Search

Comprehensive Summary Two families of cyclopentadienyl (Cp)/carboranyl heteroleptic sandwiched organolanthanide complexes, namely [Ln{η5:σ‐Me2C(C5H4)(C2B10H10)}2][Li(DME)3] (1Ln, Ln = Tb, Dy, Ho, Er) and [2‐THF‐2'‐(μ2‐Cl)Li(THF)3‐2,2'‐Ln(nido‐1,7‐C2B9H11)Cp*] (2Dy), were synthesized. Family of 1Ln has been proposed based on the mixing‐ligands idea by linking Cp and nido‐dicarborllide. However, the carborane cage of [Me2C(C5H4)(C2B10H10)]2− deprotons and forms a mono‐C− anion rather than deboron to form dicarborllide dianion. Hence, the family of 1Ln features a dysprosocenium skeleton with extra two coordination of C− anions of carborllides. Such coordination geometry is more like a tetrahedron if abstracting the centroids of two coordinated Cp rings. In this cubic‐type geometry, no significant magnetic axiality is presented; only 1Dy and 1Tb show field‐induced slow magnetic relaxation behavior below 10 K. Inspired by 1Ln, the free pentamethylcyclopentadienyl (Cp*−) and nido‐dicarborllide ligands are used to sandwich central Dy3+ ion, achieving heteroleptic complex 2Dy. The bending angle by linking the centroid of Cp*−, Dy3+ and C2B32− in 2Dy is increased to 132.8(1)°. As such, the effective energy barrier for magnetic reversal (Ueff) and magnetic blocking temperature TB (ZFC) are both increased (Ueff = 616(10) K; TB = 6 K). The effort of further enhancing Ueff and TB in such heteroleptic organolanthanide sandwiches should rely on keeping increasing the ligand axiality. [ABSTRACT FROM AUTHOR]

The synthesis and structural analysis of (Me3SiC5H4)TiCl2(OAr) [OAr = O-2,6-iPr2-4-RC6H2; R = H, SiEt3] revealed that it exhibits higher catalytic activities than (tBuC5H4)TiCl2(OAr), Cp*TiCl2(OAr), with efficient comonomer incorporation in ethylene/styrene copolymerization in the presence of a methylaluminoxane (MAO) cocatalyst. The catalytic activity in the copolymerization increased upon increasing the charged styrene concentration along with the increase in the styrene content in the copolymers, whereas the activities of other catalysts showed the opposite trend. (Me3SiC5H4)TiCl2(O-2,6-iPr2C6H3) displayed the most suitable catalyst performance in terms of its activity and styrene incorporation, affording amorphous copolymers with styrene contents higher than 50 mol% (up to 63.6 mol%) and with random styrene incorporation confirmed by 13C-NMR spectra. [ABSTRACT FROM AUTHOR]

Starting from [Mn(C5H4Br)(PPh3)(CO)2] (1a), the cymantrenyl thioethers [Mn(C5H4SMe)(PPh3)(CO)2] (1b) and [Mn{C5H4–nBr(SMe)n}(PPh3)(CO)2] (n = 1 for compound 2, n = 2 for 3 and n = 3 for 4) were obtained, using either n‐butyllithium (n‐BuLi), lithium diisopropylamide (LDA) or lithium tetramethylpiperidide (LiTMP) as base, followed by electrophilic quenching with MeSSMe. Stepwise consecutive reaction of [Mn(C5Br5)(PPh3)(CO)2] with n‐BuLi and MeSSMe led finally to [Mn{C5(SMe)5}(PPh3)(CO)2] (11), only the fifth complex to be reported containing a perthiolated cyclopentadienyl ring. The molecular and crystal structures of 1b, 3, 4 and 11 were determined and were studied for the occurrence of S...S and S...Br interactions. It turned out that although some interactions of this type occurred, they were of minor importance for the arrangement of the molecules in the crystal. [ABSTRACT FROM AUTHOR]

Starting from [Mn(C5H4Br)(PPh3)(CO)2] (1a), the cymantrenyl thioethers [Mn(C5H4SMe)(PPh3)(CO)2] (1b) and [Mn{C5H4–nBr(SMe)n}(PPh3)(CO)2] (n = 1 for compound 2, n = 2 for 3 and n = 3 for 4) were obtained, using either n‐butyllithium (n‐BuLi), lithium diisopropylamide (LDA) or lithium tetramethylpiperidide (LiTMP) as base, followed by electrophilic quenching with MeSSMe. Stepwise consecutive reaction of [Mn(C5Br5)(PPh3)(CO)2] with n‐BuLi and MeSSMe led finally to [Mn{C5(SMe)5}(PPh3)(CO)2] (11), only the fifth complex to be reported containing a perthiolated cyclopentadienyl ring. The molecular and crystal structures of 1b, 3, 4 and 11 were determined and were studied for the occurrence of S...S and S...Br interactions. It turned out that although some interactions of this type occurred, they were of minor importance for the arrangement of the molecules in the crystal. [ABSTRACT FROM AUTHOR]

The reaction of [(Dpp-bian)DyI(Dme)2] (Dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene, Dme is CH3OCH2CH2OCH3) with Cp*K (Cp* is C5Me5) in toluene followed by crystallization from benzene affords crystals of the 1D coordination polymer [(Dpp-bian)DyIKCp*]n (I)·2.6C6H6 (26%) and crystals of the monomeric complex [(Dpp-bian)DyCp*(Dme)] (II)·1.5C6H6 (12%). The same reaction in 1,2-dimethoxyethane followed by crystallization from benzene makes it possible to isolate only complex II·1.5C6H6 in a yield of 48%. The synthesized compounds are characterized by IR and UV spectroscopy and elemental and thermogravimetric analyses. Their molecular structures are determined by XRD (CIF files CCDC nos. 2298407 (I) and 2298408 (II)). [ABSTRACT FROM AUTHOR]

Results of studying the catalytic properties of systems based on complexes with [Pd(Cp)(L)n]m[BF4]m (where Cp = η5-C5H5; n = 2, m = 1: L = tris(ortho-methoxyphenyl)phosphine, triphenylphosphine, tris(2-furyl)phosphine (TFP); n = 1, m = 1: L = 1,1'-bis(diphenylphosphino)ferrocene, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,5-bis(diphenylphosphino)pentane; n = 1, m = 2 or 3: L = 1,6-bis(diphenylphosphino)hexane) in the addition homo- and copolymerization of norbornene (NB) and NB derivatives have been described. It has been found that these complexes can be activated with Lewis acids (BF3⋅OEt2 or AlCl3). The productivity of the [Pd(Cp)(PPh3)2][BF4]/BF3⋅OEt2 catalyst system in NB polymerization can achieve 188 800 molNB . The homopolymerization of 5-methoxycarbonylnorbornene and the copolymerization of NB with 5-methoxycarbonylnorbornene or 5-phenylnorbornene in the presence of BF3⋅OEt2 and [Pd(Cp)(L)2][BF4] (L = PPh3 or TFP) has been studied. A hypothesis for the formation of the catalyst via the intramolecular rearrangement of the η5-Cp ligand into the η1-Cp form upon interaction with a Lewis acid has been proposed. The structure of the [Pd(Cp)(TFP)2]BF4 complex (I) has been determined by X-ray diffraction (XRD) analysis. In the crystal structure of complex I, the coordination sphere of palladium is characterized by a slight distortion of the square planar geometry of the central atom, while the cyclopentadiyl moiety is in an eclipsed conformation. Based on XRD data, the steric hindrance of the TFP ligand has been determined (cone angle is 149°). [ABSTRACT FROM AUTHOR]

