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Borylation of a tungsten‐bound N2 ligand and halide abstraction provides access to a cationic complex with an unprecedented linear NNBR ligand. This complex undergoes [3+2] cycloaddition with azides, and an unexpected chain‐extension reaction with an iminoborane, leading to a complex with a five‐atom B/N chain. These two [NNBR]‐containing complexes, inorganic analogues of E. O. Fischer's alkynylcarbynes, are very rare examples of molecules containing all‐inorganic chains of sp‐hybridized atoms. [ABSTRACT FROM AUTHOR]

[Display omitted] • The triazolate Pd(II) complex binds to lysozyme via the loss of triazolato ligand. • Agreement between the experimental and theoretical studies regarding the high stability of N2 triazolate complex over the N1 and N3 analogues. • Triazolate complexes exhibited comparable selective antifungal activity to reference drug. • The complexes are safe to normal cell line and are compatible with the red blood cells. Modern classes of antimicrobials are crucial because most drugs in development today are basically antibiotic derivatives. Even though a large number of metal-based compounds have been studied as antimicrobial agents, relatively few studies have examined the antimicrobial properties of Pd(II) and Pt(II) compounds. The [3+2] cycloaddition reactions of [M(N 3)L]PF 6 (M = Pd(II) and Pt(II); L = 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine) with 4,4,4-trifluoro-2-butynoic acid ethyl ester gave the corresponding triazolate complexes. The reaction products were fully characterized with a variety of analytical and spectroscopic tools including X-ray crystallographic analysis. The crystal structure of [Pd(triazolatoCF3,COOCH2CH3)L]PF 6 provided cut-off evidence that the kinetically formed N1-triazolato isomer favoured the isomerization to the thermodynamically stable N2-analogue. The experimental work was complemented with computational work to get an insight into the nature of the predominant triazolate isomer. The lysozyme binding affinity of the triazolate complexes was examined by mass spectrometry. An analysis of the lysozyme Pd(II) adducts suggests a coordinative covalent mode of binding via the loss of the triazolato ligand. The free ligand and its triazolate complexes displayed selective toxicity against Candida albicans and Cryptococcus neoformans , while no cytotoxicity was observed against the normal human embryonic kidney cell line. [ABSTRACT FROM AUTHOR]

In dieser Publikation stellen wir einen neuartigen Ansatz zur Herstellung eines diskreten Dimers aus chiralem Phthalocyanin (Pc) vor, wobei wir die flexible Molekülgeometrie von Helicenen nutzen, die eine strukturelle Vernetzung und eine starke Aggregationstendenz von Pcs ermöglicht. Die synthetisierte [7]Helicen‐Pc‐Hybrid‐Molekularstruktur, Zink‐[7]Helicenocyanin (Zn‐7HPc), bildet ausschließlich ein stabiles Dimer aus zwei homochiralen Molekülen. Die Dimerisierungskonstanten wurden auf 8.96×106 M−1 bzw. 3.42×107 M−1 in THF bzw. DMSO geschätzt, was auf eine bemerkenswerte Stabilität des Dimers hindeutet. Darüber hinaus zeigt Zn‐7HPc ein chirales Selbstorganisationsverhalten, so dass sich auch in der racemischen Probe bevorzugt ein homochirales Dimer bildet. Die zwei Phthalocyanin‐Untereinheiten in der dimeren Form interagieren stark miteinander, was sich in einer großen Komproportionierungskonstante und der Beobachtung einer IV‐CT‐Bande für den thermodynamisch stabilen gemischt‐valenten Zustand zeigt. [ABSTRACT FROM AUTHOR]

In this communication, we demonstrate a novel approach to prepare a discrete dimer of chiral phthalocyanine (Pc) by exploiting the flexible molecular geometry of helicenes, which enables structural interlocking and strong aggregation tendency of Pcs. Synthesized [7]helicene‐Pc hybrid molecular structure, zinc‐[7]helicenocyanine (Zn‐7HPc), exclusively forms a stable dimeric pair consisting of two homochiral molecules. The dimerization constants were estimated to be as high as 8.96×106 M−1 and 3.42×107 M−1 in THF and DMSO, respectively, indicating remarkable stability of dimer. In addition, Zn‐7HPc exhibited chiral self‐sorting behavior, which resulted in preferential formation of a homochiral dimer also in the racemic sample. Two phthalocyanine subunits in the dimeric form strongly communicate with each other as revealed by a large comproportionation constant and observation of an IV‐CT band for the thermodynamically stable mixed‐valence state. [ABSTRACT FROM AUTHOR]

Introduction of the propyl-sulfonic acid group at N1 of the coordinated 2-(2-pyridyl)benzimidazole ligand (L) in [RhCl(η5-C5Me5)L](CF3SO3) gives rise to a water-soluble complex, which can bind to the model protein lysozyme via non-covalent interactions. The complex shows selective moderate toxicity against Cryptococcus neoformans (MIC = 21.6–43.3 μM) and exhibits no cytotoxicity to healthy HEK293 cells. [ABSTRACT FROM AUTHOR]

The behavior of the redox‐active aminotroponiminate (ATI) ligand in the coordination sphere of bismuth has been investigated in neutral and cationic compounds, [Bi(ATI)3] and [Bi(ATI)2Ln][A] (L=neutral ligand; n=0, 1; A=counteranion). Their coordination chemistry in solution and in the solid state has been analyzed through (variable‐temperature) NMR spectroscopy, line‐shape analysis, and single‐crystal X‐ray diffraction analyses, and their Lewis acidity has been evaluated by using the Gutmann–Beckett method (and modifications thereof). Cyclic voltammetry, in combination with DFT calculations, indicates that switching between ligand‐ and metal‐centered redox events is possible by altering the charge of the compounds from 0 in neutral species to +1 in cationic compounds. This adds important facets to the rich redox chemistry of ATIs and to the redox chemistry of bismuth compounds, which is, so far, largely unexplored. [ABSTRACT FROM AUTHOR]

