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The main feedstock for the value-added phosphorus chemicals used in industry and research is white phosphorus (P

Electrophilic fluorophosphonium triflates bearing pyridyl (3[OTf]) or imidazolyl (4[OTf])-substituents act as intramolecular frustrated Lewis pairs (FLPs) and reversibly form 1 : 1 adducts with CO2 (5+ and 6+ ). An unusual and labile spirocyclic tetrahedral intermediate (72+ ) is observed in CO2 -pressurized (0.5-2.0 bar) solutions of cation 4+ at low temperatures, as demonstrated by variable-temperature NMR studies, which were confirmed crystallographically. In addition, cations 3+ and 4+ actively bind carbonyls, nitriles and acetylenes by 1,3-dipolar cycloaddition, as shown by selected examples.

Platinum complexes aggregate into polymorphs with different intermolecular interactions leading to different photophysical properties. Strong intermolecular interactions stabilize the aggregate to such an extent that the polymorphs can be separated directly by column chromatography. Solid‐state structures as well as quantum‐chemical calculations confirmed the effect of the interactions on the photophysical properties., The interactions causing the action: Square planar platinum complexes aggregate into polymorphs with different intermolecular interactions leading to unique photophysical properties. Strong intermolecular interactions stabilize the aggregate to such an extent that the polymorphs can be separated by column chromatography. Solid‐state structures, quantum chemical calculations, concentration‐dependent excitation–emission spectroscopy, and solid‐state emission spectroscopy help to rationalize and shed light on the nature of this phenomenon.

The reaction of UO2(OAc)2 ⋅ 2H2O with the biologically inspired ligand 2‐salicylidene glucosamine (H2 L1) results in the formation of the anionic trinuclear uranyl complex [(UO2)3(μ3‐O)(L1)3]2− (1 2−), which was isolated in good yield as its Cs‐salt, [Cs]2 1. Recrystallization of [Cs]2 1 in the presence of 18‐crown‐6 led to formation of a neutral ion pair of type [M(18‐crown‐6)]2 1, which was also obtained for the alkali metal ions Rb+ and K+ (M=Cs, Rb, K). The related ligand, 2‐(2‐hydroxy‐1‐naphthylidene) glucosamine (H2 L2) in a similar procedure with Cs+ gave the corresponding complex [Cs(18‐crown‐6)]2[(UO2)3(μ3‐O)(L2)3 ([Cs(18‐crown‐6)]2 2). From X‐ray investigations, the [(UO2)3O(Ln)3]2− anion (n=1, 2) in each complex is a discrete trinuclear uranyl species that coordinates to the alkali metal ion via three uranyl oxygen atoms. The coordination behavior of H2 L1 and H2 L2 towards UO2 2+ was investigated by NMR, UV/Vis spectroscopy and mass spectrometry, revealing the in situ formation of the 1 2− and 2 2−dianions in solution., Investigation of the coordination behavior of salicylidene glucosamine (H2 L1) towards uranyl ions (UO2 2+) revealed the exclusive formation of a trinuclear anionic uranyl complex [(UO2)3(μ3‐O)(L1)3]2− (1 2−), which was isolated by precipitation with the alkali metals ions Cs+, Rb+, and K+. Recrystallization of the Cs salt in the presence of 18‐crown‐6 in DMF led to the formation of the solvated ion pair [Cs(18‐crown‐6)]2 1, in which coordination of the Cs+ ion by three uranyl oxygen atoms was observe.

The in situ electrophilic fluorination of phosphanes with commercially available bench-stable N-fluorobenzenesulfonimide (NFSI), followed by subsequent methylation of the [N(PhSO2)2]− anion with MeOTf yields a family of electrophilic fluorophosphonium cations as triflate salts. Most of these fluorophosphonium triflate salts are remarkably Lewis acidic and form isolable adducts in stoichiometric reactions with suitable donors such as N,N-dimethylformamide (DMF). Furthermore, their catalytic capabilities were tested in the transformation of formamides into N-sulfonyl formamidines in the reaction with Na[N(SO2Ph)2] and the proposed mechanism is validated by DFT calculations.

Structural investigations of three actinide(IV) 4-phosphoryl 1H-pyrazol-5-olate complexes (An = Th(IV), U(IV), Np(IV)) and their cerium(IV) analogue display the same metal coordination in the solid state. The mononuclear complexes show the metal centre in a square antiprismatic coordination geometry composed by the two O-donor atoms of four deprotonated ligands. Detailed solid state analysis of the U(IV) complex shows that dependent on the solvent used altered arrangements are observable, resulting in a change in the coordination polyhedron of the U(IV) metal centre to bi-capped trigonal prismatic. Further, single crystal analyses of the La(III) and Ce(III) complexes show that the ligand can also act as a neutral ligand by protonation of the pyrazolyl moiety. All complexes were comprehensively characterized by NMR, IR and Raman spectroscopy. A single resonance in each of the 31P NMR spectra for the La(III), Ce(III), Ce(IV), Th(IV) and Np(IV) complex indicates the formation of highly symmetric complex species in solution. Extended X-ray absorption fine structure (EXAFS) investigations provide evidence for the same local structure of the U(IV) and Np(IV) complex in toluene solution, confirming the observations made in the solid state.

