Thiosemicarbazide Ligands Research Articles

Immobilized molybdenum–thiosemicarbazide Schiff base complex on the surface of magnetite nanoparticles as a new nanocatalyst for the epoxidation of olefins

In this work, a new magnetically recoverable nanocatalyst was developed by immobilization of thiosemicarbazide ligand on the surface of silica coated magnetite nanoparticles (SCMNPs) through Schiff base condensation and followed complexation with MoO2(acac)2. Characterization of the prepared nanocatalyst was performed with different physicochemical methods such as Fourier transform infrared (FT-IR) and atomic absorption spectroscopies, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The prepared catalyst catalyzed the epoxidation of olefins and allyl alcohols with tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide (CHP) quantitatively with excellent selectivity toward the corresponding epoxides under mild reaction conditions.

Poly[[(μ2-4,4′-bipyridyl-κ2N:N′)bis{μ2-N-[2-(2-hydroxybenzoyl)carbamothioyl]acetamidato-κ4O,N,O′:S}bis(nitrato-κ2O,O′)dicadmium] dimethylformamide tetrasolvate

The asymmetric unit of the title complex, {[Cd2(C10H10N3O3S)2(C10H8N2)(NO3)2]·4C3H7NO}n, consists of one CdII cation, one N-[2-(2-hy­droxy­benzo­yl)carbamo­thio­yl]acetamidate ligand, half a 4,4′-bipyridyl ligand, one coordinating nitrate anion and two di­methyl­formamide solvent mol­ecules of crystallization. The bipyridine ligand is completed by inversion symmetry. The metal cation exhibits a distorted penta­gonal–bipyramidal coordination geometry provided by two O and one N atoms of the thio­semicarbazide ligand, two O atoms of the nitrate anion, one S atom of a neighbouring thio­semicarbazide ligand and one 4,4′-bi­pyridine N atom. The bridging role of the thio­semicarbazide ligand through the S atom leads to centrosymmetric binuclear units, which are further linked by 4,4′-bi­pyridine units, forming polymeric chains extending along the b-axis direction. An intra­molecular N—H⋯O hydrogen bond occurs. The crystal structure also features N—H⋯O and O—H⋯O hydrogen bonds, leading to the formation of a three-dimensional network.

(anti-Chloridothiosemicabazide-κS)bis(triphenylphosphane-κP)copper(I) 0.48-hydrate

In the mononuclear title complex, [CuCl(CH5N3S)(C18H15P)2]·0.48H2O, the CuI ion is in a slightly distorted tetra­hedral coordination geometry formed by two P atoms from two tri­phenyl­phosphane ligands, one S atom from a thio­semicarbazide ligand and one chloride anion. An intra­molecular N—H⋯N hydrogen bond [graph-set motif S(5)] stabilizes the thio­semicarbazide ligand in its anti conformation, and an intra­molecular N—H⋯Cl hydrogen bond between the hydrazine N—H group and the chloride anion influences the arrangement and orientation of the ligands around the metal center. A weak intra­molecular C—H⋯Cl hydrogen bond is also present. In the crystal, complex mol­ecules are connected through N—H⋯Cl hydrogen bonds originating from the amide –NH2 group, and through O—H⋯S and O—H⋯Cl hydrogen bonds involving the solvent water mol­ecule. Both the direct N—H⋯Cl hydrogen bonds as well as the bridging hydrogen bonds mediated by the water mol­ecule connect the complex mol­ecules into zigzag chains that propagate along [010]. The solvent water mol­ecule is partially occupied, with a refined occupancy of 0.479 (7).

Novel Bis-C,N-Cyclometalated Iridium(III) Thiosemicarbazide Antitumor Complexes: Interactions with Human Serum Albumin and DNA, and Inhibition of Cathepsin B

A series of new organoiridium(III) complexes [Ir(N-C)(2)(N-S)]Cl (HN-C = 2-phenylpyridine (Hppy), N-S = methyl thiosemicarbazide (1), phenyl thiosemicarbazide (2) and naphtyl thiosemicarbazide (3)) have been synthesized and characterized. The crystal structure of (1) has been established by X-ray diffraction, showing the thiosemicarbazide ligand bound to the iridium atom as N,S-chelate. The cytotoxicity studies show that they are more active than cisplatin (about 5-fold) in T47D (breast cancer) at 48 h incubation time. On the other hand, very low resistance factors (RF) of 1-3 in A2780cisR (cisplatin-resistant ovarian carcinoma) at 48 h were observed (RF ≈ 1). Ir accumulation in T47D cell line after 48 h continuous exposure for complexes 1-3 are higher than that corresponding to cisplatin (about 10 times). The complexes 1-3 bind strongly to HSA with binding constants of about 10(4) M(-1) at 296 K, binding occurring at the warfarin site I for 2. Complexes 2 and 3 are also capable of binding in the minor groove of DNA as shown by Hoechst 33258 displacement experiments. Furthermore, complex 2 is also a good cathepsin B inhibitor (an enzyme implicated in a number of cancer related events), being the enzyme reactivated by cysteine.