Two novel sizable multicharged cationic complexes, of the formulae [(η6–-[12]CPP)[Ru(η5–-Cp)]12]Χ12 and [(η6–-[11]CPP)[Ru(η5–-Cp)]11]Χ11, CPP = cycloparaphenylene, Cp = cyclopentadienyl, X = [PF6]−, (1), (3) and [Cl]−, (2), (4), were synthesized and characterized using NMR techniques, high-resolution mass spectrometry, and elemental analyses. Complexes (1) and (3) were stable in acetone and acetonitrile solutions over 48 h. In contrast, the water-soluble (2) and (4) begin to decompose in aqueous media after 1 h, due to the [Cl]− tendency for nucleophilic attack on ruthenium of the {Ru(η5–-Cp)} units. Fluorescence quenching experiments conducted during the stability window of (2) with the d(5′-CGCGAATTCGCG-3′)2-EtBr adducts revealed remarkably high values for Ksv = 1.185 × 104 ± 0.025 M−1 and Kb = 3.162 × 105 ± 0.001 M−1. Furthermore, the cytotoxic activity of (2) against A2780, A2780res, and MCF-7 cancer cell lines shows that it is highly cytotoxic with IC50 values in the range of 4.76 ± 1.85 to 16 ± 0.81 μΜ. [ABSTRACT FROM AUTHOR]

Novel full-sandwich (η5-Cp)-Ru-paraphenylene complexes with the general formula [(η5-Cp)nRu(η6-L)](PF6)n where n = 1–3 and L = biphenyl, p-terphenyl and p-quaterphenyl, were synthesized and characterized by means of spectroscopic and analytical techniques. The structures of the complexes [(η5-Cp)Ru(η6-biphenyl)](PF6) (1), [(η5-Cp)Ru(η6-terphenyl)](PF6) (3) and [(η5-Cp)2Ru(η6-terphenyl)](PF6)2 (4) was determined by X-ray single crystal methods. The interaction of the complexes [(η5-Cp)Ru(η6-quaterphenyl)]Cl, (6)Cl, and [(η5-Cp)2Ru(η6-quaterphenyl)]Cl2, (7)Cl2, with the DNA duplex d(5′-CGCGAATTCGCG-3′)2 was studied using NMR techniques. The results showed that both complexes interacted non-specifically with both the minor and major grooves of the helix. Specifically, (6)Cl exhibited partial binding through intercalation between the T7 and T8 bases of the sequence without disrupting the C–G and A–T hydrogen bonds. Fluorometric determination of the complexes' binding constants revealed a significant influence of the number of connected phenyl rings in the paraphenylene ligand (L) on the binding affinity of their complexes with the d(5′-CGCGAATTCGCG-3′)2. The complexes (6)Cl and (7)Cl2 were found to be highly cytotoxic against the A549 lung cancer cell line, with complex (6) being more effective than (7) (IC50 for (6)Cl: 17.45 ± 2.1 μΜ, IC50 for (7)Cl2: 65.83 ± 1.8 μΜ) and with a selectivity index (SI) (SI for (6)Cl: 1.1 and SI for (7)Cl2: 4.8). [ABSTRACT FROM AUTHOR]

A new cationic palladium complex [Pd(η5-C5H5)(PPh2Cy)2]BF4 (I) is prepared by the reaction of [Pd(acac)(PCyPh2)2]BF4 with cyclopentadiene in the presence of BF3·OEt2. The structure of complex I is determined by XRD. Results of the DFT studies at the BP86-D3/def2-TZVP level of theory along with QTAIM and NOCV methods suggest that the hapticity of the cyclopentadienyl ligand in I adopts an intermediate type of coordination between η3 and η5. Compound I demonstrates a catalytic activity in the reaction of 1,3-butadiene telomerization with methanol with a catalyst turnover number up to 43100 (mol·BD)/(mol·Pd) for 6 h and a 76% selectivity to telomeres. [ABSTRACT FROM AUTHOR]

We have re‐examined the reactivity of the manganese dinitrogen complex [Cp(CO)2Mn(N2)] (1, Cp=η5‐cyclopentadienyl, C5H5) with phenylithium (PhLi). By combining experiment and density functional theory (DFT), we have found that, unlike previously reported, the direct nucleophilic attack of the carbanion onto coordinated dinitrogen does not occur. Instead, PhLi reacts with one of the CO ligands to provide an anionic acylcarbonyl dinitrogen metallate [Cp(CO)(N2)MnCOPh]Li (3) that is stable only below −40 °C. Full characterization of 3 (including single crystal X‐ray diffraction) was performed. This complex decomposes quickly above −20 °C with N2 loss to give a phenylate complex [Cp(CO)2MnPh]Li (2). The latter compound was erroneously formulated as an anionic diazenido compound [Cp(CO)2MnN(Ph)=N]Li in earlier reports, ruling out the claimed and so‐far unique behavior of the N2 ligand in 1. DFT calculations were run to explore both the hypothesized and the experimentally verified reactivity of 1 with PhLi and are fully consistent with our results. Direct attack of a nucleophile on metal‐coordinated N2 remains to be demonstrated. [ABSTRACT FROM AUTHOR]

We have re‐examined the reactivity of the manganese dinitrogen complex [Cp(CO)2Mn(N2)] (1, Cp=η5‐cyclopentadienyl, C5H5) with phenylithium (PhLi). By combining experiment and density functional theory (DFT), we have found that, unlike previously reported, the direct nucleophilic attack of the carbanion onto coordinated dinitrogen does not occur. Instead, PhLi reacts with one of the CO ligands to provide an anionic acylcarbonyl dinitrogen metallate [Cp(CO)(N2)MnCOPh]Li (3) that is stable only below −40 °C. Full characterization of 3 (including single crystal X‐ray diffraction) was performed. This complex decomposes quickly above −20 °C with N2 loss to give a phenylate complex [Cp(CO)2MnPh]Li (2). The latter compound was erroneously formulated as an anionic diazenido compound [Cp(CO)2MnN(Ph)=N]Li in earlier reports, ruling out the claimed and so‐far unique behavior of the N2 ligand in 1. DFT calculations were run to explore both the hypothesized and the experimentally verified reactivity of 1 with PhLi and are fully consistent with our results. Direct attack of a nucleophile on metal‐coordinated N2 remains to be demonstrated. [ABSTRACT FROM AUTHOR]