Synthesis of mixed‐substituted tetraphosphetanes (RP−PtBu)2 (R=Ph (4), Py (5); Py=2‐pyridyl) is achieved from the condensation of dipyrazolylphosphanes RPpyr2 (R=Py (1), Ph (3); pyr=3,5‐dimethylpyrazolyl) as P1‐building block (R−P) and tBuPH2 in an equimolar ratio. Compound 5 is of special interest since the presence of two pyridyl‐substituents as well as the P4‐core allows for a rich coordination chemistry with coinage metal salts [Cu(MeCN)4][OTf], Ag[OTf] and in situ formed [Au(tht)][OTf] (tht=tetrahydrothiophene). Both tetraphosphetanes undergo alkylation reaction with MeOTf to give a series of tetraphosphetanium and tetraphosphetanediium triflate salts with additional methylation of the pyridyl‐moiety in case of 5 resulting in interesting novel cyclic trications. Harsh reaction condition and an excess of MeOTf converts 5 into the cyclic trication [‐P(MePy)PMe2P(MePy)PtBu‐]3+ (13 3+; MePy=1‐methylpyridiniumyl) through the elimination of isobutene. This salt undergoes a complicated rearrangement reaction involving a P−P/P−P bond metathesis to form trication [‐P(MePy)3PtBu‐]3+ (17 3+) when reacted with Me2PPMe2., Choose your donor: A convenient route towards mixed‐substituted tetraphosphetanes was established, enabling the synthesis of (PhP‐PtBu)2 and (PyP‐PtBu)2 (Py=2‐pyridyl) in good yields. The coordination chemistry of (PyP‐PtBu)2 was investigated by reacting it with coinage metal triflate salts. Further methylation studies on both tetraphosphetanes revealed an interesting chemistry of multiply charged, cylic polyphosphanes.

Three unprecedented helical nanographenes (1, 2, and 3) containing an azulene unit are synthesized. The resultant helical structures are unambiguously confirmed by X‐ray crystallographic analysis. The embedded azulene unit in 2 possesses a record‐high twisting degree (16.1°) as a result of the contiguous steric repulsion at the helical inner rim. Structural analysis in combination with theoretical calculations reveals that these helical nanographenes manifest a global aromatic structure, while the inner azulene unit exhibits weak antiaromatic character. Furthermore, UV/Vis‐spectral measurements reveal that superhelicenes 2 and 3 possess narrow energy gaps (2: 1.88 eV; 3: 2.03 eV), as corroborated by cyclic voltammetry and supported by density functional theory (DFT) calculations. The stable oxidized and reduced states of 2 and 3 are characterized by in‐situ EPR/Vis–NIR spectroelectrochemistry. Our study provides a novel synthetic strategy for helical nanographenes containing azulene units as well as their associated structures and physical properties., An odd contribution: Azulene‐embedded helical nanographenes with global aromaticity are synthesized by a Scholl‐type cyclization. X‐ray crystallographic analysis clearly reveals the formation of an azulene unit in the helical π‐system. The embedded azulene core adopts a highly twisted conformation and is less aromatic than pristine azulene.

Detailed investigations of the reaction pathway to trinuclear oxo-bridged uranyl complexes.

Effective receptors for the separation of Li + from a mixture with other alkali metal ions under mild conditions remains an important challenge that could benefit from new approaches. In this study, it is demonstrated that the 4-phosphoryl pyrazolones, H L 2 -H L 4 , in the presence of the typical industrial organophosphorus co-ligands tributylphosphine oxide (TBPO), tributylphosphate (TBP) and trioctylphosphine oxide (TOPO), are able to selectively recognise and extract lithium ions from aqueous solution. Structural investigations in solution as well as in the solid state reveal the existence of a series of multinuclear Li + complexes that include dimers (TBPO, TBP) as well as rarely observed trimers (TOPO) and represent the first clear evidence for the synergistic role of the co-ligands in the extraction process. Our findings are supported by detailed NMR, MS and extraction studies. Liquid-liquid extraction in the presence of TOPO revealed an unprecedented high Li + extraction efficiency (78%) for H L 4 compared to the use of the industrially employed acylpyrazolone H L 1 (15%) and benzoyl-1,1,1-trifluoroacetone (52%) extractants. In addition, a high selectivity for Li + over Na + , K + and Cs + under mild conditions (pH ~ 8.2) confirms that H L 2 -H L 4 represent a class of ligands that are very effective extractants for use in lithium separation.

