Dithiooxamide Ligands Research Articles

Halogen-Bonding-Mediated Radical Reactions: The Unexpected Behavior of Piperazine-Based Dithiooxamide Ligands in the Presence of Diiodine.

N,N'-Dialkylpiperazine-2,3-dithiones (R2pipdt) were recognized as a class of hexa-atomic cyclic dithiooxamide ligands with peculiar charge-transfer donor properties toward soft electron-acceptors such as noble metal cations and diiodine. The latter interaction is nowadays better described as halogen bonding. In the reaction with diiodine, R2pipdt unexpectedly provides the corresponding triiodide salts, differently from the other dithiooxamides, which instead typically achieve ligand·nI2 halogen-bonded adducts. In this paper, we report a combined experimental and theoretical study that allows elucidation of the nature of the cited products and the reasons behind the unpredictable behavior of these ligands. Specifically, low-temperature single-crystal X-ray diffraction measurements on a series of synthetically obtained R2pipdt (R = Me, iPr, Bz)/I3 salts, complemented by neutron diffraction experiments, were able to experimentally highlight the formation of [R2pipdtH]+ cations with a -S-H bond on the dithionic moiety. Differently, with R = Ph, a benzothiazolylium cation, resulting from an intramolecular condensation reaction of the ligand, is obtained. Based on density functional theory (DFT) calculations, a reasonable reaction mechanism where diiodine plays the fundamental role of promoting a halogen-bonding-mediated radical reaction has been proposed. In addition, the comparison of combined experimental and computational results with the corresponding reactions of N,N'-dialkylperhydrodiazepine-2,3-dithione (R2dazdt, a hepta-atomic cyclic dithiooxamide), which provide neutral halogen-bonded adducts, pointed out that the difference in the torsion angle of the free ligands represents the structural key factor in determining the different reactivities of the two systems.

New molybdenum(VI) and vanadium(IV) complexes with 3-aminopyridine and dithiooxamide ligands spectroscopic characterization, DFT calculations, and in vitro cytotoxic activity

Two molybdenum(VI) complexes C1, [MoO2(acac)(APY)] and C2, [MoO2(DTO)(APY)]·H2O, and two vanadium (IV) complexes C3, [VO(H2O)3(APY)]SO4·3/2H2O and C4, [VO(DTO)(H2O)(APY)]SO4, (where APY = 3-aminopyridine, acac = acetylacetone, and DTO = dithiooximide). The complexes were characterized by different spectral techniques such as FTIR, UV–Vis., 1H NMR, mass spectroscopy, and theoretical calculations. The FTIR spectra showed that the (APY) ligand was coordinated by the nitrogen atom of the amine group. The DTO ligand coordinated in different ways depending on the central metal by the two nitrogen atoms with vanadium V(IV), and by the two sulfur atoms with the molybdenum(VI). The mass spectra confirmed the mononuclear structure for all the prepared complexes. The Mo(VI) complexes were diamagnetic, whereas the V(IV) complexes were paramagnetic. The calculations revealed that the prepared complexes were more stable than the free ligands and their HOMOs were (−0.373 and −0.347 a.u.) for molybdenum(VI) complexes and (−0.502 and −0.496) for vanadyl complexes; respectively whereas the LUMOs values were (−0.282 and −0.289 a.u.) for molybdenum(VI) complexes and (−0.418 and −0.429 a.u.) for vanadium(IV) complexes. The complexes were more polarized and softer than the free ligands. The results confirmed that the transition of the electrons is easier in the complexes than the ligands which suggest using the prepared complexes in the photocell in future studies. Based on the obtained experimental and calculated data, distorted pyramidal structures for the V(IV) and Mo(VI) complexes were proposed. The prepared complexes were examined as anti-cancer complexes against different types of cell lines, the cytotoxic activity of the complexes data showed that the C2 complex is the best candidate to be used as an anti-cancer drug.