We have re‐examined the reactivity of the manganese dinitrogen complex [Cp(CO)2Mn(N2)] (1, Cp=η5‐cyclopentadienyl, C5H5) with phenylithium (PhLi). By combining experiment and density functional theory (DFT), we have found that, unlike previously reported, the direct nucleophilic attack of the carbanion onto coordinated dinitrogen does not occur. Instead, PhLi reacts with one of the CO ligands to provide an anionic acylcarbonyl dinitrogen metallate [Cp(CO)(N2)MnCOPh]Li (3) that is stable only below −40 °C. Full characterization of 3 (including single crystal X‐ray diffraction) was performed. This complex decomposes quickly above −20 °C with N2 loss to give a phenylate complex [Cp(CO)2MnPh]Li (2). The latter compound was erroneously formulated as an anionic diazenido compound [Cp(CO)2MnN(Ph)=N]Li in earlier reports, ruling out the claimed and so‐far unique behavior of the N2 ligand in 1. DFT calculations were run to explore both the hypothesized and the experimentally verified reactivity of 1 with PhLi and are fully consistent with our results. Direct attack of a nucleophile on metal‐coordinated N2 remains to be demonstrated. [ABSTRACT FROM AUTHOR]

We have re‐examined the reactivity of the manganese dinitrogen complex [Cp(CO)2Mn(N2)] (1, Cp=η5‐cyclopentadienyl, C5H5) with phenylithium (PhLi). By combining experiment and density functional theory (DFT), we have found that, unlike previously reported, the direct nucleophilic attack of the carbanion onto coordinated dinitrogen does not occur. Instead, PhLi reacts with one of the CO ligands to provide an anionic acylcarbonyl dinitrogen metallate [Cp(CO)(N2)MnCOPh]Li (3) that is stable only below −40 °C. Full characterization of 3 (including single crystal X‐ray diffraction) was performed. This complex decomposes quickly above −20 °C with N2 loss to give a phenylate complex [Cp(CO)2MnPh]Li (2). The latter compound was erroneously formulated as an anionic diazenido compound [Cp(CO)2MnN(Ph)=N]Li in earlier reports, ruling out the claimed and so‐far unique behavior of the N2 ligand in 1. DFT calculations were run to explore both the hypothesized and the experimentally verified reactivity of 1 with PhLi and are fully consistent with our results. Direct attack of a nucleophile on metal‐coordinated N2 remains to be demonstrated. [ABSTRACT FROM AUTHOR]

A series of molybdenum(II) compounds [(η5‐Cp')Mo(CO)2(L2)][BF4] (Cp'=C5H4(CH2)2SPh, C9H6(CH2)2OMe, L2=N,N‐chelating ligand) have been synthesized and characterized by spectroscopic and analytical methods including X‐ray crystallography. The in vitro assay on human leukemia cells MOLT‐4 has shown that the substitution in the π‐ligand in combination with suitable N,N‐chelating ligand can lead to species with cytotoxicity considerably higher than reported to cisplatin. Unusually high activity was observed for compounds bearing phenanthroline ligands [{η5‐C9H6(CH2)2OMe}Mo(CO)2(3,4,7,8‐Me4phen)][BF4] (IC50=0.7±0.3 μM) and [{η5‐C9H6(CH2)2OMe}Mo(CO)2(4,7‐Ph2phen)][BF4] (IC50 values 0.8±0.4 μM). [ABSTRACT FROM AUTHOR]

For the first time, an extensive theoretical comparative study of the electronic structure and spectra of the η5-cyclopentadienyl half-sandwich [(Cp)(EPh3)], E = Se, Te) organochalcogenides was carried out using direct space electronic structure calculations within hybrid, meta, and meta-hybrid DFT GGA functionals coupled with double-ζ polarized 6-31G* and correlation-consistent triple-zeta cc-pVTZ-pp basis sets. The absence of covalent bonding between the cyclopentadienyl (Cp) ligands and Te/Se coordination centers was revealed. It was found that the chalcogens are partially positively charged and Cp ligands are partially negatively charged, which directly indicates a visible ionic contribution to Te/Se-Cp chemical bonding. Simulated UV–Vis absorption spectra show that all complexes have a UV-active nature, with a considerable shift in their visible light absorption due to the addition of methyl groups. The highest occupied molecular orbitals exhibit π-bonding between the Te/Se centers and Cp rings, although the majority of the orbital density is localized inside the Cp π-system. The presence of the chalcogen atoms and the extension of π-bonds across the chalcogen-ligand interface make the species promising for advanced photovoltaic and light-emitting applications. [ABSTRACT FROM AUTHOR]

The Pd(II) complexes [Pd(Cp)(L)n]m[BF4]m were synthesized via the reaction of cationic acetylacetonate complexes with cyclopentadiene in the presence of BF3∙OEt2 (n = 2, m = 1: L = PPh3 (1), P(p-Tol)3, tris(ortho-methoxyphenyl)phosphine (TOMPP), tri-2-furylphosphine, tri-2-thienylphosphine; n = 1, m = 1: L = dppf, dppp (2), dppb (3), 1,5-bis(diphenylphosphino)pentane; n = 1, m = 2 or 3: 1,6-bis(diphenylphosphino)hexane). Complexes 1–3 were characterized using X-ray diffractometry. The inspection of the crystal structures of the complexes enabled the recognition of (Cp–)⋯(Ph-group) and (Cp–)⋯(CH2-group) interactions, which are of C–H...π nature. The presence of these interactions was confirmed theoretically via DFT calculations using QTAIM analysis. The intermolecular interactions in the X-ray structures are non-covalent in origin with an estimated energy of 0.3–1.6 kcal/mol. The cationic palladium catalyst precursors with monophosphines were found to be active catalysts for the telomerization of 1,3-butadiene with methanol (TON up to 2.4∙104 mol 1,3-butadiene per mol Pd with chemoselectivity of 82%). Complex [Pd(Cp)(TOMPP)2]BF4 was found to be an efficient catalyst for the polymerization of phenylacetylene (PA) (catalyst activities up to 8.9 × 103 gPA·(molPd·h)−1 were observed) [ABSTRACT FROM AUTHOR]

Chiral cyclopentadienyl rhodium (CpRh) complexes have emerged as a class of powerful catalysts for enantioselective C–H activation reactions. In terms of Cp ligand development, the mainstream is to design chiral ligands with C 2 symmetry in order to avoid the problem of Cp face selectivity during their metalation with rhodium. In recent years, CpRh catalysts with diastereotopic or enantiotopic Cp faces were also revealed and successfully applied in asymmetric C–H activation. These advances are summarized in this short review together with perspectives for their future development. 1 Introduction 2 Cp Ligands with Diastereotopic Cp Faces 3 Cp Ligands with Enantiotopic Cp Faces 4 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