Reaction between bromo tricarbonyl manganese(I) and N,N′-bis(phenyl)-1,4-diaza-1,3-butadiene ligands, bearing different electron-donating and electron-withdrawing groups R = OCH3, Cl, and NO2 in the ortho- and para-positions on the phenyl substituent, afforded [MnBr(CO)3(N–N)] complexes. The influence of the character and position of the substituent on the dark stability and carbon monoxide releasing kinetics was systematically investigated and correlated with the data of the time-dependent density functional theory calculations. The combined UV/Vis and IR data clearly revealed that the aerated solutions of [MnBr(CO)3(N–N)] in either coordinating or noncoordinating solvents are dark stable and the fluctuations observed during the incubation period especially in the case of the nitro derivatives may be attributed to the exchange of the axial bromo ligand with the coordinating solvent molecules. The free ligands and nitro complexes were non-cytotoxic to HepG2 cells under both the dark and illumination conditions. In the dark, Mn(I) compounds, incorporating o-OCH3 and o-Cl, exhibited excellent cytotoxicity with IC50 values of 18.1 and 11.8 μM, while their para-substituted analogues were inactive in the dark and active upon the irradiation at 365 nm with IC50 values of 5.7 and 6.7 μM, respectively. [ABSTRACT FROM AUTHOR]

The lysozyme binding affinity and the electronic properties of [ReX(CO)3(terpy-κ2N1,N2)] (X = Br− and triazolateCOOCH2CH3,CF3) were reported. The triazolate complex was prepared in a [3 + 2] cycloaddition click reaction. The bromo compound reacted with lysozyme affording adducts with Re(CO)3+ fragments, while the triazolate compound persisted. A red shift of the MLCT band of the triazolate compound in progressively less polar solvents may be due to the negative solvatochromism. [ABSTRACT FROM AUTHOR]

The titled carbon monoxide releasing molecule is capable of release CO upon illumination at 468 nm and demonstrates selective cytotoxicity towards human acute monocytic leukaemia in the dark without causing any harmful effect to the normal mice bone marrow stromal cells. [Display omitted] The reaction between bromo pentacarbonyl manganese(I) and two equivalents of 1-(chloromethyl)-1H-benzotriazole (BTZ-CH 2 Cl) afforded visible-light induced carbon monoxide releasing molecule of the general formula, fac -[MnBr(CO) 3 (BTZ-CH 2 Cl) 2 ]. The solvatochromism, dark-stability and photolysis profile of the titled complex was examined in organic solvents with various hydrogen-bonding propensities, coordinating capabilities, and solvent polarities as well as in the presence of proteins. The number of CO equivalents released from the titled complex upon the exposure to a 468 nm LED light was determined using myoglobin assay. The titled complex displayed selective cytotoxicity towards human acute monocytic leukaemia in the dark without causing any harmful effect to the normal mice bone marrow stromal cells. [ABSTRACT FROM AUTHOR]

Large silver(I) clusters stabilized by the dianionic carba‐closo‐dodecaboranylethynyl ligand were obtained. Crystallization of polymeric {Ag2(12‐C≡C‐closo‐1‐CB11H11)}n from dimethyl sulfoxide afforded [Ag14(12‐C≡C‐closo‐1‐CB11H11)7(DMSO)12]·DMSO that contained an AgI10 cage augmented by four AgI ions. Crystals of [Ag16(12‐C≡C‐closo‐1‐CB11H11)8(THF)12]·2THF were obtained from anhydrous THF and {Ag2(12‐C≡C‐closo‐1‐CB11H11)}n. In the presence of moisture the similar but water‐containing complex [Ag16(12‐C≡C‐closo‐1‐CB11H11)8(THF)12(H2O)2]·2.5THF was identified. Both silver(I) clusters are composed of a central octahedral AgI6 unit and ten further silver(I) ions bonded via argentophilic interactions. [Ag14(12‐C≡C‐closo‐1‐CB11H11)7(DMSO)12]·DMSO and [Ag16(12‐C≡C‐closo‐1‐CB11H11)8(THF)12]·2THF were characterized by elemental analysis and vibrational (IR and Raman) as well as NMR spectroscopy. In addition, the crystal structures of [Ag25(12‐C≡C‐closo‐1‐CB11H11)12(CH3CN)13.5(OH)]·0.5CH3CN and [Ag25(12‐C≡C‐closo‐1‐CB11H11)12{(CH3)2CO}13.5(H2O)Cl]·15(CH3)2CO were determined. Both compounds contain AgI14 rhombic dodecahedrons augmented by eleven silver(I) ions. A hydroxide or a chloride template ion is present in the center of the rhombic dodecahedron, respectively. [ABSTRACT FROM AUTHOR]

Osmium(II) PNP pincer complexes bearing a hemilabile pyridyl-pyrazolide (PyrPz) ligand have been synthesised, and their reactivity towards Lewis acidic bismuth compounds has been examined. Reactions with BiCl3 resulted in chlorine-atom-transfer to give an osmium(III) species. Reactions with cationic bismuth species led to adduct formation through N → Bi bond formation via the PyrPz ligand. Theoretical analyses revealed that steric interactions hamper Os → Bi bond formation and indicate that such interactions are possible upon reducing the steric profile around the osmium atom. Analytical techniques include NMR, IR, and EPR spectroscopy, cyclic voltammetry, elemental analysis and DFT calculations. [ABSTRACT FROM AUTHOR]

