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The document is the contents list of the New Journal of Chemistry, published on October 28, 2024. It includes a list of communications and papers featured in the journal, covering various topics in chemistry such as catalytic synthesis, hydroesterification, nanoparticles, luminescence, and drug delivery. The journal is published by The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. [Extracted from the article]

Using (bis)diethoxyphosphoryl ferrocene [Fc(O＝P(OEt)2)2] and transition metal carboxylates – [M2(μ-OOCR)4(CH3CN)2], M = CuII, R = tBu, (C5H4)Mn(CO)3 (Cym) or [M3(μ-OOCR)6(CH3CN)2], M = NiII, CoII, R = Cym, a series of heterometallic polymers with metal cores {Cu2Fe}n (1), {Cu2Mn4Fe}n (2) {Ni2Mn4Fe}n (3), and {Co2Mn4Fe}n (4) were obtained under mild conditions. Compounds 1 and 2 showed antibacterial activity against a Mycobacterium smegmatis strain in vitro. [ABSTRACT FROM AUTHOR]

Organometallic complexes, which include ligands such as carbon monoxide (CO), carbenes, alkyls, phenyls, p-bound alkynes, alkenes, cyclopentadienyls, and arenes, have been extensively utilized in fields like materials chemistry and catalysis. These complexes also offer opportunities for the development of new medications with unique modes of action. Specifically, we are interested in anticancer drugs that can enhance the effectiveness of platinum treatments, broaden their range of action, reduce adverse effects, and prevent resistance. The distinct physiochemical properties of organometallic complexes have made them valuable in homogeneous catalysis, including the production of lead compounds and therapeutic possibilities. Over the past 20 years, a small group of researchers worldwide has explored the medical applications of these compounds’ unique characteristics, such as their structural diversity, potential for ligand exchange, and redox and catalytic properties. The results have been remarkable, and it is anticipated that numerous other organometallic compounds will undergo clinical trials in the coming years in addition to those already underway. In this brief study, we outline the advantages that organometallic metal complexes have over coordination compounds and pure organic molecules. [ABSTRACT FROM AUTHOR]

The Raman spectra of ferrocene crystals were measured at pressures up to 20 GPa, and an abnormally large bandwidth of intermolecular phonons at ambient pressure was found. With an increase in the pressure, the bandwidth increased to a maximum at ~2 GPa and then decreased to a minimum at ~4 GPa, which was equal to the pressure‐independent bandwidth of intramolecular phonons. The unusual behavior of the bandwidth was related to the instability of a ferrocene molecule caused by jumps between its D5d and D5h conformations. A decrease in the time of jumps between the conformations to the period of crystal lattice vibrations led to a loss of coherence and broadening of intermolecular phonon bands. The energy barrier between the conformations was determined to be ~17.6 meV/molecule under ambient conditions and 80 meV/molecule at 4.9 GPa. An increase in the barrier with pressure was due to the enhancement of the crystal field, which resulted in the inhibition of the jumps and the stabilization of the molecule in the D5d conformation. [ABSTRACT FROM AUTHOR]

Biradicals are important intermediates in the formation and breaking of a chemical bond. Their use as molecular switches is of particular interest. Much less is known about tetraradicals, which can, for example, consist of two biradical(oid) units. Here we report the synthesis of the first persistent phosphorus‐centred tetraradical bound to a transition metal fragment. Starting from a zirconocene complex, rac‐(ebthi)ZrCl2 (rac‐(ebthi)=1,2‐ethylene‐1,10‐bis(η5‐tetrahydroindenyl), two cyclo‐1,3‐diphospha‐pentane‐1,3‐diyls were successfully introduced, which finally led to the isolation of a deep green zirconcene‐bridged bis(biradicaloid) complex (5) that can act as a double molecular switch. Under the influence of light (570 nm), this tetraradical forms a transannular bond in each of the two five‐membered biradical units, leading to the formation of housane 5 h. Upon irradiation at 415 nm, the reverse reaction is observed, fully recovering tetraradical 5. Through single‐crystal‐to‐single‐crystal transformation, both stable species of the molecular switch could be structurally characterised using SCXRD. The switching under the influence of light and the activation of molecular hydrogen were analysed in solution using NMR and UV spectroscopy. It was found that the addition of one or two equivalents of molecular hydrogen can be switched on and off by light. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Chemical Communications" published in 2024. It includes various articles on topics such as responsive theranostic agents, cationic ligands, green synthesis of zeolite, and transition metal oxide clusters. The journal is published by The Royal Society of Chemistry and focuses on connecting the world with the chemical sciences. The document provides a comprehensive overview of the articles included in the journal issue. [Extracted from the article]

Reactions between [(TrenTIPS)UVI≡N] (1, TrenTIPS = {N(CH2CH2NSiPri3)3}3−) and [MII(η5-C5R5)2] (M/R = Cr/H, Mn/H, Fe/H, Ni/H) were intractable, but M/R = Co/H or Co/Me afforded [(TrenTIPS)UV＝N-(η1:η4-C5H5)CoI(η5-C5H5)] (2) and [(TrenTIPS)UIV–NH2] (3), respectively. For M/R = V/H [(TrenTIPS)UIV–N＝VIV(η5-C5H5)2] (4), was isolated. Complexes 2–4 evidence one-/two-electron uranium reductions, nucleophilic nitrides, and partial N-atom transfer. [ABSTRACT FROM AUTHOR]

The synthesis of group IV metallocene precatalysts for the polymerization of propylene generally yields two different isomers: The racemic isomer that produces isotactic polypropylene (iPP) and the meso isomer that produces atactic polypropylene (aPP). Due to its poor physical properties, aPP has very limited applications. To avoid obtaining blends of both polymers and thus diminish the mechanical and thermal properties of iPP, the meso metallocene complexes need to be separated from the racemic ones tediously—rendering the metallocene‐based polymerization of propylene industrially far less attractive than the Ziegler/Natta process. To overcome this issue, we established an isomerization protocol to convert meso metallocene complexes into their racemic counterparts. This protocol increased the yield of iPP by 400 % while maintaining the polymer's excellent physical properties and was applicable to both hafnocene and zirconocene complexes, as well as different precatalyst activation methods. Through targeted variation of the ligand frameworks, methoxy groups at the indenyl moieties were found to be the structural motifs responsible for an isomerization to take place—this experimental evidence was confirmed by density functional theory calculations. Liquid injection field desorption ionization mass spectrometry, as well as 1H and 29Si nuclear magnetic resonance studies, allowed the proposal of an isomerization mechanism. [ABSTRACT FROM AUTHOR]