[LC RP((PhP)2C2H4)][OTf] (4 a,b[OTf]) and [LC iPrP(PPh2)2][OTf] (5 b[OTf]) were prepared from the reaction of imidazoliumyl‐substituted dipyrazolylphosphane triflate salts [LC RP(pyr)2][OTf] (3 a,b[OTf]; a: R=Me, b=iPr; LC R=1,3‐dialkyl‐4,5‐dimethylimidazol‐2‐yl; pyr=3,5‐dimethylpyrazol‐1‐yl) with the secondary phosphanes PhP(H)C2H4P(H)Ph) and Ph2PH. A stepwise double P−N/P−P bond metathesis to catena‐tetraphosphane‐2,3‐diium triflate salt [(Ph2P)2(LC MeP)2][OTf]2 (7 a[OTf]2) is observed when reacting 3 a[OTf] with diphosphane P2Ph4. The coordination ability of 5 b[OTf] was probed with selected coinage metal salts [Cu(CH3CN)4]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph2PPLC iPr)Au}4][OTf]4 (9[OTf]4) was unexpectedly formed as a result of a chloride‐induced P−P bond cleavage. The weakly coordinating triflate anion enables the formation of the expected copper(I) and silver(I) complexes [(5 b)M(CH3CN)3][OTf]2 (M=Cu, Ag) (10[OTf]2, 11[OTf]2)., Cationic 1,2,3‐triphospholanium salts [LC RP((PhP)2C2H4)][OTf] and dicationic catena‐tetraphosphane‐2,3‐diidum salt [(Ph2P)2(LC MeP)2][OTf]2 were obtained from reactions of Lewis basic phosphanes with dipyrazolylphosphanes [LC RP(pyr)2][OTf] (pyr=3,5‐dimethylpyrazol‐1‐yl). Reaction of triphosphane salt [LC RP(PPh2)2][OTf] with AuCl(tht) led to the cationic gold complex [{(Ph2PPLC iPr)Au}4][OTf]4, which forms a helical structure in the solid state.

Electrophilic fluorophosphonium triflates bearing pyridyl (3[OTf]) or imidazolyl (4[OTf])‐substituents act as intramolecular frustrated Lewis pairs (FLPs) and reversibly form 1 : 1 adducts with CO2 (5 + and 6 +). An unusual and labile spirocyclic tetrahedral intermediate (7 2+) is observed in CO2‐pressurized (0.5–2.0 bar) solutions of cation 4 + at low temperatures, as demonstrated by variable‐temperature NMR studies, which were confirmed crystallographically. In addition, cations 3 + and 4 + actively bind carbonyls, nitriles and acetylenes by 1,3‐dipolar cycloaddition, as shown by selected examples., Extending the FLP library: Electrophilic fluorophosphonium triflates bearing pyridyl or imidazolyl substituents act as intramolecular N/P frustrated Lewis pairs that are capable of small molecule activation, that is, reversible CO2 sequestration and binding of carbonyls, nitriles and acetylenes.

Structural investigations of three actinide(iv) 4-phosphoryl 1H-pyrazol-5-olate complexes (An = Th(iv), U(iv), Np(iv)) and their cerium(iv) analogue display the same metal coordination in the solid state. The mononuclear complexes show the metal centre in a square antiprismatic coordination geometry composed by the two O-donor atoms of four deprotonated ligands. Detailed solid state analysis of the U(iv) complex shows that dependent on the solvent used altered arrangements are observable, resulting in a change in the coordination polyhedron of the U(iv) metal centre to bi-capped trigonal prismatic. Further, single crystal analyses of the La(iii) and Ce(iii) complexes show that the ligand can also act as a neutral ligand by protonation of the pyrazolyl moiety. All complexes were comprehensively characterized by NMR, IR and Raman spectroscopy. A single resonance in each of the 31P NMR spectra for the La(iii), Ce(iii), Ce(iv), Th(iv) and Np(iv) complex indicates the formation of highly symmetric complex species in solution. Extended X-ray absorption fine structure (EXAFS) investigations provide evidence for the same local structure of the U(iv) and Np(iv) complex in toluene solution, confirming the observations made in the solid state.

The studies reported here focus on the extraction of La(III), Eu(III), and Yb(III) by chelating hexadentate 3-alkoxy-2-hydroxyphenyl substituted diimine ligands using the extraction system Ln(NO3)3–Zn(NO3)2–NaNO3–buffer–H2O/diimine-n-caprylic acid–CHCl3. Significant synergistic enhancement has been observed for the Ln(III) extraction from nitrate media in the presence of Zn(II) and n-caprylic acid. These effects can be interpreted by self-assembly of heterodinuclear Zn(II)/Ln(III) complexes with both deprotonated extractants in the organic phase taking into account solution and solid-state structural studies. The structures identified and the extraction behavior as well as the different factors influencing the process will be discussed in detail. The goals of these experiments are to find preferred structure-extractability relationships for the synergistic systems investigated.

Invited for the cover of this issue is the group of Jan J. Weigand at Technische Universität Dresden. The image depicts a puzzle illustrating the coinage metal cations and the methyl group, from which the three-dimensional structure of a multiply methylated tetraphosphetane arises. Read the full text of the article at 10.1002/chem.202001360.

A novel method for the one-pot synthesis of diannulated 1,4,2-diazaphospholium triflate salts by a Me3SiOTf-mediated self-condensation of dichlorophosphaneyl aza-(poly)cyclic aromatic hydrocarbons ...