Reaction between 2-(2′-pyridyl)benzimidazole derivatives and [{IrCl(η5-C5Me5)}2(μ-Cl)2] afforded mono- and binuclear "piano-stool" Ir(III) compounds of type [IrnCln(η5-C5Me5)n(L)]Cln (n = 1, L = LET (1) and LSO3H (2); n = 2, L = LBN (3)), which were fully characterized, including the X-ray crystallographic analysis of 1. While the free ligands and compound 3 exhibited no toxicity to the tested microbes, compound 1 was highly potent against bacteria (MIC = 12.9–25.8 nM) and fungi (MIC < 0.40 nM). However, complex 1 induced damage to non-malignant cell lines (human embryonic kidney (HEK293), CC50 = 0.995 μg mL−1) and human RBCs (HC10 = 10.9 μg mL−1 and HC50 > 32 μg mL−1). Interestingly, complex 2, bearing the benzimidazole ligand with an alkylated sulfonate side chain (LSO3H), was selectively potent against C. neoformans with MIC value of 11.2 nM and was non-toxic to HEK293. According to DNA binding studies, compounds 1–3 could be considered as moderate metallo intercalators with a binding constant of 5.0 × 104–1.0 × 105 M−1. Alternatively, evidence was obtained, from ESI-MS measurements, for the non-covalent mode of binding of 2 to hen egg white lysozyme, while compounds 1 and 3 decomposed during the interaction with that protein. This may be attributed to the electrostatic and H-bonding interactions between the polar sulfonate group and charged protein side-chains. [ABSTRACT FROM AUTHOR]

Photostable mono‐ and binuclear silver(I) complexes derived from terpyridine ligands (4′‐(2‐pyridyl)‐2,2′:6′,2′′‐terpyridine (LPY) (1), 4′‐(4‐phenyl morpholine)‐2,2′:6′,2′′‐terpyridine (Lmorph) (2) and 1,4‐bis (2,2′:6′,2′′‐terpyridin‐4′yl) benzene (LDB) (3)) were synthesized and fully characterized in the solution and solid‐state including [1H–15N] heteronuclear multiple bond coherence (HMBC) NMR analysis and single‐crystal X‐ray analysis of five‐coordinates [Ag2(LPY)2(CH3CN)2](SO3CF3)2. Based on the NMR and ESI‐MS data, complex 1 exists as dimeric species, formed by head‐to‐tail interaction, while monomeric species of 3 predominantly exist in the same solvents. The protein binding affinity of 1–3 was investigated by using hen white egg lysozyme (HEWL). To explore where the metalation site of HEWL is, the interactions between the complexes and histidine were studied by NMR. The morpholine ligand and its Ag(I) complex (2) exhibited interesting antimicrobial activity. In comparison with AgOSO2CF3, compounds 1–3 displayed lower cytotoxicity to non‐malignant human embryonic kidney (HEK293) cells, and induced negligible haemoglobin release. [ABSTRACT FROM AUTHOR]

A series of Pd(II) complexes of the general formula [PdX(NNS)] (X = Cl, Br, I, NCS and phenyl-tetrazole-thiolato; NNS = 2-quinolinecarboxyaldehyde-N4-phenylthiosemicarbazone) was tested against four malignant cell lines for their antiproliferative properties and the outcomes were compared to those seen in normal mouse splenocytes. Various auxiliary ligands were substituted in order to investigate the impact of the character of the ligand on the cytotoxicity of this class of Pd(II) complexes. The iodo complex was the most cytotoxic compound towards the Caco-2 cell line in this study. The improved apoptosis and necrosis cell modes were in accordance with the fragmentation results of DNA, which revealed increased fragmentation terminals, especially in isothiocyanate and tetrazole-thiolato complexes. After 24 hours, at half the IC50 of each complex, the complex-treated cells exhibited considerable genotoxicity when compared to the corresponding non-treated control especially in the case of isothiocyanate and tetrazole-thiolato complexes. [ABSTRACT FROM AUTHOR]

Human acute monocytic leukaemia cells were tested under both dark and light conditions for their susceptibility to Mn(I) and Ru(II) carbonyl complexes with a diphenyl pyridyl phosphine coligand. The Ru(II) complex (IC50 = 7.13 ± 0.8 μM) displayed higher outstanding potency against leukaemia than the Mn(I) analogue (54.58 ± 4.1 μM) in the dark and both complexes were completely harmless to healthy mouse bone marrow cells. [ABSTRACT FROM AUTHOR]

Introduction of tetrazolate moiety in the coordination sphere of Pd(II) complex, functionalized with tridentate benzimidazole ligand, via the catalyst [3+2] cycloaddition reaction, gave rise to potential antibacterial properties. [Display omitted] Two [PdN 3 L]PF 6 complexes (L = 2,6-bis(1-ethyl-benzimidazol-2́-yl)pyridine (LBZ) and 4-(2-pyridyl)-2,2′:6′,2′'-terpyridine (LPY)) underwent catalyst-free 1,3-dipolar cycloaddition coupling with phenyl isothiocyanate at the room temperature giving the corresponding tetrazole–thiolato complexes. 1H NMR studies showed that the N1-isomer appeared first in the catalyst-free coupling, then gradually isomerized to the more stable tetrazole–thiolato isomer. The interconversion of N1-isomer into the S-isomer is accompanied by a decrease of the greater steric demand of the 5-membered ring. Tetrazolate complex of LBZ displayed higher antifungal activity (MIC ≤ 0.25 μg/mL) than the chloride analogue (MIC = 0.5–1.0 μg/mL) and the reference drug, Fluconazole (MIC = 0.125–8.0 μg/mL) against Candida albicans and Cryptococcus neoformans. The treated non-cancerous human embryonic kidney cells (HEK293) showed no cytotoxicity and no haemolysis release at the measured concentrations of the chloride complex of LBZ and tetrazolate complex of LPY. [ABSTRACT FROM AUTHOR]

Four NHC complexes of rhodium and iridium of the general structure [RhI(COD)(NHC)], [IrCl(COD)(NHC)], [IrCl(CO) 2 (NHC)], and [Ir(N 3 )(COD)(NHC)] (NHC = N -heterocyclic carbene) were synthesised and characterised, including X-ray structure determination for all three iridium compounds. Release of carbon monoxide from [IrCl(CO) 2 (NHC)] occurred via a rapid bolus of CO on a very short timescale, independent of whether the experiment was performed in the dark or with UV-light illumination, thus establishing the compound as a novel ligand-exchange triggered CO-releasing molecule (CORM). The azide complex represents the first iridium–NHC complex containing an azide ligand. [ABSTRACT FROM AUTHOR]

