 (20 mg/mL in DMSO) displayed inhibition zones of 10 mm against both S. aureus and E. coli, and the same concentration of the respective complex raised this activity to 15 and 12 mm against these bacterial strains, respectively. As a comparison, ampicillin inhibited these bacterial strains by 21 and 25 mm, respectively. Screening assay by HL1 on four human cancer cells revealed the most enhanced activity against the breast MCF-7 cells. The induced growth inhibitions in the MCF-7 cells by all compounds (0–100 μg/mL) have been detected. The ligands {HL1 and HL2} and complex C2 gave inhibitions with IC50 values of 52.4, 145.4 and 49.9 μM, respectively. These results are more meaningful in comparison with similar cobalt complexes, but less efficient compared with the inhibition with IC50 of 9.66 μM afforded by doxorubicin. In addition, doxorubicin, HL1 and HL2 induced cytotoxicity towards healthy BHK cells with IC50 values of 36.42, 54.8 and 110.6 μM, but surviving fractions of 66.1% and 62.7% of these cells were detected corresponding to a concentration of 100 μg/mL of the complexes (136.8 μM of C1 and 131.4 μM of C2).

The synthesis and reactivity of sterically demanding phosphaarsanes TerR1P-AsR2 (3) is described. These species were selectively synthesized via metathesis reactions of Ter-stabilized [Ter = 2,6-bis(2,4,6-trimethylphenyl)phenyl] potassium phosphides TerR1PK (1) with the N-heterocyclic chloroarsane ClAs{N(tBu)CH2}2 (2). Conversion of the n-butyl-substituted phosphaarsane 3c with the reactive heterocumulene CS2 leads to an insertion into the P-As bond, yielding the phosphane arsanyldithiocarboxylate TerR1P-C(S)S-AsR2 (4c) as a new structural motif. Because full conversion of 3c with CS2 requires long reaction times, an alternative synthetic route is reported herein, involving the conversion of 2 with phosphane dithiocarboxylates TerR1-C(S)SK (5), enabling synthetic access to a wider range of phosphane arsanyldithiocarboxylates. These interpnictogen dithiocarboxylates show an interesting bonding situation with a significantly elongated As-S bond due to negative hyperconjugation within the molecule. All products along the reaction path were fully characterized.

The preparative access to and first group 10 metal complexes of novel 1

The reaction of the singlet biradical [P(μ-NTer)]

Electrophilic aromatic substitution (EAS) can provide a straightforward approach to the efficient synthesis of functionalized complex aromatic molecules. In general, Lewis acids serve as a beneficial stimulus for the formation of a Wheland complex, the intermediate in the classical S

The chemistry of silylated sulfuric acid, O2 S(OSiMe3 )2 (T2 SO4 , T=Me3 Si; also known as bis(trimethylsilyl) sulfate), has been studied in detail with the aim of synthesizing the formal autosilylation products of silylated sulfuric acid, [T3 SO4 ]+ and [TSO4 ]- , in analogy to the known protonated species, [H3 SO4 ]+ and [HSO4 ]- . The synthesis of the [TSO4 ]- ion only succeeds when a base, such as OPMe3 that forms a weakly coordinating cation upon silylation, is reacted with T2 SO4 , resulting in the formation of [Me3 POT]+ [TSO4 ]- . [T3 SO4 ]+ salts could be isolated starting from T2 SO4 in the reaction with [T-H-T]+ [B(C6 F5 )4 ]- or T+ [CHB11 Br6 H5 ]- when a weakly coordinating anion is used as counterion. All silylated compounds could be crystallized and structurally characterized.

A concise and modular synthesis of pyrrolo[1,2-a][1,6]- and [1,8]naphthyridines by a one-pot two-step reaction consisting of electrophilic acylation followed by an alkyne-carbonyl-metathesis reaction as the final cyclization step is reported. This developed synthetic methodology allows the facile synthesis of these heterocyclic core structures in mainly high overall yields under metal-free conditions. Reaction conditions are carefully optimized and display a novel supplement to access these tricyclic heterocyclic compounds.

A variety of 4-methoxysalicylates and related polyketide-type phenols are regioselectively prepared by formal [3+3] cyclocondensations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 3-oxo-orthoesters. Cycloalkyl-substituted salicylates were prepared for the first time.