Platinum(II), palladium(II), and gold(III) complexes of dianionic, secondary dithiooxamide ligands

Reactions of the complexes cis-[PtCl2(PPh3)2], [PdCl2(dppe)] (dppe = Ph2PCH2CH2PPh2) and the N,C-cycloaurated gold(III) complexes [AuCl2(2-benzylpyridyl)] and [AuCl2(C6H4CH2NMe2)] with the secondary dithiooxamide EtNHC(S)C(S)NHEt in refluxing methanol with Et3N base gave good yields of the respective neutral dithiooxamide complexes containing a doubly deprotonated dithiooxamide ligand. The Pt and Pd complexes, as well as [Au{SC(NEt)C(NEt)S}(C6H4CH2NMe2)], were characterized by single-crystal X-ray diffraction. In all complexes the ligand is S,S-bonded to the metal center. The complexes were also characterized by NMR spectroscopy and ESI mass spectrometry.

Functionalization of SBA-15 by dithiooxamide towards removal of Co (II) ions from real samples: Isotherm, thermodynamic and kinetic studies

In this study, mesoporous SBA-15 was functionalized by dithiooxamide ligand through sodium dodecyl sulfate as intermediate. The obtained nanocomposite was considered as a strong adsorbent towards selective removal of the cobalt (II) ions from the industrial wastewater samples. Transmission Electron Microscopy (TEM) analysis, Brunauer-Emmett-Teller (BET) analysis, elemental CHNS (carbon, hydrogen, nitrogen, and sulfur) analysis, and thermo-gravimetric analysis (TGA) were used for characterization, particle size determination, confirming the presence of the used ligand, and measuring the nanocomposite stability, respectively. Effective parameters on the removal of the cobalt (II) ions such as pH, adsorbent dosage, concentration, and contact time have been evaluated. Results showed that the Freundlich isotherm has a bit better correlation coefficient compared to Langmuir isotherm (0.96 versus 0.94, respectively). The maximum amount of Co (II) ions adsorption on 1 g of nanocomposite (qm) is calculated to be 2500 mg/g that points to the excellent adsorption. Kinetic analyses were conducted using pseudo-first and second-order models and the regression results showed that the pseudo-second-order model is more accurate for the study of the cobalt adsorption due to the higher correlation coefficient (0.99 versus 0.83) compared to the pseudo-first-order model. The result of the present study points that the suggested nanocomposite can be positively used in treating industrial effluents containing cobalt ions.

Quantum-chemical modeling of exchange coupling in the magnetic sublattice of bifunctional compounds containing heterometallic complexes of 3d and 4d metals with oxalate and dithiooxamide ligands

To find components of the magnetic sub-lattice of bi-functional compounds with maximum ferromagnetic exchange coupling, quantum-chemical calculations of complexes [(L)2M1III(L)M2II(L)2]5- are performed (M1III and M2II are tri- and divalent atoms of 3d and 4d transition metals M1III (Cr, Mo) and M2II (Ni, Co, Tc, Ru, Rh, Pd), L is dithiooxamide or oxalate). Calculations of the geometric structure of the complex are performed at the B3LYP/LANL2DZ level and calculations of J constants are performed at the B3LYP/TZV level. The replacement of a divalent atom of 3d metal by a divalent atom of 4d metal leads to an increase of J, whereas the replacement of a trivalent atom of 3d metal by a trivalent atom of 4d metal does not change the value of J. It is concluded that there is a correlation of J with a total change in the spin density on the M1III and M2II metals in the complexes compared to the M13+ and M22+ isolated cations.