In this work, facial tricarbonylmanganese(I) complexes [Mn(bpeaCH2C6H4R)(CO)3]PF6 incorporating a functionalized 2,2-bis(pyrazolyl)ethylamine (bpea) ligand with R = I, C≡CH, and CHO have been explored for their utility in bioorthogonal coupling to carrier peptides bearing N-terminal alkyne, azide, and aminoxy residues. As a model system, the transforming growth factor β-recognizing (TGF-β) peptide sequence R′-Leu-Pro-Leu-Gly-Asn-Ser-His-OH was used in which R′ is the reactive group complementary to the metal complex functionality. The use of catalyst-free oxime ligation gave the most stable conjugate with no degradation observed by HPLC over 96 h even after repeated freeze-thaw cycles. Both the parent complex as well as the functionalized peptide were investigated for photoactivated CO delivery to heme proteins by using the myoglobin assay and found to have essentially identical release properties. This work has established a new strategy for the conjugation of photoactivatable CO-releasing molecules (PhotoCORMs) to biological carrier systems. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of laterally extended azabora[5]‐, ‐[6]‐ and ‐[7]helicenes, assembled from N‐heteroaromatic and dibenzo[g,p]chrysene building blocks is described. Formally, the π‐conjugated systems of the pristine azaborole helicenes were enlarged with a phenanthrene unit leading to compounds with large Stokes shifts, significantly enhanced luminescence quantum yields (Φ) and dissymmetry factors (glum). The beneficial effect on optical properties was also observed for helical elongation. The combined contributions of lateral and helical extensions resulted in a compound showing green emission with Φ of 0.31 and |glum| of 2.2×10−3, highest within the series of π‐extended azaborahelicenes and superior to emission intensity and chiroptical response of its non‐extended congener. This study shows that helical and lateral extensions of π‐conjugated systems are viable strategies to improve features of azaborole helicenes. In addition, single crystal X‐ray analysis of configurationally stable [6]‐ and ‐[7]helicenes was used to provide insight into their packing arrangements. [ABSTRACT FROM AUTHOR]

• Selective toxicity towards C. neoformans. • Rh(III) triazolate compound exhibited higher activity than reference Fluconazole drug. • Rh(III) compounds exhibited higher binding affinity towards macromolecules than Ir(III) analogues. • Correlation between antifungal activity and type of the axial ligand. [Display omitted] Recently, screening attempts for potential antimicrobial drugs based on metal-based compounds have shown an unpredictably high hit rate for some classes of organometallic compounds (9.9%) compared to some organic compounds (0.87%) submitted to the same assays. Herein, we report the influence of the axial ligand (X = Cl and triazolateCOOC2H5,CF3) on the antimicrobial activity of [Rh 2 (X) 2 (η5-C 5 Me 5) 2 L]2+ (L = 1,1′-(Hexane-1,6-diyl)bis[2-(pyridin-2-yl)1H-benzimidazole]) against some bacterial and fungal pathogens as well as healthy cells. The compatibility with red blood cells was also examined. The stability of the compounds in presence of a model lysozyme protein was followed to gather insight into the activation profiles. Triazolate compound was prepared under a mild reaction via catalyst-free [3+2] cycloaddition reaction of azide analogue with 4,4,4-trifluoro-2-butynoic acid ethyl ester. While triazolate complex exhibited higher antifungal activity (MIC = 4.8–9.7 μM) against C. neoformans than Fluconazole (MIC = 26.1 μM), the chloro analogue dispalyed no activity towards the same microorganism. [ABSTRACT FROM AUTHOR]

Aminotroponiminates, bismuth, cationic species, redox chemistry, redox-active ligands Keywords: aminotroponiminates; bismuth; cationic species; redox chemistry; redox-active ligands EN aminotroponiminates bismuth cationic species redox chemistry redox-active ligands 6104 6104 1 04/09/21 20210407 NES 210407 B Redox chemistry with bismuth b : Snapshots of the redox chemistry of heavy p-block elements are difficult to obtain and remain rare to date. [Extracted from the article]

The photophysical properties and lysozyme affinities of [ReX(CO) 3 (L– k2N1,N2)] (L = 4′-(4-phenyl morpholine)-2,2′:6′,2′'-terpyridine, X = Br– (1), N 3 – (2), and triazolate (3)) complexes were investigated. • The kinetically formed triazolate N(1) type favored the isomerization to N(2) form. • Negative solvatochromism was observed in the case of triazolate compound. • The promising antimicrobial activity of the ligand was diminished upon complex formation. • Probability of exchange of the bromo ligand with the coordinating solvents. [ReX(CO) 3 (L– k2N1,N2)] (L = 4′-(4-phenyl morpholine)-2,2′:6′,2′'-terpyridine, X = Br– (1), N 3 – (2), and triazolate (3)) complexes were synthesized, and characterized using different spectroscopic and analytical tools including single-crystal X-ray diffraction analysis of 2. The 1,3-dipolar cycloaddition reaction between 2 , and 4,4,4-trifluoro-2-butynoic acid ethyl ester afforded triazolate 3. Although, the crystal structure of 2 showed that the azide ligand is terminally coordinated to Re(CO) 3 + unit, the 19F and 1H NMR analyses of 3 provided conversant evidences that the kinetically formed N(1) triazolate bound isomer favoured the isomerization to N(2) form. The photophysical properties of 1–3 were investigated by recording the absorption spectra of the compounds in solvents of different polarities. Complexes 1 and 3 were screened for their potential antimicrobial activities. The protein binding affinity of 1 , and 3 towards hen white egg lysozyme revealed that the bromide complex exchanges Br– with that protein, while the triazolate analogue sticked around. [ABSTRACT FROM AUTHOR]