Two novel sizable multicharged cationic complexes, of the formulae [(η6–-[12]CPP)[Ru(η5–-Cp)]12]Χ12 and [(η6–-[11]CPP)[Ru(η5–-Cp)]11]Χ11, CPP = cycloparaphenylene, Cp = cyclopentadienyl, X = [PF6]−, (1), (3) and [Cl]−, (2), (4), were synthesized and characterized using NMR techniques, high-resolution mass spectrometry, and elemental analyses. Complexes (1) and (3) were stable in acetone and acetonitrile solutions over 48 h. In contrast, the water-soluble (2) and (4) begin to decompose in aqueous media after 1 h, due to the [Cl]− tendency for nucleophilic attack on ruthenium of the {Ru(η5–-Cp)} units. Fluorescence quenching experiments conducted during the stability window of (2) with the d(5′-CGCGAATTCGCG-3′)2-EtBr adducts revealed remarkably high values for Ksv = 1.185 × 104 ± 0.025 M−1 and Kb = 3.162 × 105 ± 0.001 M−1. Furthermore, the cytotoxic activity of (2) against A2780, A2780res, and MCF-7 cancer cell lines shows that it is highly cytotoxic with IC50 values in the range of 4.76 ± 1.85 to 16 ± 0.81 μΜ.

Novel full-sandwich (η5-Cp)-Ru-paraphenylene complexes with the general formula [(η5-Cp)nRu(η6-L)](PF6)n where n = 1–3 and L = biphenyl, p-terphenyl and p-quaterphenyl, were synthesized and characterized by means of spectroscopic and analytical techniques. The structures of the complexes [(η5-Cp)Ru(η6-biphenyl)](PF6) (1), [(η5-Cp)Ru(η6-terphenyl)](PF6) (3) and [(η5-Cp)2Ru(η6-terphenyl)](PF6)2 (4) was determined by X-ray single crystal methods. The interaction of the complexes [(η5-Cp)Ru(η6-quaterphenyl)]Cl, (6)Cl, and [(η5-Cp)2Ru(η6-quaterphenyl)]Cl2, (7)Cl2, with the DNA duplex d(5′-CGCGAATTCGCG-3′)2 was studied using NMR techniques. The results showed that both complexes interacted non-specifically with both the minor and major grooves of the helix. Specifically, (6)Cl exhibited partial binding through intercalation between the T7 and T8 bases of the sequence without disrupting the C–G and A–T hydrogen bonds. Fluorometric determination of the complexes’ binding constants revealed a significant influence of the number of connected phenyl rings in the paraphenylene ligand (L) on the binding affinity of their complexes with the d(5′-CGCGAATTCGCG-3′)2. The complexes (6)Cl and (7)Cl2 were found to be highly cytotoxic against the A549 lung cancer cell line, with complex (6) being more effective than (7) (IC50 for (6)Cl: 17.45 ± 2.1 μΜ, IC50 for (7)Cl2: 65.83 ± 1.8 μΜ) and with a selectivity index (SI) (SI for (6)Cl: 1.1 and SI for (7)Cl2: 4.8).

The resonantly-stabilized cyclopentadienyl radical (C 5 H 5) is a key species in the combustion and molecular growth kinetics of mono and poly-aromatic hydrocarbons (M/PAHs). At intermediate-to-low temperatures, the C 5 H 5 reaction with the hydroperoxyl radical (HO 2) strongly impacts the competition between oxidation to smaller products and growth to PAHs, precursors of soot. However, literature estimates for the HO 2 + C 5 H 5 reaction rate are inaccurate and inconsistent with recent theoretical calculations, thus generating discrepancies in global combustion kinetic models. In this work, we perform state-of-the-art theoretical calculations for the HO 2 + C 5 H 5 reaction including variable reaction coordinate transition state theory for barrierless channels, accurate thermochemistry, and multi-well master equation (ME) simulations. Contrary to previous studies, we predict that OH + 1,3-C 5 H 5 O is the main reaction channel. The new rate constants are introduced in two literature kinetic models exploiting our recently developed ME based lumping methodology and used to perform kinetic simulations of experimental data of MAHs oxidation. It is found that the resonantly-stabilized 1,3-C 5 H 5 O radical is the main C 5 H 5 O isomer, accumulating in relevant concentration in the system, and that the adopted lumping procedure is fully consistent with results obtained with detailed kinetics. The reactivity of C 5 H 5 O with OH and O 2 radicals is included in the kinetic mechanisms based on analogy rules. As a result, C 5 H 5 O mostly reacts with O 2 producing smaller C 3 /C 4 species and large amounts of C 5 H 4 O, suggesting that further investigations of the reactivity of both C 5 H 5 O and C 5 H 4 O with oxygenated radicals is necessary. Overall, this work presents new reliable rate constants for the HO 2 + C 5 H 5 reaction and provides indications for future investigations of relevant reactions in the sub-mechanisms of cyclopentadiene and MAH oxidation. [ABSTRACT FROM AUTHOR]

New divalent lanthanoid and alkaline earth metal complexes bearing the 1,3‐bis(diphenylphosphano)cyclopentadienyl ligand have been synthesised using the redox‐transmetallation protolysis (RTP) approach. From the reaction of the corresponding metal, diphenylmercury and the proligand C5H4(PPh2)2, the compounds [M(η5‐C5H3(PPh2)2‐1,3)2(S)] (with M=Yb, S=(thf)2 or M=Yb, Eu, Ca, Sr, Ba, S=dme) were isolated and characterised by X‐ray diffraction and multinuclear NMR spectroscopy. These compounds may provide a platform for early‐late heterobimetallic complexes. [ABSTRACT FROM AUTHOR]

A series of potassium salts of di- and tri-arylsubstituted cyclopentadienes has been obtained by the metalation of the corresponding cyclopentadienes with benzylpotassium in THF media. Crystals of all compounds, afforded by recrystallization from THF/hexane, diglyme-THF/hexane and toluene/hexane mixtures, have been studied by X-ray diffraction. All studied potassium cyclopentadienides exhibit the luminescence at room temperature and overall quantum yield of photoluminescence for potassium salt of diarylsubstituted cyclopentadiene is 18%. [ABSTRACT FROM AUTHOR]

[Display omitted] Mononuclear [CpNd(BH 4) 2 L] borohydrides comprising L = 1,3,5-trimethyl-1,3,5-triazacyclohexane (Me 3 tach) and L = 1,4,7-trimethyl-1,4,7-triazacyclononane (Me 3 tacn) were obtained and structurally characterized. Their catalytic activity in coordination–insertion ring-opening poly-merization of ε-caprolactone was studied. [ABSTRACT FROM AUTHOR]