Structural, spectral, DFT, pH-metric and biological studies on Cr(III), Mn(II) and Fe(III) complexes of dithione heterocyclic thiosemicarbazide ligand

Cr(III), Mn(II) and Fe(III) complexes derived from the quadruple potential dithione heterocyclic thiosemicarbazide ligand (H2PET) have been prepared and characterized by conventional techniques. The isolated complexes were assigned the formulae, [Cr(HPET)(H2O)2Cl2]·3H2O, [Mn(HPET)(H2O)Cl]2 and [Fe(HPET)(H2O)2Cl2]·H2O, respectively. IR data revealed that the ligand behaves as monobasic bidentate through (CN)py and (CS) groups in both Cr(III) and Fe(III) complexes. In the binuclear Mn(II) complex, H2PET acts as NSNS monobasic tetradente via (CN)py, (CS), (CS) and the new azomethine, (NC)* groups. An octahedral geometry for all complexes was proposed. The bond lengths, bond angles, HOMO, LUMO and dipole moment have been calculated by DFT using materials studio program to confirm the geometry of H2PET and its metal complexes. The ligand association constant and the stability constants of its complexes in addition to the thermodynamic parameters were calculated from pH metrically at 298, 308 and 318°K in 50% dioxane–water mixture, respectively. Also, the kinetic and thermodynamic parameters for the different thermal degradation steps of the complexes were determined by Coats–Redfern and Horowitz–Metzger methods. Moreover, the anti-oxidant (using ABTS and DPPH methods), anti-hemolytic, and cytotoxic activities of the compounds have been tested.

Neutral Gold Complexes with Tridentate SNS Thiosemicarbazide Ligands

Na[AuCl(4)]·2H(2)O reacts with tridentate thiosemicarbazide ligands, H(2)L1, derived from N-[N',N'-dialkylamino(thiocarbonyl)]benzimidoyl chloride and thiosemicarbazides under formation of air-stable, green [AuCl(L1)] complexes. The organic ligands coordinate in a planar SNS coordination mode. Small amounts of gold(I) complexes of the composition [AuCl(L3)] are formed as side-products, where L3 is an S-bonded 5-diethylamino-3-phenyl-1-thiocarbamoyl-1,2,4-triazole. The formation of the triazole L3 can be explained by the oxidation of H(2)L1 to an intermediate thiatriazine L2 by Au(3+), followed by a desulfurization reaction with ring contraction. The chloro ligands in the [AuCl(L1)] complexes can readily be replaced by other monoanionic ligands such as SCN(-) or CN(-) giving [Au(SCN)(L1)] or [Au(CN)(L1)] complexes. The complexes described in this paper represent the first examples of fully characterized neutral Gold(III) thiosemicarbazone complexes. All the [AuCl(L1)] compounds present a remarkable cell growth inhibition against human MCF-7 breast cancer cells. However, systematic variation of the alkyl groups in the N(4)-position of the thiosemicarbazone building blocks as well as the replacement of the chloride by thiocyanate ligands do not considerably influence the biological activity. On the other hand, the reduction of Au(III) to Au(I) leads to a considerable decrease of the cytotoxicity.

Elaborated 1H NMR study for the ligitional behavior of two thiosemicarbazide derivatives towards some heavy metals (Sn(II), Sb(III), Pb(II) and Bi(III)), thermal, antibacterial and antifungal studies

A new series of heavy metal complexes are prepared. Sn(II), Sb(III), Pb(II) and Bi(III) are the metal ions used in complexation with two thiosemicarbazide ligands. The IR and 1H NMR spectra of the free ligands display their presence in thiole–thione forms coincide with each other. The IR spectra of the complexes support the presence of 2:2 molar ratio (M:HL) with HL 1 ligand and 1:1 beside 1:2 with HL 2. The ligand coordinates as bi molecules in some complexes and displays two tautomer forms at the same complex molecule 1H NMR spectra of Sn(II) and Sb(III) complexes were done and comes coincide with IR data. The electronic spectral analysis displays a lower shift appearance in n → π* charge transfer band in most isolated complexes. As well as, a new band is shinned in visible region with Sb(III), Bi(III) complexes and Sn(II)–HL 2. This band is pointed to its use in spectrophotometric analysis for these metal ions. The TG analysis for all isolated compounds was briefly discussed. The molecular modeling parameters support the stability of thiole form of the free ligands in comparing with their thiones by a small difference. The antibacterial and antifungal activities were studied against some organisms and reveal the priority of most investigated complexes.