• Toxicity of morpholine ligand to normal cell line was diminished by metal carbonyl formation and inorganic click reaction. • Extension of iClick reaction to two metal centers complexes. • Photoactivation at 525 nm. • The investigated ligands and complexes exhibited lower haemolysis values. • Solubility of tricarbonyl Mn(I) compexes increased by inorganic click reaction. The photoinduced fac -[MnBr(CO) 3 (L– k2N1,N2)] (L = 4′-(2-pyridyl)-2,2′:6′,2′'-terpyridine (LPy) (1) and 4′-(4-phenyl morpholine)-2,2′:6′,2′'-terpyridine (Lmorph) (2)) and fac -[Mn 2 Br 2 (CO) 6 (LDTP– k2N1,N2)] (LDTP = 1,4-bis(2,2′:6′,2′'-terpyridin-4′yl)benzene) (3) complexes, capable of release CO at 525 nm, were synthesized and fully characterized using different analytical and spectral tools. Compounds 1 – 3 had poor solubility or decomposed in most of the organic solvents, and thus they are unsuitable for the phototherapeutic CO applications. Reaction between azide complexes (4 – 6), prepared by exchange of the axial Br− ligand of 1 – 3 , with ethyl 4,4,4-trifluoro-2-butynoate afforded triazolate complexes (7 – 9), which had good solubility in the organic solvents. The potential of 7 – 9 to act as photoinduced CO releasing molecules was studied at two excitation wavelengths, 468 and 525 nm. The ligand Lmorph and its complex (8) were strongly potent to Escherichia coli , Candida Albicans and Cryptococcus neoformans. All the ligands and complexes (except 8) exhibited cytotoxicity to the normal human cell line; human embryonic kidney cells (HEK293), but they had good compatibility with the human red blood cells (RBCs) at 32 μg/mL. [ABSTRACT FROM AUTHOR]

To recognize the metalation site for lysozyme, the interactions between HEWL and imidazole (a model of histidine) were investigated. The coordination of thiourea based Ru(II) cymene complexes proceeds via the detachment of the heterocyclic coordination arm. Half-sandwich (η6- p -cymene) complexes bearing either neutral functionalized N,S -bidentate thiourea ligands or a mono-negative N,N -aminoquinoline ligand were screened for their antibacterial and antifungal activities as well as cell viability against non-malignant HEK293 (human embryonic kidney cells). The haemolysis parameters (HC 10 and HC 50) were determined to get some information about the compatibility of the toxic compounds with the blood components. The protein binding affinity of hen white egg lysozyme (HEWL), a model protein, towards the synthesized (η6- p -cymene) complexes was investigated by ESI-MS. Metalation of HEWL was achieved through both covalent and non-covalent modes of interaction. To recognize if the metalation site of HEWL is the His15 side chain, the reactions between the complexes and imidazole were theoretically and experimentally studied by quantum chemical calculations, UV–Vis and NMR. Exchange of the nitrogen coordination site of the thiourea ligand from the pyridine to the benzothiazole moiety induced higher potency against Staphylococcus aureus , Candida albicans and Cryptococcus neoformans var. grubii. [ABSTRACT FROM AUTHOR]

A systematic study on Lewis‐acid/base adducts of N‐heterocyclic carbenes (NHCs) and the cyclic (alkyl)(amino)carbene cAACMe (1‐(2,6‐di‐iso‐propylphenyl)‐3,3,5,5‐tetramethyl‐pyrrolidin‐2‐ylidene) with antimony(III) chlorides of the general formula SbCl2R (R=Cl, Ph, Mes) is presented. The reaction of the NHCs Me2ImMe (1,3,4,5‐tetra‐methyl‐imidazolin‐2‐ylidene), iPr2ImMe (1,3‐di‐isopropyl‐4,5‐dimethyl‐imidazolin‐2‐ylidene), Mes2Im, Dipp2Im (R2Im=1,3‐di‐organyl‐imidazolin‐2‐ylidene; Mes=2,4,6‐trimethylphenyl, Dipp=2,6‐di‐isopropylphenyl) and cAACMe with antimony(III) compounds SbCl2R (R=Cl (1), Ph (2) and Mes (3)) yields the adducts NHC ⋅ SbCl2R (R=Cl (4), Ph (5) and Mes (6); NHC=Me2ImMe (a), iPr2ImMe (b), Dipp2Im (c) and Mes2Im (d)) and cAACMe ⋅ SbCl2R (R=Cl (4 e) and Ph (5 e)). Thermal treatment of (Dipp2Im) ⋅ SbCl2Ar (Ar=Ph (5 c) and Mes (6 c)) in benzene leads to isomerization to the backbone coordinated aNHC‐adduct aDipp2Im ⋅ SbCl2Ar (Ar=Mes (7) and Ph (8)) ("a" denotes "abnormal" coordination mode of the NHC) in high yields. One of the chloride substituents at antimony of 7 can be abstracted by GaCl3 or Ag[BF4] to obtain the imidazolium salts [aDipp2Im ⋅ SbClMes][BF4] (9) and [aDipp2Im ⋅ SbClMes][GaCl4] (10). [ABSTRACT FROM AUTHOR]

Hydrosilanes undergo mild, uncatalyzed single and double 1,2-addition across the B–B triple bonds of diborynes, leading to an unsymmetrical silyldiborene and compounds with novel non-cluster three-membered B2Si rings. The reactions are a new addition to the very few catalyst- and alkali-metal-free methods available for the construction of B–Si bonds. [ABSTRACT FROM AUTHOR]

The reaction of a pyridyl-substituted, doubly Lewis base-stabilised diborene with different amounts of copper(I) precursors led to the formation of the first chelating π-diborene complexes, the first π-diborene complexes in which metals are bound to both faces of the B＝B bond, and the first mixed-metal π-diborene species. [ABSTRACT FROM AUTHOR]

