Cationic Complexes Research Articles

Synthesis, Structural, and Quantum Chemical Analysis of Neutral and Cationic Ruthenium(II) Complexes with Nicotinate-Polyethylene Glycol Ester Ligands

Ruthenium(II/III)-based compounds have gained significant interest due to the biocompatibility of ruthenium, its similarity to iron, and the possibility for structural diversification through the choice of ligands. In this contribution, two novel ligands, (2-(2-methoxyethoxy)ethyl nicotinate hydrochloride) and (2-[2-(2-methoxyethoxy)ethoxy]ethyl nicotinate hydrochloride) (pyCOO(CH2CH2O)nCH3: L2, n = 2; L3, n = 3), were synthesized and characterized via ESI-HRMS, as well as IR and NMR spectroscopies. Their structures were optimized at the B3LYP/6-311++G(d,p) level of theory, and NMR chemical shifts were predicted, along with the most important intramolecular interactions. Additionally, two neutral complexes of the general formula [RuCl2(η6-p-cym) (L-κN)] (L = L2: 2; L3: 3) and two cationic complexes of the general formula [RuCl(η6-p-cym)(L-κN)2][PF6] (L = L1: 4; L2: 5) were obtained and characterized. The optimization of the structures was performed at the B3LYP/6-31+G(d,p)(H,C,N,O,Cl)/LanL2DZ(Ru) level of theory. Structural features were described, and intramolecular stabilization interactions were outlined.

Palladium and platinum complexes of primary 2-pyridinethioamide

Primary thioamide, 2-pyridinethioamide reacts with palladium and platinum compounds K2PdCl4, K2PtCl4 and Pd(CH3COO)2 to give the products [PdCl2(2-pyridinethioamide)].2DMF (1), [PtCl2(2-pyridinethioamide)] (2a), [Pd(2-pyridinethioamide)2]Cl2 (3), [Pt(2-pyridinethioamide)2]Cl2 (4) and [Pd(2-pyridinethioamidinate)2] (5), respectively. The structures 1, [PtCl(DMSO)(2-pyridinethioamidinate)] (2b), which was obtained from crystallization of 2a in DMSO, 4 and 5 were determined by X-ray crystallography. Compound 3 was spectroscopically analyzed and found to have a structure similar to that of 4. The ligand coordinates in a neutral form in complexes 1, 2a, 3 and 4, but in 2b and 5 it exists in a deprotonated form. Compounds 3 and 4 are cationic complexes with Cl− counterions in the structure. The ligand prefers coordination as the bidentate N(py),S-mode in all the crystallized compounds. In the bis-chelates, the sulfur and the nitrogen atoms are mutually trans-located. Computational DFT calculations and topological charge density analysis were utilized to clarify the coordination modes and to interpret the spectral information.

Investigations into the AuI and PtII Coordination Chemistry of Bidentate “cis‐Spanning” Ligands

AbstractThe novel bidentate PP and PN ligands o‐(Ph2P)−C6H4−C≡C−PPh2 (LPP) and o‐(Ph2P)−C6H4−4−(C5H9N−Me) (LPN), respectively, have been designed as long‐range “cis‐spanning“ ligands for the stabilization of heterodinuclear complexes containing two metal atoms in close proximity. The synthesis of heterodinuclear, formal AuIPtII complexes with the ligand LPP is straightforward. In the course of a one‐pot reaction, a surprisingly high selectivity for the coordination of AuCl and Pt(CNC) (CNC=2,6‐diphenylpyridine‐o,o’‐diate) to the phenyl‐bound and the alkyne‐bound PPh2 sites of LPP is observed, respectively. Chloride abstraction from the resulting heterodinuclear complex [(ClAu)(o‐Ph2P)−C6H4−C≡C−PPh2(Pt{CNC})] with Ag[SbF6] causes metal–metal bond formation and the generation of the cationic complex [LPPAuPt(CNC)][SbF6]. The high site selectivity for the coordination of the two metals to LPP was investigated by stoichiometric reactions of the ligand with one equivalent of the corresponding precursors. While analogous complexation experiments with LPN have not been successful, the synthesis of the heterodinuclear complex [(ClAu)(o‐Ph2P)−C6H4−4‐(C5H9N−Me)(PtCl2{dmso})] and of [LPN(AuCl)2] confirm the ability of LPN to serve as a ditopic ligand. In this context, it is noteworthy that [LPN(AuCl)2] constitutes the first amine–AuCl complex featuring a tertiary amine.