Poly[bis(μ-4-benzoyl-1-isonicotinoylthiosemicarbazide-κ2N:S)dichloridocadmium(II)

The asymmetric unit of the title complex, [CdCl(2)(C(14)H(12)N(4)O(2)S)(2)](n), consists of one Cd(II) ion located on the crystallographic inversion centre, one 4-benzoyl-1-isonicotinoylthiosemicarbazide ligand and one chloride ligand. The central Cd(II) ion adopts a distorted octahedral coordination geometry formed by two pyridyl N atoms of two ligands, two S atoms of two other ligands and two chloride ligands. The thiosemicarbazide ligands act as bridges, linking the metal ions into a two-dimensional layered structure parallel to the bc plane. Intermolecular N-H...O hydrogen bonds and C-H...pi interactions exist between adjacent layers.

Different intermolecular interactions in azido[2-(diphenylphosphino)benzaldehyde semicarbazonato-κ2P,N1,O]nickel(II)

The title compound, [Ni(C(20)H(17)N(3)OP)(N(3))], is the first complex with a semicarbazide-based ligand having a P atom as one of the donors. The influence of the P atom on the deformation of the coordination geometry of the Ni(II) ion is evident but less expressed than in the cases of complexes with analogous seleno- and thiosemicarbazide ligands. The torsion angles involving the two bonds formed by the P atom within the six-membered chelate ring have the largest values [C-P-Ni-N = 24.3 (2) degrees and C-C-P-Ni = -24.2 (4) degrees ], suggesting that the P atom considerably influences the conformation of the ring. Two types of N-H...N hydrogen bond connect the complex units into chains.

Bis(thiosemicarbazide)nickel(II) bis[2-(thiosemicarbazonomethyl)benzenesulfonate] dihydrate

In the title compound, [Ni(CH5N3S)2](C8H8N3O3S2)2·2H2O, the NiII atom lies on a inversion centre and is four-coordinated by two N and two S atoms of two thio­semicarbazide ligands in an almost square-planar coordination. In the crystal structure, the molecules are linked into a three-dimensional network via C—H⋯O, C—H⋯N, N—H⋯O, N—H⋯S and O—H⋯O hydrogen bonds.

Reactivity of Thiosemicarbazides with Redox Active Metal Ions: Controlled Formation of Coordination Complexes versus Heterocyclic Compounds

The reactions of 1,1-dimethyl-4-phenylthiosemicarbazide (LH) with Cu(II) and Sn(IV) have been investigated. If THF or methanol is used as solvent with Cu(II), oxidative cyclisation and coupling are observed, yielding a 1,2,4-thiadiazole or a 1,3,4-thiadiazolium salt. SnI(4) is also able to induce oxidative coupling of two thiosemicarbazide ligands, yielding 1,2,4-thiadiazolium or 1,2,4-triazolium salts, with I(3)(-) as the counterion, depending on the reaction conditions. By contrast, reaction of LH with SnI(4) in acetone yields a 1,3-thiazolium salt, with I(-) as counterion. Reaction with Cu(II) salts or SnI(4) in basic media leads to the formation of metal complexes containing two deprotonated thiosemicarbazide ligands. In the reaction of CuCl(2) in water in the presence of acid a complex containing two neutral ligands is obtained. Reactions with SnCl(4) are not able to induce ligand cyclisation, although a coordination compound with two neutral ligands was isolated from methanol.

Oxotechnetium(V) Complexes with a Novel Class of Tridentate Thiosemicarbazide Ligands

A novel tridentate thiosemicarbazide-type ligand class with an SNS donor set, H(2)L(1), was prepared by reactions of N-[N',N'-dialkylamino(thiocarbonyl)]benzimidoyl chlorides with thiosemicarbazides. H(2)L(1) ligands readily react with (NBu(4))[TcOCl(4)] in MeOH under the formation of red oxotechnetium(V) complexes of composition [TcOCl(L(1))]. The monomeric, five-coordinate compounds are air-stable and bind (L(1))(2-) tridentate in the equatorial coordination sphere. The compounds represent the first examples of oxotechnetium(V) complexes with NS chelate-bonded thiosemicarbazones.

