Molecular Structures Of 2b Research Articles

Further Exploration of Aza-Cobalt-Cyclobutenes on CoIII(TIM) Complexes: Reactivity and Spectroelectrochemistry

The reaction between [CoIII(TIM)Cl2]PF6 (TIM is 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene) and electron-rich terminal alkynes (HC2Y, Y = 4-N,N-bis(4-methoxyphenyl)aniline (TPA) or Fc) yielded a pair of constitutional isomers: 1-aza-2-cobalt-cyclobutene-containing trans-[Co(TIM′)((HC═C)Y)Cl]+ (1a (TPA) and 2a (Fc); TIM′ is the resultant derivative of TIM) and σ-coordinated trans-[Co(TIM)(C2Y)Cl]+ (1b (TPA) and 2b (Fc)). Additionally, the reactivity of the 1-aza-2-cobalt-cyclobutene species was explored based on trans-[Co(TIM′)((HC═C)Fc)Cl]PF6 (2a) because of its good synthetic yield. The reaction of 2a with AgOTf in MeCN resulted in trans-[Co(TIM′)((HC═C)Fc)(NCMe)](PF6)(OTf) (3), and the reaction with KCN in MeOH yielded trans-[Co(TIM′)((HC═C)Fc)CN]PF6 (4). Similarly, trans-[Co(TIM)(C2Ph)(CN)]PF6 (5) was prepared from the reaction between KCN and trans-[Co(TIM)(C2Ph)Cl]PF6. Molecular structures of 1b and 3–5 were established through single crystal X-ray diffraction. Electrochemical studies of 2–4 revealed that these complexes display an irreversible CoIII reduction as well as a reversible one electron ferrocenyl oxidation between 0.11 and 0.18 V (vs Fc+1/0). UV–vis spectroelectrochemical studies revealed a CoIII to Fc+ charge-transfer upon the one electron oxidation of 2a and 2b.

Synthesis and characterization of the titanium catalysts supported by pyrrolide-benzoxazole ligands and their application in ethylene polymerization

The novel pyrrolide-benzoxazole [NN] titanium complexes TiL2Cl2 [L = 2-(5-R-benzo-[d]xazol-2-yl)-pyrrole, R = H (2a), R = CH3 (2b), R = tBu (2c), R = Cl (2d)] were synthesized. All the complexes were fully characterized by 1H, 13C NMR spectra and elemental analyses and the molecular structures of 2b and 2d were determined by single crystal X-ray diffraction. In the presence of methylaluminoxane (MAO), the titanium complexes showed moderate catalytic activities for ethylene polymerization to afford high-molecular-weight polymers.

Synthesis, crystal structures and Hirshfeld analyses of phosphonothioamidates (EtO)2P(=O)C(=S)N(H)R (R = Cy, Bz) and their coordination on CuI and HgX2 (X = Br, I)

The phosphonothioamidates (EtO)2P(=O)C(=S)N(H)R (L1 R = Cy; L2 R = Bz) have been prepared by nucleophilic addition of K[(EtO)2P(=O)] to R–N = C=S and crystallographically analyzed. Both compounds are associated pairwise through strong intermolecular N–H···O bonding giving rise to 10-membered supramolecular macrocycles. This intermolecular bonding has also been studied by Hirshfeld analysis of L1 and L2. Complexation of L on CuI in MeCN solution affords the dinuclear rhomboid-shaped thione complexes [{Cu(μ2-I)2Cu}(η1-L)2] (1a,b). Crystallographic characterization of 1a reveals that L1 is ligated exclusively via the thione function to the trigonal Cu(I) centers, which are interconnected through a short Cu–Cu bond of 2.6207(4) Å. In the solid state, individual dimeric complexes are associated through intermolecular N–H···O bonding generating a supramolecular 1D ribbon. The dinuclear complexes [{XHg(μ2-X)2HgX}(η1-L)2] (2a X = Br, L = Cy; 2b X = Br, L = Bz; 2c X = I, L = Bz) were formed by stoichiometric addition of L to HgX2. The molecular structures of 2b and 2c have been elucidated by X-ray diffraction studies, which show that individual complexes are connected through intermolecular N–H···O bonding generating a supramolecular 1D ribbon. Treatment of L1 with two equivalents of HgBr2 produces the tetranuclear compound [Hg4Br8(κ1-L1)2] 3, whose unusual bromide-bridged architecture has been elucidated by X-ray crystallography.

