Pd Center Research Articles

New 3D and 2D supramolecular heteroleptic palladium(II) dithiocarbamates as potent anticancer agents

Three new heteroleptic palladium(II) dithiocarbamates with better in vitro anticancer activity than cisplatin were synthesized and characterized by different analytical techniques, elemental analysis, FTIR, NMR, and single crystal X-ray diffraction analysis. The Pd center is chelated by dithiocarbamate ligand {4-benzylpiperazine-1-carbodithioate (1) and (3) or (4-(2-methoxyphenyl)piperazine-1-carbodithioate (2)}, triorganophosphine {tris-(4-flourophenyl)-phosphine (1) and (2) or tris-(4-chlorophenyl)phosphine (3)}, and a chloro-group, resulting in a square planar geometry. The packing diagram reveals a 3D network (1 and 2) and a 2D network (3) composed of various 1D chains in which the molecules are linked via hydrogen bonds (1–3) and halide⋯π (1, 3) interactions. The anticancer activities of complexes against HeLa cell line varies in the sequence 2 (23.438 μM) > 1 (38.293 μM) > 3 (47.554 μM) > cisplatin (78.075 μM). The cytotoxicity of these complexes is due to their strong induction of oxidative stress and DNA-damage ability leading to apoptosis.

ChemInform Abstract: Excellent Suzuki—Miyaura Catalytic Activity of a New Pd(II) Complex with Sulfonamide—Schiff Base Ligand.

AbstractThe novel catalyst exhibits excellent cross‐coupling activity.

Synthesis, spectroscopic characterization, X-ray crystal structure and biological activities of homo- and heterobimetallic complexes with potassium-1-dithiocarboxylatopiperidine-4-carboxylate

Six homobimetallic organotin(IV) carboxylates dithiocarboxylates of the general formula R2(Cl)SnSSCLCOOSn(Cl)R2 (R=Me: 1; n-Bu: 2; Ph: 3)/R3SnSSCLCOOSnR3 (R=Me: 4; n-Bu: 5; Ph: 6), a trinucleartin(IV) derivative [Ph2(Cl)SnSSCLCOO]2SnPh2 (7), three heterobimetallic (Sn, Pd) products of the type Cl2PdSSCLCOOSnR3 (R=Me: 8; Bu: 9; Ph: 10) and a palladium complex KOOCLCSSPdSSCLCOOK (11) were synthesized from potassium 1-dithiocarboxylatopiperidine-4-carboxylate (KSSCLCOOK) insitu. The structures of the complexes were verified by spectroscopic techniques (FT-IR, UV–Visible, 1H NMR, 13C NMR, EI-MS/ESI) and TGA. FT-IR data indicated a bidentate binding mode of the carboxylate/dithiocarbamate group, with tetra and penta-coordinated arrangements around Pd(II) and Sn(IV) centers in solid state. In solution state, a trigonal bipyramidal environment around Sn(IV) and a square planar geometry of Pd(II) was justified by NMR (1H and 13C) and UV–Vis spectroscopies. In heteronuclear products (8–10), the ligand develops linkage through oxygen and sulfur donor sites to Sn(IV) and Pd(II), respectively. The mass fragmentation and thermal degradation patterns were excellently agreed with the molecular composition of products. Single crystal XRD analysis of the complex 6 demonstrated that the geometry of sulfur bonded tin(IV) lies between tetrahedral and trigonal bipyramidal, while a distorted trigonal bipyramidal arrangement was verified for oxygen bonded Sn(IV). The synthesized complexes exhibited antimicrobial activities against various strains of bacteria and fungi by disc diffusion method and their minimal inhibitory concentrations were also found. The nature of the coordinated metal played a major role in biological actions of such complexes. While Pd(II) incorporation chiefly induces SS-DNA binding capacity and ALPs inhibition in complexes, the coordination with Sn(IV) stimulates the antibacterial and antifungal potentials. The complexes exhibited sufficiently lower hemolytic activities as compared to triton X-100 (positive control, 100% lysis) and higher than PBS (negative control, 0% lysis).