Synthesis, structural characterization and cytostatic properties of N,N-dicyclohexyldithiooxamide complexes of antimony(III) halides (SbX3, X: Br or I)

The novel antimony(III) halide complexes with the bi-dentate substituted dithiooxamide ligand, N,N-dicyclohexyldithiooxamide (HDTOA) of formulae {[SbBr3(HDTOA)1.5]}n (1) and {[SbI3(HDTOA)1.5].C6H6}n (2), were prepared by reacting antimony(III) bromide or antimony(III) iodide with HDTOA in 1:1 molar ratio. The compounds were characterized by their m.p., FT-IR spectroscopy, Raman spectroscopy, 1H, 13C NMR spectroscopy, Thermal Gravimetric – Differential Thermal Analysis (TG-DTA) and single crystal X-ray diffraction analysis. Both complexes are polymeric consisting by [SbX3(HDTOA)1.5] building blocks. The octahedral geometric demand of the metal center is covered by three halides and three sulfur atoms from three different HDTOA ligands with facial conformation in both complexes. Each ligand bridged two metal centers of two units, through sulfur donor atoms, acting as bi-dentate bridging ligand. Complexes 1 and 2 were also tested for in vitro cytotoxic activity against human breast adenocarcinoma (MCF-7) and human cervical adenocarcinoma (HeLa) cells. Principal components analysis (PCA) was performed to discriminate the significant physicochemical molecular descriptors while regression analysis successfully related the experimental inhibitory concentrations, (IC50) to the independent variables indexed by PCA. The calculated IC50 values are satisfactorily compared with the measured inhibitory activity of the complexes.

Synthesis, structural characterization and cytotoxicity of the antimony(III) chloride complex with N,N-dicyclohexyldithiooxamide

The reaction of antimony(III) chloride with the bidentate substituted dithiooxamide ligand, N,N-dicyclohexyldithiooxamide (HDTOA), in 1:1 molar ratio, leads to the formation of the polymeric complex {[SbCl3(HDTOA)1.5]}n (1). The complex was characterized by FT-IR spectroscopy, 1H,13C NMR spectroscopy and TG–DTA analysis. Crystal and molecular structure of 1 was determined by X-ray diffraction analysis. Complex 1 ([C21H36Cl3N3S3Sb]) crystallizes in trigonal space group, with a=13.8829(2)Å, b=13.8829(2)Å, c=27.3440(5)Å, α=90.00°, β=90.00°, γ=120.00° and Z=12. The complex is polymeric consisting by [SbCl3(HDTOA)1.5] building blocks. The octahedral geometric demand of the metal center is covered by three mutually cis chlorides and three sulfur atoms from three different HDTOA ligands. Each HDTOA ligand bridged two metal centers of two units through their sulfur donor atoms, acting as bidentate bridging ligand forming a 3D network. Complex 1 was also, evaluated for its in vitro cytotoxic activity against leiomyosarcoma (LMS) and human breast adenocarcinoma (MCF-7) cell lines. The ID50 values were higher than the corresponding of cisplatin against these cell lines. Partial Least Squares (PLS) regression analysis was carried out to correlate the variation of the ID50 values (Y-variables) with the variations of energetic parameters (X-variables), calculated from molecular docking calculation.

Magnetic exchange coupling in transition metal complexes with bidentate bridging ligands: a quantum chemical study

The exchange coupling constants (J) were calculated and the spin density distributions were analyzed in the B3LYP/TZV approximation for the complex anions [L2M(1)IIILM(2)IIL2]n−, where L is ligand (L is oxalate, oxamide, dithiooxamide, hydroxamate) and M(1) and M(2) are atoms of the tri- and divalent 3d-transition metals, respectively, and n- is the charge of the anion. The largest J values were found for the complexes formed by the CrIII-NiII and CrIII-CoII pairs with the dithiooxamide ligands. Differences between the calculated and experimental J values are at most a few cm−1.