Honey-like Odor Meets Single-Ion Magnet: Synthesis, Crystal Structure, and Magnetism of Cobalt(II) Complex with Aromatic Trans-Cinnamic Acid

The hexacoordinate Co(II) complex [Co(neo)2(cin)][BPh4]·½Me2CO (1·½Me2CO) containing trans-cinnamic acid (Hcin) and neocuproine (neo) was prepared. The compound 1·½Me2CO was characterized via single-crystal X-ray analysis, FT-IR spectroscopy, and magnetic measurements. The coordination polyhedron of the complex cation adopts a deformed octahedron shape, and cinnamate exhibits a bidentate mode of coordination, which is unusual for mononuclear Co(II) cinnamate complexes. The analysis of DC magnetic measurements with zero-field splitting (ZFS) spin Hamiltonian revealed large magnetic anisotropy defined by the axial ZFS parameter D = +53.2 cm−1. AC susceptibility measurements revealed the slow relaxation of magnetization under the applied field; thus, 1·½Me2CO behaves as a field-induced single-molecule magnet. The analysis of magnetic properties was also supported by CASSCF/NEVPT2 calculations.

Binding Properties of Small Electrophilic Anions [B6 X5 ]- and [B10 X9 ]- (X=Cl, Br, I): Activation of Small Molecules Based on π-Backbonding.

Superelectrophilic anions constitute a special class of molecular anions that show strong binding of weak nucleophiles despite their negative charge. In this study, the binding characteristics of smaller gaseous electrophilic anions of the types [B6 X5 ]- and [B10 X9 ]- (with X=Cl, Br, I) were computationally and experimentally investigated and compared to those of the larger analogues [B12 X11 ]- . The positive charge of vacant boron increases from [B6 X5 ]- via [B10 X9 ]- to [B12 X11 ]- , as evidenced by increasing attachment enthalpies towards typical σ-donor molecules (noble gases, H2 O). However, this behavior is reversed for σ-donor-π-acceptor molecules. [B6 Cl5 ]- binds most strongly to N2 and CO, even more strongly than to H2 O. Energy decomposition analysis confirms that the orbital interaction is responsible for this opposite trend. The extended transition state natural orbitals for chemical valence method shows that the π-backdonation order is [B6 X5 ]- >[B10 X9 ]- >[B12 X11 ]- . This predicted order explains the experimentally observed red shifts of the CO and N2 stretching fundamentals compared to those of the unbound molecules, as measured by infrared photodissociation spectroscopy. The strongest red shift is observed for [B6 Cl5 N2 ]- : 222 cm-1 . Therefore, strong activation of unreactive σ-donor-π-acceptor molecules (commonly observed for cationic transition metal complexes) is achieved with metal-free molecular anions.

Cationic Rhodium Diphosphane Complexes as Efficient Catalysts for the Semi‐Hydrogenation of Dehydroisophytol

AbstractThe selective reduction of terminal alkynes to alkenes was investigated using common cationic diphosphane rhodium complexes of the type [Rh(PP)(diolefin)]X (PP=diphosphane, X=anion). The effectiveness of the catalyst was demonstrated in the semi‐hydrogenation of dehydroisophytol (DIP), an industrial produced intermediate of vitamin E. The present study highlights the high activity and good selectivity of this simple catalytic system. However, deactivation increases at higher DIP concentrations. Several strategies to circumvent the deactivation are presented.

Possible Roles of Transition Metal Cations in the Formation of Interstellar Benzene via Catalytic Acetylene Cyclotrimerization.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous interstellar molecules. However, the formation mechanisms of PAHs and even the simplest cyclic aromatic hydrocarbon, benzene, are not yet fully understood. Recently, we reported the statistical and dynamical properties in the reaction mechanism of Fe+-catalyzed acetylene cyclotrimerization, whereby three acetylene molecules are directly converted to benzene. In this study, we extended our previous work and explored the possible role of the complex of other 3d transition metal cations, TM+ (TM = Sc, Ti, Mn, Co, and Ni), as a catalyst in acetylene cyclotrimerization. Potential energy profiles for bare TM+-catalyst (TM = Sc and Ti), for TM+NC--catalyst (TM = Sc, Ti, Mn, Co, and Ni), and for TM+-(H2O)8-catalyst (TM = Sc and Ti) systems were obtained using quantum chemistry calculations, including the density functional theory levels. The calculation results show that the scandium and titanium cations act as efficient catalysts in acetylene cyclotrimerization and that reactants, which contain an isolated acetylene and (C2H2)2 bound to a bare (ligated) TM cation (TM = Sc and Ti), can be converted into a benzene-metal-cation product complex without an entrance barrier. We found that the number of electrons in the 3d orbitals of the transition metal cation significantly contributes to the catalytic efficiency in the acetylene cyclotrimerization process. On-the-fly Born-Oppenheimer molecular dynamics (BOMD) simulations of the Ti+-NC- and Ti+-(H2O)8 complexes were also performed to comprehensively understand the nuclear dynamics of the reactions. The computational results suggest that interstellar benzene can be produced via acetylene cyclotrimerization reactions catalyzed by transition metal cation complexes.