We report the synthesis of heteroleptic dysprosium complexes of the 1,2,4-tris(trimethylsilyl)cyclopentadienyl ligand (Cp‴={C5H2(SiMe3)3-1,2,4}), and diamagnetic yttrium analogues, by salt metathesis protocols from KCp‴ and molecular lanthanoid halide or borohydride precursors: [{Ln(Cp‴)2(μ-Cl)2K}2]∞ (1-Ln ; Ln = Y, Dy), [Ln(Cp‴)2(THF)(Cl)] (2-Ln ; Ln = Y, Dy), [Y(Cp‴)2(η3-C3H5)] (3-Y), [Y(Cp‴)(BH4)2(THF)] (4-Y), [Dy(Cp‴)(BH4)(μ-BH4)]4 (5-Dy) and [Ln(Cp‴)2(BH4)] (6-Ln ; Ln = Y, Dy); several crystals of [Dy(Cp‴)2(BH4)(THF)] (7-Dy) formed on one occasion during the isolation of 6-Dy. Efforts to prepare the isolated lanthanoid metallocenium cations [Ln(Cp‴)2]+ for Y and Dy were not successful by the anion abstraction methods investigated herein; however, several crystals of the contact ion-pair complex [Y(Cp‴)2{(μ-Ph)2BPh2}] (8-Y) formed from the reaction of 3-Y with [NEt3H][BPh4]. On one occasion during the preparation of 3-Y we isolated several crystals of [Mg(Cp‴)(THF)(μ-Cl)]2. Complexes 1–6 and [NEt3H][BPh4] were all structurally authenticated by single crystal XRD and characterised by IR spectroscopy and elemental analysis, with magnetic susceptibility for dysprosium complexes determined by the Evans method, and yttrium analogues studied by multinuclear NMR spectroscopy; complexes 7-Dy , 8-Y , and [Mg(Cp‴)(THF)(μ-Cl)]2 were characterised by single crystal XRD only. The magnetic properties of 5-Dy were probed by SQUID magnetometry and ab initio calculations. We report the synthesis and characterisation of a series of heteroleptic yttrium and dysprosium 1,2,4-tris(trimethylsilyl)cyclopentadienyl complexes containing halide, borohydride or allyl co-ligands. Attempts to abstract co-ligands and install weakly coordination anions to generate lanthanoid metallocenium cations were unsuccessful, which we attribute to side reactions with 1,2,4-tris(trimethylsilyl)cyclopentadienyl rings. [ABSTRACT FROM AUTHOR]

The Pd(II) complexes [Pd(Cp)(L)n]m[BF4]m were synthesized via the reaction of cationic acetylacetonate complexes with cyclopentadiene in the presence of BF3∙OEt2 (n = 2, m = 1: L = PPh3 (1), P(p-Tol)3, tris(ortho-methoxyphenyl)phosphine (TOMPP), tri-2-furylphosphine, tri-2-thienylphosphine; n = 1, m = 1: L = dppf, dppp (2), dppb (3), 1,5-bis(diphenylphosphino)pentane; n = 1, m = 2 or 3: 1,6-bis(diphenylphosphino)hexane). Complexes 1–3 were characterized using X-ray diffractometry. The inspection of the crystal structures of the complexes enabled the recognition of (Cp–)⋯(Ph-group) and (Cp–)⋯(CH2-group) interactions, which are of C–H…π nature. The presence of these interactions was confirmed theoretically via DFT calculations using QTAIM analysis. The intermolecular interactions in the X-ray structures are non-covalent in origin with an estimated energy of 0.3–1.6 kcal/mol. The cationic palladium catalyst precursors with monophosphines were found to be active catalysts for the telomerization of 1,3-butadiene with methanol (TON up to 2.4∙104 mol 1,3-butadiene per mol Pd with chemoselectivity of 82%). Complex [Pd(Cp)(TOMPP)2]BF4 was found to be an efficient catalyst for the polymerization of phenylacetylene (PA) (catalyst activities up to 8.9 × 103 gPA·(molPd·h)−1 were observed)

Ruthenium complexes are emerging as one of the most promising classes of complexes for cancer therapy. However, their limited aqueous solubility may be the major limitation to their potential clinical application. In view and to contribute to the progress of this field, eight new water-soluble Ru(II) organometallic complexes of general formula [RuCp(mTPPMS)n(L)] [CF3SO3], where mTPPMS = diphenylphosphane-benzene-3-sulfonate, for n = 2, L is an imidazole-based ligand (imidazole, 1-benzylimidazole, 1-butylimidazole, (1-(3-aminopropyl)imidazole), and (1-(4-methoxyphenyl)imidazole)), and for n = 1, L is a bidentate heteroaromatic ligand (2-benzoylpyridine, (di(2-pyridyl)ketone), and (1,2-(2-pyridyl)benzo-[b]thiophene)) were synthesized and characterized. The new complexes were fully characterized by NMR, FT-IR, UV–vis., ESI-HRMS, and cyclic voltammetry, which confirmed all the proposed molecular structures. The antiproliferative potential of the new Ru(II) complexes was evaluated on MDAMB231 breast adenocarcinoma, A2780 ovarian carcinoma, and HT29 colorectal adenocarcinoma cell lines, showing micromolar (MDAMB231 and HT29) and submicromolar (A2780) IC50 values. The interaction of complex 6 with human serum albumin (HSA) and fatty-acid-free human serum albumin (HSAfaf) was evaluated by fluorescence spectroscopy techniques, and the results revealed that the ruthenium complex strongly quenches the intrinsic fluorescence of albumin in both cases. [ABSTRACT FROM AUTHOR]

The structure and bonding properties of 16 complexes formed by trivalent f elements (M=U, Np, Pu and lanthanides except for Pm and Pr) with cyclopentadienyl (Cp) and cyclohexylisonitrile (C≡NCy) ligands, (Cp)3M(C≡NCy), were studied by a joint experimental (XRD, NMR) and theoretical (DFT) analysis. For the large La(III) ion, the bis-adduct (Cp)3La(C≡NCy)2 could also be synthesized and characterized. The metal–ligand interactions, focusing on the comparison of the actinides and lanthanides as well as on the competition of the two different ligands for M, were elucidated using the Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) models. The results point to interactions of comparable strengths with the anionic Cp and neutral C≡NCy ligands in the complexes. The structural and bonding properties of the actinide complexes reflect small but characteristic differences with respect to the lanthanide analogues. They include larger ligand-to-metal charge transfers as well as metal–ligand electron-sharing interactions. The most significant experimental marker of these covalent interactions is the C≡N stretching frequency. [ABSTRACT FROM AUTHOR]

The electron‐rich cyclopentadienyl and the analogous indenyl and fluorenyl ligands (collectively denoted here as Cp') have been impactful in stabilizing electron‐deficient metal centers including the highly electropositive alkaline earths. Being in the s‐block, the group 2 metals follow a major periodic variation in their atomic and ionic properties which is reflected in those Cp' compounds. This article presents an overview of this class of compounds for all the five metals from beryllium to barium (radium is excluded for its radioactivity), highlighting their systematic variation. [ABSTRACT FROM AUTHOR]

A series of potassium salts of di- and tri-arylsubstituted cyclopentadienes has been obtained by the metalation of the corresponding cyclopentadienes with benzylpotassium in THF media. Crystals of all compounds, afforded by recrystallization from THF/hexane, diglyme-THF/hexane and toluene/hexane mixtures, have been studied by X-ray diffraction. All studied potassium cyclopentadienides exhibit the luminescence at room temperature and overall quantum yield of photoluminescence for potassium salt of diarylsubstituted cyclopentadiene is 18%.