Triphosphanes R′2PP(R)PR′2 (9a,c: R = Py; 9b R = BTz), 1,3-diphenyl-2-pyridyl-triphospholane 9d and pentaphospholanes (RP)5 (13: R = Py; 18: R = BTz) are obtained in high yield of up to 98% from the reaction of dipyrazolylphosphanes RPpyr2 (5: R = Py; 6: R = BTz; pyr = 1,3-dimethylpyrazolyl) and the respective secondary phosphane (R′2PH, R′ = Cy (9a,b), tBu (9c); PhPH(CH2)2PHPh (9d)). The formation of derivatives 9a–d proceeds via a condensation reaction while the formation of 13 and 18 can only be explained by a selective scrambling reaction. We realized that the reaction outcome is strongly solvent dependent as outlined by the controlled scrambling reaction pathway towards pentaphospholane 13. In our further investigations to apply these compounds as ligands we first confined ourselves to the coordination chemistry of triphosphane 9a with respect to coinage metal salts and discussed the observation of different syn- and anti-isomeric metal complexes based on NMR and X-ray analyses as well as quantum chemical calculations. Methylation reactions of 9a with MeOTf yield triphosphan-1-ium Cy2MePP(Py)PCy2+ (10+) and triphosphane-1,3-diium Cy2MePP(Py)PMeCy22+ (112+) cations as triflate salts. Salt 11[OTf]2 reacts with pentaphospholane 13 in an unprecedented chain growth reaction to give the tetraphosphane-1,4-diium triflate salt Cy2MePP(Py)P(Py)PMeCy22+ (19[OTf]2) via a P–P/P–P bond metathesis reaction. The latter salt is unstable in solution and rearranges via a rare [1,2]-migration of the Cy2MeP-group followed by the elimination of the triphosph-2-en-1-ium cation [Cy2MePPPMeCy2]+ (20+) to yield a novel 1,4,2-diazaphospholium salt (21[OTf]).

Herein, we report the design and synthesis of a series of novel cationic nitrogen-doped nanographenes (CNDNs) with nonplanar geometry and axial chirality. Single-crystal X-ray analysis reveals helical and cove-edged structures. Compared to their all-carbon analogues, the frontier orbitals of the CNDNs are energetically lower lying, with a reduced optical energy gap and greater electron-accepting behavior. Cyclic voltammetry shows all the derivatives to undergo quasireversible reductions. In situ spectroelectrochemical studies prove that, depending on the number of nitrogen dopants, either neutral radicals (one nitrogen dopant) or radical cations (two nitrogen dopants) are formed upon reduction. The concept of cationic nitrogen doping and introducing helicity into nanographenes paves the way for the design and synthesis of expanded nanographenes or even graphene nanoribbons with cationic nitrogen dopants.

Wir berichten uber Design und Synthese einer Serie von neuen kationischen stickstoffdotierten Nanographenen (CNDN) mit einer nichtplanaren Geometrie und axialer Chiralitat. Einkristall-Rontgendiffraktometrie beweist deren helikale und teils “Cove”-terminierte Struktur. Verglichen mit den reinen Kohlenstoffanalogen liegen die Grenzorbitale der CNDN energetisch tiefer, was zu einer verringerten optischen Energielucke und einer erhohten Elektronenaffinitat fuhrt. Alle Derivate zeigen in cyclovoltammetrischen Untersuchungen quasireversibles Reduktionsverhalten. Abhangig von der Zahl an Stickstoffdotanden ist es moglich, neutrale Radikale (bei einem Stickstoffdotanden) oder Radikalkationen (bei zwei Stickstoffdotanden) wahrend des Reduktionsprozesses uber In-situ-Spektroelektrochemie zu analysieren. Kationische Stickstoffdotierung kombiniert mit Helizitat erschliest neue Wege fur das Design und die Synthese von ausgedehnten Nanographenen und Nanographenstreifen.

The formal two-electron reduction of the cyclo-tri(phosphonio)methanide dication 12+ results in a ring-opening reaction via C–P bond cleavage to yield the unique phosphanyl-functionalized carbodiphosphorane 2. In situ spectroelectrochemical investigations of the reduction of dication 12+ and the oxidation of 2 give insights into the mechanism of this unusual and reversible bond cleavage reaction. Compound 2 features in total three lone pairs of electrons, facilitating the preparation of mono-, di-, and trigold complexes.

The reaction of LGa (L = Dipp(4-(Dipp-imino)pent-2-en-2-yl)amide; Dipp: 2,6-diisopropylphenyl) and white phosphorus was revisited. A plethora of unprecedented polyphosphanes in addition to the known monoinserted product LGaP4 (1) are observed. An optimized synthesis of the hitherto unknown hexaphosphane (LGa)2P6 (3) is presented, and its subsequent selective derivatization with Bronsted acids, MeOTf, Ph2ECl (E = P, As), and NaOCP provides access to a wealth of functionalized hexa- and heptaphosphanes.

Tri(phosphonio)methanide dication 32+ , prepared from a trifluoromethylsulfanylphosphonium dication (12+ ) via an intramolecular electrophilic aromatic substitution reaction, is an unexpected P-based, water-resistant Lewis acid that is capable to selectively and reversibly bind fluoride ions from organic/aqueous biphasic solution. The formed complex is an unusual fluorophosphorane ([3-F]OTf). The multiple donor-acceptor interactions of 32+ that are crucial for the fluoride fixation have been elucidated by quantum chemical calculation. Compound [3-F]OTf can also be used as a convenient anhydrous fluoride ion source and was probed as a suitable catalyst of the silylotrifluoromethylation of various aldehydes.