Bei der Synthese von Gruppe IV Metallocen‐Präkatalysatoren für die Polymerisation von Propylen werden im Allgemeinen zwei verschiedene Isomere gebildet: Das racemische Isomer, das isotaktisches Polypropylen (iPP) produziert und das meso‐Isomer, das ataktisches Polypropylen (aPP) produziert. Aufgrund seiner vergleichbar schlechten physikalischen Eigenschaften ist die Anwendung von aPP sehr begrenzt. Um Mischungen beider Polymere zu vermeiden, was die mechanischen und thermischen Eigenschaften von iPP zu verschlechtern würde, müssen die meso Metallocenkomplexe mühsam von den racemischen Komplexen getrennt werden, was die Metallocen‐basierte Polymerisation von Propylen industriell weit weniger attraktiv macht als das Ziegler/Natta‐Verfahren. Um dieses Problem zu umgehen, haben wir ein Isomerisierungsprotokoll zur Umwandlung von meso Metallocenkomplexen in ihre racemischen Analoga entwickelt. Dieses Protokoll steigerte die Ausbeute an iPP um 400 %, wobei die hervorragenden physikalischen Eigenschaften des Polymers beibehalten wurden; es war sowohl auf Hafnocen‐, als auch auf Zirkonocenkomplexe, sowie auf verschiedene Methoden zur Aktivierung des Präkatalysators anwendbar. Durch gezielte Variation der Liganden wurden Methoxygruppen an den Indenylsubstituenten als die für eine Isomerisierung verantwortlichen Strukturmotive gefunden ‐ dieser experimentelle Nachweis wurde durch Dichtefunktionaltheorieberechnungen bestätigt. Flüssig‐Injektion‐Feld‐Desorption‐Ionisierung‐Massenspektrometrie, sowie 1H‐ und 29Si‐Kernresonanzstudien ermöglichten den Vorschlag eines Isomerisierungsmechanismus. [ABSTRACT FROM AUTHOR]

The synthesis of one achiral and two chiral propylene‐bridged dititanocenes and their evaluation as catalysts in titanium(III) catalyzed ketone‐nitrile coupling reactions are reported. A reaction progress kinetics analysis of the cross‐coupling between acetophenone and benzyl cyanide reveals that, using a dinuclear titanocene catalyst, the order in catalyst is reduced from two to one in comparison to a mononuclear catalyst. Although the obtained coupling yields and enantioselectivities did not reach the results obtained with the latter, these examples constitute a proof of concept for the templated C─C coupling through coordination of ketone and nitrile to the two tethered titanium centers of a dinuclear catalyst. [ABSTRACT FROM AUTHOR]

The recently described crystalline cyclic (alkyl)(amino)carbene with a 1,1’‐ferrocenylene (fc) backbone fc(CPh2−C−NMes) (A, Mes=mesityl) is highly reactive due to its particularly pronounced ambiphilicity and is thermally not stable in solution due to an intramolecular insertion of the divalent carbon atom into a methyl C−H bond of the Mes substituent. The closely related congener fc(CPh2−C−N‐p‐C6H4‐tBu) (1) cannot undergo such an insertion reaction. Nevertheless, 1 is too short‐lived for isolation due to a rapid 1,2‐shift of a phenyl group, furnishing the isomeric cyclic enamine fc[C(Ph)=C(Ph)−N‐p‐C6H4‐tBu] (1’) in a specific decomposition process unprecedented for CAACs. Trapping of 1 was possible with carbon monoxide, elemental selenium and with [CuBr(SMe2)], respectively affording the aminoketene 1=C=O, the selenoamide 1=Se and the homoleptic CuI complex [Cu(1)2][CuBr2]. 1 is an even stronger ambiphile than A according to NMR spectroscopic data. Similar to A, 1 does not react with H2, because the experimentally observed intramolecular process is kinetically more favourable according to DFT results. [ABSTRACT FROM AUTHOR]

The various steps in the mechanism of olefin polymerizations mediated by neutral rare‐earth metallocene complexes are discussed. The complexes are either trivalent hydride and alkyl rare‐earth compounds or divalent metallocenes that are activated by the monomer via an oxidation step. The stereospecific polymerizations of conjugated dienes based on the association of a cationic metallocene complex and an alkylaluminum and the polymerization mechanism based on monomer insertion into an aluminum‐carbon bond are also discussed. The exploitation of metallocene complexes for the copolymerization of olefins with conjugated dienes is the subject of a third part of this review. The synthesis of new elastomers called ethylene butadiene rubber (EBR) is highlighted. Finally, the use of rare‐earth metallocenes in macromolecular engineering is detailed. This includes the synthesis of functional polyolefins and block copolymers including thermoplastic elastomers. [ABSTRACT FROM AUTHOR]

The metallocenes ferrocene (Cp2Fe, 1), nickelocene (Cp2Ni, 2), and cobaltocene (Cp2Co, 3) crystallize in the same space group (P21/a) and they have the same shape and similar size. Therefore, they form solid solutions with random distribution of the different molecules when crystallized from solution. Alternatively, the solid metallocenes can be ground together manually, and the solid solutions form at any molar ratio within minutes. The metallocenes 2 and 3 are paramagnetic. Solid solutions of 1/3 and 2/3 have been studied by paramagnetic solution and solid-state NMR spectroscopy. The effect of the paramagnetic species on the other components in the solid solutions has been investigated. The impact on the chemical shifts is limited. However, the halfwidths and the signal shapes, as defined by the rotational sideband intensities, change with increasing amounts of paramagnetic components. The 1H T1 relaxation times are shortened for diamagnetic protons in the presence of paramagnetic metallocenes in the solid solutions. It has been demonstrated that all metallocenes mix at the molecular level within the polycrystalline samples. The EPR spectra of the solid solutions are dominated by the most intensive signal of any paramagnetic metallocene in the solid samples. [ABSTRACT FROM AUTHOR]

Methylaluminoxane (MAO) is used as a precatalyst activator for million ton2scale production of commercial polyolefins, but its precise structure and associated activation mechanisms have been a fundamental research puzzle for more than 40 years. We report here the crystallographic characterization of an active MAO component, which reveals a discrete two-dimensional sheet cluster [Al33O26(CH3)47][Al(CH3)3]2 featuring two trimethylaluminum units, Al(CH3)3, coordinated to two unsaturated aluminum sites. Our structural data are consistent with the hypothesis that the active sites bear coordinated Al(CH3)3 and provide [Al(CH3)2]+ for precatalyst activation. Quantum chemical calculations revealed the most preferred sites for [Al(CH3)2]+ abstraction (a change in Gibbs free energy of 0.0 kilocalories per mole). Olefin polymerization tests on metallocenes activated with the crystallized MAO show higher activities than with the commercial MAO. [ABSTRACT FROM AUTHOR]