Transition metal borylene complexes of the type [(OC)5M＝BN(SiMe3)(tBu)] (M = Cr, Mo, W) have been synthesised by salt elimination of the corresponding dibromoborane and the dianionic metallates Na2[M(CO)5]. The borylene complexes have been characterised by multinuclear solution-state NMR spectroscopy and solid-state molecular structure determination. The group 6 borylene complexes can be used to effectively transfer the borylene ligand to other transition metal complexes by replacing one or two carbonyl ligands upon irradiation of the reaction mixture with UV light. This borylene transfer reaction led to the formation of new terminal and bridging borylene complexes which cannot be formed by the corresponding salt elimination reactions, including a rare example of a bis(terminal borylene) complex and only the second reported terminal borylene complex of an early transition metal (vanadium). [ABSTRACT FROM AUTHOR]

Mono‐ and binuclear benzimidazole based half‐sandwich organoruthenium(II) compounds; [Run(triazolateCOOCH3,COOCH3)n(η6‐p‐Cym)nL]0/+/2+ (n = 1, L = LCH2CH3 (7) and HLSO3H (8); n = 2, L = LDTP (9)) were synthesized by [3+2] free catalyzed cycloaddition reaction of azide complexes 4–6 with electron‐poor alkyne dimethyl acetylene dicarboxylate. In comparison with the parent [RunCln(η6‐p‐Cym)nL]0/+/2 complexes (1–3), the lysozyme binding affinity of the corresponding triazolate compounds 7–9 was investigated by electrospray ionization mass spectrometry. Complexes bearing benzimidazole ligand with an alkylated sulfonate side chain (2 and 8) are able to bind lysozyme noncovalently, which have not been clearly seen by other investigated Ru(II) complexes. The complexes were assessed for their potential antimicrobial activity against some representative microbes. Complex 9 exhibits antifungal activity against C. albicans (MIC = 24 nm) and C. neoformans (MIC = 12 nm), perfect blood compatibility as well as no toxicity to non‐malignant cell line (human embryonic kidney cells (HEK293). [ABSTRACT FROM AUTHOR]

In this contribution, we reported the three‐dimensional (3D) analogues of N‐heterocyclic carbene (NHC)‐stabilized 9‐borafluorenium and 9‐borafluorene radical. The radical was fully characterized by cyclic voltammetry (CV), UV‐Vis absorption spectroscopy, electron paramagnetic resonance (EPR) and single‐crystal X‐ray diffraction analyses. The distinct boron‐centered radical character of 9‐borafluorene radical was corroborated by DFT calculations and EPR analysis. [ABSTRACT FROM AUTHOR]

The title compound, C23H18FNO4, crystallized as a racemate. It exhibits a cis conformation with respect to the F atom and the methine H atom. The piperidine ring has a screw-boat conformation. The methoxyphenyl ring and the phenyl ring are inclined to the mean plane of the isoquinoline ring system by 89.85 (4) and 46.62 (5)°, respectively, and by 78.15 (5)° to one another. In the crystal, molecules are linked by an O--H...O hydrogen bond forming chains propagating along the a-axis direction. The chains are linked by C--H...F hydrogen bonds, forming layers lying parallel to the ab plane. [ABSTRACT FROM AUTHOR]

2,3-Bis(dimethylamino)-substituted B2N2C2 heterocycles underwent selective dimethylamino/hydride exchange with either one or two equivalents of BH3 ⋅SMe2 to give the corresponding cyclic monohydrido- or ( cis)1,2-dihydridodiboranes(4), respectively. Upon either heating or irradiation in solution, the latter underwent ring contraction to the corresponding five-membered BN2C2 heterocycles, whereas irradiation of the 1,2-dimethylaminoethene-supported 1,2-dihydridodiborane(4) in the presence of PEt3 gave an unprecedented unsymmetrical 1,1-dihydrodiborane(5) phosphine adduct. [ABSTRACT FROM AUTHOR]

The first terminal manganese phosphinidene complex was quantitatively synthesized from a terminal alkylborylene complex. Its structure and bonding, as well as the reaction mechanism, were investigated through a combination of experimental and computational studies. [ABSTRACT FROM AUTHOR]

Der erste Manganphosphinidenkomplex wurde quantitativ aus einem terminalen Alkylborylenkomplex erhalten. Dessen Struktur, Bindungssituation sowie der zugrundeliegende Reaktionsmechanismus wurden durch eine Kombination experimenteller und theoretischer Studien untersucht. In einem unerwarteten einstufigen Prozess wurde der erste neutrale terminale Gruppe ‐ 7 ‐ Phosphinidenkomplex aus einem terminalen Borylenkomplex erhalten. [ABSTRACT FROM AUTHOR]

The cytotoxicity of two tricarbonyl Mn(I) complexes of the general formula fac-[MnBr(CO)3L] (L = quinoline-2-carboxaldehyde (A) and 8-amino quinoline (B)) towards triple negative breast cancer (MDA-MB-231) was reported. Complexes A and B released CO when exposed to 468 nm light. Compound B has a dose-dependent cytotoxicity, with half maximal inhibitory concentration values of 19.62 μM and 11.43 μM before and after illumination, respectively. Co-treatment of MDA-MB-231 with paclitaxel (30 nM) and complex B (10 μM) resulted in a 50% reduction in cell viability. [ABSTRACT FROM AUTHOR]