Synthesis of antiaromatic polycyclic hydrocarbons (PHs) is challenging because the high energy of their highest occupied molecular orbital and low energy of their lowest unoccupied molecular orbital cause them to be reactive and unstable. In this work, two large antiaromatic acene analogues, namely, cyclopenta[pqr]indeno[2,1,7-ijk]tetraphene (CIT, 1a) and cyclopenta[pqr]indeno[7,1,2-cde]picene (CIP, 1b), as well as a curved antiaromatic molecule with 48 π-electrons, dibenzo[a,c]diindeno[7,1,2-fgh:7',1',2'-mno]phenanthro[9,10-k]tetraphene (DPT, 1c), are synthesized on the basis of the corona of indeno[1,2-b]fluorene. These three antiaromatic PHs possess a narrow energy gap down to 1.55 eV and exhibit high kinetic stability under ambient conditions. Moreover, these compounds display reversible electron transfer processes in both the cathodic and anodic regimes. Their cation and anion radicals are characterized by in situ vis-NIR absorption and electron paramagnetic resonance spectroelectrochemistry. The X-ray crystallographic analysis confirms that while CIP and CIT manifest planar structures, DPT shows a curved π-conjugated carbon skeleton. The synthetic strategy starting from ortho-substituted benzene units to construct five-membered rings in this work provides a unique entry to novel pentagon-embedding or curved antiaromatic polycyclic hydrocarbons. In addition, besides the detailed chemical and physical investigations, microscale single-crystal fiber field-effect transistors were also fabricated.

The polarized, cationic diphosphene [(Cl ImDipp )P=P(Dipp)]+ as the triflate salt 7[OTf](Cl ImDipp =4,5-dichloro-1,3-bis(Dipp)-imidazol-2-yl; Dipp=2,6-diisopropylphenyl) reacts with azides of type RN3 (R=Dipp or Dmp; Dmp=2,5-dimethylphenyl) in a [2+3] cycloaddition reaction followed by the release of N2 and a subsequent electrocyclic ring-closing reaction to azadiphosphiridine salts [(Cl ImDipp )P-P(Dipp)-N(R)]10a,b[OTf] (R=Dipp or Dmp). The reaction of 7[X] (X=OTf, GaCl4 ) with the electron-rich azides Me3 SiN3 and NaN3 give the unusual diphosphenimine derivatives [(Cl ImDipp )P-P(Dipp)=N(SiMe3 )]+ (11[OTf]) and [(Cl ImDipp )P-P(Dipp)=N(GaCl3 )] (12), respectively, featuring an acyclic P2 N moiety. Theoretical calculations provide insights into the reaction mechanisms to the cyclic and acyclic forms, in which the thermodynamic stability of the latter prevents the electrocyclic ring closure.

Herein, aiming at optimization of the polymerization process leading to a family of hole- and electron-conducting 1,1,2,2-ethenetetrathiolate-based polymers, such as poly(nickel-1,1,2,2-ethenetetrathiolate), poly[Kx(Ni-ett)], we investigated transformations of the monomer precursor 1,3,4,6-tetrathiapentalene-2,5-dione (TPD) occurring under polymerization conditions. We found that only one ring of TPD opens upon its reaction with potassium methoxide under inert conditions at room temperature which leads to the formation of potassium 2-oxo-1,3-dithiol-4,5-dithiolate (K2[3]). Heating of K2[3] under reflux in methanol solution under inert conditions opens the second ring, however the resulting product is not potassium ethenetetrathiolate (K4[2]), the product of an exhaustive methanolysis of TPD, but potassium tetrathiooxalate (K2[4]), the product of the decarbonylation of K2[3]. Preliminary experiments reveal that the involvement of K2[4] in the polymerization process is beneficial for reproducible formation of high quality 1,1,2,2-ethenetetrathiolate-based polymers suitable for thermoelectric applications.

The synthesis and characterization of two heterobimetallic complexes [K([18]crown‐6){(η4‐C14H10)Fe(μ‐η4:η2‐P4)Ga(nacnac)}] (1) (C14H10 = anthracene) and [K(dme)2{(η4‐C14H10)Co(μ‐η4:η2‐P4)Ga(nacnac)}] (2) with strongly reduced P4 units is reported. Compounds 1 and 2 are prepared by reaction of the gallium(III) complex [(nacnac)Ga(η2‐P4)] (nacnac = CH[CMeN(2,6‐iPr2C6H3)]2) with bis(anthracene)ferrate(1–) and ‐cobaltate(1–) salts. The molecular structures of 1 and 2 were determined by X‐ray crystallography and feature a P4 chain which binds to the transition metal atom via all four P atoms and to the gallium atom via the terminal P atoms. Multinuclear NMR studies on 2 suggest that the molecular structure is preserved in solution., John Wiley & Sons, Ltd.