The stable ferrocene‐based N‐heterocyclic silylenes fc[(N{B})2Si] (A; fc=1,1'‐ferrocenylene, {B}=(HCNDipp)2B, Dipp=2,6‐diisopropylphenyl) and fc[(NDipp)2Si] (B) are compared in a study focussing on their reactivity towards a range of small to moderately sized molecular substrates, viz. P4, S8, Se8, MesN3 (Mes=mesityl), RC≡CH, and RC≡CR (R=Ph, SiMe3). The Dipp‐substituted congener B exhibits a more pronounced ambiphilicity and is sterically less congested than its 1,3,2‐diazaborolyl‐substituted relative A, in line with the higher reactivity of the former. The difference in reactivity is obviously due more to electronic than to steric reasons, as is illustrated by the fact that both A and B react with the comparatively bulky substrate MesN3 under mild conditions to afford the corresponding silanimine fc[(N{B})2Si=NMes] and fc[(NDipp)2Si=NMes], respectively. The heavier ketone analogues fc[(N{B})2Si=E] (E=S, Se, Te) are readily available from A and the corresponding chalcogen. In contrast, the reaction of the more reactive silylene B with elemental sulfur or selenium is unspecific, affording product mixtures. However, fc[(NDipp)2Si=Se] is selectively prepared from B and (Et2N)3PSe; the Te analogue is also accessible, but crystallises as head‐to‐tail dimer. [ABSTRACT FROM AUTHOR]

The stable ferrocene‐based N‐heterocyclic silylenes fc[(N{B})2Si] (A; fc=1,1'‐ferrocenylene, {B}=(HCNDipp)2B, Dipp=2,6‐diisopropylphenyl) and fc[(NDipp)2Si] (B) are compared in a study focussing on their reactivity towards a range of small to moderately sized molecular substrates, viz. P4, S8, Se8, MesN3 (Mes=mesityl), RC≡CH, and RC≡CR (R=Ph, SiMe3). The Dipp‐substituted congener B exhibits a more pronounced ambiphilicity and is sterically less congested than its 1,3,2‐diazaborolyl‐substituted relative A, in line with the higher reactivity of the former. The difference in reactivity is obviously due more to electronic than to steric reasons, as is illustrated by the fact that both A and B react with the comparatively bulky substrate MesN3 under mild conditions to afford the corresponding silanimine fc[(N{B})2Si=NMes] and fc[(NDipp)2Si=NMes], respectively. The heavier ketone analogues fc[(N{B})2Si=E] (E=S, Se, Te) are readily available from A and the corresponding chalcogen. In contrast, the reaction of the more reactive silylene B with elemental sulfur or selenium is unspecific, affording product mixtures. However, fc[(NDipp)2Si=Se] is selectively prepared from B and (Et2N)3PSe; the Te analogue is also accessible, but crystallises as head‐to‐tail dimer. [ABSTRACT FROM AUTHOR]

The synthesis of group 4 metal 1‐metallacyclobuta‐2,3‐dienes as organometallic analogues of elusive 1,2‐cyclobutadiene has so far been limited to SiMe3 substituted examples. We present the synthesis of two Ph substituted dilithiated ligand precursors for the preparation of four new 1‐metallacyclobuta‐2,3‐dienes [rac‐(ebthi)M] (M=Ti, Zr; ebthi=1,2‐ethylene‐1,10‐bis(η5‐tetrahydroindenyl)). The organolithium compounds [Li2(RC3Ph)] (1 b: R=Ph, 1 c: R=SiMe3) as well as the metallacycles of the general formula [rac‐(ebthi)M(R1C3R2)] (2 b: M=Ti, R1=R2=Ph, 2 c: M=Ti, R1=Ph, R2=SiMe3; 3 b: M=Zr, R1=R2=Ph; 3 c: M=Zr, R1=Ph, R2=SiMe3) were fully characterised. Single crystal X‐ray diffraction and quantum chemical bond analysis of the Ti and Zr complexes reveal ligand influence on the biradicaloid character of the titanocene complexes. X‐band EPR spectroscopy of structurally similar Ti complexes [rac‐(ebthi)Ti(Me3SiC3SiMe3)] (2 a), 2 b, and 2 c was carried out to evaluate the accessibility of an EPR active triplet state. Cyclic voltammetry shows that introduction of Ph groups renders the complexes easier to reduce. 13C CPMAS NMR analysis provides insights into the cause of the low field shift of the resonances of metal‐bonded carbon atoms and provides evidence of the absence of the β−C−Ti interaction. [ABSTRACT FROM AUTHOR]

Exploration of the reduction chemistry of the 2,2'‐bipyridine (bipy) lanthanide metallocene complexes Cp*2LnCl(bipy) and Cp*2Ln(bipy) (Cp* = C5Me5) resulted in the isolation of a series of complexes with unusual composition and structure including complexes with a single Cp* ligand, multiple azide ligands, and bipy ligands with close parallel orientations. These results not only reveal new structural types, but they also show the diverse chemistry displayed by this redox‐active platform. Treatment of Cp*2NdCl(bipy) with excess KC8 resulted in the formation of the mono‐Cp* Nd(III) complex, [K(crypt)]2[Cp*Nd(bipy)2], 1, as well as [K(crypt)][Cp*2NdCl2], 2, and the previously reported [K(crypt)][Cp*2Nd(bipy)]. A mono‐Cp* Lu(III) complex, Cp*Lu(bipy)2, 3, was also found in an attempt to make Cp*2Lu(bipy) from LuCl3, 2 equiv. of KCp*, bipy, and K/KI. Surprisingly, the (bipy)1− ligands in neighboring molecules in the structure of 3 are oriented in a parallel fashion with intermolecular C⋅⋅⋅C distances of 3.289(4) Å, which are shorter than the sum of van der Waals radii of two carbon atoms, 3.4 Å. Another product with one Cp* ligand per lanthanide was isolated from the reaction of [K(crypt)][Cp*2Eu(bipy)] with azobenzene, which afforded the dimeric Eu(II) complex, [K(crypt)]2[Cp*Eu(THF)(PhNNPh)]2, 4. Attempts to make 4 from the reaction between Cp*2Eu(THF)2 and a reduced azobenzene anion generated instead the mixed‐valent Eu(III)/Eu(II) complex, [K(crypt)][Cp*Eu(THF)(PhNNPh)]2, 5, which allows direct comparison with the bimetallic Eu(II) complex 4. Mono‐Cp* complexes of Yb(III) are obtained from reactions of the Yb(II) complex, [K(crypt)][Cp*2Yb(bipy)], with trimethylsilylazide, which afforded the tetra‐azido [K(crypt)]2[Cp*Yb(N3)4], 6, or the di‐azido complex [K(crypt)]2[Cp*Yb(N3)2(bipy)], 7 a, depending on the reaction stoichiometry. A mono‐Cp* Yb(III) complex is also isolated from reaction of [K(crypt)][Cp*2Yb(bipy)] with elemental sulfur which forms the mixed polysulfido Yb(III) complex [K(crypt)]2[Cp*Yb(S4)(S5)], 8 a. In contrast to these reactions that form mono‐Cp* products, reduction of Cp*2Yb(bipy) with 1 equiv. of KC8 in the presence of 18‐crown‐6 resulted in the complete loss of Cp* ligands and the formation of [K(18‐c‐6)(THF)][Yb(bipy)4], 9. The (bipy)1− ligands of 9 are arranged in a parallel orientation, as observed in the structure of 3, except in this case this interaction is intramolecular and involves pairs of ligands bound to the same Yb atom. Attempts to reduce further the Sm(II) (bipy)1− complex, Cp*2Sm(bipy) with 2 equiv. of KC8 in the presence of excess 18‐crown‐6 led to the isolation of a Sm(III) salt of (bipy)2− with an inverse sandwich Cp* counter‐cation and a co‐crystallized K(18‐c‐6)Cp* unit, [K2(18‐c‐6)2Cp*]2[Cp*2Sm(bipy)]2 ⋅ [K(18‐c‐6)Cp*], 10. [ABSTRACT FROM AUTHOR]