The installation of electron-withdrawing functional groups at the carbocyclic backbone of aminotroponiminate (ATI) ligands is a versatile method for influencing the electronic properties of the resulting ATI complexes. We report here Li, Na, and K salts of an ATI ligand with a phenylsulfinyl substituent in the backbone. It is demonstrated that the sulfinyl group actively contributes to the coordination chemistry of these complexes, effectively competing with neutral donor ligands such as thf or pyridine in the solid state (XRD), in solution (DOSY NMR spectroscopy), and in the gas phase (DFT). The impact of the phenylsulfinyl group on the redox properties of the complexes have been investigated and access to sodium sodiate species through ligand-induced disproportionation has been studied. Transfer of the ATI ligand to the heavy p-block element bismuth has been demonstrated. Analytical techniques applied in this work include multinuclear and DOSY NMR spectroscopy, cyclic voltammetry, DFT calculations, and single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Hückel π aromaticity is typically a domain of carbon-rich compounds. Only very few analogues with non-carbon frameworks are currently known, all involving the heavier elements. The isolation of the triboracyclopropenyl dianion is presented, a boron-based analogue of the cyclopropenyl cation, which belongs to the prototypical class of Hückel π aromatics. Reduction of Cl2BNCy2 by sodium metal produced [B3(NCy2)3]2-, which was isolated as its dimeric Na+ salt (Na4[B3(NCy2)3]2·2 DME; 1) in 45% yield and characterized by single-crystal X-ray diffraction. Cyclic voltammetry measurements established an extremely high oxidation potential for 1 (Epc=-2.42 V), which was further confirmed by reactivity studies. The Hückel-type π aromatic character of the [B3(NCy2)3]2- dianion was verified by various theoretical methods, which clearly indicated π aromaticity for the B3 core of a similar magnitude to that in [C3H3]+ and benzene. [ABSTRACT FROM AUTHOR]

Hückel-p-Aromatizität wird üblicherweise bei kohlenstoffreichen Verbindungen beobachtet. Analoge Systeme mit kohlenstofffreien Grundgerüsten sind äuβerst selten, wobei die bekannten Beispiele ausschlieβlich auf schwereren Elementen aufbauen. Wir konnten nun das Triboracyclopropenyl- Dianion synthetisieren, ein Bor-basiertes Analogon des klassischen Cyclopropenyl-Kations, das zu den prototypischen Hückel-p-Aromaten zählt. Die Reduktion von Cl2BNCy2 mit elementarem Natrium lieferte Na4[B3(NCy2)3]-2DME (1), das in 45 % Ausbeute isoliert und mittels Einkristall-Röntgenstrukturanalyse charakterisiert wurde. Elektrochemische Messungen offenbarten ein auβergewöhnlich hohes Oxidationspotential für 1 (Epc = --2.42 V), das sich auch in Reaktivitätsstudien widerspiegelte. Die Gegenwart eines Hückel-artigen p- Elektronensystems in [B3(NCy2)3]2-- wurde mittels unterschiedlicher theoretischer Ansätze nachgewiesen. Die p-Aromatizität des B3-Systems ist demnach ähnlich stark ausgeprägt wie in [C3H3]+ und Benzol. [ABSTRACT FROM AUTHOR]

A heterocyclic manganese complex (4) derived from a carbonyl–borylene coupling reaction undergoes isomerisation, during which the former borylene moiety migrates to the cyclopentadienyl ligand and inserts into a C–H bond. This reaction and a computational study of its mechanism are discussed. [ABSTRACT FROM AUTHOR]

Reaction of different combinations of aryl(dihalo)boranes and trialkylsilyl iron metallates, a route previously used to prepare a terminal iron arylborylene complex, is found to lead to three distinct new reaction outcomes, including unselective decomposition, an inert iron(ii) (boryl)(silyl) complex, and a dinuclear bis(μ-silylene) complex. The latter result is to our knowledge the first example of a 1,2-alkylborane elimination, in contrast to the facile and ubiquitous 1,1-alkylborane elimination observed from (alkyl)(boryl) transition metal complexes, and is also a novel route to bridging silylene complexes. [ABSTRACT FROM AUTHOR]

The first example of a complex containing an η3-coordinated borirene ligand bound to a single metal atom was prepared by photolytic transfer of an arylborylene ligand to diphenylacetylene and loss of three CO ligands from the precursor. The η3-borirene complex possesses a chromium(0) atom which is also bound to one phenyl group in an η6 fashion. The complex was isolated in 15 % yield along with the corresponding metal-free borirene, which was isolated in 62 % yield. The bonding between the chromium center and the borirene ring was studied computationally by DFT methods. [ABSTRACT FROM AUTHOR]

Ein erstes Beispiel für einen einkernigen Komplex mit einem η3-koordinierten Borirenliganden wurde durch photolytischen Transfer eines Arylborylens auf Diphenylacetylen und Abspaltung von drei CO-Gruppen aus dem Edukt erhalten. Der η3-Borirenkomplex enthält ein Chrom(0)-Zentrum, das zusätzlich η6-artig an eine Phenylgruppe koordiniert. Der Komplex wird mit 15 % Ausbeute isoliert, und außerdem fällt das Metall-freie Boriren in 62 % Ausbeute an. Die Bindung des Chromzentrums an den Borirenring wurde mit DFT-Methoden untersucht. [ABSTRACT FROM AUTHOR]

The oxidation of doubly cyclic alkyl(amino)carbene-stabilised closed-shell 1,4-diborabenzene with sulfur or selenium yields S4/S5- or Se4-bridged hexa-1,4-dienes, respectively, whereas that of the related open-shell singlet biradical 9,10-diboraanthracene with O2, sulfur or selenium yields the endoperoxo- or S/Se-bridged bicyclic species, respectively. [ABSTRACT FROM AUTHOR]