Tetracationic cyclo-tetraphosphane [(LC)4P4]4+ as triflate salt (LC = 4,5-dimethyl-1,3-diisopropyl-imidazol-2-yl) is obtained from the reduction of [LCPCl2]+ with 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine and represents the first salt of the cationic cyclo-phosphane series with the general formula [LnPn]n+., Tetracationic cyclo-tetraphosphane [(LC)4P4]4+ as triflate salt (3[OTf]4) (LC = 4,5-dimethyl-1,3-diisopropyl-imidazol-2-yl) is obtained in high yield from the reduction of [LCPCl2]+ (4[OTf]) with 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine (6) and represents the first salt of the cationic cyclo-phosphane series with the general formula [LnPn]n+. Theoretical calculations reveal the electrophilic nature of the P atoms within the P4-ring due to the influence of the imidazoliumyl-substituents. Further reduction of 3[OTf]4 with 6 affords the unexpected formation of the notricyclane P7-type cation [(LC)3P7]3+ (9[OTf]3). Selective transition metal mediated [2 + 2]-fragmentation of 34+ is achieved when 3[OTf]4 is reacted with Fe2(CO)9, Pd(PPh3)4 and Pt(PPh3)4 leading to the formation of the dicationic diphosphene complexes [(η2-LCP 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 PLC)Fe(CO)4]2+ (12[OTf]2) and [(η2-LCP 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 PLC)M(PPh3)2]2+ (13[OTf]2 for M = Pd; 14[OTf]2 for M = Pt). In contrast, the reaction of 3[OTf]4 with an excess of AuCl(tht) gives rise to the formation of the five-membered ring complex [((LC)4P4)AuCl2]3+ (15[OTf]3), where the Au(i) atom reductively inserts into a P–P bond of 34+.

The impact of the strongly electron donating carbodiphosphorane moiety in the series of tri(phosphonio)methanide dications as triflate salts [(Ph3P)2CP(X)Ph2][OTf]2 (X = H, Me, CN, NCS, OH, Cl, OTf, F) deriving from [(Ph3P)2CPPh2][OTf] (19[OTf]) is presented. The influence of the introduced substituents X on the electronic structures of these dications is investigated by means of detailed NBO analysis, NMR spectroscopy and X-ray analysis.

Two novel 46-membered Co(II) metallomacrocycles, [Co2Cl4(L1)2]·CH2Cl2 and [Co2(NO3)2(L1)2(H2O)2⊂(NO3)](NO3)·4H2O, with 1,4-bis[4-(2-pyridylmethylideneamino)phenyloxy]benzene (L1) have been synthesized and characterized. Both Co(II) centers in these dinuclear complexes possess an octahedral coordination environment formed by a N4 donor set of two L1 ligands and two chloride or one monodentate nitrate and one water molecule, respectively. Whereas in the first case disordered solvent molecules are present in the macrocycle's cavity in the second one a nitrate anion is embedded. Furthermore, the molecular structures of L1, L3 and L4 were determined and solution studies of the complex formation of these ligands with Co(II), Ni(II) and Cu(II) in dichloromethane/methanol (v/v = 1:1) using UV/Vis and ESI-MS spectroscopic measurements were performed. In contrast to the self-assembling behavior of the bis(2-pyridylimine) ligand L1 the bis(3-pyridylimine) ligand L4 was also demonstrated to form metallogels when reacted with NiCl2·6H2O in tetrahydrofuran under defined conditions.

P–P condensation reactions in the coordination sphere of cobalt give access to unique organyl-substituted pentaphosphido complexes., Rare mono- and diorganopentaphosphido cobalt complexes are accessible by P–P condensation using the unprecedented, reactive cobalt-gallium tetraphosphido complex [K(dme)2{(MesBIAN)Co(μ-η4:η2-P4)Ga(nacnac)}] (2). Compound 2 was prepared in good yield by reaction of [K(Et2O){(MesBIAN)Co(η4-1,5-cod)}] [1, BIAN = bis(mesitylimino)acenaphthene diimine, cod = 1,5-cyclooctadiene] with [Ga(nacnac)(η2-P4)] (nacnac = CH[CMeN(2,6-iPr2C6H3)]2). Reactions with R2PCl (R = iPr, tBu, and Cy) selectively afford [(MesBIAN)Co(cyclo-P5R2)] (3a–c), which feature η4-coordinated 1,1-diorganopentaphosphido ligands. The mechanism of formation of these species has been studied by 31P{1H} NMR spectroscopy and DFT calculations. In the case of 3a (R = iPr), it was possible to identify the intermediate [(MesBIAN)Co(μ-η4:η2-P5iPr2)Ga(nacnac)] (4) by single-crystal X-ray diffraction. A related, monosubstituted organopentaphosphido cobalt complex [(MesBIAN)Co(μ-η4:η1-P5tBu)GaCl(nacnac)] (5) was isolated by reacting dichloroalkylphosphane tBuPCl2 with 2. Heterobimetallic complexes such as 2 thus may enable the targeted construction of a range of new metal-coordinated polyphosphorus frameworks by P–P condensation.