(Thiocyanato-κN)bis(thiosemicarbazide-κS)copper(I)

In the title complex, [Cu(CH5N3S)2(NCS)], the non-H part of the mol­ecule is strictly planar, lying on the mirror plane at y = 0.25. The Cu atom lies at the centre of a triangle formed by the coordination of three monodentate groups, viz. two thio­semicarbazide ligands and one NCS− anion. Weak inter­molecular N—H⋯S inter­actions generate a two-dimensional network.

Topological Features of Both Electron Density and Electrostatic Potential in the Bis(thiosemicarbazide)zinc(II) Dinitrate Complex

The experimental electron density of the bis(thiosemicarbazide)zinc(II) dinitrate complex, [Zn(CH5N3S)2](NO3)2,was studied. The Hansen-Coppens multipole model was used to extract the electron density from high-resolution X-ray diffraction data collected at 100 K. Careful strategies were designed for the electron density refinements regarding the charge transfer between the anionic and the cationic parts of the complex. Particular attention was also paid to the treatment of the electron density of the zinc atom interacting with two thiosemicarbazide ligands in a tetrahedral coordination. Nevertheless, the filled 3d valence shell of Zn was found unperturbed, and only the 4s shell was engaged in the metal-ligand interaction. Topological properties of both electron density and electrostatic potential, including kinetic and potential energy densities, and atomic charges were reported to quantify a metal-ligand complex with particular Zn-S and Zn-N bonds and hydrogen-bonding features. Chemical activities were screened through the molecular surface on which the three-dimensional electrostatic potential function was projected. The experimental results were compared to those obtained from gas-phase quantum calculations, and a good agreement was reached between these two approaches. Finally, among other electrostatic potential critical points, the values at the maxima corresponding to the nuclear sites were used as indices of the hydrogen-bonding capacity of the thiosemicarbazide ligand.

Synthesis, characterization and antimicrobial studies on metal complexes with a naphthofuran thiosemicarbazide derivatives

Complexes of the type MLCl2, where M = Co(II), Cu(II), Ni(II), Zn(II), Cd(II) and Hg(II) and L is a thiosemicarbazide ligand derived from reaction between naphthofuran-2-carboxyhydrazide and p-chlorophenylisothiocynate (NCClPT)/p-bromophenylisothiocynate (NCBrPT) characterized by elemental analysis, conductance, magnetic susceptibility measurements, UV-Vis, IR, 1H NMR, and ESR. The thiosemicarbazide ligands are bidentate by coordinating through the oxygen of the carbonyl group and the nitrogen of the hydrazide residue. Based on the results, we propose structures for all the metal complexes. Both the ligands and their complexes have been screened for their fungicidal and bactericidal activities.

The structural influence of ligand coordination and hydrogen bonding capabilities in the crystal engineering of metal thiosemicarbazide compounds with malonate

The reaction of sodium malonate with the thiosemicarbazide complexes [M(L)2](NO3)2 [M = Ni, Zn; L = NH2NHC(S)NH2 (tsc), NH2NHC(S)NHEt (Ettsc)] afforded the compounds [Ni(tsc)2]2[Ni(κ2-malonate)2(OH2)2][NO3]2·4H2O 1, [Ni(Ettsc)2][Ni(κ2-malonate)2(OH2)2]·4H2O 2, [Ni(Ettsc)3][Hmalonate]NO3·2H2O 3, {[Zn(tsc)(μ-κ1,κ2-malonate)]·H2O}n4 and [Zn2(Ettsc)3(μ,-κ1,κ2-malonate)(OH2)][NO3]25, all of which have been crystallographically characterised. For compounds 1, 2, 4 and 5, coordination of malonate to a metal centre is observed, in conjunction with displacement of one or more thiosemicarbazide ligands. In contrast, a ligand redistribution reaction occurs in 3 leading to a tris(4-ethylthiosemicarbazide)nickel(II) cation, with hydrogen malonate [Hmalonate]− included as an anion. Compounds 1–3 and 5 are ionic, with the ions connected into hydrogen-bonded networks. Compound 4 forms coordination polymers, which are linked into the gross structure via hydrogen bonds. The nature of malonate coordination is dependent on the metal, whilst the hydrogen bonding capabilities of the thiosemicarbazide ligand influence the interactions observed in forming the three-dimensional structures.