An unusually large and structurally complex charge-neutral polynuclear cluster, hexa-μ2-azido-di-μ3-chlorido-hexa-μ2-hydroxido-di-μ3-oxido-hexakis(pentamethylcyclopentadienyl)hexathorium–diethyl ether–tetrahydrofuran (1/0.56/ 1.44), [Th3(C10H15)6Cl3(N3)6(OH)6O2]0.56C4H10O1.44C4H8O or [Th3(Cp*)3- (O)(OH)3]2Cl2(N3)60.56C4H10O1.44C4H8O (Cp* = [pentamethylcyclopentadienyl]), has been crystallized as a mixed tetrahydrofuran/diethyl ether solvate and structurally characterized. The molecule contains a number of unusual features, the most notable being a finite yet exceptionally long cyclic metal-azido chain. These rare features are the consequence of both sterically protecting Cp* ligands and highly bridging oxide and hydroxide ligands in the same system and illustrate the interesting new possibilities that can arise from combining organometallic and solvothermal f-block element chemistry. [ABSTRACT FROM AUTHOR]

Die Reaktion von CHI3 mit sechs Äquivalenten CrCl2 in THF bei tiefen Temperaturen ergibt [Cr3Cl3(μ2‐Cl)3(μ3‐CH)(thf)6] als den ersten in hohen Ausbeuten isolierbaren CrIII‐μ3‐Methylidinkomplex. Substitution der terminalen Chlorido‐Liganden via Salzmetathese mit Alkalimetall‐Cyclopentadieniden generiert die isostrukturellen Halbsandwich‐Chrom(III)‐μ3‐Methylidine [CpR3Cr3(μ2‐Cl)3(μ3‐CH] (CpR=C5H5, C5Me5, C5H4SiMe3). Neben‐ und Zersetzungsprodukte des Cl/CpR‐Austausches konnten identifiziert und für [Cr4(μ2‐Cl)4(μ2‐I)2(μ4‐O)(thf)4] und [(η5‐C5H4SiMe3)CrCl(μ2‐Cl)2Li(thf)2] strukturell charakterisiert werden. Der Cl/CpR‐Austausch verändert das effektive magnetische Moment bei Raumtemperatur dramatisch von μeff=9.30/9.11 μB (Lösung/Feststoff) zu 3.63/4.32 μB (CpR=C5Me5). Die Reaktionen von [Cr3Cl3(μ2‐Cl)3(μ3‐CH)(thf)6] mit Aldehyden und Ketonen produzierten komplexe Produktmischungen durch Sauerstoff/Methylidin‐Austausch, welche teilweise als Radikalrekombinationsprodukte durch GC/MS Analyse und 1H‐NMR‐Spektroskopie identifiziert werden konnten. [ABSTRACT FROM AUTHOR]

The crystal structure of decakis(μ-chloro)-tetrakis(1,2,4-triphenylcyclopentadienyl)-hexakis(tetrahydrofuran)-di-potassium-tetra-neodymium(III) tetrahydrofuran trisolvate, 1, is reported. The centrosymmetric complex 1 has a rare tetranuclear core [Ln4K2Cl10] and crystalizes in triclinic space group (P 1 ¯ ) with unit cell parameters: a = 11.9858(3) Å, b = 14.0698(3) Å, c = 19.8129(4) Å, α = 74.1120(4)°, β = 81.2073(4)°, γ = 83.9521(4)° and Z = 1. The catalytic system based on 1 and nBuMg(O-2,6-tBu2-4-MeC6H2) exhibits moderate activity in coordinative chain transfer polymerization of ethylene. In case of the system 1/nBu2Mg, oligomerisation of ethylene was not detected. The mono(cyclopentadienyl) complex {[1,2-Ph2-4-(2-MeOC6H4)C5H2]NdCl5K(THF)2}2(THF)3 has been obtained from NdCl3(THF)2.5 and K[1,2-Ph2-4-(2-MeOC6H4)C5H2] (1:1) in THF, crystallized from a THF/hexane mixture, and structurally characterized. [ABSTRACT FROM AUTHOR]

• Metal-ligand bonding in lanthanide(III) complexes is ionic in nature • Quantitative calculations reveal that metal-ligand bonding in lanthanide-metallocene complexes has a very significant covalent contribution • Metal-ligand covalency in lanthanide metallocene complexes involves the vacant lanthanide 6 s , 5 d and 6 p shells [Display omitted] Metal-ligand bonding in bis(cyclopentadienyl) and bis(cyclobutadienyl) lutetium(iii) complexes was studied in a variety of geometries using density functional theory. Based on analysis of the orbitals, the Morokuma–Ziegler–Rauk extended transition state method and natural orbitals of the chemical valence, the bonding interaction is dominantly ionic with a very important covalent contribution. The relative contribution of covalency is so large that it should not be neglected even in qualitative treatments of the electronic structure. The covalency arises from electron donation from the ligand HOMOs and HOMO–1 orbitals to the vacant 5 d , 6 s and 6 p orbitals at the Lu 3 + ion. While 5 d and the 6 s orbitals play the most important part, the 6 p orbitals also make a comparable contribution. A similar bonding picture emerges both in realistic low-symmetry metallocenes and idealized high-symmetry geometries. The results put to question the common view of the metal–ligand bonding in lanthanide complexes as completely or almost completely of ionic character, and have implications in the design of crystal-fields in lanthanide complexes when targeting specific magnetic properties. [ABSTRACT FROM AUTHOR]