Zigzag-edged nanographene with two rows of fused linear acenes, called as n-peri-acene (n-PA), is considered as a potential building unit in the arena of organic electronics. n-PAs with four (peri-tetracene, 4-PA), five (peri-pentacene, 5-PA) or more benzene rings in a row have been predicted to show open-shell character, which would be attractive for the development of unprecedented molecular spintronics. However, solution-based synthesis of open-shell n-PA has thus far not been successful because of the poor chemical stability. Herein we demonstrated the synthesis and characterization of the hitherto unknown 4-PA by a rational strategy in which steric protection of the zigzag edges playing a pivotal role. The obtained 4-PA possesses a singlet biradical character (y0 = 72%) and exhibits remarkable persistent stability with a half-life time (t1/2) of ∼3 h under ambient conditions. UV–vis–NIR and electrochemical measurements reveal a narrow optical/electrochemical energy gap (1.11 eV) for 4-PA. Moreover, t...

The reaction of imidazoliumyl-substituted P((III)) cations of type [L((R,Me))PCl2](+) (3a,b(+); L(R,Me) = imidazolium-2-yl a: R = Me; b: R = iPr) with (Me3Si)2S leads to the formation of tetra-cationic, eight-membered phosphorus sulfur heterocycles [L((R,Me))PS]4(4+) (9a,b(4+)), which can be explained by the tetramerization of the intermediately formed cationic phosphorus monosulfide [L((R,Me))PS](+) (8a,b(+)). The P4S4 ring adopts a crown conformation as observed for cyclo-S8. The Lewis base DMAP (4-dimethylaminopyridine) initiates a deoligomerization- and dismutation reaction of 9a,b(4+) to give P((I)) centered cation [L((R,Me))2P](+) (12a,b(+)) and phosphorus disulfide [(DMAP)2PS2](+) (14(+)).

Ag0.8In2.4Te4 (= AgIn3Te5) and Ag0.5In2.5Te4 (= AgIn5Te8) form solid solutions with CdIn2Te4, which are interesting as materials for photovoltaics or with respect to their thermoelectric properties. The corresponding crystal structures are related to the chalcopyrite type. Rietveld refinements of high-resolution synchrotron powder diffraction data measured at K-absorption edges of Cd, Ag, In, and Te and electron diffraction reveal the symmetry as well as the element and vacancy distribution in Ag0.8In2.4Te4 (= AgIn3Te5)/Ag0.5In2.5Te4 (= AgIn5Te8) mixed crystals such as Ag0.25Cd0.5In2.25Te4 and Ag0.2Cd0.75In2.1Te4. All compounds of the solid solution series (CdIn2Te4)x(Ag0.5In2.5Te4)1-x exhibit the HgCu2I4 structure type (space group I4̅2m) with completely ordered vacancies but disordered cations. The uniform cation distribution and thus the local charge balance are comparable to that of CdIn2Te4. In contrast, Ag0.8In2.4Te4 (= AgIn3Te5) crystallizes in the space group P4̅2c with disordered cations and partially ordered vacancies. This is corroborated by bond-valence sum calculations and the fact that there is a Vegard-like behavior for compounds with 0.5x in the pseudobinary system (CdIn2Te4)x(Ag0.8In2.4Te4)1-x. Owing to the different structures, there is no complete solid solution series between CdIn2Te4 and AgIn3Te5. All compounds in this work are n-type semiconductors with a low electrical conductivity (∼1 S/m) and rather high absolute Seebeck coefficients (up to -750 μV/mK; 225 °C). Electrical band gaps (Eg) determined from the Seebeck coefficients as well as (more reliably) from the electrical conductivity range between 0.19 and 1.13 eV.

Porous organic polymers (POPs) have attracted significant attention towards molecular adsorption in recent years due to their high porosity, diverse functionality and excellent chemical stability. In this work, we present a systematic case study on the formation of thiazolo[5,4-d]thiazole (TzTz) linkages through model compounds and its integration to synthesize a set of three novel, thermo-chemically stable TzTz-linked POPs, namely TzTz-POP-3, TzTz-POP-4, and TzTz-POP-5 with triphenylbenzene, tetraphenylpyrene and tetra(hydroxyphenyl)methane cores, respectively. Interestingly, the integrated TzTz moiety of the represented TzTz-POP-3 renders chemoselective removal of organic dye fluorescein (FL) from a mixture with parafuchsine (FU) in aqueous solution. The TzTz-POP-3 offered excellent chemoselectivity of ≈1:7 (FL:FU), compared to alike porous materials demonstrated for similar applications due to the presence of multiple active anchoring sites coupled with permanent porosity and appropriate pore window.