We show that the carboxyl-functionalized ionic liquid 1-(carboxymethyl)pyridinium bis(trifluoromethylsulfonyl)imide [HOOC-CH

The oxidation of silylated hydrazine, (Me

Within the second funding period of the SPP 1708 “Material Synthesis near Room Temperature”,which started in 2017, we were able to synthesize novel anionic species utilizing Ionic Liquids (ILs) both, as reaction media and reactant. ILs, bearing the decomposable and non‐innocent methyl carbonate anion [CO3Me]−, served as starting material and enabled facile access to pseudohalide salts by reaction with Me3Si−X (X=CN, N3, OCN, SCN). Starting with the synthesized Room temperature Ionic Liquid (RT‐IL) [nBu3MeN][B(OMe)3(CN)], we were able to crystallize the double salt [nBu3MeN]2[B(OMe)3(CN)](CN). Furthermore, we studied the reaction of [WCC]SCN and [WCC]CN (WCC=weakly coordinating cation) with their corresponding protic acids HX (X=SCN, CN), which resulted in formation of [H(NCS)2]− and the temperature labile solvate anions [CN(HCN)n]− (n=2, 3). In addition, the highly labile anionic HCN solvates were obtained from [PPN]X ([PPN]=μ‐nitridobis(triphenylphosphonium), X=N3, OCN, SCN and OCP) and HCN. Crystals of [PPN][X(HCN)3] (X=N3, OCN) and [PPN][SCN(HCN)2] were obtained when the crystallization was carried out at low temperatures. Interestingly, reaction of [PPN]OCP with HCN was noticed, which led to the formation of [P(CN)2]−, crystallizing as HCN disolvate [PPN][P(CN⋅HCN)2]. Furthermore, we were able to isolate the novel cyanido(halido) silicate dianions of the type [SiCl0.78(CN)5.22]2− and [SiF(CN)5]2− and the hexa‐substituted [Si(CN)6]2− by temperature controlled halide/cyanide exchange reactions. By facile neutralization reactions with the non‐innocent cation of [Et3HN]2[Si(CN)6] with MOH (M=Li, K), Li2[Si(CN)6] ⋅ 2 H2O and K2[Si(CN)6] were obtained, which form three dimensional coordination polymers. From salt metathesis processes of M2[Si(CN)6] with different imidazolium bromides, we were able to isolate new imidazolium salts and the ionic liquid [BMIm]2[Si(CN)6]. When reacting [Mes(nBu)Im]2[Si(CN)6] with an excess of the strong Lewis acid B(C6F5)3, the voluminous adduct anion {Si[CN⋅B(C6F5)3]6}2− was obtained., The reaction of ionic liquids (ILs) with methylcarbonate anions like [R3MeE][CO3Me] (E=N: R=Et, nPr, nBu; E=P, R=Ph) with Me3Si−X (X=CN, N3, OCN, SCN) or H2SiF6 led to quantitative formation of pseudohalide salts [R3MeE]X or fluorosilicates, e. g. [R3MeN]2[SiF6]. From these precursors, novel anionic species like [B(OMe)3(CN)]− or cyanido(halido)silicates of the type [SiCl0.78(CN)5.22]2−, [SiF(CN)5]2− and [Si(CN)6]2− were obtained. Functionalization of the hexacyanidosilicate with the Lewis acid B(C6F5)3 led to the voluminous WCA {Si[CN⋅B(C6F5)3]6}2−. Beside [H(NCS)2]−, highly labile solvate anions of the type [X(HCN)2]− (X=CN, SCN), [X(HCN)3]− (X=CN, N3, OCN) and [P(CN⋅HCN)2]− were obtained from IL‐like mixtures, when starting from [WCC]X ([WCC]=[Ph4P], [PPN]) and neat HCN.

A pair of diastereomeric dinuclear complexes, [Tp′(CO)BrW{μ‐η2‐C,C′‐κ2‐S,P‐C2(PPh2)S}Ru(η5‐C5H5)(PPh3)], in which W and Ru are bridged by a phosphinyl(thiolato)alkyne in a side‐on carbon P,S‐chelate coordination mode, were synthesized, separated and fully characterized. Even though the isomers are similar in their spectroscopic properties and redox potentials, the like‐isomer is oxidized at W while the unlike‐isomer is oxidized at Ru, which is proven by IR, NIR and EPR‐spectroscopy supported by spectro‐electrochemistry and computational methods. The second oxidation of the complexes was shown to take place at the metal left unaffected in the first redox step. Finally, the tipping point could be realized in the unlike isomer of the electronically tuned thiophenolate congener [Tp′(CO)(PhS)W{μ‐η2‐C,C′‐κ2‐S,P‐C2(PPh2)S}Ru(η5‐C5H5)‐(PPh3)], in which valence trapped WIII/RuII and WII/RuIII cationic species are at equilibrium., Diastereomers differ in physical properties: A case of real metal/metal redox isomerism is observed in a dinuclear complex with a particularly short bridging ligand. The two stereogenic complex moieties at W and Ru, respectively, are linked by an alkyne based phosphine thiolate chelate ligand. Oxidation of the like isomer pertains to tungsten, whereas the unlike isomer is oxidised at ruthenium. The diastereomers show opposite redox behaviour!