With the progression in the field of bioinorganic chemistry, the role of transition metal complexes as the most widely used therapeutics is becoming a more and more attractive research area. The complexes of transition metals possess a great variety of attractive pharmacological properties, including anticancer, anti-inflammatory, antioxidant, anti-infective, etc., activities. Transition metal complexes have proven to be potential alternatives to biologically active organic compounds, especially as antitumor agents. The performance of metal coordination compounds in living systems is anticipated to differ generally from the action of non-metal-containing drugs and may offer unique diagnostic and/or therapeutic opportunities. In this review, the rapid development and application of metallocenes and metal complexes of elements from Groups 4 to 7 in cancer diagnostics and therapy have been summarized. Most of the heavy metals discussed in the current review are newly discovered metals. That is why the use of their metal-based compounds has attracted a lot of attention concerning their organometallic and coordination chemistry. All of this imposes more systematic studies on their biological activity, biocompatibility, and toxicity and presupposes further investigations. [ABSTRACT FROM AUTHOR]

Hafnium catalysts for olefin polymerization are often very sensitive to the nature of cocatalysts, especially if they contain "free" aluminium trialkyls. Herein, cocatalyst effects in Hf-catalysed propene polymerization are examined for four Hf catalysts belonging to the family of CS-symmetric (Hf-CS-Met) and C2-symmetric (Hf-C2-Met) metallocenes, as well as of octahedral (Hf-OOOO) and pentacoordinated (Hf-PyAm) "post-metallocenes". The performance of the recently developed {[iBu2(PhNMe2)Al]2(μ-H)}+[B(C6F5)4]− (AlHAl) cocatalyst is compared with that of established systems like methylalumoxane, phenol-modified methylalumoxane and trityl borate/tri-iso-butylaluminium. The worst catalytic performance is observed with MAO. Conversely, the best cocatalyst varies depending on the Hf catalyst used and the performance indicator of interest, highlighting the complexity and importance of selecting the right precatalyst/cocatalyst combination. AlHAl proved to be a suitable system for all catalysts tested and, in some cases, it provides the best performance in terms of productivity (e.g. with hafnocenes). Furthermore, it generally leads to high molecular weight polymers, also with catalysts enabling easy chain transfer to Al like Hf-PyAm. This suggests that AlHAl has a low tendency to form heterodinuclear adducts with the cationic active species, therefore preventing the formation of dormant sites and/or termination events by chain transfer to Al. [ABSTRACT FROM AUTHOR]

In order to elucidate the dependence of the structure and reactivity of the bimetallic hydride intermediates formed in the systems metallocene—organoaluminum compound—activator on the nature of the transition metal atom and ligand environment, we used NMR spectroscopy to study reactions of a series of L2MCl2 complexes (M = Hf, Zr; L2 = Cp2, (CpMe)2, ansa-(Me2C)2Cp2, ansa-Me2CInd2) with HAlBui2 and MMAO-12 activator. As a result, M, Al-bimetallic intermediates containing [L2MH3] and [(L2M)2H3] type moieties were detected for both hafnium and zirconium complexes with cyclopentadienyl ligands. The [L2ZrH3] type structure predominates in the system based on the ansa-bis-indenyl zirconium complex. The detected complexes provide associates with MMAO-12 [L2MH3]·MAO and [(L2M)2H3]·MAO. The MAO-associated intermediates of the [(L2M)2H3] type are precursors of the catalytically active sites for alkene dimerization. In the system based on ansa-bis-indenyl zirconium complex, the intermediate of the [L2MH3] type affords a set of hydride structures, presumably cationic, which lead to alkene oligomerization. [ABSTRACT FROM AUTHOR]

The combination of different donor moieties often results in unconventional coordination behavior. This contribution describes the synthesis of a new hybrid ligand, phosphanylferrocene amidine Ph2PfcN=CHNMe2 (1; fc=ferrocene‐1,1′‐diyl), and its coordination behavior toward the light platinum metals. Reacting compound 1 with [PdCl2(MeCN)2] produced the chelate complex [PdCl2(1‐κ2P,N)] and the bis (phosphane) complex trans‐[PdCl2(1‐κP)2], depending on the ligand‐to‐metal stoichiometry. Halide removal from [PdCl2(1‐κ2P,N)] with Na[BARF] afforded the chloride‐bridged dimer [Pd2(μ‐Cl)2(1‐κ2P,N)2][BARF]2, which was presumably in equilibrium with the mononuclear κ3‐complex [PdCl(1‐κ3Fe,P,N)][BARF] in solution (BARF=tetrakis [3,5‐bis(trifluoromethyl)phenyl]borate). The reactions of 1 with the isoelectronic precursors [(arene)MCl(μ‐Cl)]2 (M/arene=Ru(II)/p‐cymene, and Rh(III)/C5Me5) generated the respective bridge‐cleavage products [(arene)MCl2(1‐κP)], which transformed into the P,N‐chelate complexes [(arene)MCl(1‐κ2P,N)][BARF] when treated with Na[BARF] as a chloride scavenger. All this suggests preferential coordination the phosphane moiety to soft metal ions, while the coordination of the amidine moiety can be induced through changing the reaction stoichiometry or by generating a vacant coordination site at the metal ion. The compounds were characterized using a combination of standard spectroscopic methods (multinuclear NMR, IR, and ESI MS) and single‐crystal X‐ray crystallography, and compounds 1 and 3 were further studied by cyclic voltammetry. [ABSTRACT FROM AUTHOR]