Nanographenes, namely polycyclic aromatic hydrocarbons (PAHs) with nanoscale dimensions (>1 nm), are atomically precise cutouts from graphene. They represent prime models to enhance the scope of chemical and physical properties of graphene through structural modulation and functionalization. Defined nitrogen doping in nanographenes is particularly attractive due to its potential for increasing the number of π-electrons, with the possibility of introducing localized antiaromatic ring elements. Herein we present azomethine ylide homocoupling as a strategy to afford internally nitrogen-doped, non-planar PAH in solution and planar nanographene on surfaces, with central pyrazine rings. Localized antiaromaticity of the central ring is indicated by optical absorption spectroscopy in conjunction with theoretical calculations. Our strategy opens up methods for chemically tailoring graphene and nanographenes, modified by antiaromatic dopants., Polyaromatic hydrocarbons can be precisely manipulated to yield ever more complex and discrete graphene analogs, such as nanographenes. Here, the authors use azomethine ylide homocoupling to insert an antiaromatic pyrazine ring into the core of a nanographene, and characterize the molecule’s unique electronic character.

The synthesis of inorganic N–P(III)-Ch-based macrocycles [−PhP–NMe–PPh–Ch−]2 (8Ch; Ch = S, Se) is presented by incorporating two nitrogen, two chalcogen, and four phosphorus atoms. The macrocycles are conveniently obtained via the cyclocondensation reaction of Na2Ch (Ch = S, Se) with the acyclic dichlorodiphosphazane ClPhP–NMe–PClPh (9). Treatment with elemental sulfur (S8) or gray selenium (Segray) results in an oxidative ring contraction to give 1,3,2,4-thiazadiphosphetidine 2,4-disulfide (10S) and 1,3,2,4-selenazadiphosphetidine 2,4-diselenide (10Se), respectively. Macrocycles 8Ch are excellent multidentate ligands for transition metal complexation, as demonstrated by the isolation of mono-, di- tri-, and tetranuclear silver sandwich complexes. The polynuclear silver complexes are comprehensively characterized, including detailed NMR and X-ray analysis.

Synthesis of the triflyloxyphosphonium dication is presented bearing two electrophilic sites which are selectively addressable by different nucleophiles., A carbodiphosphorane ((Ph3P)2C) mediated synthesis of the first triflyloxyphosphonium dication (12+) bearing two electrophilic sites is presented. Depending on the nucleophile, 12+ reacts selectively either at the sulfur atom of the triflyloxy moiety or at the directly attached phosphorus atom. In substitution reactions at the phosphorus atom the triflyloxy moiety serves as a leaving group and enables the synthesis of rare examples of pseudo-halophosphonium dications.

A series of lanthanoid and iodine containing compounds of formulae [Ln(IPhacac)3(dmf)2], [K(dmf)2{Ln(IPhacac)4}]n and [Ln5(OH)5(IPhacac)10] {(IPhacac) = bis(para-iododibenzoyl)methanide} have been prepared and structurally characterised. X-ray crystallography establishes that the compounds exist as monomers [Ln(IPhacac)3(dmf)2] {Ln = Pr (1), Nd (2), Tb (5), Dy (6)} and [Yb(IPhacac)3(dmf)2][Yb(IPhacac)3(dmf)(H2O)] (7) (dmf = N,N-dimethylformamide), polymers [K(dmf)2{Ln(IPhacac)4}]n {Ln = Nd (2a), Eu (3a), Gd (4a), Tb (5a), Dy (6a)} and pentanuclear clusters [Ln5(OH)5(IPhacac)10] {Ln = Tb (5b), Dy (6b), Yb (7b)}.

This review aims to highlight and comprehensively summarize recent developments in the field of mixed-coordinate phosphorus chemistry. Particular attention is focused on the synthetic approaches to compounds containing at least two directly bonded phosphorus atoms in different coordination environments and their unexpected properties that are derived from spectroscopic and crystallographic data. Novel substance classes are discussed in order to supplement previous reviews about mixed-coordinate phosphorus compounds.

A high-yielding and facile synthesis for diphosphane monochalcogenides (1(Ch)((R))) and their constitutional isomers, diphosphanylchalcoganes (2(Ch)((R))), was developed, featuring a condensation reaction between chlorophosphanes (R2PCl) and sodium chalcogenides (Na2Ch, Ch = S, Se, (Te)). The optimized protocol selectively yields either 1(Ch)((R)) (R2(Ch)PPR2) or 2(Ch)((R)) (Ch(PR2)2) depending upon the steric demand of the substituents R. Reaction pathways consistent with the distinct reaction outcomes are proposed. The application of 1(Ch)((R)) and 2(Ch)((R)) as an interesting class of ligands is exemplarily demonstrated by the preparation of selected transition metal complexes.

A chiral palladacycle-promoted enantioselective asymmetric hydrophosphination of substituted methylidenemalonate esters using diphenylphosphine that provides direct access to chiral tertiary phosphines is reported. Screening of three easily accessible C,N and C,P palladacycles as catalysts for this synthetic scenario provided insights into critical factors in catalyst design that influence the activation and stereochemistry in Pd(II)-catalyzed asymmetric P–H addition reactions involving such activated substrates.

This review aims to highlight and comprehensively summarize recent developments in the field of mixed-coordinate phosphorus chemistry. Particular attention is focused on the synthetic approaches to compounds containing at least two directly bonded phosphorus atoms in different coordination environments and their unexpected properties that are derived from spectroscopic and crystallographic data. Novel substance classes are discussed in order to supplement previous reviews about mixed-coordinate phosphorus compounds.