Nucleophilic Substitution on 4-Nitro- and 4-Methoxy-3-pyridinecarboxylic Acid-1-oxides

1-Oxides of 4-nitro-3-pyridinecarboxylic acid (3) and methyl 4-methoxy-3-pyridinecarboxylate (5) were converted to 4-(diphenylmethyl)amino (7), 4-phenylthio (8), 4-phenylamino (9) and 4-(2-methylpropyl)-amino (6) derivatives by reaction with the corresponding nucleophiles. The 4-phenylamino derivative 9 was alkylated with bromoethane to form the corresponding ethyl ester of the 1-ethoxypyridinium salt 10.     

Synthesis of modified fragments of fibrinogen and their effect on the activity of proteolytic enzymes

New analogues of the Gly-Pro-Arg and Arg-Gly-Asp fragments of fibrinogen were synthesized: Gly-Pro-Arg-Pro (I), Gly-Pro-Arg-Pro-Met-OMe (II), Gly-Pro-Arg-Pro-Phe (III), Gly-Pro-Arg-Pro-Asp (IV), Gly-Pro-Arg-Pro-Glu (V), and Arg-Asn-Trp-Asp (VI). Their effect on the activity of proteases of various types was studied with the method of lysis of fibrin plates. All the peptides were found to inhibit plasmin activity (by 60–85%) and the γ-subunit of nerve growth factor (by 55–93%). Tetrapeptide (VI) proved to be an effective inhibitor of tissue activator of plasminogen and the γ-subunit of nerve growth factor (by 96 and 93%, respectively). The peptides exerted practically no effect on the activity of urokinase and moderately inhibited the activity of streptokinase [(III), IV), and (VI)], papain [(I), (II), IV), and (VI)], subtilisin [(V) and (VI)], α-chymotrypsin [(III), (V), and VI)], and Bacillus subtilis metalloprotease (VI). They inhibit trypsin [except for (I) and (III)] when applied on fibrin plates at a concentration of 1 × 10^?2 M, while, at the concentration of 1 × 10^?3 M, (I) and (II) induced an increase in proteolytic activity by 35 and 47%, respectively.     

Synthesis of Pyrrolo[2′,3′:4,5]Furo[3,2-c]Pyridine-2-Carboxylic Acids

1H-Pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylic acid (6a) and its 1-methyl (6b) and 1-benzyl (6c) derivatives were synthesized. 3-(5-Methoxycarbonyl-4H-furo[3,2-b]-pyrrole-2-yl)propenoic acid (1) was converted to the corresponding azide 2, which in turn was cyclized to give 3 by heating in diphenylether. The pyridone 3 obtained was aromatized with phosphorus oxychloride, then reduced with zinc in acetic acid to give methyl 1H-pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylate (5), which by hydrolysis gave the corresponding carboxylic acid 6a.     

Metal–drug synergy: new ruthenium(II) complexes of ketoconazole are highly active against Leishmania major and Trypanosoma cruzi and nontoxic to human or murine normal cells

In our ongoing search for new metal-based chemotherapeutic agents against leishmaniasis and Chagas disease, six new ruthenium–ketoconazole (KTZ) complexes have been synthesized and characterized, including two octahedral coordination complexes—cis,fac-[Ru^IICl₂(DMSO)₃(KTZ)] (1) and cis-[Ru^IICl₂(bipy)(DMSO)(KTZ)] (2) (where DMSO is dimethyl sulfoxide and bipy is 2,2′-bipyridine)—and four organometallic compounds—[Ru^II(η⁶-p-cymene)Cl₂(KTZ)] (3), [Ru^II(η⁶-p-cymene)(en)(KTZ)][BF₄]₂ (4), [Ru^II(η⁶-p-cymene)(bipy)(KTZ)][BF₄]₂ (5), and [Ru^II(η⁶-p-cymene)(acac)(KTZ)][BF₄] (6) (where en is ethylenediamine and acac is acetylacetonate); the crystal structure of 3 is described. The central hypothesis of our work is that combining a bioactive compound such as KTZ and a metal in a single molecule results in a synergy that can translate into improved activity and/or selectivity against parasites. In agreement with this hypothesis, complexation of KTZ with Ru^II in compounds 3–5 produces a marked enhancement of the activity toward promastigotes and intracellular amastigotes of Leishmania major, when compared with uncomplexed KTZ, or with similar ruthenium compounds not containing KTZ. Importantly, the selective toxicity of compounds 3–5 toward the leishmania parasites, in relation to human fibroblasts and osteoblasts or murine macrophages, is also superior to the selective toxicities of the individual constituents of the drug. When tested against Trypanosoma cruzi epimastigotes, some of the organometallic complexes displayed activity and selectivity comparable to those of free KTZ. A dual-target mechanism is suggested to account for the antiparasitic properties of these complexes.     