1,3-Dipolar cycloaddition to the FeSC fragment 20. Preparation and properties of carbonyliron complexes of di-thiooxamide. Reactivity of the mononuclear (di-thiooxamide)Fe(CO) 3 towards dimethyl acetylenedicarboxylate

Reaction of Fe 2(CO) 9 at room temperature in THF with the di-thiooxamides (L), SC{N(R,R′)}C{(R,R′)N}S [R=Me, R′–R′=(CH 2) 2 ( a); R=H, R′= iPr ( b); R=H, R′=iPr ( c), R=H, R′=benzyl ( d); R=H, R′=H ( e)], results for ligands a– d initially in the formation of the mononuclear σ-S, σ-S′ chelate complexes Fe(CO) 3(L) ( 7a– d), which could be isolated in case of 7a and 7d. Under the reaction conditions, complexes 7a– d react further with [Fe(CO) 4] fragments to give three types of Fe 2(CO) 6(L) complexes ( 8a– d) in high yields, depending on the di-thiooxamide ligand used together with traces of the known complex S 2Fe 3(CO) 9 ( 14). The molecular structures of these complexes have been established by the single crystal X-ray diffraction determinations of 8a, 8b and 8d. In the reaction with ligand e the corresponding complex 7e was not detected and the well-known complexes 14 and S 2Fe 3(CO) 9 ( 15) were isolated in low yield. In situ prepared 7a reacts in a slow reaction with 1 equiv. of dimethyl acetylene dicarboxylate in a 1,3-dipolar cycloaddition reaction to give the stable initial ferra [2.2.1] bicyclic complex 10a in 60% yield. In complex 10a an additional Fe(CO) 4 fragment is coordinated to the sulfido sulfur atom of the cycloadded FeSC fragment. When a toluene solution of 10a is heated to 50 °C it loses two terminal CO ligands to give the binuclear FeFe bonded complex 11a in almost quantitative yield. The molecular structures of 10a and 11a have been confirmed by single crystal X-ray diffraction. Reaction of 7d at room temperature with 2 equiv. of dimethyl acetylene dicarboxylate results in the mononuclear complex 12d in 5% yield. The molecular structure of 12b has been established by single crystal X-ray diffraction and comprises a tetra dentate ligand with two ferra-sulpha cyclobutene, and a ferra-disulpha cyclopentene moiety. When the reaction is performed at 60 °C a low yield of 2,3,4,5-thiophene tetramethyl tertracarboxylate is obtained besides complex 12d.

C−S Bond Cleavage and C−C Coupling in Cyclopentadienylchromium Complexes To Give the First Dithiooxamide-Bridged and Doubly Dithiocarbamate-Bridged Double Cubanes: [Cp6Cr8S8{(C(S)NEt2)2}] and [Cp6Cr8S8(S2CNEt2)2

Thermolysis of the dithiocarbamate complex 1 led to the formation of the thiocarbenoid complex 2 and two double cubanes: 3, which has an intercubane Cr-Cr bond and a dithiooxamide ligand in the μ-η2 ,η4 bonding mode, and 4, which contains two dithiocarbamate ligands in the μ-η1 ,η2 bonding mode.

C-S Bond Cleavage and C-C Coupling in Cyclopentadienylchromium Complexes To Give the First Dithiooxamide-Bridged and Doubly Dithiocarbamate-Bridged Double Cubanes: [Cp6 Cr8 S8 {(C(S)NEt2 )2 }] and [Cp6 Cr8 S8 (S2 CNEt2 )2

Thermolysis of the dithiocarbamate complex 1 led to the formation of the thiocarbenoid complex 2 and two double cubanes: 3, which has an intercubane Cr-Cr bond and a dithiooxamide ligand in the μ-η2 ,η4 bonding mode, and 4, which contains two dithiocarbamate ligands in the μ-η1 ,η2 bonding mode.