Electrocatalytic Sensing of Carbon Dioxide, Oxygen and Inert Inorganic Analytes at Network Films of Transition Metal Complexes

Nanostructured metallic Pd centers have been generated by electroreduction of PdII within the coordination architecture of tridentate Schiff-base-ligands. The resulting Pd nanoparticles (diameters, 5-10 nm) are stabilized and activated by ligand nitrogens, and the electrocatalytic system exhibits appreciable activity toward reduction of CO2 in 0.1 M KHCO3 (pH=8.8). Comparison has also been made to the behavior of conventional Pd nanoparticles. In addition to low degree of agglomeration and high active surface area of the Schiff-base-ligand-supported Pd nanocenters, specific interactions between electron-donor N-coordination sites and metallic Pd are expected. Furthermore, such Pd catalysts are highly active during reduction of O2 in alkaline medium (0.1 M KOH). Finally, the potent catalytic properties of Pd have been explored to study reduction of highly inert arsenate(V), OAs(OH)3, analytes in acid medium (0.5 M H2SO4).

Multifunctional Single-Site Catalysts for Alkoxycarbonylation of Terminal Alkynes.

A multifunctional copolymer (PyPPh2 -SO3 H@porous organic polymers, POPs) was prepared by combining acidic groups and heterogeneous P,N ligands through the copolymerization of vinyl-functionalized 2-pyridyldiphenylphosphine (2-PyPPh2 ) and p-styrene sulfonic acid under solvothermal conditions. The morphology and chemical structure of the copolymer were evaluated using a series of characterization techniques. Compared with traditional homogeneous Pd(OAc)2 /2-PyPPh2 / p-toluenesulfonic acid catalyst, the copolymer supported palladium catalyst (Pd-PyPPh2 -SO3 H@POPs) exhibited higher activity for alkoxycarbonylation of terminal alkynes under the same conditions. This phenomenon could be attributed to the synergistic effect between the single-site Pd centers, 2-PyPPh2 ligands, and SO3 H groups, the outstanding swelling properties as well as the high enrichment of the reactant concentration by the porous catalyst. In addition, the catalyst could be reused at least 4 times without any apparent loss of activity. The excellent catalytic reactivity and good recycling properties make it an attractive catalyst for industrial applications. This work paves the way for advanced multifunctional porous organic polymers as a new type of platform for heterogeneous catalysis in the future.

Principles of formation of catalytic systems for oxidation of aliphatic thiols based on d-element complexes

Mechanism of catalytic selective oxidation of aliphatic thiols RSH into disulfides R2S2 has been suggested basing on quantum-chemical DFT simulation (M06/Def2-TZVP) of coordination compounds of d-elements and using the principle of complementarity. The active center of the catalytic system is a binuclear fragment {M(m-OH)2M′}n+ formed due to hydrolysis of the starting mononuclear d-element compound. The catalysts based on Pd(II) and Pt(II) binuclear active centers are spatially similar throughout the process. The chief interrelated functions of the binuclear catalysts are spatial approaching of two thiolate anions RS– in the inner sphere of the bridged coordination compound required for the disulfide (–S–S–) cross-linking and providing for two-electron redox transfer during the transformation of these anions into disulfide (СH3)2S2.

Esterification, transesterification and hydrogenation reactions of polyunsaturated compounds catalyzed by a recyclable polymer supported palladium catalyst

Aliphatic and aromatic carboxylic acids were converted into their corresponding esters using a polymer supported palladium(II) β-ketoesterate complex under hydrogen atmosphere in the presence of catalytic bromobenzene in alcohols. This method was also applicable to the transesterification of esters. Good to excellent yields were obtained for different aliphatic or aromatic starting materials. The esterification (or transesterification) was promoted by the in situ generation of HBr from bromobenzene, which provided a mild acidic reaction environment. Pd(II) centers were converted into polymer stabilized metal nanoparticles (the true active species) under reaction conditions. The palladium catalyst exhibited a remarkable activity and was reusable for eight consecutive cycles. The present system was also tested for the preparation of partially hydrogenated fatty acid methyl esters, starting from a mixture composed by highly polyunsaturated esters and free carboxylic acids, taken as a model acidic feedstock for biodiesel upgrading.