Perspectives on the reaction force constant

A synchronous, concerted chemical process is rigorously divided by the reaction force F(R), the negative gradient of V(R), into “reactant” and “product” regions which are dominated by structural changes and an intervening “transition” region which is electronically intensive. The reaction force constant κ(R), the second derivative of V(R), is negative throughout the transition region, not just at the nominal transition state, at which κ(R) has a minimum. This is consistent with experimental evidence that there is a transition region, not simply a specific point. We show graphically that significant nonsynchronicity in the process is associated with the development of a maximum of κ(R) in the transition region, which increases as the process becomes more nonsynchronous. (We speculate that for a nonconcerted process this maximum is actually positive.) Thus, κ(R) can serve as an indicator of the level of nonsynchronicity.

Synthesis of some quinolinyl chalcone analogues and investigation of their anticancer and synergistic anticancer effect with doxorubicin

Two derivatives of 2-(4-acetylanilino)quinolines (IIIa, b) were synthesized as scaffolds for synthesis of open chalcone analogues (Va-f) through Claisen-Schmidt condensation with a set of aromatic aldehydes (IVa-d). Derivatives (Va, b) were further manipulated into cyclic ??,??-unsaturated ketones by Michael-addition of acetylacetone and ethylacetoacetate affording derivatives (VI?CVII). Deethoxycarboxylation of derivatives (VIIa, b) afforded cyclohexenons (VIIIa, b) allowing formation of a mini library of ??,??-unsaturated ketones for screening their anticancer and synergistic anticancer effect with doxorubicin using colon cancer cell line (Caco-2). Two open enones, (Vb) and (Ve), showed significant anticancer activity with IC₅₀ of 5.0 and 2.5 ??M respectively. Only one cyclic enone, (VIa) showed synergistic anticancer activity with doxorubicin at 10 ??M.     

Protonation,alkylation, addition and redox reactions of 16, 17 and 18 valence electron [Mo(L)(NO)('S4')] complexes [L = SPh,PMe3, NO; 'S4'2– = 1,2-Bis-(2-mercaptophenylthio)ethane(2-)]

In the quest for complexes modelling functional characteristics of metal sulfur oxidoreductases, a series of molybdenum nitrosyl complexes with sulfur-dominated coordination sphere was synthesized. Treatment of the 16, 17 and 18 valence electron (VE) complexes [Mo(L)(NO)('S₄')] (1–3) [L?=?SPh (1), PMe₃ (2), NO (3), 'S₄'^2–?=?1,2-bis-(2-mercaptophenylthio) ethane(2-)] with the Brönsted acid HBF₄ resulted in formation of different types of products. 1 and 3 were reversibly protonated at one thiolate atom of the 'S₄'^2– ligand;2, however, yielded the phosphonium salt [HPMe₃]BF₄ and the dinuclear [Mo(NO)('S₄')]₂. Alkylation of 1, 2 and 3 by Me₃OBF₄ or Et₃OBF₄ uniformly resulted in high yields of [Mo(L)(NO)(R-'S₄')]BF₄ complexes [L?=?SPh: R?=?Me (5), Et (6); L?=?PMe₃: R?=?Me (7); L?=?NO: R?=?Me (8), Et (9)] in which one thiolate atom of the 'S₄'^2– ligand had become alkylated; the NMR spectra of 5, 6, 8 and 9 indicated that only one out of four theoretically possible diastereoisomers had formed. 5 and 6 were characterized also by single-crystal X-ray structure analyses. A comparison of ν(NO) bands and redox potentials (cyclic voltammetry) of parent complexes and alkylated derivatives showed that alkylation leads to a decrease in electron density at the molybdenum center and to a positive shift in redox potentials. The 16 VE complex 1 could be reduced, also chemically, to give the corresponding 17 VE anion [1]^–, and inserted elemental sulfur into the Mo-SPh bond, forming the 18 VE phenylperthio complex [Mo(η²–SSPh)(NO)('S₄')] (11) which, upon reaction with PPh₃, gave SPPh₃ and regenerated the parent complex 1. These results are discussed with regard to the sequence of proton and electron transfer steps occurring in substrate conversions catalyzed by metal sulfur oxidoreductases.     