Structural manipulation through selective substitution of hydrogen bonding groups: the supramolecular structures of bis(thiosemicarbazidato)nickel complexes

Deprotonation of a coordinated thiosemicarbazide by a dicarboxylate species competes with the previously reported formation of cation⋯anion tapes via charge-augmented hydrogen bonding between the thiosemicarbazide ligands and the carboxylates. This has resulted in the formation of five bis(thiosemicarbazidato)nickel complexes, [Ni(tscato)2] (1), [Ni(Metscato)2] (2), [Ni(Me2tscato)2] (3), [Ni(Me3tscato)2] (4) and [Ni(EtMe2tscato)2] (5), all of which have been structurally characterised [tscato = H2NC(S)NNH2, Metscato = HMeNC(S)NNH2, Me2tscato = H2NC(S)NNMe2, Me3tscato = HMeNC(S)NNMe2, EtMe2tscato = HEtNC(S)NNMe2]. [Ni(tscato)2] has been structurally characterised before, though the crystal structure analysis of 1 reveals it to be a polymorph of the previously reported complex. The effect of removing hydrogen bond donors through the substitution of NH hydrogen atoms by alkyl groups on the supramolecular structure of the products is assessed.

Bis(thiosemicarbazide-S,N)zinc(II) dinitrate.

In the title compound, [Zn(CH5N3S)2](NO3)2, the zinc(II) ion is located on the twofold axis and chelated by two thiosemicarbazide ligands with Zn—S and Zn—N distances of 2.0904 (17) and 2.2672 (6) Å, respectively. Thus the central zinc(II) is four-coordinated and in a distorted tetrahedral geometry. The inter- and intramolecular hydrogen bonds formed between thiosemicarbazide ligands and nitrate anions assemble the molecules into a one-dimensional chain.

Synthesis and characterization of bis(2,2′-bipyridine) ruthenium complexes containing thiosemicarbazide ligands: unique redox series

Two series of heterochelates of ruthenium(II) containing two bipyridyl molecules and a bidentate chelating sulfurnitrogen donor ligand in the form of 4-aryl substituted thiosemicarbazides have been synthesized and characterized. The first series of complexes are dicationic in which the ring substituted 4-aryl thiosemicarbazides (NS) are chelated in the keto form through the hydrazinic nitrogen and the thione sulfur atom. They are of the [Ru(bpy) 2NS] +2 type. The second series have the general formula [Ru(bpy) 2NS] +1 in which the thiosemicarbazide moiety remains chelated to the Ru II centre through the hydrazinic nitrogen and the deprotonated thiolato S-atom. All the complexes have been characterized by elemental analysis, UV-vis, IR and EPR spectroscopy. The complexes were found to constitute a three membered redox series which were investigated by cyclic voltammetry.

The influence of the chelate effect on supramolecular structure formation: synthesis and crystal structures of zinc thiourea and thiosemicarbazide complexes with terephthalate

The lability of the ligand with a potential hydrogen bond donor–hydrogen bond donor arrangement was found to be the predominant factor in determining the structures of the adducts formed between zinc(II) complexes of thiourea [tu, NH2C(S)NH2] and thiosemicarbazide [tsc, NH2C(S)NHNH2] and the terephthalate anion [tere, C6H4(CO2–)2-1,4]. Reaction of [Zn(tsc)2][NO3]2, containing the bidentate thiosemicarbazide ligand, with sodium terephthalate led to a hydrogen-bonded structure, [Zn(tsc)2(OH2)2][tere]·2H2O, 1, in which the cations and anions are linked into chains through charge-augmented double hydrogen bonds between two NH protons on the tsc ligands and two oxygen lone pairs on the carboxylate. This chain formation is similar to that previously observed for related nickel complexes, although there are major differences in the way in which these chains are linked together into sheets. In contrast to the thiosemicarbazide complex, the reaction of [Zn(tu)4][NO3]2, containing unidentate thiourea ligands, with sodium terephthalate led to the formation of a co-ordinatively-bonded polymer, [Zn2(µ-tu)(tu)2(µ-tere)2]·4H2O, 2, in which the terephthalate anions have displaced some of the thiourea ligands from each zinc co-ordination sphere. The zigzag tapes formed by the terephthalate ligands bridging zinc atoms are linked together into double strands via bridging thiourea ligands.