Enhancing the Cation-Binding Ability of Fluorescent Calixarene Derivatives: Structural, Thermodynamic, and Computational Studies.

Novel fluorescent calix[4]arene derivatives L1 and L2 were synthesized by introducing phenanthridine moieties at the lower calixarene rim, whereby phenanthridine groups served as fluorescent probes and for cation coordination. To enhance the cation-binding ability of the ligands, besides phenanthridines, tertiary-amide or ester functionalities were also introduced in the cation-binding site. Complexation of the prepared compounds with alkali metal cations in acetonitrile (MeCN), methanol (MeOH), ethanol (EtOH), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) was investigated at 25 °C experimentally (UV spectrophotometry, fluorimetry, microcalorimetry, and in the solid state by X-ray crystallography) and by means of computational techniques (classical molecular dynamics and DFT calculations). The thermodynamic parameters (equilibrium constants and derived standard reaction Gibbs energies, reaction enthalpies, and entropies) of the corresponding reactions were determined. The tertiary-amide-based compound L1 was found to have a much higher affinity toward cations compared to ester derivative L2, whereby the stabilities of the ML1+ and ML2+ complexes were quite solvent-dependent. The stability decreased in the solvent order: MeCN ≫ EtOH > MeOH > DMF > DMSO, which could be explained by taking into account the differences in the solvation of the ligands as well as free and complexed alkali metal cations in the solvents used. The obtained thermodynamic quantities were thoroughly discussed regarding the structural characteristics of the studied compounds, as well as the solvation abilities of the solvents examined. Molecular and crystal structures of acetonitrile and water solvates of L1 and its sodium complex were determined by single-crystal X-ray diffraction. The results of computational studies provided additional insight into the L1 and L2 complexation properties and structures of the ligands and their cation complexes.

Sorption Properties of Cobalt-Rich Ferromanganese Crusts of the Kotzebue Guyot of the Magellanic Mountains Relative to Cations of Rare Earth Metals

The article presents the results of experimental studies of the sorption properties of ferromanganese crusts (CMC) of Kotzebue guyot relative to rare earth metal cations (REM). It is established that the crusts are a natural highly selective sorbent of REM cations. The sorption of REM cations occurs on ore minerals ‒ Fe-vernadite, vernadite, Mn-feroxigite, goethite. The crusts are characterized by a high exchange capacity – 1.67‒3.28 mg-eq/g, which increases in the series: Lu Gd Dy La, Sm Nd Y Eu) ⪡ Ce. Absorption of REM cations proceeds by an ion-exchange equivalent mechanism, in the case of Ce3+ cations ‒ according to the superequivalent mechanism with respect to the cations of the exchange complex of ore minerals ‒ Na+, K+, Ca2+, Mg2+, Mn2+, Ni2+, which contribute 95–98% to the total capacity of minerals.

Transformation of Acetylene to Ethenylidene, Carbene, Acetylide, Vinyl, and Olefin Groups with Cp*Fe(1,2-Cy2PC6H4S).

Tautomerization of C2H2 at half-sandwich compound Cp*Fe(1,2-Cy2PC6H4S) exclusively produces an iron ethenylidene, Cp*Fe(=C=CH2)(1,2-Cy2PC6H4S) (2). Protonation of the ethenylidene causes nucleophilic attack of the Cα by sulfur, affording a sulfur-tethered carbene complex, [Cp*Fe=C(CH3)SC6H4PCy2]+ (3+). This Fischer-type carbene complex undergoes an unusual isomerization by migrating a hydrogen atom from the β-CH3 group to the α-C, leading to the formation of an olefin complex [Cp*Fe(η4-CH=CH2SC6H4PCy2]+ (4+). Compound 2 also displays diverse redox reactivities. It transforms to a neutral acetylide ferric complex (5) when reacting with free radical scavengers and to a cationic vinyl complex [Cp*Fe(η3-C(=CH2)SC6H4PCy2]+ (6+) upon 1e- oxidation. The interconversion between the vinyl and acetylide complexes can be realized through protonation/deprotonation reactions.