Mesomorphic Dithiooxamide Complexes of Platinum(II)

Complexation of non-mesomorphic dithiooxamide ligands to Pt(II) leads to square planar complexes which exhibit mesomorphic properties. The synthesis of these complexes was accomplished in three steps: the formation of bisamides, starting from conveniently substituted anilines, their conversion into dithiooxamides and the reaction of these sulfur derivatives with [PtCl2(dmso)2]. Four, eight and twelve-chained complexes were obtained and their behaviour as potentially mesomorphic material was studied. The eight-chained complexes 21 (n = 12–16) and the twelve-chained complexes 22 (n = 8,11,13) exhibit columnar mesophases which have been characterised by optical microscopy, X-ray scattering and related miscibility studies.

Long chain secondary dithiooxamides as ligands for the synthesis of platinum(II) metallomesogens

In the search for platinum complexes of secondary dithiooxamides (RNHCS) 2 (termed as R 2H 2DTO), showing metallomesogenic properties, several [Pt(R 2HDTO) 2] were synthesised starting from cis-[Pt(Me 2SO) 2Cl 2]. The paper is mainly devoted to the co-ordination chemistry of long chain dithiooxamides which in some cases show a different behaviour with respect to R 2H 2DTO bearing small substituents on nitrogen atoms. The observed reactivity appears related only in part to the lower basicity of amide nitrogen atoms in diaryl- with respect to dialkyl-dithiooxamides, and differently populated conformations of the complexes seem to play an important role. Mesophase formation for [Pt(R 2HDTO) 2] with R = 3,4-[CH 3(CH 2) 9O] 2C 6H 3 and 3,4-[CH 3(CH 2) 11O] 2C 6H 3 is suggested by polarising optical microscopy and differential scanning calorimetry. The synthesis of analogous bis-chelates, but with two different dithiooxamide ligands, is also described.

The infrared spectra of complexes with planar dithiooxamides X. The Cu(LH 2) 2X 1 complexes

In this article, the preparation, X-ray powder results and vibrational properties of a new type of complex with planar dithiooxamides are discussed. In acetonitrile, Cu(I) can form complexes with the formula Cu(LH 2) 2X 1 (X = Cl, Br) where LH 2 is an N, N'-disubstituted dithiooxamide. Complexes with N, N'-dimethyldithiooxamide and N, N'-diethyldithiooxamide have been prepared. A thorough vibrational analysis with infrared and Raman techniques was performed, assisted by H/D and 63Cu/ 65Cu isotope substitution. The vibrational study indicates the presence of an inversion centre in the structure. This leads to the proposal of a very unusual six-coordinate structure for these compounds, with the two dithiooxamide ligands, having S-cis conformation, coordinated to the same copper and with the halogens bridged between two different copper atoms. Confirmation of this result was attempted by X-ray analysis, but although several methods were tried to obtain crystals, only powder X-ray data could be obtained, which could not give a definitive answer. Since such six-coordinate Cu(I) has never been described before, a less rigourous interpretation of the vibrational data was followed, leading to a square-pyramidal five-coordinate structure, with a rather weak bond between Cu(I) and a terminal halogen. The latter structure, with the data available up to now, seems a bit more likely, since five-coordination for Cu(I) has already been described.

Studies on biologically active complexes of cobalt(II) and nickel(II) with dithiooxamide-derived ligands

A number of cobalt(II) and nicke(II) complexes with novel dithiooxamide ligands derived from precursors such as benzonitrile, benzosulfonamide, benzaldehyde, benzoic acid, and phenol have been synthesized and characterized on the basis of their elemental analysis molar conductance, magnetic moment, H NMR and electronic and IR spectral data. These ligands and their complexes have been screened for their antibacterial activities against bacterial species Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, and Tuberculi bacilli. The studies indicate that in comparison to the ligands their metal complexes are more potent and antibacterial.