A computational approach to design energetic ionic liquids

The present work deals with the theoretical estimation of ion-pair binding energies and the energetic properties of four ion pairs formed by combining the 1-butyl-2,4-dinitro-3-methyl imidazolium ion with nitrate (I), perchlorate (II), dinitramide (III), or 3,5-dinitro-1,2,4-triazolate (IV) anions. The counterpoise-corrected ion-pair binding energies were calculated for each ion pair at the B3LYP/6-311+G(d,p) level of theory. Results show that the cation–anion interaction is strongest for ion pair I and weakest for IV, indicating that the nitrate (I) has a greater tendency to exist as a stable ionic salt whereas the 3,5-dinitro-1,2,4-triazolate (IV) may exist as an ionic liquid. Natural bond orbital (NBO) analysis and electrostatic potential (ESP) mapping revealed that charge transfer occurs in all of the ion pairs, but is greatest (0.25e) for ion pair I and smallest (0.03e) for IV, resulting in ion pair I being the least polarized. A nucleus-independent chemical shift (NICS) study revealed that the aromaticity of the 1-butyl-2,4-dinitro-3-methyl imidazolium ion significantly increases in ion pair IV, indicating that this has the greatest charge delocalization among all of the four ion pairs considered. Studies of thermodynamic and detonation properties showed that ion pair II is the most energetic ion pair in terms of its detonation velocity (D = 7.5 km s^?1) and detonation pressure (P = 23.1 GPa). It is also envisaged that ion pair IV would exist as an energetic azolium azolate type ionic liquid that could be conveniently used as a secondary explosive characterized by detonation parameters D and P of 6.9 km s^?1 and 19.3 GPa, respectively. These values are comparable to those of conventional explosives such as TNT.     

Cytotoxic metabolites from the cultures of endophytic fungi from Panax ginseng

Two strains of endophytic fungi, Penicillium melinii Yuan-25 and Penicillium janthinellum Yuan-27, with strong anti-Pyricularia oryzae activity, were obtained from the roots of Panax ginseng. Based on bioactivity-oriented isolation, a new benzaldehyde derivative, ginsenocin (1), together with six known compounds, methyl 2,4-dihydroxy-3,5,6-trimethylbenzoate (2), 3,4,5-trimethyl-1,2-benzenediol (3), penicillic acid (4), mannitol (5), ergosterol (6), and ergosterol peroxide (7), were separated from the EtOAc extract of Yuan-25 culture, while brefeldin A (8) was isolated as the major constituent from the EtOAc extract of Yuan-27 culture. The chemical structures were determined based on spectroscopic methods. All the isolated compounds 1–8 were evaluated for their cytotoxicity against six human cancer cell lines. Brefeldin A (8) was the most cytotoxic constituent against all the tested cell lines with IC₅₀ values <0.12 μg/ml, while ginsenocin (1) and penicillic acid (4) also exhibited potent cytotoxicity with IC₅₀ values ranging from 0.49 to 7.46 μg/ml. Our results suggest that endophytic fungi isolated from P. ginseng are a promising natural source of potential anticancer agents.     

Zinc complexes with 1,2,4-triazole functionalized amino acid derivatives: Synthesis, structure and β-lactamase assay

Coordinating abilities of 4R-1,2,4-triazole derivatives (R = glycine ethyl ester (L1), glycine (L2), diethylamino malonate (L3), methionine (L4) and diethyl aminomethylphosphonate (L5)) towards Zn^II ions have been studied in solution, in solid state and versus three zinc-β-lactamases. The crystal structure of [Zn₃(L4)₆(H₂O)₆] (6) is described; it is the first crystal structure involving a 1,2,4-triazole functionalized methionine. It forms a trinuclear complex with central zinc octahedrally coordinated by only L4, whereas terminal zinc ions coordination sphere is completed by three water molecules. L4 exhibits a dual functionality of a bridging bidentate ligand as well as an anion. A dense hydrogen bonding network connects these trinuclear entity into a 3D supramolecular network. The Zn^II ions in 6 are held at equidistance (3.848 Å) which coincidently matches with the corresponding Zn?Zn distance in the binuclear zinc enzyme from Bacillus cereus (3.848 and 4.365 Å). Among L1-L5 screened for β-lactamase assay, L4 shows modest inhibition for BcII enzyme.     