Reaction between [RuCl2(CO)2]n and 1H-benzimidazol-2-ylmethyl-(N-phenyl)amine ligands (LR) functionalized with various electron-donating and electron-withdrawing substituents on the phenyl ring (R = H, 4-CH3, 4-Cl, 4-COOCH3, and 3-COOCH3) afforded the dark-stable photoactivatable carbon monoxide prodrugs of the general formula [RuCl2(CO)2LR]. Release of the CO molecules from the Ru(II) compounds was examined by monitoring the electronic and IR spectra upon illumination at 365 nm. A noticeable decrease in the intensities of the two characteristic ν(C≡O) modes for Ru(CO) II2 species, and the growth of two new bands for the mono-carbonyl species and free CO, were the main features of the photolysis profiles. The cytotoxicity of the complexes towards breast cancer (MCF-7) cells was assessed with and without illumination at 365 nm. All the complexes except that with a 4-COOCH3 group (IC50 = 45.08 ± 3.5 μM) are nontoxic under dark conditions. Upon illumination, all the compounds acquired cytotoxicity in the following order: H > 4-COOCH3 > 4-CH3 > 4-Cl > 3-COOCH3. Investigation of the cytotoxicity of the CO-depleted fragments showed that the light-induced cytotoxicity can be attributed to the liberated CO and CO-depleted metal fragments, including the liberated benzimidazole ligands. [ABSTRACT FROM AUTHOR]

Aminotroponiminate (ATI) ligands are a versatile class of redox‐active and potentially cooperative ligands with a rich coordination chemistry that have consequently found a wide range of applications in synthesis and catalysis. While backbone substitution of these ligands has been investigated in some detail, the impact of electron‐withdrawing groups on the coordination chemistry and reactivity of ATIs has been little investigated. We report here Li, Na, and K salts of an ATI ligand with a nitro‐substituent in the backbone. It is demonstrated that the NO2 group actively contributes to the coordination chemistry of these complexes, effectively competing with the N,N‐binding pocket as a coordination site. This results in an unprecedented E/Z isomerisation of an ATI imino group and culminates in the isolation of the first "naked" (i. e. without directional bonding to a metal atom) ATI anion. Reactions of sodium ATIs with silver(I) and tritylium salts gave the first N,N‐coordinated silver ATI complexes and unprecedented backbone substitution reactions. Analytical techniques applied in this work include multinuclear (VT‐)NMR spectroscopy, single‐crystal X‐ray diffraction analysis, and DFT calculations. [ABSTRACT FROM AUTHOR]

Boroles are attracting broad interest for their myriad and diverse applications, including in synthesis, small molecule activation and functional materials. Their properties and reactivity are closely linked to the cyclic conjugated diene system, which has been shown to participate in cycloaddition reactions, such as the Diels‐Alder reaction with alkynes. The reaction steps leading to boranorbornadienes, borepins and tricyclic boracyclohexenes from the thermal reaction of boroles with alkynes are seemingly well understood as judged from the literature. Herein, we question the long‐established mechanistic picture of pericyclic rearrangements by demonstrating that seven‐membered borepins (i. e. heptaphenylborepin and two derivatives substituted with a thienyl and chloride substituent on boron) exist in a dynamic equilibrium with the corresponding bicyclic boranorbornadienes, the direct Diels‐Alder products, but are not isolable products from the reactions. Heating gradually converts the isomeric mixtures into fluorescent tricyclic boracyclohexenes, the most stable isomers in the series. Results from mechanistic DFT calculations reveal that the tricyclic compounds derive from the boranorbornadienes and not the borepins, which were previously believed to be intermediates in purely pericyclic processes. [ABSTRACT FROM AUTHOR]

Cyclic alkyl(amino)carbene‐stabilized (cyano)hydroboryl anions were synthesized by deprotonation of (cyano)dihydroborane precursors. While they display boron‐centered nucleophilic reactivity towards organohalides, generating fully unsymmetrically substituted cyano(hydro)organoboranes, they show cyano‐nitrogen‐centered nucleophilic reactivity towards haloboranes, resulting in the formation of hitherto unknown linear 2‐aza‐1,4‐diborabutatrienes. [ABSTRACT FROM AUTHOR]

Das Konzept der Aromatizität und der Antiaromatizität ist seit langem bekannt, und zahlreiche Belege für dieses Phänomen wurden durch Moleküle, welche auf Elementen des p‐, d‐ und f‐Blocks des Periodensystems der Elemente (PSE) basieren, geliefert. Aufgrund der begrenzten Varianz des Oxidationszustandes von s‐Block‐Metallen konnten diese bisher nicht mit komplexen π‐Bindungssystemen interagieren. Daher gibt es keine bzw. nur schlecht beschriebene Beispiele für antiaromatische Systeme mit s‐Block‐Metallen. Durch die Verwendung von spektroskopischen, strukturanalytischen und quantenchemischen Methoden konnte eine heterocyclische Verbindung hergestellt und charakterisiert werden, welche das Erdalkalimetall Beryllium enthält und signifikante Antiaromatizität aufweist. Weiterhin beschreiben wir die Reaktivität gegenüber Lewis‐Basen und die chemische Reduktion dieser Verbindung. [ABSTRACT FROM AUTHOR]

The concepts of aromaticity and antiaromaticity have a long history, and countless demonstrations of these phenomena have been made with molecules based on elements from the p, d, and f blocks of the periodic table. In contrast, the limited oxidation‐state flexibility of the s‐block metals has long stood in the way of their participation in sophisticated π‐bonding arrangements, and truly antiaromatic systems containing s‐block metals are altogether absent or remain poorly defined. Using spectroscopic, structural, and computational techniques, we present herein the synthesis and authentication of a heterocyclic compound containing the alkaline earth metal beryllium that exhibits significant antiaromaticity, and detail its chemical reduction and Lewis‐base‐coordination chemistry. [ABSTRACT FROM AUTHOR]

Bei der Einelektronenreduktion eines durch eine cyclisches (Alkyl)(amino)carben (CAAC) stabilisierten Arylborylen‐Carbonylkomplexes erfolgt die Bildung eines dimeren Borylketyl‐Radikalanions, bedingt durch eine intramolekulare Arylmigration zum CO Kohlenstoffatom. Computergestützte Analyse liefert Hinweise auf eine radikalanionische [(CAAC)B(CO)Ar].− Zwischenstufe. Weiterführende Reduktion des entstandenen Komplexes liefert ein hoch nukleophiles (Boranyliden)methanolat. [ABSTRACT FROM AUTHOR]