Tetradentate dithiooxamide ligands and their nickel complexes. Synthesis, characterization, and crystal structure of a mononuclear neutral complex, Ni((c-C5H9)NHC(S)C(S)N(CH2)2NC(S)C(S)NH(c-C5H9))

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTetradentate dithiooxamide ligands and their nickel complexes. Synthesis, characterization, and crystal structure of a mononuclear neutral complex, Ni((c-C5H9)NHC(S)C(S)N(CH2)2NC(S)C(S)NH(c-C5H9))Qiu Yun Ye, Yoshiharu Nakano, Greg R. Frauenhoff, David R. Whitcomb, Fusao Takusagawa, and Daryle H. BuschCite this: Inorg. Chem. 1991, 30, 7, 1503–1510Publication Date (Print):April 1, 1991Publication History Published online1 May 2002Published inissue 1 April 1991https://doi.org/10.1021/ic00007a016RIGHTS & PERMISSIONSArticle Views190Altmetric-Citations15LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (963 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

The thermal behavior of dithiooxamide ligands and their nickel complexes

The thermal behavior of substituted dithiooxamide ligands and their nickel complexes has been studied with differential scanning calorimetry and thermogravimetry. The thermal products were analyzed by mass spectral and IR techniques. The mechanism of the thermal decomposition of both the free ligands and metal complexes precludes the clean thermal formation of the polymeric nickel complexes from the neutral ligand derivatives, Ni(LH 2) 2Br 2.

ChemInform Abstract: Structural, Spectroscopic, and Theoretical Studies of Novel d6 fac‐Re(CO)3LBr (L: Dithiooxamide) Complexes.

AbstractIn order to elucidate the electronic and structural properties of neutral dithiooxamide ligands in transition‐metal complexes, the compounds (II) are studied in detail.

Transition-metal complexes of dithiooxamide ligands. Vibrational fine structure in the electronic spectra of symmetrically N,N'-disubstituted dithiooxamides and their divalent nickel ion complexes

Transition-metal complexes of dithiooxamide ligands. Vibrational fine structure in the electronic spectra of symmetrically N,N'-disubstituted dithiooxamides and their divalent nickel ion complexes

Studies of dioxamide and dithio-oxamide metal complexes. Part 3. Confirmation of NN′-disubstituted dithio-oxamides as SS′-bidentate chelating ligands. Crystal and molecular structures of the six-co-ordinate tin(IV) complex SnBr4L1(L1=NN′-di-n-butyldithio-oxamide) and the seven-co-ordinate bismuth(III) complex BiCl3(L2)2(L2=NN′-diethyldithio-oxamide)

Crystal structures of two metal complexes with NN′-disubstituted dithio-oxamides as bidentate chelating ligands have been determined. SnBr4L1·0.33C6H6(1; L1=NN′-di-n-butyldithio-oxamide) is monoclinic, space group C2/c, with a= 20.766(15), b= 21.245(15), c= 14.835(9)Å, β= 91.4(1)°, and Z= 12. BiCl3(L2)2·Me2CO (2; L2=NN′-diethyldithio-oxamide) is monoclinic, space group P21/c, with a= 10.568(9), b= 8.780(9), c= 30.086(15)Å, β= 101.2(1)°, and Z= 4. 1 247 [For (1)] and 2 341 [for (2)] independent reflections above background were collected and the structures refined to R 0.10 and 0.08, respectively. Complex (1) has two equivalent molecules in the asymmetric unit, one with imposed C2 symmetry. The tin atoms are six-co-ordinate octahedral, being bonded to four bromine atoms [2.527(11)–2.625(13)Å] and to a bidentate dithio-oxamide ligand through sulphur [Sn–S 2.551 (25)–2.609(25)Å]. In (2), the bismuth atom is seven-co-ordinate with a pentagonal bipyramidal geometry. Chlorine atoms occupy the axial sites [2.635(10) and 2.717(10)Å] while the equatorial girdle is occupied by two bidentate ligands [Bi–S′ 2.818(13)–3.042(12)Å] and another chlorine atom [2.651(12)Å]. In both structures all the ligand –NH groups are hydrogen bonded for the most part to halogen atoms but also in (2) to the acetone solvent molecule. This intermolecular hydrogen bonding is a direct cause of ring puckering in the chelates.