Cationic cluster complex [{Mo6I8}(H2O)4(OH)2]2+ with diphenyl phosphate anions: Structure and optical properties behavior

The interaction of an aqueous solution of the cluster complex [{Mo6I8}(H2O)4(OH)2](NO3)2 with an excess of diphenyl phosphoric acid in ethanol leads to the formation of a light orange insoluble crystalline product. According to the single-crystal X-ray diffraction analysis, the crystals obtained have the composition [{Mo6I8}(H2O)4(OH)2]((PhO)2PO2)2·6H2O·2EtOH·2(PhO)2PO2H. The inclusion of such large molecules as diphenyl phosphate into the structure leads to a dramatic decrease in the packing density of cluster fragments. The study of the optical properties of the obtained compound showed that such a decrease in the density leads to a decrease in absorption and a hypsochromic shift of the absorption edge. At the same time, there is a significant increase in the luminescence intensity accompanied by a blueshift of the emission maximum in comparison with the initial compound and other related clusters.

A Simple and Versatile Strategy for Oriented Immobilization of His-Tagged Proteins on Magnetic Nanoparticles.

Oriented and covalent immobilization of proteins on magnetic nanoparticles (MNPs) is particularly challenging as it requires both the functionality of the protein and the colloidal stability of the MNPs to be preserved. Here, we describe a simple, straightforward, and efficient strategy for MNP functionalization with proteins using metal affinity binding. Our method involves a single-step process where MNPs are functionalized using a preformed, ready-to-use nitrilotriacetic acid-divalent metal cation (NTA-M2+) complex and polyethylene glycol (PEG) molecules. As a proof-of-concept, we demonstrate the oriented immobilization of a recombinant cadherin fragment engineered with a hexahistidine tag (6His-tag) onto the MNPs. Our developed methodology is simple and direct, enabling the oriented bioconjugation of His-tagged cadherins to MNPs while preserving protein functionality and the colloidal stability of the MNPs, and could be extended to other proteins expressing a polyhistidine tag. When compared to the traditional method where NTA is first conjugated to the MNPs and afterward free metal ions are added to form the complex, this novel strategy results in a higher functionalization efficiency while avoiding MNP aggregation. Additionally, our method allows for covalent bonding of the cadherin fragments to the MNP surface while preserving functionality, making it highly versatile. Finally, our strategy not only ensures the correct orientation of the protein fragments on the MNPs but also allows for the precise control of their density. This feature enables the selective targeting of E-cadherin-expressing cells only when MNPs are decorated with a high density of cadherin fragments.

Stabilization of Cyclic C4 by Four Donor Ligands: A Theoretical Study of (L)4C4 (L = Carbene).

Quantum chemical studies using density functional theory were carried out for the (L)4C4 complexes with L = cAAC, DAC, NHC, SNHC, MIC1, and MIC2. The results show that the title complexes are highly stable with respect to dissociation, (L)4C4 → C4 + 4L. However, their stability with respect to (L)4C4 → 2(L)2C2 is crucial for the assessment of their experimental viability. The (L)4C4 complexes with L = cAAC and DAC dissociate exergonically at room temperature into two (L)2C2 units. In contrast, the other (L)4C4 complexes with L = NHC, SNHC, MIC1, and MIC2 are thermochemically stable with respect to dissociation, (L)4C4 → 2(L)2C2. The computed adiabatic ionization potentials of (L)4C4 complexes with L = NHC, MIC1, and MIC2 are lower than those for the cesium atom. Particularly, (MIC1)4C4 and (MIC2)4C4 will very easily lose electrons to form cationic complexes. The SNHC ligand is the best for the experimental realization of (L)4C4 complexes, followed by NHC. The bonding analysis using charge and energy decomposition methods suggests that the (L)3C4-CL bond can be best described as a typical electron-sharing double bond with a strong σ-bond and a weaker π-bond. Therefore, the core bonding pictures in the title complexes resemble a [4]radialene. Larger substituents at the carbene ligands enhance the stability of the complexes (L)4C4 against dissociation.

Bis(N-Heterocyclic Carbene) Manganese(I) Complexes in Catalytic N-Formylation/N-Methylation of Amines Using Carbon Dioxide and Phenylsilane.