This study reports the heterogenization of metallocene catalysts on sodium dodecyl sulfate (DDS)‐modified layered double hydroxides (LDHs) for efficient ethylene–propylene (EP) slurry‐phase copolymerization. The LDH support offers considerable compositional tunability. NiFe LDHs with different anions (CO32−,NO3−,andDDS−${\mathrm{CO}}_3^{2 - },{\mathrm{\ NO}}_3^ - ,{\mathrm{\ and\ DDS}}^ - $) and metallic compositions are applied as support for the metallocene catalysts; these significantly influence the catalytic properties of the heterogenized catalyst system. The supported‐catalyst intercalating DDS− anion in the galleries of NiFe and ZnAl LDHs demonstrates a high catalytic activity. They produce EP copolymers with high molecular weights (Mw) and wide polydispersity, compared with the homogeneous Zr catalyst. Further, the supported catalyst complex containing CO32−${\mathrm{CO}}_3^{2 - }$ anion produces EP with a tenfold high Mw and demonstrate subdued catalytic activity. The higher basicity of the support is associated with the enhanced activity and the wider polydispersity of the EP pertaining to the different interactions of the catalyst molecule with the support. Overall, Ni‐containing LDH favors a higher activity, whereas Fe‐containing LDH favors a higher Mw. Therefore, NiFe‐based LDH results in both higher activity and molecular weight. 13C and 27Al magnetic angle spinning solid‐state nuclear magnetic resonance confirm the formation of the supported catalyst complex. [ABSTRACT FROM AUTHOR]

Dibenzyl zirconium(IV) complex (1), featuring an [OSSO]‐type bis(phenolate) ligand, served as a highly efficient pre‐catalyst for the polymerization of sterically bulky α‐olefins, such as vinyl cyclohexane (VCH) and 3‐methyl‐1‐butene (3‐MB). Upon activation with dried modified‐methylaluminoxane (dMMAO), the polymerization of VCH proceeded smoothly at 25°C to yield exclusively isotactic poly(VCH)s ([mm] >95%, Mw = 6500–19,400 g mol−1, PDI = 1.4), exhibiting good activity up to 924 g mmol(1)−1 h−1. The 1/dMMAO catalyst system also facilitated the polymerization of 3‐MB, producing colorless insoluble poly(3‐MB)s. DSC, TGA, and 13C CP‐MAS analyses showed the presence of highly isotactic microstructures in the resulting poly(3‐MB)s. Remarkably, the corresponding activity reached an impressive value of 898 g mmol(1)−1 h−1, surpassing that of previously reported homogeneous catalysts. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Recent decades have witnessed a rapid development of the lanthanide silicon chemistry. In this research, by reacting [(THF)3LiSiPh3] with Cp3Ln(III)(THF) (Ln(III) = Sm(III), Tb(III), Dy(III), Yb(III)) or Cp2Lu(III)Cl(THF), a series of middle‐ and heavy‐lanthanocene monosilyl/disilyl ate‐complexes ([(DME)3Li][Cp3Ln(III)SiPh3] and [(DME)3Li][Cp2Lu(III)(SiPh3)2]) were synthesized. The structures of the obtained lanthanocene monosilyl/disilyl ate‐complexes were determined by single crystal X‐ray diffraction. Together with the previously reported [(DME)3Li][Cp3La(III)SiPh3] and [(DME)3Li][Cp3Ce(III)SiPh3], a complex group comprising silyl light‐, middle‐ and heavy‐lanthanocene with identical core coordination pattern are presented. The structure analysis of this group of complexes showed that their key geometric parameters, including the Ln(III)–Si bond lengths and Ln(III)–Si–Cph/Cph–Si–Cph angles, were linearly correlated with the ionic radii of Ln(III) centers. Computational studies based on density functional theory calculations suggested the strongly polarized nature of the Ln(III)–Si bonds in these ate‐complexes. The UV‐Vis spectroscopy measurements of this group of ate‐complexes showed that the characteristic absorptions were hypsochromically shifted for complexes with heavier Ln(III) centers. In addition, as revealed by the time‐dependent density functional theory analysis, the HOMOs, in which the Ln(III)–Si σ‐bonding orbitals were the dominant components, of these complexes acted as main donor orbitals in the major electron transitions. [ABSTRACT FROM AUTHOR]

The present work describes the dynamic magnetic properties of the complex [(CpAr3)4Dy III2 Cl4K2]·3.5(C7H8) (1), synthesized by employing a tri-aryl-substituted cyclopentadienyl ligand (CpAr3), [4,4′-(4-phenylcyclopenta-1,3-diene-1,2-diyl)bis(methylbenzene) = CpAr3H]. Each Dy(III)-metallocene weakly couples via K2Cl4, displaying slow relaxation of magnetization below 14.5 K under zero applied dc field via KD3 energy levels with an energy barrier of 136.9/133.7 cm−1 on the Dy sites. The single-ion axial anisotropy energy barrier is reduced by geometrical distortion due to the coordination of two chloride ions at each Dy centre. [ABSTRACT FROM AUTHOR]

Metallocenes are privileged backbones in the fields of synthetic chemistry, catalysis, polymer science, etc. Direct C–H functionalization is undoubtedly the simplest approach for tuning the properties of metallocenes. However, owing to the presence of multiple identical C(sp2)‐H sites, this protocol often suffers from low reactivity and selectivity issues, especially for the regioselective synthesis of 1,3‐difunctionalized metallocenes. Herein, an efficient iridium‐catalyzed meta‐selective C–H borylation of metallocenes is reported. With no need of preinstalled directing groups, this approach enables a rapid synthesis of various boronic esters based on benzoferrocenes, ferrocenes, ruthenocene, and related half sandwich complex. A broad range of electron‐deficient and ‐rich functional groups are all compatible with the process. Notably, C–H borylation of benzoferrocenes takes place exclusively at the benzene ring, which is likely ascribed to the shielding effect of pentamethylcyclopentadiene. The synthetic utility is further demonstrated by easy scalability to gram quantities, the conversion of boron to heteroatoms including N3, SePh, and OAc, as well as diverse cross‐coupling reactions. [ABSTRACT FROM AUTHOR]