Synthesis, structure, DFT calculations, electrochemistry, fluorescence, DNA binding and molecular docking aspects of a novel oxime based ligand and its palladium(II) complex

A novel oxime based ligand, phenyl-(pyridine-2-yl-hydrazono)-acetaldehyde oxime (LH), and its palladium(II) complex (1) have been synthesised and spectroscopically characterised. The ligand crystallizes in the monoclinic space group (P21/c). The X-ray crystal structure of the ligand shows that it forms a hydrogen bonded helical network. The ligand has been characterised by C, H and N microanalyses, 1H and 13C NMR, ESI-MS, FT-IR and UV–Vis spectral measurements. Geometry optimizations at the level of DFT show that the Pd(II) centre is nested in a square-planar ‘N3Cl’ coordination chromophore. The diamagnetic palladium complex has been characterised by C, H and N microanalyses, FAB-MS, FT-IR, UV–Vis spectra and molar electrical conductivity measurements. The observed electronic spectrum of 1 correlates with our theoretical findings as evaluated through TD-DFT. 1 displays quasi-reversible Pd(II)/Pd(III) and Pd(III)/Pd(IV) redox couples in its CV in acetonitrile. 1 is nine-fold more emissive with respect to the binding ligand. Biophysical studies have been carried out to show the DNA binding aspects of both the ligand and complex. The binding constants for the ligand and complex were found to be 3.93×104 and 1.38×103M−1 respectively. To have an insight into the mode of binding of LH and 1 with CT DNA a hydrodynamic study was also undertaken. The mode of binding has also been substantiated through molecular docking. A promising groove binding efficacy has been revealed for the ligand.

Structurally Diverse Diazafluorene-Ligated Palladium(II) Complexes and Their Implications for Aerobic Oxidation Reactions

4,5-Diazafluoren-9-one (DAF) has been identified as a highly effective ligand in a number of Pd-catalyzed oxidation reactions, but the mechanistic basis for its utility has not been elucidated. Here, we present the complex coordination chemistry of DAF and palladium(II) carboxylate salts. Multiple complexes among an equilibrating mixture of species have been characterized by (1)H and (15)N NMR spectroscopy and X-ray crystallography. These complexes include monomeric and dimeric Pd(II) species, with monodentate (κ(1)), bidentate (κ(2)), and bridging (μ:κ(1):κ(1)) DAF coordination modes. Titration studies of DAF and Pd(OAc)2 reveal the formation of two dimeric DAF/Pd(OAc)2 complexes at low [DAF] and four monomeric species at higher [DAF]. The dimeric complexes feature two bridging acetate ligands together with either a bridging or nonbridging (κ(1)) DAF ligand coordinated to each Pd(II) center. The monomeric structures consist of three isomeric Pd(κ(1)-DAF)2(OAc)2 complexes, together with Pd(κ(2)-DAF)(OAc)2 in which the DAF exhibits a traditional bidentate coordination mode. Replacing DAF with the structurally related, but more-electron-rich derivative 9,9-dimethyl-4,5-diazafluorene (Me2DAF) simplifies the equilibrium mixture to two complexes: a dimeric species in which the Me2DAF bridges the two Pd centers and a monomeric species with a traditional κ(2)-Me2DAF coordination mode. The use of DAF in combination with other carboxylate ligands (CF3CO2(-) or tBuCO2(-)) also results in a simplified collection of equilibrating Pd(II)-DAF complexes. Collectively, the results highlight the ability of DAF to equilibrate rapidly among multiple coordination modes, and provide valuable insights into the utility of DAF as a ligand in Pd-catalyzed oxidation reactions.

A synthetic, catalytic and theoretical investigation of an unsymmetrical SCN pincer palladacycle

The SCN ligand 2-{3-[(methylsulfanyl)methyl]phenyl}pyridine, 1, has been synthesized starting from an initial Suzuki–Miyaura (SM) coupling between 3-((hydroxymethyl)phenyl)boronic acid and 2-bromopyridine. The C–H activation of 1 with in situ formed Pd(MeCN)4(BF4)2 has been studied and leads to a mixture of palladacycles, which were characterized by X-ray crystallography. The monomeric palladacycle LPdCl 6, where L-H = 1, has been synthesized, and tested in SM couplings of aryl bromides, where it showed moderate activity. Density functional theory and the atoms in molecules (AIM) method have been used to investigate the formation and bonding of 6, revealing a difference in the nature of the Pd–S and Pd–N bonds. It was found that S-coordination to the metal in the rate determining C–H bond activation step leads to better stabilization of the Pd(II) centre (by 13–28 kJ mol−1) than with N-coordination. This is attributed to the electron donating ability of the donor atoms determined by Bader charges. The AIM analysis also revealed that the Pd–N bonds are stronger than the Pd–S bonds influencing the stability of key intermediates in the palladacycle formation reaction pathway.