A series of six Mn(I) complexes with general formula [MnBr(bisNHC)(CO)3 ], having a bidentate bis(N-heterocyclic carbene) ligand (bisNHC), has been developed by varying the bridging group between the NHC donors, the nitrogen wingtip substituents and the heterocyclic ring. The synthesis of the complexes has been accomplished by in situ transmetalation of the bisNHC from the corresponding silver(I) complexes. Removal of the bromide anion affords the corresponding solvento complexes [Mn(bisNHC)(CO)3 (CH3 CN)](BF4 ). The influence of the bisNHC structure on its electron donor ability has been evaluated by FTIR and 13 C NMR spectroscopy, both in the neutral and cationic complexes. Finally, the isolated Mn(I)-bisNHC complexes have been employed as homogeneous catalysts in the reductive N-formylation and N-methylation of amines with CO2 as C1 source and phenylsilane as reducing agent, showing a high selectivity for the N-methylated product. Preliminary mechanistic investigations suggest that, in the adopted reaction conditions, the formylated product can be formed via different reaction pathways, either metal-catalyzed or not, while the methylation reaction requires the use of the Mn(I) catalyst.

Halogen Bonding and/or Covalent Bond: Analogy of 3c-4e N···I···X (X = Cl, Br, I, and N) Interactions in Neutral, Cationic, and Anionic Complexes.

X-ray structural measurements and computational analysis demonstrated the similarity of the geometries and electronic structures of the X-I···N (X = Cl, Br, I, and N) bonding in strong halogen-bonded (HaB) complexes and in the anionic or cationic halonium ions. In particular, I···N bond lengths in the solid-state associations formed by strong HaB donors (e.g., I2, IBr, ICl, and N-iodosuccinimide) and acceptors (e.g., quinuclidine or pyridines) were in the same range of 2.3 ± 0.1 Å as those in the halonium ions [e.g., the bis(quinuclidine)iodonium cation or the 1,1'-iodanylbis(pyrrolidine-2,5-dione) anion]. In all cases, bond lengths were much closer to those of the N-I covalent bond than to the van der Waals separations of these atoms. The strong N···I bonding in the HaB complexes led to a substantial charge transfer, lengthening and weakening of the I···X bonds, and polarization of the HaB donors. As a result, the central iodine atoms in the strong HaB complexes bear partial positive charges akin to those in the halonium ions. The energies and Mayer bond orders for both N···I and I···X bonds in such associations are also comparable to those in the halonium ions. The similarity of the bonding in such complexes and in halonium ions was further supported by the analysis of electron densities and energies at bond critical (3, -1) points in the framework of the quantum theory of atoms in molecules and by the density overlap region indicator. Overall, all these data point out the analogy of the symmetric N···I···N bonding in the halonium ions and the asymmetric X···I···N bonding in the strong HaB complexes, as well as the weakly covalent character of these 3c-4e interactions.

(1,2,5,6-η)-Cyclo-octa-1,5-diene](1-ethyl-4-isopropyl-1,2,4-triazol-5-yl-idene)(tri-phenylphos-phane)iridium(I) tetra-fluorido-borate di-chloro-methane sesquisolvate.

The synthesis and crystal structure of a new triazole-based N-heterocyclic carbene iridium(I) cationic complex with a tetra-fluorido-borate counter-anion and solvating di-chloro-methane, [Ir(C8H12)(C7H13N3)(C18H15P)]BF4·1.5CH2Cl2, is reported. The IrI center of the cationic complex has a distorted square-planar conformation, formed by a bidentate cyclo-octa-1,5-diene (COD) ligand, an N-heterocyclic carbene, and a triphenylphosphane ligand. There are weak hydrogen-bonding inter-actions between C-H groupings of the iridium complex and F atoms of the [BF4]- counter-ions. The atoms of the COD ligand are disordered over two sets of sites in a 0.65:0.35 ratio and two of the F atoms of the anion are disordered over adjacent sites in a 0.6:0.4 ratio. One of the di-chloro-methane solvent mol-ecules is disordered about an inversion center with 0.5 occupancy.

Formation of an Unusual Pseudo-Square Planar-Induced Mercury(II) Dimeric Complex

Due to the different crystallization methods, two Hg(II) complexes of a 19-membered NO2S2-macrocycle (L) and its oxidized ligand (HLox), exhibiting different stoichiometries, were prepared. First, mercury(II) iodide reacts with L to afford a dinuclear metallacycle complex [Hg2(L)2I4] (1) in which the mercury(II) exists outside the macrocyclic cavity. Meanwhile, the slow diffusion reaction gave an unusual pseudo-square planar-induced mercury(II) complex, which shows three separated parts with the formula [Hg2(HLox)I5]2[HgI2] (2). There are two complex cation units that are exo-coordinated, along with one unit consisting of a metal cluster anion. Surprisingly, L was oxidized in the disulfoxidized form (HLox) in this condition. NMR titration was used to monitor both the structural and binding characteristics of the complex formed between L and mercury(II) iodide in a solution.