The Lewis base-supported uranium terminal imido metallocene [η5-1,2,4-(Me3Si)3C5H2]2UvN(p-tolyl) (dmap) (1) readily reacts with various small molecules such as internal alkynes, isothiocyanates, thioketones, amidates, organic nitriles and imines, chlorosilanes, copper iodide, diphenyl disulfide, organic azides and diazoalkane derivatives. For example, treatment of 1 with PhCuCCuCPh and PhNCS forms metallaheterocycles originating from a [2 + 2] cycloaddition to yield [η5-1-(p-tolyl)NC(Ph)vCHCvC(Ph) CH2Si(Me)2-2,4-(Me3Si)2C5H2][η5-1,2,4-(Me3Si)3C5H2]U (2) and [η5-1,2,4-(Me3Si)3C5H2]2U[N(p-tolyl)C (vNPh)S](dmap) (3), respectively. The reaction of 1 with the thioketone Ph2CS forms the known uranium sulfido complex [η5-1,2,4-(Me3Si)3C5H2]2US(dmap) (4), which reacts with a second molecule of Ph2CS to give the disulfido compound [η5-1,2,4-(Me3Si)3C5H2]2U(S2CPh2) (5). The imido moiety also promotes deprotonation reactions as illustrated in the reactions with the amide PhCONH(p-tolyl), the nitrile PhCH2CN and the imine (p-tolyl)2CvNH to form the bis-amidate [η5-1,2,4-(Me3Si)3C5H2]2U[OC(Ph)N(ptolyl)] 2 (7), and the iminato complexes [η5-1,2,4-(Me3Si)3C5H2]2U[N(p-tolyl)C(CH2Ph)vNH](NvCvCHPh) (8) and [η5-1,2,4-(Me3Si)3C5H2]2U[NH(p-tolyl)][NvC(p-tolyl)2] (9), respectively. Addition of PhSiH2Cl to 1 yields [η5-1,2,4-(Me3Si)3C5H2]2U(Cl)[N(p-tolyl)SiH2Ph] (10). In contrast, the uranium(V) imido complexes [η5-1,2,4-(Me3Si)3C5H2]2UvN(p-tolyl)(I) (11) and [η5-1,2,4-(Me3Si)3C5H2]2UvN(p-tolyl)(SPh) (12), may be isolated upon addition of CuI or Ph2S2 to 1, respectively. Uranium(VI) bis-imido metallocenes [η5-1,2,4-(Me3Si)3C5H2]2UvN(p-tolyl)(vNR) (R = p-tolyl (13), mesityl (14)) and [η5-1,2,4-(Me3Si)3C5H2]2UvN(ptolyl)[ vNNv(9-C13H8)] (15) are accessible from 1 on exposure to RN3 (R = p-tolyl, mesityl) and 9-diazofluorene, respectively. Complexes 2, 3, 5, and 7-15 were characterized by various spectroscopic techniques and, in addition, compounds 2, 3, 5, and 7-13 were structurally authenticated by single-crystal X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

Syndiotactic polystyrene (SPS) refers to a type of thermoplastic material with phenyl substituents that are alternately chirally attached on both sides of an aliphatic macromolecular main chain. Owing to its excellent physical and mechanical properties, as well as its chemical stability, high transparency, and electrical insulation characteristics, SPS is used in a wide variety of technical fields. SPS is commonly produced via the stereoselective transition metal-catalyzed coordination polymerization method mediated by stereospecific catalysts, which consists of anionic mono-cyclopentadienyl derivative η5-coordinated single active metal centers (referred to as "mono-Cp'-M"), with active center metals involving Group 4 transition metals (with an emphasis on titanium) and rare-earth (RE) metals of the periodic table. In this context, the use of mono-cyclopentadienyl titanocene (mono-Cp'Ti) catalysts and mono-cyclopentadienyl rare-earth metal (mono-Cp'RE) metallocene catalysts for the syndiospecific polymerization of styrene is discussed. The effects of the mono-cyclopentadienyl ligand structure, cationic active metal types, and cocatalysts on the activity and syndiospecificity of mono-Cp' metallocene catalysts are briefly surveyed. [ABSTRACT FROM AUTHOR]

Metallocenes are highly versatile organometallic compounds. The versatility of the metallocenes stems from their ability to stabilize a wide range of formal electron counts. To date, d-block metallocenes with an electron count of up to 20 have been synthesized and utilized in catalysis, sensing, and other fields. However, d-block metallocenes with more than formal 20-electron counts have remained elusive. The synthesis and isolation of such complexes are challenging because the metal–carbon bonds in d-block metallocenes become weaker with increasing deviation from the stable 18-electron configuration. Here, we report the synthesis, isolation, and characterization of a 21-electron cobaltocene derivative. This discovery is based on the ligand design that allows the coordination of an electron pair donor to a 19-electron cobaltocene derivative while maintaining the cobalt–carbon bonds, a previously unexplored synthetic approach. Furthermore, we elucidate the origin of the stability, redox chemistry, and spin state of the 21-electron complex. This study reveals a synthetic method, structure, chemical bonding, and properties of the 21-electron metallocene derivative that expands our conceptual understanding of d-block metallocene chemistry. We expect that this report will open up previously unexplored synthetic possibilities in d-block transition metal chemistry, including the fields of catalysis and materials chemistry. The synthesis and isolation of d-block metallocenes with more than 18-electron is challenging since metal–carbon bonds become weaker with increasing deviation from the 18-electron configuration. Here the authors report a formal 21-electron cobaltocene derivative by coordination of a two-electron donor to a 19-electron cobaltocene derivative while maintaining the cobalt-carbon bonds. [ABSTRACT FROM AUTHOR]

The deconvolution of the molecular weight distribution (MWD) of polyolefins into Schultz–Flory most probable distributions has become the standard method to identify the number of site types on multiple‐site‐type olefin polymerization catalysts such as Ziegler–Natta, Phillips, and some supported metallocenes. This method has been used to quantify the effect of polymerization conditions and catalyst formulations on polyolefin MWD and olefin polymerization kinetics. Related methods have also been developed to deconvolute other polyolefin microstructure features, such as the chemical composition and comonomer sequence length distributions. In this paper, I explain the premises behind these deconvolution models and review the publications in this area, highlighting the advantages, disadvantages, and misuses of these methods. I also propose a revised formulation on how to model the MWD of polyolefins made with multiple‐site‐type catalysts using ratio distributions for propagation and chain transfer frequencies. The main objective of this overview article is to highlight the strengths, but also show the pitfalls, of polyolefin microstructure deconvolution methods. [ABSTRACT FROM AUTHOR]

Benzene‐1,2,4,5‐tetrathiolate (btt) has been used as a bridging ligand to prepare a redox active (molybdenocene dithiolene)‐based bimetallic complex Cp2Mo(btt)MoCp2, which exhibits four successive electron transfers up to the tetracation. Spectro‐electrochemical investigations together with DFT and TD‐DFT calculations evidence that the two electroactive MoS2C2 metallacycles are electronically coupled in the monocationic as in the dicationic state. Two salts of the dication [Cp2Mo(btt)MoCp2]2+ have been structurally characterized with PF6− and HSO4− counterions, showing different chair or boat conformations associated with variable folding angles of the two MoS2C2 metallacycles along the S−S hinge. The bis‐oxidized dicationic complex exhibits a diradical character, with both radicals essentially localized on the metallacycles and with antiferromagnetic coupling evidenced from magnetic susceptibility measurements. [ABSTRACT FROM AUTHOR]