Excellent Suzuki–Miyauracatalytic activity of a new Pd(II) complex with sulfonamide–Schiff base ligand

A new air‐stable Pd(II) complex containing a sulfonamide–Schiff base ligand has been synthesized, characterized and investigated as a catalyst for the Suzuki–Miyaura reactions of aryl halides with arylboronic acids. Theoretical calculations (B3LYP) and spectroscopic evidence suggest that the sulfonamide–Schiff base coordinates to the Pd centre through sulfonamide nitrogen (SO2NH2) rather than imine (CHN). The complex shows excellent cross‐coupling activity with aryl bromides in water at room temperature and aryl chlorides in isopropanol at 60°C. Copyright © 2016 John Wiley & Sons, Ltd.

Branched Selectivity in the Pd‐Catalysed Methoxycarbonylation of 1‐Alkenes

AbstractThe methoxycarbonylation of alkenes by palladium(II) complexes with P,O‐donor ligands [(2‐methoxyphenyl)diphenylphosphine (L‐2), bis(2‐methoxyphenyl) phenyl phosphine (L‐3) and tris(2‐methoxyphenyl) phosphine (L‐4)] has been investigated. The results show that the Pd complexes derived from these ligands provide high regioselectivity for the branched esters from 1‐pentene and 1‐hexene (>80 %). Various parameters (including temperature, pressure, acid concentration) were optimized to improve the performance of the catalyst system. Higher temperatures afforded higher regioselectivity; but effected rapid catalyst decomposition. Acceptable turnover frequencies, conversions as well as catalyst stability could be obtained at higher L/Pd ratios. The dramatic change in regioselectivity is rationalised on the basis of the hemi‐lability of the o‐methoxy moiety, which may lead to ligand dissociation from L2PdX2 (L=ligand, X=Cl) rather than the expected dissociation of X. In support of our hypothesis, direct evidence for the coordination of the o‐methoxy to the Pd centre was demonstrated by the crystal structure. To the best of our knowledge, this work provides the first reported route to valuable branched esters through the methoxycarbonylation of alkenes at suitable rates.

Computationally deciphering palladium‐catalyzed reaction mechanisms

Computational studies receive increased attention in the mechanistic exploration of transition metal catalyzed reactions. Especially in Pd catalysis, numerous mechanistic insights could be gained by the use of computational tools to complement experimental studies in order to provide a more detailed mechanistic picture. This includes not only the exploration of novel mechanistic scenarios, but also the comparison of different plausible reaction pathways. The current intense use of calculations in mechanistic studies of Pd‐catalyzed reactions has encouraged constant advancements in the field. However, a number of challenges will be faced in the computational treatment of Pd reactivities, including tackling conformational space, charged molecules, varying ligation states and the description of complexes bearing multiple Pd centers. Their careful consideration may enrich the mechanistic picture of numerous Pd‐catalyzed reactions, but may also encourage further development of computational methodology. WIREs Comput Mol Sci 2016, 6:226–242. doi: 10.1002/wcms.1244This article is categorized under: Electronic Structure Theory > Density Functional Theory

A DFT Study on the Conversion of Aryl Iodides to Alkyl Iodides: Reductive Elimination of R-I from Alkylpalladium Iodide Complexes with Accessible β-Hydrogens.

DFT calculations have been performed on the palladium-catalyzed carboiodination reaction. The reaction involves oxidative addition, alkyne insertion, C-N bond cleavage, and reductive elimination. For the alkylpalladium iodide intermediate, LiOtBu stabilizes the intermediate in non-polar solvents, thus promoting reductive elimination and preventing β-hydride elimination. The C-N bond cleavage process was explored and the computations show that PPh3 is not bound to the Pd center during this step. Experimentally, it was demonstrated that LiOtBu is not necessary for the oxidative addition, alkyne insertion, or C-N bond cleavage steps, lending support to the conclusions from the DFT calculations. The turnover-limiting steps were found to be C-N bond cleavage and reductive elimination, whereas oxidative addition, alkyne insertion, and formation of the indole ring provide the driving force for the reaction.