High Antiproliferative Activity of Hydroxythiopyridones over Hydroxypyridones and Their Organoruthenium Complexes

Hydroxypyr(id)ones are a pharmaceutically important class of compounds that have shown potential in diverse areas of drug discovery. We investigated the 3-hydroxy-4-pyridones 1a–1c and 3-hydroxy-4-thiopyridones 1d–1f as well as their Ru(η6-p-cymene)Cl complexes 2a–2f, and report here the molecular structures of 1b and 1d as determined by X-ray diffraction analysis. Detailed cell biological investigations revealed potent cytotoxic activity, in particular of the 3-hydroxy-4-thiopyridones 1d–1f, while the Ru complexes of both compound types were less potent, despite still showing antiproliferative activity in the low μM range. The compounds did not modulate the cell cycle distribution of cancer cells but were cytostatic in A549 and cytotoxic in NCI-H522 non-small lung cancer cells, among other effects on cancer cells.

One-pot synthesis of cobalt complexes with 2,6-bis(arylimino)phenoxyl/phenthioxyl ligands and catalysis on isoprene polymerization.

Several cobalt complexes supported by 2,6-bis(arylimino)phenoxyl/phenthioxyl ligands κ2N,X-Ar[NXN]CoCl(THF) (1a, X = O, Ar = 2,6-Me2C6H3; 1b, X = O, Ar = 2,6-iPr2C6H3; 2a, X = S, Ar = 2,6-Me2C6H3; 2b, X = S, Ar = 2,6-iPr2C6H3) were synthesized by direct oxygen(sulfur) insertion into the C-Co bond of the mixed-valence cobalt complexes {κ2C,N,η6-Ar[NCN]Co-κN-CoCl(μ-Cl)}2. Crystallization of 1b in the presence of water gave the hydrolysis product 1b'. Treatment of Ar[NCN]Li with dioxygen followed by the addition of CoCl2 afforded the heteroatomic complexes {κ2N,O-Ar[NON]Co(μ-Cl)2Li}2 (3a, Ar = 2,6-Me2C6H3; 3b, Ar = 2,6-iPr2C6H3) or κ2N,O-Ar[NON]Co2Cl2(μ-Cl)2Li(THF)2 (4a, Ar = 2,6-Me2C6H3; 4b, Ar = 2,6-iPr2C6H3) depending on the amount of CoCl2 used. The Co(iii)/Li heterometallic complex 3b' with imino-phenoxyl-amino ligands was formed probably via a redox reaction of 3b. The reactions of Ar[NCN]Li with elemental sulfur and CoCl2 gave κ2N,S-Ar[NSN]Co2Cl2(μ-Cl)2Li(THF)2 (5a, Ar = 2,6-Me2C6H3; 5b, Ar = 2,6-iPr2C6H3) respectively. These complexes were well characterized by FT-IR and elemental analyses, and the molecular structures of 1b', 3b', 4a, and 4b were confirmed by X-ray crystallography. Upon activation with Al2Et3Cl3 in toluene, these complexes showed high activities in isoprene polymerization affording cis-1,4 enriched polymers with a moderate molecular weight (0.85-4.72 × 104 Da).