Coordination and fragmentation chemistry of CyMe4-BTPhen complexes with lanthanides and actinides: A combined investigation by ESI-MS and DFT calculations.

To further understand the complexation and fragmentation during the extraction process, the formation of 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-12,4-benzotriazin-3-yl)-1,10-phenanthroline (CyMe4-BTPhen) complexes with lanthanides (Ln = La, Ce, Nd, Sm, Eu, Yb) and actinides (UO22+, Th4+) was observed by electrospray ionization mass spectrometry (ESI-MS) technique and density functional theory (DFT) calculations. Mass spectrometry titrations showed the variation relationship of different complexes in acetonitrile. For lanthanides, the major complexes were 1:2 species ([Ln(L)2]3+ and [Ln(L)2(NO3)]2+) with a ratio of 1:2, which were observed at the initial addition of Ln3+, whereas the species ([Ln(L)(NO3)2]+) with a ratio of 1:1 was detected when the [Ln]/[L] concentration ratio reached 1.0. For UO22+ and Th4+ complexes, 1:1 or 1:2 species ([UO2L(NO3)]+, Th(L)2(NO3)3+ and Th(L)2(NO3)22+) were formed. The fragmentation chemistry of both the ligand and the complex cations was characterized in detail by collision-induced dissociation. The fragmentation process of CyMe4-BTPhen was unfolded sequentially on both sides of the ligand by cleavage of C-C and C-N bonds. DFT calculations provided a detailed analysis of the structures and thermodynamics of those complexes, which indicated that the stable complexes formed in acetonitrile solution were consistent with the ESI-MS results.

Redox Activity of IrIII Complexes with Multidentate Ligands Based on Dipyrido-annulated N-Heterocyclic Carbenes: Access to High Valent and High Spin State with Carbon Donors.

Synthetic strategies to access high-valent iridium complexes usually requireuse of π donating ligands bearing electronegative atoms (e.g. amide or oxide) or σ donating electropositive atoms (e.g. boryl or hydride). Besides the η5-(methyl)cyclopentadienyl derivatives, high-valent η1 carbon-ligated iridium complexes are challenging to synthesize. To meet this challenge, this work reports the oxidation behavior of an all-carbon-ligated anionic bis(CCC-pincer) IrIII complex. Being both σ and π donating, the diaryl dipyrido-annulated N-heterocyclic carbene (dpa-NHC) IrIII complex allowed a stepwise 4e- oxidation sequence. The first 2e- oxidation led to an oxidative coupling of two adjacent aryl groups, resulting in formation of a cationic chiral IrIII complex bearing a CCCC-tetradentate ligand. A further 2e- oxidation allowed isolation of a high-valent tricationic complex with a triplet ground state. These results close a synthetic gap for carbon-ligated iridium complexes and demonstrate the electronic tuning potentialof organic π ligands for unusual electronic properties.

Complexing Properties of Synthesized 1,3,5-Triaza-7-Phosphaadamantane Derivatives Towards Some Lanthanides and Transition Metal Cations With Significant Antimicrobial and Antioxidant Activities.

The synthesis of new water-soluble N-alkylated derivatives of 1,3,5-triaza-7-phosphaadamantane is presented. Ru(PPh3)2Cl2 has been used to react with 1-(4-nitrobenzyl)-3,5-triaza-1-azonia-7-phosphaadamantane bromide (PTAR). By using elemental analysis, NMR, and IR spectroscopy, the obtained compounds were identified. The UV-visible absorption spectroscopy has been used to monitor the complexation of various transition metal cations. Studies on conductivity have been utilized to validate the complexes' stoichiometries. Using the disc diffusion method, five bacteria strains were used for the study of the antimicrobial activity of compounds 1-3. All tested pathogens, including M luteus LB 141107, were found to have strong biologic activity against the compounds tested in this study. Additionally, DPPH (2,2-diphenyl-1-picrylhydrazyl) has been tested for its ability to scavenge hydrogen peroxide and free radicals. According to our results, these compounds exhibit excellent radical scavenging properties.