Synthesis and characterization of the P,C-palladacycles with bridging and chelating dinitrogen ligands and ONIOM calculations on the pyrazine-bridged organometallic polymers (n = 1 to n = 10)

In this report we investigated the reaction of bromo-bridged cyclopalladated complex of tri-o-tolylphosphine with aromatic and aliphatic bidentate N-donor ligands (pyrazine, 4,4'-bipyridine, 1,2-bis(4-pyridyl)ethane, 1,3-bis(4-pyridyl)propane, ethylenediamine). These reactions lead to the new P,C-palladacycles which were fully characterized by IR, NMR spectroscopies and CHN analysis. Interestingly, the linear organometallic polymer with a zig-zag manner was obtained and determined by X-ray crystallography in which the pyrazine rigid molecules act as the bridging ligands between Pd(II) centres. To understand the reason of this polymerization process, two layers ONIOM (QM:QM) calculations were performed on the organometallic polymer [Pd(P(o-tolyl)3)(pyrazine)]n (n = 1 to 10) in order to study the stability trend of polymer as a function of size (n). The infrared (IR) spectrum of the [Pd(P(o-tolyl)3)(pyrazine)]n was calculated for different values of n and its evolution with the size of polymer was observed. The shapes of HOMO, LUMO and the energy gap between them were also studied with increasing n.

Square planar Pd(II) complexes derived from 1-ethyl-3-phenylthiourea, 3-mercapto-4-methyl-1,2,4-triazole and 2-mercapto-5-methyl-1,3,4-thiadiazole: Syntheses, spectral, structural characterization and photoluminescence properties

The reaction of PdCl2 with 1-ethyl-3-phenyl-thiourea (Heptu), 3-mercapto-4-methyl-4H-1,2,4-triazole (Hmmtrz) and 2-mercapto-5-methyl-1,3,4-thiadiazole (Hmthd) respectively, yielded three new complexes [Pd(eptu)2] (1), [Pd(Hmmtrz)4]Cl2 (2) and [Pd(Hmthd)4]Cl2·2CHCl3 (3). These complexes have been isolated in pure form and characterized by elemental analyses, IR, NMR and single crystal X-ray diffraction technique. In all compounds the metal ion adopts a square-planar geometry. Two nitrogen and two sulfur atoms from the monoanionic eptu ligand in complex 1 are bonded to Pd(II) centre in trans fashion. Complexes 2 and 3 are salt-like and the metal centre is bonded through four neutral ligands. The electrical neutrality in these complexes is maintained by the presence of two chlorides as counter ions. Migration of hydrogen, within the ligand framework in complexes 2 and 3, from sulfur to nitrogen is observed that resulted in the thione form of the ligand and its coordination to the metal centre in both the complexes. Complex 2 is stabilized by intermolecular CH⋯N and intramolecular NH⋯Cl hydrogen bonding leading to an extended structure. Complex 3 is stabilized by intermolecular CH⋯S hydrogen bonding. Complexes 1–3 are fluorescent materials which upon excitation at 31000, 38600 and 32300cm−1 exhibit an emission at 25200, 27000 and 26700cm−1, respectively.

Factors Controlling Stability and Reactivity of Dimeric Pd(II) Complexes in C–H Functionalization Catalysis

We have systematically explored the factors impacting the stability and reactivity of the [Pd(O2CR)2]2 and [Pd(OAc)(DG-Ar)]2 dimers in Pd(OAc)2-catalyzed and directing group (DG)-assisted C–H functionalization using density functional theory (DFT) calculations. It was shown that the palladium acetate dimer stability (vs the monomer) predominantly arises from interactions between the paddlewheel ligands and the Pd centers. R-substitution in Pd(O2CR)2 leading to an increase (or decrease) in the electron density of the ligand orbitals polarizes the Pd–ligand interaction and weakens (or strengthens) the stability of the [Pd(O2CR)2]2 dimer relative to the monomer. The nature of the substrate/ligand-Pd interaction is shown to be another factor contributing to the nuclearity and reactivity of the Pd-acetates in directing group-assisted C–H functionalization. For the [Pd(OAc)(DG-Ar)]2 dimer, we have found that the major interactions contributing to the stability of the dimer are the bridging acetate interactions ...

ChemInform Abstract: A Simple and Novel Amide Ligand Based on Quinoline Derivative Used for Palladium‐Catalyzed Suzuki Coupling Reaction.