1,2-Diborolanes with strong donor substituents: Synthesis and high antimicrobial activity

1,2-diborolanes with strong and without strong donor substituents have been described, and are also referred to as 1,2-diboracyclopentane. The 1,2-diaryl/alkyl-amino-1,2-diboracyclopentanes 2, 3, and 4 were obtained in good yield after the reaction of 1,2-dichloro-1,2-diboracyclopentane 1 with ArNHLi and Me3Si-NR2. The structures of these new derivatives were characterized by nuclear magnetic resonance spectroscopy. The molecular structures of 2b, 2c, 2e, 4, and 5f were also determined by single-crystal X-ray diffraction. The newly synthesized 1,2-borolanes are stable in air and showed particularly high activity against some Gram-positive bacteria.

CNC]-Pincer Cobalt Hydride Catalyzed Distinct Selective Hydrosilylation of Aryl Alkene and Alkyl Alkene

The reactions of unsymmetrical N-heterocyclic carbene (NHC) [CNC]-pincer preligands with CoMe(PMe3)4 gave rise to NHC [CNC]-pincer cobalt(III) hydrides, [(CcarbeneNaminoCnaphthyl)Co(H)(PMe3)2] (3a) and (3b), via Csp2–H activation and the unexpected trans-bischelate [Ccarbene, Namino] cobalt(II) complexes 4a and 4b via a disproportionation reaction, respectively. It was found that both 3a and 3b are efficient catalysts for hydrosilylation of alkenes. With aryl alkenes as substrates, 3a has high Markovnikov selectivity in excellent yields, while 3a is an efficient anti-Markovnikov catalyst in good yields with alkyl alkenes as substrates. The catalytic process could be promoted with pyridine N-oxide as an initiator. The catalytic mechanisms for the two different selectivities were proposed. Complexes 3a, 3b, 4a, and 4b were characterized by spectroscopic methods, and the molecular structures of 3b, 4a, and 4b were determined by single crystal X-ray diffraction.

Synthesis and in vitro cytotoxicity studies of Pd(II) and Pt(II) acetamide complexes: Molecular structures of trans-[PdCl2(bzmta)2].DMF (bzmta = 2-acetylamino-6-methylbenzothiazole) and cis-[PtCl2(bzta)2].2DMF (bzta = 2-acetylaminobenzothiazole)

Trans-[PdCl2(bzta)2] (bzta = 2-acetylaminobenzothiazole) (1a), trans-[PdCl2(bzmta)2] (bzmtaH = 2-acetylamino-6-methylbenzothiazole) (1b), trans-[PdCl2(bzcta)2] {bzcta = 2-acetylamino(6-chlorobenzothiazole)} (1c), cis-[PtCl2(bzta)2] (2a), cis-[PtCl2(bzmta)2] (2b) and cis-[PtCl2(bzcta)2] (2c) have synthesized and fully characterized; the molecular structures of 1b.dmf and 2a.2dmf reveal that the acetamide ligands are coordinated through the nitrogen atom of the heterocyclic ring. The anticancer effects of 1a and 2a-c were tested against a wide-range of cancer cell lines. All show cytotoxic activity, but are less effective than cis-platin. Unexpectedly, the palladium complex 1a was more active than the platinum complexes 2a-c, suggesting that future studies on related palladium complexes may be fruitful.

Synthesis and catalytic activity of cationic dinuclear palladium (II) complexes supported by thioether ligands containing two di-(2-picolyl) amine arms

The design, synthesis and characterization of a series of dithioether ligands featuring two di-(2-picolyl)amine arms (2a–2d) and their corresponding cationic dinuclear palladium (II) complexes (3a–d) are reported. Crystal structures of ligand 2b and complexes 3b and 3d were determined by X-ray diffraction studies. The molecular structures of 3b and 3d display each of the two di-(2-picolyl)amine fragments coordinated to one palladium(II) atom in a (κ3-N,N,N) tridentate fashion and with the cationic metal centers displaying square-planar geometries. Weak interactions between the metal centers and the thioether fragments are observed. All bimetallic complexes 3a–d were tested as catalytic precursors in the Suzuki couplings of different o- or p-substituted iodo- or bromoaryls with boronic acids. The overall catalytic results indicate that complex 3b is the best precursor of the series demonstrating even more efficient performance compared to commercial palladium sources such as Pd(OAc)2 and the Nájera Catalysts.