Altering the donor properties of phosphane ligands through substituent variation is an established tool in coordination chemistry and catalysis. This contribution describes the synthesis of two new hybrid donors (L) combining 1,3,5,7‐tetramethyl‐2,4,6‐trioxa‐8‐phosphaadamantane‐8‐yl (PCg) and nitrile donor groups at different molecular scaffolds, viz. ferrocene‐1,1′‐diyl (fc) and 1,2‐phenylene. These ligands were used to prepare dimeric Au(I) complexes [Au2(μ(P,N)‐L)2][SbF6]2, which were evaluated as silver‐free, preformed catalysts in Au‐mediated cycloisomerization of (Z)‐3‐methylpent‐2‐en‐4‐yn‐1‐ol to 2,3‐dimethylfuran. The catalyst featuring the ferrocene‐based ligand, viz. [Au2(μ(P,N)‐CgPfcCN)2][SbF6]2, showed the best catalytic performance at low catalyst loading (0.5 or 0.15 mol.%), which exceeded that of its diphenylphosphanyl analog [Au2(μ(P,N)‐Ph2PfcCN)2][SbF6]2 studied earlier and the prototypical Au(I) precatalyst [Au(PPh3)(MeCN)][SbF6]. [ABSTRACT FROM AUTHOR]

The strategy of modifying phosphane ligands through substituent variation has been widely applied in coordination chemistry and catalysis. This contribution focuses on unsymmetric ferrocene diphosphanes with electronically distinct phosphane moieties, Ph2PfcCH2PAr2 (Ar=Ph, 1; 3,5‐C6H3Me2, 2; and 3,5‐C6H3(CF3)2, 3; fc=ferrocene‐1,1′‐diyl), which were synthesized and converted to the corresponding selenides (1Se–3Se) and Pd(0) complexes [Pd(L‐κ2P,P′)(η2‐ma)] (5–8 for L=1–3 and dppf, ma=maleic anhydride). All compounds were characterized by NMR spectroscopy, ESI MS and elemental analysis, and the structures of 2, 1Se ⋅ CHCl3, 2Se and 5 ⋅ PhMe were determined by X‐ray diffraction analysis. In addition, the redox behavior of 1–3 and 5–8 was studied by cyclic voltammetry and rationalized through DFT calculations. The prepared Pd(0) complexes and their model compound [Pd(dppf‐κ2P,P′)(η2‐ma)] were employed in Pd‐catalyzed C−H arylation of benzoxazole with chlorobenzene in n‐butanol in the presence of K3PO4 as the base, and the catalytic results were compared with the collected characterization data, including the 1JPSe coupling constants determined for 1Se–3Se, as a measure of ligand basicity. [ABSTRACT FROM AUTHOR]

A detailed mathematical model of the propylene‐1‐hexene copolymerization based on the two‐dimensional probability generation function technique is developed. It calculates the joint molecular weight‐copolymer composition distribution (MWD‐CCD) of the copolymer, as well as the average copolymer composition distribution, the molecular weight distribution (MWD), the copolymer composition distribution (CCD), average molecular weights and composition, and yield. The parallelized execution of the model code allows for obtaining the different copolymer microstructure distributions efficiently. The model allows for reaching a thorough understanding of the copolymer microstructure under different operating conditions of a semibatch reactor. It also has the potential to become a powerful tool for selecting operating conditions to obtain a material with target molecular properties. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are salts with low melting points and are useful as electrolytes and solvents. We have developed ILs containing cationic metal complexes, which form a family of functional liquids that exhibit unique physical properties and chemical reactivities originating from metal complexes. Our study explores the liquid chemistry in the field of coordination chemistry, where solid‐state chemistry is currently the main focus. This review describes the molecular design, physical properties, and reactivities of organometallic ILs containing sandwich or half‐sandwich complexes. This paper mainly covers stimuli‐responsive ILs, whose magnetic properties, solvent polarities, colors, or structures change by the application of external fields, such as light, heat, and magnetic fields, or by reaction with coordinating molecules. [ABSTRACT FROM AUTHOR]

Modern industry of advanced polyolefins extensively uses Group 4 metallocene and post-metallocene catalysts. High-throughput polyolefin technologies demand the use of heterogeneous catalysts with a given particle size and morphology, high thermal stability, and controlled productivity. Conventional Group 4 metal single-site heterogeneous catalysts require the use of high-cost methylalumoxane (MAO) or perfluoroaryl borate activators. However, a number of inorganic phases, containing highly acidic Lewis and Brønsted sites, are able to activate Group 4 metal pre-catalysts using low-cost and affordable alkylaluminums. In the present review, we gathered comprehensive information on MAO- and borate-free activating supports of different types and discussed the surface nature and chemistry of these phases, examples of their use in the polymerization of ethylene and α-olefins, and prospects of the further development for applications in the polyolefin industry. [ABSTRACT FROM AUTHOR]

Ferrocene‐based N‐heterocyclic plumbylenes fc[(NSiMe2R)2Pb:] (1; fc=1,1'‐ferrocenylene) are easily accessible by transamination from [(Me3Si)2N]2Pb and the corresponding 1,1'‐diaminoferrocene derivatives fc(NHSiMe2R)2. They may form unconventional dimers 2 by a process, which causes the cleavage of a cyclopentadienyl C−H bond and the formation of a Pb−C and an N−H bond. The monomer‐dimer equilibrium (2 1⇆2) has been addressed experimentally and computationally. It critically depends on the steric demand of the N‐substituents SiMe2R, which has been varied systematically by using homologues with aliphatic (R=methyl, ethyl, isopropyl, tert‐butyl) and aromatic units (R=phenyl, mesityl, ferrocenyl). Even in the sterically least congested case (R=methyl), dimerization is only slightly exergonic. It eventually becomes prohibitively endergonic with increasingly larger substituents and is thus not observed for R=tert‐butyl, mesityl, and ferrocenyl. R=phenyl represents a borderline case, where the dimer is still detectable in the equilibrium mixture, albeit as a very minor component, in accord with the slightly endergonic Gibbs free energy change calculated for its formation. Addition of 4‐dimethylaminopyridine (DMAP) to the monomer‐dimer equilibrium mixtures cleanly affords the corresponding adducts [1(DMAP)], irrespective of the equilibrium composition. [ABSTRACT FROM AUTHOR]