Ruthenium complexes are emerging as one of the most promising classes of complexes for cancer therapy. However, their limited aqueous solubility may be the major limitation to their potential clinical application. In view and to contribute to the progress of this field, eight new water-soluble Ru(II) organometallic complexes of general formula [RuCp(mTPPMS)n(L)] [CF3SO3], where mTPPMS = diphenylphosphane-benzene-3-sulfonate, for n = 2, L is an imidazole-based ligand (imidazole, 1-benzylimidazole, 1-butylimidazole, (1-(3-aminopropyl)imidazole), and (1-(4-methoxyphenyl)imidazole)), and for n = 1, L is a bidentate heteroaromatic ligand (2-benzoylpyridine, (di(2-pyridyl)ketone), and (1,2-(2-pyridyl)benzo-[b]thiophene)) were synthesized and characterized. The new complexes were fully characterized by NMR, FT-IR, UV–vis., ESI-HRMS, and cyclic voltammetry, which confirmed all the proposed molecular structures. The antiproliferative potential of the new Ru(II) complexes was evaluated on MDAMB231 breast adenocarcinoma, A2780 ovarian carcinoma, and HT29 colorectal adenocarcinoma cell lines, showing micromolar (MDAMB231 and HT29) and submicromolar (A2780) IC50 values. The interaction of complex 6 with human serum albumin (HSA) and fatty-acid-free human serum albumin (HSAfaf) was evaluated by fluorescence spectroscopy techniques, and the results revealed that the ruthenium complex strongly quenches the intrinsic fluorescence of albumin in both cases.

The structure and bonding properties of 16 complexes formed by trivalent f elements (M=U, Np, Pu and lanthanides except for Pm and Pr) with cyclopentadienyl (Cp) and cyclohexylisonitrile (C≡NCy) ligands, (Cp)3M(C≡NCy), were studied by a joint experimental (XRD, NMR) and theoretical (DFT) analysis. For the large La(III) ion, the bis-adduct (Cp)3La(C≡NCy)2 could also be synthesized and characterized. The metal–ligand interactions, focusing on the comparison of the actinides and lanthanides as well as on the competition of the two different ligands for M, were elucidated using the Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) models. The results point to interactions of comparable strengths with the anionic Cp and neutral C≡NCy ligands in the complexes. The structural and bonding properties of the actinide complexes reflect small but characteristic differences with respect to the lanthanide analogues. They include larger ligand-to-metal charge transfers as well as metal–ligand electron-sharing interactions. The most significant experimental marker of these covalent interactions is the C≡N stretching frequency.

Metal-mediated [2+2+2] cycloadditions of unsaturated molecules to cyclic and polycyclic organic compounds are a versatile synthetic route affording good yields and selectivity under mild conditions. In the last two decades, in silico investigations have unveiled important details about the mechanism and the energetics of the whole catalytic cycle. Particularly, a number of computational studies address the topic of half-sandwich catalysts which, due to their structural fluxionality, have been widely employed, since the 1980s. In these organometallic species, the metal is coordinated to an aromatic ring, typically the ubiquitous cyclopentadienyl anion, C5 H5– (Cp) or to the Cp moiety of a larger polycyclic aromatic ligand (Cp′). During the catalytic process, the metal continuously 'slips' on the ring, changing its hapticity. This phenomenon of metal slippage and its implications for the catalyst's performance are discussed in this work, referring to the most important computational mechanistic studies reported in literature for Rh(I) half-metallocenes, with the purpose of providing hints for a rational design of this class of compounds. 1 Introduction 2 Mechanism of Metal-Catalyzed Acetylene [2+2+2] Cycloaddition to Benzene and the Problem of the Indenyl Effect 2.1 Acetylene-Acetonitrile [2+2+2] Co-cycloaddition to 2-Methylpyridine: Evidence of the Indenyl Effect 2.2 Heteroaromatic Catalysts and the Evidence of a Reverse Indenyl Effect 2.3 Booth's Mechanistic Hypothesis and the Evidence of the Indenyl Effect 3 Structure–Reactivity Correlation: The Slippage-Span Model 4 Conclusions and Perspectives [ABSTRACT FROM AUTHOR]

Eight cyclopentadienyl U(III) iodide complexes have been synthesized from UI3 and crystallographically characterized to show the variations that can occur with this ligand set and uranium in the +3 oxidation state: (C5Me5)2UI(THF), {[K(OEt2)2][(C5Me5)2U(µ–I)2]}2, [K(18-crown-6)][(C5Me5)2U(µ–I)2], [K(2.2.2-cryptand)][(C5Me5)2UI2], [Li(THF)4][(C5Me5)2UI2], [Li(THF)3][(C5Me5)2UI(µ–I)], {[K(18-crown-6)]2(µ–toluene)}{[C5H3(SiMe3)2]2UI(µ–I)}2 and [(C5Me5)U]3(µ3–I)2 (µ–I)3I(THF)2. The structures show that small modifications in synthetic and crystallization procedures lead to changes in the coordination mode of the isolated product such that many structural options are available that can only be defined by X-ray crystallography. These variations highlight the many low energy options available in the reaction chemistry of this combination of metal and ligands. [ABSTRACT FROM AUTHOR]

Diene and cyclopentadienyl rhodium halides are very often used as catalysts for various transformations. Herein we analyze the advantages and limitations of classical and more recent synthetic methods for the preparation of these catalysts with a focus on the compounds with chiral ligands. [ABSTRACT FROM AUTHOR]

A new chiral cyclopentadiene CpmyrH was synthesized from the natural terpene (R)‐myrtenal in 5 steps and about 40 % total yield. The key step was the reaction of vinyl‐dibromocyclopropane derivative with MeLi which provided the diene CpmyrH via Skattebøl rearrangement. The reaction of CpmyrH with [(cod)Rh(OAc)]2 gave the rhodium(I) complex (Cpmyr)Rh(cod) and subsequent oxidation with halogens X2 gave the rhodium(III) complexes [(Cpmyr)RhX2]2 (X = Br, I). Complex (Cpmyr)Rh(cod) in combination with benzoyl peroxide catalyzed the C–H activation of O‐pivaloyl‐phenylhydroxamic acid and its subsequent annulation with alkenes giving dihydroisoquinolones with high yield (70–90 %) but moderate enantioselectivity (16–36 % ee). [ABSTRACT FROM AUTHOR]