Pyrimidine-2,4,6-trione copper(II) complexes and their catalytic activities in the peroxidative oxidation of cyclohexane

The 5-[(N-arylamino)-methylene]pyrimidine-2,4,6-trione derivatives were prepared from reaction of N-arylamine derivatives with 5-formyl-pyrimidine-2,4,6-trione derivatives and characterized by elemental analysis, ATR-FTIR, 1H and 13C NMR spectroscopy. The Cu(II) complexes were synthesized via reaction of two equivalent of pyrimidine-2,4,6-trione ligands with one equivalent of Cu(OAc)2.H2O and characterized by elemental analysis and ATR-FTIR spectroscopy. Also, the molecular structures of 3b and 3f were determined by single crystal X-ray diffraction technique. 3b is six coordinated copper(II) complex and the geometry around Cu(II) is distorted elongated octahedral coordination while 3f is four coordinated copper(II) complex and the Cu(II) atom has a perfect square planar geometry. Furthermore, the synthesized Cu(II) complexes were used as catalyst for the peroxidative oxidation of cyclohexane and they showed moderate activity under mild condition in acetonitrile.

H2O‐Catalyzed Route to Early Lanthanide Tribromide THF and DME Solvates from Oxides

A convenient one‐pot synthetic protocol towards THF and DME solvates of lanthanum and other early lanthanide tribromides was developed using the water‐catalyzed reaction of lanthanide(III) oxides with highly reactive Me3SiBr in situ formed from commercially available disilane Si2Me6 and Br2. This practical route allows to obtain the target lanthanum tribromide solvates [LaBr3(thf)4] (1a) and [LaBr3(dme)2]2 (1b) as well as analogous early lanthanide molecular tribromide solvates [NdBr3(thf)4] (2a), [NdBr3(dme)2] (2b), [SmBr3(thf)2] (3a), and [SmBr3(dme)2] (3b) difficult to prepare by other solution‐based procedures. The molecular structure of 1b·2CH2Cl2 was determined by an XRD study.

Reactivity of titanium imidazolin-2-iminato complexes with 2,6-diisopropylaniline and 2-{(2,6-diisopropylphenyl)-iminomethyl}pyrrole

We report the reactions of imidazolin-2-iminato titanium complexes [(ImRN)Ti(NMe2)3] (R = Mes, 2b; R = Dipp, 2c; Mes = mesityl, Dipp = 2,6-diisopropylphenyl) with 2,6-diisopropylaniline in a 1:3 molar ratio to yield the titanium imido complexes of composition [(ImRNH)Ti = N(Dipp)(HNDipp)2] (R = Mes, 3b; R = Dipp, 3c) in good yield by the Ti-Niminato bond cleavage at 60 °C. In contrast, the reaction of [(ImRN)Ti(NMe2)3] with 2,6-diisopropylaniline in a 1:1 molar ratio afforded mono-substituted products [(ImRN)Ti(NMe2)2(HNDipp)] (R = Mes, 4b; R = Dipp, 4c) in good yield. The reaction of [(ImRN)Ti(NMe2)3] with the iminopyrrole ligand [2-(2,6-iPr2C6H3-N = CH)C4H3NH] (NDippPyH) in a 1:1 ratio afforded mixed ligands, titanium complexes [(ImRN)Ti(NMe2)2(NDipp-Py)] (R = tBu, 5a; R = Dipp, 5c) with imidazolin-2-iminato and iminopyrrolide ligands. Molecular structures of 3b, 3c, 4c, 5a, and 5c were determined by single-crystal X-ray analysis. The solid-state structures of 3b and 3c clearly indicate the formation of true Ti = N double bonds, measuring 1.730(2) Å and 1.727(1) Å, respectively. The solid-state structures of 5a and 5c reveal the formation of five-coordinate titanium complexes.