Since the discovery in the early 1980s, the soluble divalent metallocenes of lanthanides have become a steadily growing field in organometallic chemistry. The predominant part of the investigation has been performed with samarium, europium, and ytterbium, whereas only a few reports dealing with other rare earth elements were disclosed. Reactions of these metallocenes can be divided into two major categories: (1) formation of Lewis acid–base complexes, in which the oxidation state remains +II; and (2) single electron transfer (SET) reductions with the ultimate formation of Ln(III) complexes. Due to the increasing reducing character from Eu(II) over Yb(II) to Sm(II), the plethora of literature concerning redox reactions revolves around the metallocenes of Sm and Yb. In addition, a few reactivity studies on Nd(II), Dy(II) and mainly Tm(II) metallocenes were published. These compounds are even stronger reducing agents but significantly more difficult to handle. In most cases, the metals are ligated by the versatile pentamethylcyclopentadienyl ligand: (C5Me5). Other cyclopentadienyl ligands are fully covered but only discussed in detail, if the ligand causes differences in synthesis or reactivity. Thus, the focus lays on three compounds: [(C5Me5)2Sm], [(C5Me5)2Eu] and [(C5Me5)2Yb] and their solvates. We discuss the synthesis and physical properties of divalent lanthanide metallocenes first, followed by an overview of the reactivity rendering the full potential of these versatile reactants. [ABSTRACT FROM AUTHOR]

The incorporation of fluorinated substituents in cyclopentadienyl anions leads to distinct changes in the properties of the corresponding metal complexes, e.g., with regards to electrochemical properties or metal–ligand bonding energies. This review summarizes the synthetic challenges of the preparation and coordination of fluorinated cyclopentadienyl anions. 1 Introduction 2 Fluorinated Cyclopentadienyls 3 Cyclopentadienyls with One CF3 Group 4 Cyclopentadienyls with Four CF3 Groups 5 Cyclopentadienyls with Five CF3 Groups 6 Cyclopentadienyls with 'Fluorous Ponytails' 7 Cyclopentadienyls with C6 F5 Groups 8 Trends in Interaction Energies 9 Conclusion [ABSTRACT FROM AUTHOR]

The benzene ligand at CpV(η6--C6H6) (1) is exchanged for pentafulvenes. Using sterically demanding pentafulvenes gives a clean exchange reaction, yielding vanadium pentafulvene (2a and 2b) and benzofulvene complexes (3a and 3b). The molecular structures of the target compounds suggest a π-η5:σ-η¹ coordination mode with a vanadiumIII center. With the sterically low demanding 6,6-dimethylpentafulvene, a C--H activation at the leaving ligand is observed, yielding the ring-substituted vanadoceneII 4. The reactivity of the pentafulvene complexes was investigated. A series of unprecedented vanadoceneIII compounds were synthesized: Under mild conditions, E--H splitting of 4- tert-butylphenol, diphenylamine, and 2,6-diisopropylaniline yield well characterized examples of rare vanadoceneIII phenolate and amide complexes. Insertion reactions into the V--Cexo bond of the pentafulvene complexes by multiple bond containing substrates were found for acetone, 4-chlorobenzonitril and N,N'-dicyclohexylcarbodiimide. [ABSTRACT FROM AUTHOR]

Reactions of 1,3,5-trimethyl-triazacyclohexane (Me3tach) with common rare-earth metal iodide, chloride, and triflate salts were examined to determine the capacity of this inexpensive chelate to provide alternative precursors for THF-free reactions. The reaction of LaI3(THF)4 and CeI3(THF)4 with 1,3,5-trimethyl-triazacyclohexane in THF generated toluene soluble (Me3tach)2LnI3, 1-Ln, in which the Ln center has a tri-capped trigonal prismatic geometry with two eclipsed Me3tach rings. Reaction with NdI3(THF)3.5 forms the analogous 1-Nd, but a different structure with one outer sphere iodide, [(Me3tach)2NdI2][I], 2-Nd, is also accessible and has a structure reminiscent of bent metallocenes. The reaction of LaCl3 and Me3tach forms the less soluble (Me3tach)2LaCl3, which has a structure analogous to 1-Ln with eclipsed Me3tach rings. The mono-ring yttrium complex, (Me3tach)YCl3(THF)2, could be isolated from the reaction of YCl3 with Me3tach. Reactions of La(OTf)3 with Me3tach were sensitive to the presence of residual proton sources as exemplified by the isolation of {[(Me3tach)La(μ-OH)(μ-OTf)]2(μ-OTf)2}2, 5-La, and [HMe3tach][(Me3tach)2La-(OTf)4], 6-La. SmI2 reacts with Me3tach to produce the Sm(II) complex, (Me3tach)2SmI2(THF), 7-Sm, but 2-Sm can also form in this reaction. Complexes of the larger 1,4,7-trimethyltriazacyclononane (Me3tacn) ligand, namely (Me3tacn)LaI3(THF), (Me3tacn)YCl3, and (Me3tacn)SmI2(THF) were synthesized for comparison. Several examples of the protonated ligands with simple counteranions, [HMe3tach][X] (X = Cl, Br, I) and [HMe3tacn][OTf], were identified in the course of these studies. [ABSTRACT FROM AUTHOR]

To understand the synergistic catalytic effect on the thermal degradation of Ammonium Perchlorate (AP) when the metal fragments are in the same molecule or not, we compared three reported compounds: [(Cp*)2Ni] (1), [(Cp*)2Ru] (2), and [Cp*Ni-s-Ic'-RuCp*] (3), as potential burning rate catalysts. We conducted a differential scanning calorimetry (DSC) analysis of compound (3), which showed an increase in the high-temperature decomposition (HTD) of AP to 418 °C and a decrease in the energy release to 938 J·g-1. These results were compared to those of the different metallocenes, namely (1) (HTD: 434 °C and 1300 J·g-1), (2) (HTD: 361 °C and 1828 J·g-1), and the mixture of (1+2) (HTD: 354 °C and 2054 J·g-1). Our results suggest that the mixture of metallocenes is a suitable and competitive alternative to be used as an enhancer of solid composite propellants. In addition, cyclic voltammetry is used to investigate the electrochemical processes of compounds (1), (2), and (3). The electrochemically active species exhibit noteworthy oxidation peaks, revealing electronic communication between the three different compounds in the cases of (1), (2), and (3), as evidenced by the results obtained from the analysis. [ABSTRACT FROM AUTHOR]

With the progression in the field of bioinorganic chemistry, the role of transition metal complexes as the most widely used therapeutics is becoming a more and more attractive research area. The complexes of transition metals possess a great variety of attractive pharmacological properties, including anticancer, anti-inflammatory, antioxidant, anti-infective, etc., activities. Transition metal complexes have proven to be potential alternatives to biologically active organic compounds, especially as antitumor agents. The performance of metal coordination compounds in living systems is anticipated to differ generally from the action of non-metal-containing drugs and may offer unique diagnostic and/or therapeutic opportunities. In this review, the rapid development and application of metallocenes and metal complexes of elements from Groups 4 to 7 in cancer diagnostics and therapy have been summarized. Most of the heavy metals discussed in the current review are newly discovered metals. That is why the use of their metal-based compounds has attracted a lot of attention concerning their organometallic and coordination chemistry. All of this imposes more systematic studies on their biological activity, biocompatibility, and toxicity and presupposes further investigations.