Tetramethylaluminato/halogenido(X) ligand exchange reactions in half‐sandwich complexes [CpRLa(AlMe4)2] are feasible in non‐coordinating solvents and provide access to large coordination clusters of the type [CpRLaX2]x. Incomplete exchange reactions generate the hexalanthanum clusters [CpR6La6X8(AlMe4)4] (CpR=Cp*=C5Me5, X=I; CpR=Cp′=C5H4SiMe3, X=Br, I). Treatment of [Cp*La(AlMe4)2] with two equivalents Me3SiI gave the nonalanthanum cluster [Cp*LaI2]9, while the exhaustive reaction of [Cp′La(AlMe4)2] with the halogenido transfer reagents Me3GeX and Me3SiX (X=I, Br, Cl) produced a series of monocyclopentadienyl rare‐earth‐metal clusters with distinct nuclearity. Depending on the halogenido ion size the homometallic clusters [Cp′LaCl2]10 and [Cp′LaX2]12 (X=Br, I) could be isolated, whereas different crystallization techniques led to the aggregation of clusters of distinct structural motifs, including the desilylated cyclopentadienyl‐bridged cluster [(μ‐Cp)2Cp′8La8I14] and the heteroaluminato derivative [Cp′10La10Br18(AlBr2Me2)2]. The use of the Cp′ ancillary ligand facilitates cluster characterization by means of NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The electronic structure and spectroscopy of some representative dinuclear compounds containing CpM(CO)3 and CpM(CO)2 groups were studied using TDDFT (Time Dependent Density Functional Theory). These compounds contain Cp (cyclopentadienyl) as a ligand, and M can be Cr, Mo or W. Their main electronic transitions were calculated and the results are in good agreement with the experimental data. This allows the assignment of some bands whose origin was not clear. In all the cases, the carbonyls and Cp groups restrict the symmetry. The molecular orbitals that would be involved in M-M bonding interact strongly with the carbonyls and show unusual shapes and occupations. The strongest electronic bands are caused by σ→σ* transitions in most of the molecules containing CpM(CO)3 groups, whereas in molecules such as Cp(CO)2M≡M(CO)2Cp the most intense bands are produced by π→π* transitions. The origin of other bands is now explained. The effect of the solvent on the electronic transitions and the use of EOM-CCSD method in some compounds were also checked. [ABSTRACT FROM AUTHOR]

Resonance-stabilized cyclopentadienyl radicals are important intermediate species in the combustion of transportation fuels. It not only serves as precursors for polycyclic aromatic hydrocarbon (PAH) formation, but also involves in the formation of fundamental PAH precursors such as propargyl and acetylene. In this work, the unimolecular reactions of the cyclopentadienyl radicals are theoretically studied based on high-level quantum chemistry and RRKM/master equation calculations. Stationary points on the potential energy surface (PES) are calculated at the CCSD(T)/CBS//M06–2X/6–311++(d,p) level of theory. The branching ratios of unimolecular reactions of the cyclopentadienyl radicals are analyzed for a broad temperature range from 500 to 2500 K and pressures from 0.01 to 100 atm. It is found that the isomerization reaction of the cyclopentadienyl radical via 1,2-hydrogen transfer dominates at low temperatures and high pressures, while the well-skipping decomposition reaction which forms propargyl and acetylene is important at high temperatures and low pressures. Both the decomposition reaction of the cyclopentadienyl radicals and its reverse reaction show pronounced pressure dependence, and their reaction rate constants are compared against available low-pressure experimental measurements and theoretical studies. The temperature- and pressure-dependent rate coefficients for important reactions involved on the C 5 H 5 PES are calculated and updated in a chemical kinetic model. Impacts of the unimolecular reactions of the cyclopentadienyl radicals on the PAH formation are explored by the numerical modeling of a low-pressure cyclopentene counterflow diffusion flame. [ABSTRACT FROM AUTHOR]

Resonance-stabilized radical chain (RSRC) reactions were recently proposed as alternative formation and growth pathways of polycyclic aromatic hydrocarbons (PAHs). In the present study, the growth of indene from the resonance-stabilized cyclopentadienyl radical following a series of RSRC sequences is investigated. Temperature- and pressure-dependent rate coefficients for acetylene addition reactions to the cyclopentadienyl, vinylcyclopentadienyl, cycloheptatrienyl, and benzyl radicals are determined based on high-level quantum chemistry and RRKM/master equation calculations. The acetylene addition to the resonance-stabilized cyclopentadienyl radical can generate resonance-stabilized vinylcyclopentadienyl, cycloheptatrienyl, and benzyl radicals. The formation reaction of cycloheptatrienyl has the highest rate constant compared to those of vinylcyclopentadienyl and benzyl. The acetylene addition to the above three resonance-stabilized C 7 H 7 isomers forms indene. It is found that the indene formation reaction from C 2 H 2 addition to benzyl has the highest rate constant, while that from C 2 H 2 addition to cycloheptatrienyl is the lowest. The impacts of the investigated reactions on indene formation are then numerically explored in both counterflow diffusion and laminar premixed flame configurations. Results indicate that the RSRC pathways via C 2 H 2 addition to vinylcyclopentadienyl and cycloheptatrienyl radicals have marginal contributions to indene formation. [ABSTRACT FROM AUTHOR]

Complex (η5-C5H5)2Fe2(CO)4 (I) reacts with 1,3-dimethylimidazolium-2-carboxylate Me2ImCO2 to give asymmetric binuclear carbene iron complex (η5-C5H5)2Fe2(CO)3(Me2Im) (II) (Me2Im = 1,3-dimethylimidazol-2-ylidene). The oxidation of compound II with elemental iodine proceeds via two mechanisms, symmetrical and asymmetrical, to form four products: (η5-C5H5Fe(CO)2(Me2Im)I (III), (η5-C5H5)Fe(CO)2I (IV), (η5-C5H5Fe(CO)2(Me2Im)I3 (V), and ferrocene (VI). In each case, two pairs of reaction products have formed, two of which include NHC ligand: neutral iron(III) complex and ionic complex V. Optimal synthesis conditions to obtain preferably one of these complexes have been found. Geometry and transition state energy of supposed reaction mechanism have been calculated by quantum chemistry methods. [ABSTRACT FROM AUTHOR]

• Ruthenium cationic complexes derived from diazafluorenone derivative ligands. • CpRu(II) complexes showed better antimicrobial and anticancer activity. • Complex 1 showed the highest cytotoxicity towards DL cell line. We have successfully synthesized a series of eight versatile, half-sandwich ruthenium(II) cationic complexes [(Cp/Ind)Ru(к2 (N∩N) L)(PPh 3)]PF 6 (1–8), where L represents a 4,5-diazafluorenone derivative ligand. These complexes were isolated as their hexafluorophosphate salts and subjected to thorough characterization using various spectroscopic techniques such as FT-IR, NMR, UV and Mass. Furthermore, single-crystal X-ray diffraction studies determined the molecular structures of representative complexes 1, 7 , and 8. We screened the synthesized complexes and ligands in vitro to assess their potential antibacterial activity against three bacterial strains: the Gram-positive Staphylococcus aureus , the Gram-negative Escherichia coli and Klebsiella pneumoniae. Remarkably, all the compounds exhibited potent antibacterial activity against the tested organisms. In addition, we conducted a cell viability assessment to evaluate the cytotoxicity of the free ligands. The results indicated that the ligands did not demonstrate statistically significant cytotoxicity. However, it is noteworthy that complex 1 displayed more pronounced cytotoxic effects on the DL cell line, followed by complexes 3, 5 , and 7. [Display omitted] [ABSTRACT FROM AUTHOR]