Synthesis, characterization, X-ray structure, computational studies, and bioassay of novel compounds combining thiophene and benzimidazole or 1,2,4-triazole moieties

BackgroundDue to their interesting and versatile biological activity, thiophene-containing compounds have attracted the attention of both chemists and medicinal chemists. Some of these compounds have anticancer, antibacterial, antiviral, and antioxidant activity. In addition, the thiophene nucleus has been used in the synthesis of a variety of heterocyclic compounds.ResultsIn the present work, two novel thiophene-containing compounds, 4-phenyl-2-phenylamino-5-(1H-1,3-a,8-triaza-cyclopenta[α]inden-2-yl)-thiophene-3-carboxylic acid ethyl ester (3) and 5-(1H-Imidazo[1,2-b] [1,2,4] triazol-5-yl)-4-phenyl-2-phenylamino-thiophene-3-carboxylic acid ethyl ester (4), have been synthesized by reaction of 5-(2-bromo-acetyl)-4-phenyl-2-phenylaminothiophene-3-carboxylic acid ethyl ester (2) with 2-aminobenzimidazole and 3-amino-1H-1,2,4-triazole in the presence of triethylamine, respectively. Compound 2, on the other hand, was prepared by bromination of 5-acetyl-4-phenyl-2-phenylaminothiophene-3-carboxylic acid ester (1). Structures of the newly prepared compounds were confirmed by different spectroscopic methods such as 1H-NMR, 13C-NMR, and mass spectrometry, as well as by elemental analysis. Furthermore, bromination of compound 1 led to the formation of two constitutional isomers (2a and 2b) that were obtained in an 80:20 ratio. Molecular structures of 2b were confirmed with the aid of X-ray crystallography. Compound 2 was crystallized in the triclinic, P-1, a = 8.8152 (8) Å, b = 10.0958 (9) Å, c = 12.6892 (10) Å, α = 68.549 (5)°, β = 81.667 (5)°, γ = 68.229 (5)°, V = 976.04 (15) Å3, Z = 2, and was found in two isomeric forms regarding the position of the bromine atom. The antibacterial and antifungal activities of the prepared compounds were evaluated.ConclusionsThree new thiophene derivatives were synthesized in good yield. Antimicrobial screening revealed that compound 3 was a promising candidate as a potential antibacterial and antifungal agent; it exhibits remarkable activity against the studied bacterial strains, especially the gram negative bacteria E. coli in addition to some fungi. More work is needed to evaluate its safety and efficacy.

Reactivity of triruthenium diphosphine clusters with 3,5-bis(trifluoromethyl)mercaptobenzene: Electronic and steric influence of diphosphines onto coordination modes of thiolate, capping sulfide, and phosphide groups to a Ru3 clusters

The bridge diphosphine triruthenium clusters [Ru3(μ-κ2P,P′-diphosphine)(CO)10] 1a–1c [diphosphine = dppe, dfppe and dppm, respectively] react with 3,5-bis(trifluoromethyl)mercaptobenzene under refluxing THF, resulting in the oxidative addition of the thiol, to give isostructural compounds [Ru3(μ-H)(μ-κS-SC6H3(CF3)2)(μ-κ2P,P′-diphosphine)(CO)8] [diphosphine = dppe (2a); dfppe (2b) and dppm (2c)] in moderate yields. The thermal hydrogenation reaction of clusters 2a or 2b gives the bridge diphosphine asymmetric dihydride isomeric compounds [Ru3(μ-H)2(μ3-S)(μ-κ2P2-diphosphine)(CO)7] [diphosphine = dppe (3a) and dfppe (3b)] that promote the formation of chelate diphosphine asymmetric dihydride isomers [Ru3(μ-H)2(μ3-S)(κ2P,P′-diphosphine)(CO)7] [diphosphine = dppe (4a) and dfppe (4b)] respectively. Moreover, the hydrogenation reaction of 2a yielded the chelate diphosphine symmetric dihydride isomer [Ru3(μ-H)2(μ3-S)(κ2P,P′-dppe)(CO)7] (5a). The hydrogenation reaction of 2b also yielded [Ru3(μ-H)(μ3-S){μ-κ2P,P′-P(C6F5)CH2CH2P(C6F5)2}(CO)7] (6b), where a C–P bond rupture promoted the formation of a phosphide group in a 50 electron unsaturated cluster. The new clusters have been characterized by spectroscopic methods, and the molecular structures of 2b, 2c, 3a, 3b, 5a, and 6b have been determined by single crystal X-ray diffraction studies.