Sterically demanding secondary potassium phosphides (4) were synthesized and investigated. Reaction with halophosphanes (5) yields diphosphanes (6), whereas reaction with CS2 yields phosphanyl dithioformates (10). These can be further converted to the corresponding phosphanyl esters of dithioformic acid R2P-C(S)S-PR2 (8). One of these thioesters (8) was found to undergo a migration reaction, resulting in the formation of a phosphanylthioketone with an additional phosphanylthiolate group (9), which was used as a chiral ligand in gold coordination chemistry. The phosphanyl migration reaction was investigated by spectroscopic and theoretical methods, revealing a first-order reaction via a cyclic transition state. All species mentioned were fully characterized.

Tetrahydrocarbazoles and perhydrocyclohepta[b]indoles undergo a catalytic cascade singlet oxygenation in alkaline medium, which leads to chiral tricyclic perhydropyrido‐ and perhydroazepino[1,2‐a]indoles in a single operation. These photooxygenation products are new synthetic equivalents of uncommon C,N‐diacyliminium ions and can be functionalized with the aid of phosphoric acid organocatalysis., Splashing down the ponds: The cascade photooxygenation of tetrahydrocarbazoles and cyclohepta[b]indoles leads to chiral tricyclic perhydropyrido‐ and perhydroazepino[1,2‐a]indoles, which are precursors to uncommon C,N‐diacyliminium ions.

Functionalized imidazolium cations were combined with the hexacyanidosilicate anion, [Si(CN)6]2���, by salt metathesis reactions with K2[Si(CN)6], yielding novel ionic compounds of the general formula [R���Ph(nBu)Im]2[Si(CN)6] {R = 2-Me (1), 4-Me (2), 2,4,6-Me = Mes (3), 2-MeO (4), 2,4-F (5), 4-Br (6); Im = imidazolium}. All synthesized imidazolium hexacyanidosilicates decompose upon thermal treatment above 95 ��C (96 ��� 164 ��C). Furthermore, the hexa-borane-adduct [Mes(nBu)Im]2{Si[(CN)B(C6F5)3]6}��6CH2Cl2 (7), which is thermally stable up to 215 ��C, was obtained from the reaction of 3 with Lewis acidic B(C6F5)3. In CH3CN solution, decomposition of the hexaadduct to the Lewis-acid-base adduct CH3CN���B(C6F5)3 and [(C6F5)3B��(��-CN)��B(C6F5)3]��� was observed. All synthesized compounds were isolated in good yields and were completely characterized including single crystal structure elucidations. �� 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Although pure hydrogen cyanide can spontaneously polymerize or even explode, when initiated by small amounts of bases (e.g. CN- ), the reaction of liquid HCN with [WCC]CN (WCC=weakly coordinating cation=Ph4 P, Ph3 PNPPh3 =PNP) was investigated. Depending on the cation, it was possible to extract salts containing the formal dihydrogen tricyanide [CN(HCN)2 ]- and trihydrogen tetracyanide ions [CN(HCN)3 ]- from liquid HCN when a fast crystallization was carried out at low temperatures. X-ray structure elucidation revealed hydrogen-bridged linear [CN(HCN)2 ]- and Y-shaped [CN(HCN)3 ]- molecular ions in the crystal. Both anions can be considered members of highly labile cyanide-HCN solvates of the type [CN(HCN)n ]- (n=1, 2, 3 …) as well as formal polypseudohalide ions.

The reaction of TMP-NH2 [TMP = m,m-(CF3)2-C6H3] with 2 equiv of n-BuLi led to the in situ formation of Li2[N-TMP], which, after the addition of BiCl3, formed a [Cl-Bi(μ3-N-TMP)]4-type heterocubane in up to 30% yield. Transmetalation reactions, thought of as alternatives, starting from the analogous tin–nitrogen heterocubane [Sn(μ3-N-TMP)]4 and BiCl3 resulted in the isolation of a complex reaction mixture from which different Bi–N and Bi–Sn–N cage compounds could be isolated. The structures of all cage compounds that contain bismuth are discussed, and the thermodynamics of the formation of [Cl-Bi(μ3-N-TMP)]4 are highlighted. In an attempt to isolate Li2[N-TMP], generated in situ from TMP-NH2 and 2 equiv of n-BuLi, it was possible to isolate a lithium salt with a negatively charged lithium cluster of the type [Li9(N-TMP)5F]2– with an unusual Li9N5F skeleton.