Abstract This paper discusses the synthesis of the amide ligand N,N-diisopropyl quinoline-2-carboxamide from quinoline-2-carboxylic acid and diisopropylamine. The prepared ligand was utilized in the palladium catalyzed Suzuki cross-coupling reaction in ethanol-water 1:1 (v/v). The reaction exhibited high catalytic efficiency with low Pd loading (0.05 mol %) under mild reaction conditions (at 60–90 °C under air atmosphere). In this study, the catalyst was successfully used in coupling reactions between various aryl halides with phenylboronic acid to obtain desired products in excellent yields. Spectrometric methods of 1 H NMR, 13 C NMR, and HR-MS were used to characterize this amide ligand, and its binding properties toward the Pd center were also investigated in detail via HR-MS measurements.

Microbiology, Clinical Spectrum and Outcome of Peritonitis in Patients Undergoing Peritoneal Dialysis in India: Results from a Multicentric, Observational Study

Background: Peritoneal dialysis related peritonitis is a major risk factor for drop out of patients on Continuous ambulatory peritoneal dialysis (CAPD) and Automated peritoneal dialysis (APD). Factors affecting PD related peritonitis and center specific microbiological data are lacking in India. A multicentric prospective observational study was designed to overcome the gaps in the existing data regarding causative organism and outcome. Methods: The present study was a prospective, uncontrolled, open-label; observational study conducted in 21 centers representing all the four geographical regions (North, South, East and West) of India between April 2010 and December 2011. Results: A total of 244 patients on chronic PD with peritonitis were enrolled in the study from 21 centres covering the different geographical areas of India. A total of 244 episodes (patients 244) were identified to meet the criteria for the definition of peritonitis. Climatically, 44 (18.1%) episodes occurred during winter and 35 (14.3%) in summer. Amongst the 85 samples that were culture positive, 38 (44.7%) were in the monsoon season followed by 23 (27.1%) in the postmonsoon, 18 (21.2%) during winter and 11 (12.9%) during summer. Maximum culture positivity (72.7%) was observed with an automated technique. Micro-organisms could be isolated in only 85 cases (35.3%) while the remaining samples were culture negative (156/241, 64.7% of samples). Organisms isolated were Gram negative in 47.8%, Gram positive in 36.7%, fungal in 13.3% and Mycobacterium tuberculosis in 2.2%. Conclusion: This large multicenter study of peritonitis offers insights into the etiology and outcomes of infectious complications of PD in India that are germane to clinical decision making.

New Pd(II) hemichelates devoid of incipient bridging COPd interactions.

In organometallic chemistry the commonly known Sidgwick-Langmuir 18 electron rule is constantly being probed for further discovery of molecular compounds that arise as exceptions. The present study examines the formation and the structure of three novel hemichelates of Pd(ii) derived from the reaction of in situ-formed indene and hydrophenanthrene-based organometallic anions with three different μ-chloro-bridged palladacycles. Electronic structure and interaction behavior have been calculated with methods of the density functional theory at the (ZORA) MetaGGA-D TPSS-D3(BJ), GGA-D PBE-D3(BJ), and hybrid PBE0-dDsC dispersion corrected levels, all with the implementation of all electron triple zeta single polarization basis set. A particular focus of the theoretical investigation was made on the nature of the interaction between the [Cr(CO)3] moiety and the Pd(ii) centers, which according to X-ray diffraction analyses lack significant incipient bridging COPd character. Structures were further assessed - Natural Bonding Orbitals (NBO), Quantum Theory of Atoms in Molecules (QTAIM), and Extended Transition State with Natural Orbitals for Chemical Valence (ETS-NOCV) analysis methods. As a result, intramolecular interactions of interest, primarily around the Pd atom, were analyzed as a measure of natural atomic orbital (NAO) contributions to the natural bonding orbital (NBO) formation, QTAIM analysis with special attention to the bonding critical points (BCPs), as well as energetic analysis of intramolecular interaction forces by Energy Decomposition Analysis (EDA). Theoretical analyses confirm that attractive electrostatics dominate the stabilization of Pd(ii) hemichelates. In the case of complexes , and we expand the known amount of 14 electron transition metal complexes that can be synthesized via reliable synthetic methods. However, complex presented some means of stability but was more reactive to moisture and air under laboratory conditions and escaped thorough analytical characterization.