Synthesis and characterization of dialkylaluminum arylimine complexes

A series of six new aluminum(III) complexes with o-metalated arylimine ligands [o-C6H4(CHNR') (R' = 2,6-iPr2C6H3, 2,6-Me2C6H3)] have been synthesized from the reactions of R2AlCl (R = Me, Et) with o-C6H4(CHNR')Li (R' = 2,6-iPr2C6H3, 2,6-Me2C6H3, t-Bu) in pentane. The complexes all have 4 coordinate pseudo-tetrahedral aluminum centers ligated by two alkyl groups and one bidentate ligand moiety. All six complexes 2a–4b have been fully characterized by 1H and 13C NMR spectroscopy and the molecular structures of 2b and 3a were determined by X-ray crystallography.

Zirconium and hafnium complexes with new tetra-azane ligands: Synthesis, characterization and catalytic properties for ethylene polymerization

Two new anilido-imine tetra-azane ligands, 1,2-[(2′-(ArNH)C6H4HCN)]2C6H4 (Ar=2,6-Me2C6H3 (L1H2) and 2,6-iPr2C6H3 (L2H2)), were synthesized by the condensation reaction of o-phenylenediamine with the corresponding 2-(arylamino)benzaldehyde, and their zirconium and hafnium complexes, L1MCl2 (M=Zr (1b), Hf (1c)) and L2MCl2 (M=Zr (2b), Hf (2c)), were synthesized in high yields (61–66%) by the reactions of L1Li2 and L2Li2 with MCl4 in toluene. Direct HCl-elimination reactions of L1H2 with MCl4 (M=Ti, Zr, Hf) in toluene at 140°C under vacuum afforded the products L1HMCl3 [M=Ti (1a′), Zr (1b′), Hf (1c′)] with a partially deprotonated tridentate ligand in good to high yields (48–70%). All the new complexes were characterized by 1H and 13C NMR spectroscopy and the molecular structures of 1b and 2c were determined by single crystal X-ray diffraction analysis. The metal centers in both complexes are six-coordinated with a distorted octahedral geometry. Upon activation with MAO or AlR3/Ph3CB(C6F5)4, complexes 1b–1c and 2b–2c all exhibit moderate catalytic activity for ethylene polymerization and produce linear polyethylene with ultra-high molar masses (100–184×104g/mol).

Synthesis and Structures of N‐Heterocyclic Carbene–Sulfonate Ruthenium Complexes and Their Applications in the Ring‐Opening Metathesis Polymerization of Norbornene

AbstractA series of N‐heterocyclic carbene–sulfonate (NHC–sulfonate) p‐cymene ruthenium complexes (2a–2d) were synthesized in high yields from the reactions of NHC–sulfonate ligands with Ag2O and [(p‐cymene)RuCl2]2. All of the complexes were characterized fully by 1H and 13C NMR spectroscopy, high‐resolution mass spectrometry, and elemental analysis. The molecular structures of 2b and 2d were determined by single‐crystal X‐ray diffraction analysis. Upon activation with Et2AlCl, the ruthenium complexes 2a–2d showed excellent activities for the ring‐opening metathesis polymerization of norbornene and produced polymers with high molecular weights and narrow molecular weight distributions. Complex 2a can also efficiently catalyze the copolymerization of norbornene and cyclooctene. All of the obtained polymers were characterized by 1H and 13C NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC).

C–N Coupling of Isocyanide Ligands Promoted by Acetylide Addition to Diiron Aminocarbyne Complexes

The bis-isocyanide aminocarbyne diiron complexes [Fe2{μ-CN(Me)(R)}(μ-CO)(CNR′)2(Cp)2][SO3CF3] (R = R′ = Xyl, 1a; R = Me, R′ = Xyl, 1b; R = Xyl, R′ = tBu, 1c; Xyl = 2,6-C6H3Me2) and the analogous thiocarbyne complex [Fe2{μ-CS(Me)}(μ-CO)(CNXyl)2(Cp)2][SO3CF3], 2, were prepared in high yields from [Fe2{μ-C(E)}(μ-CO)(CO)2(Cp)2][SO3CF3] [E = N(Me)(R) or SMe, respectively], by reaction with Me3NO in the presence of the appropriate isocyanide. The addition of LiC≡CR′′ to 1a–b promoted intramolecular C–N coupling between the two isocyanide moieties, resulting in the formation of [Fe2(μ-CO){μ-CN(Me)(R)}{μ-C(NXyl)N(Xyl)C(C≡CR′′)}(Cp)2] (R = Xyl, R″ = Ph, 3a; R = Xyl, R″ = Tol, 3b; R = Me, R″ = Ph, 3c; Tol = 4-C6H5Me), in ca. 60% yields. The reaction of 1a with LiC≡CSiMe3 proceeded with coupling between two dinuclear units, to give the tetranuclear complex C2[Fe2(μ-CO)(Cp)2{μ-CN(Me)(Xyl)}{μ-C(NXyl)N(Xyl)C}]2, 4, in 65% yield. The reaction of 2 with LiC≡CTol resulted in the formation of a mixture of nonidentified products. The new complexes were purified by alumina chromatography and fully characterized by analytical techniques, IR and NMR spectroscopy. The molecular structures of 3b and 4 were ascertained by X-ray diffraction studies.

Palladium (II) and platinum (II) complexes containing organometallic thiosemicarbazone ligands: Synthesis, characterization, X-ray structures and antitubercular evaluation

A new series of palladium (II) and platinum (II) complexes containing ferrocenyl and cyrhetrenyl thiosemicarbazone ligands were synthesized and characterized. The two-step reaction of the organometallic thiosemicarbazones with i) K2MCl4 and ii) PPh3 and their subsequent recrystallization from CH2Cl2/hexane yielded the binuclear complexes [Mˋ{MLn(η5-C5H4)C(H)NNC(S)NHR}–(Cl)(PPh3)] (M′Pd, Pt; MLnRe(CO)3, FeCp; RH, CH3). The structures of the products were inferred from elemental analyses and IR, 1H and 31P NMR spectroscopies. The molecular structures of 2b and 3d were confirmed by single crystal X-ray analysis. All complexes were screened in vitro against Mycobacterium tuberculosis and exhibited only moderate activity in the low micromolar range.

Cyrhetrenyl and ferrocenyl 1,3,4-thiadiazole derivatives: Synthesis, characterization, crystal structures and in vitro antitubercular activity

A new series of cyrhetrenyl and ferrocenyl 1,3,4-thiadiazoles (TDZs) were designed, synthesized and characterized. The condensation–cyclization reaction of organometallic-cyanide with the corresponding thiosemicarbazide produces the ferrocenyl-TDZs (3a–c) and cyrhetrenyl analogues (4ac). The structures of all products were inferred from their elemental analysis, 1H and 13C NMR spectra and MS. The molecular structures of 3b and 4b were confirmed using X-ray crystallography. The electronic effects of cyrhetrenyl (4a–c) and ferrocenyl (3a–c) bound directly to the thiadiazole ring have been correlated with the chemical shift of the exocyclic amine proton and 13C shift of the carbon at the 5-position. The X-ray crystal structure of 3b and 4b indicates that the rhenium compound 4b possesses a more extensive conjugated π-system. The activity of the new organometallic-TDZs was evaluated in vitro against Mycobacterium tuberculosis. The incorporation of any organometallic fragment into the thiadiazole skeleton showed a comparable but lower antitubercular activity than isoniazid.