Dicopper(II) and dinickel(II) complexes of Schiff-base macrocycles derived from 5,5-dimethyl-1,9-diformyldipyrromethane

The synthesis and characterisation of two dicopper(II) and two dinickel(II) macrocyclic complexes, [Cu^II₂L^Pr] (10), [Cu^II₂L^Bu] (11), [Ni^II₂L^Pr] (12) and [Ni^II₂L^Bu] (13), are reported. The two new Schiff-base macrocycles (L^Pr)⁴⁻ and (L^Bu)⁴⁻ are isolated as dimetallic complexes 10-13 by the [2+2] condensation of 5,5-dimethyl-1,9-diformyldipyrromethane (9) and 1,3-diaminopropane or 1,4-diaminobutane, respectively, using Cu²⁺ or Ni²⁺ template ions. Single crystal X-ray structure determinations carried out on 10-13 show that each metal atom is in a square planar N₄ geometry, being bound to two deprotonated pyrrole nitrogen atoms of one dipyrromethane unit and to the two adjacent imine nitrogen atoms. NMR spectra obtained for the two dinickel(II) complexes 12 and 13 show that in CDCl₃ solution they are highly symmetrical and diamagnetic.     

Synthesis and spectroscopic and X-ray structural characterisation of some para-substituted triaryltin(pentacarbonyl)manganese(I) complexes

A series of para-substituted triaryltin(pentacarbonyl)manganese(I) compounds [(p-XC₆H₄)₃SnMn(CO)₅: II, X=CH₃; III, X=CH₃O; IV, X=CH₃S; V, X=F; VI, X=Cl; VII, X=CH₃S(O₂)] is reported for comparison with the known phenyl analogue I. IR data [ν(CO)] as well as complete ¹¹⁹Sn/⁵⁵Mn/¹³C solution NMR results are given for I-VII. Chemical shifts, ¹¹⁹Sn versus ⁵⁵Mn, except I, correlate well, but have differing single parameter (SP) correlations, ¹¹⁹Sn versus σ_I and ⁵⁵Mn versus σ°_p. These results are compared with previous SP studies of the ¹¹⁹Sn solution NMR spectra of the series, (p-XC₆H₄)₄Sn and (p-XC₆H₄)₃SnY (Y=Cl, Br, I). Full crystal structures are reported for compounds II-VI. All are similar to that of I, with the Mn(CO)₅ moiety being a distorted tetragonal pyramid, and having a quasi-mirror plane through the central C₄MnSnC₃ skeleton. The Ar₃Sn are distorted trigonal propellers with ring torsion angles in the range 30-80°, the exception being IV with one torsion angle of 22°.     

2-Phenylpyridine ruthenacycles as effectors of glucose oxidase activity: inhibition by RuII and activation by RuIII

Cyclometalated Ru^II derivatives of 2-phenylpyridine (Hphpy) [Ru(phpy)(bpy)₂]Cl (1a) and [Ru(phpy)(phen)₂]Cl (1b) (bpy is 2,2′-bipyridine, phen is 1,10-phenanthroline) behave as noncompetitive inhibitors of glucose oxidase from Aspergillus niger in the enzyme-catalyzed oxidation of d-glucose by O₂ into the corresponding lactone at pH 5.0 and 25 °C. The enzymatic activity has been measured by monitoring the O₂ consumption. The inhibition constants K _i are 0.036 and 0.017 M for 1a and 1b, respectively, indicating that 1b inhibits the enzymatic activity more efficiently than 1a. The well-known coordination compound [Ru(bpy)₃]Cl₂ (2) behaves, in contrast, as a competitive inhibitor, with K _i = 0.018 M under the same conditions. The monophasic consumption of O₂ in the case of 1a, 1b, and 2 is replaced by a distinct two-phase kinetics in the presence of the cyclometalated Ru^III compound [Ru(phpy)(bpy)₂]Cl₂ (3), which was obtained from 1a in the presence of a large excess of H₂O₂ and the iron TAML activator. Interestingly, the rates of the first and the second phases are influenced by 3 in a different way. The rate of the first phase is noticeably higher in the presence of Ru^III, although the dependence is nonmonotonic and maximal acceleration is observed at the lowest loadings of 3. The rate of the second phase decreases monotonically on increasing the concentration of the ruthenium complex in solution. The nonmonotonic action of 3 was confirmed by using the doubly cyclometalated Ru^III derivative [Ru(phpy)₂(bpy)]Cl. The diverse rate variations induced by 3 accounted for acceleration by Ru^III of the O₂ reduction by the reduced form of glucose oxidase during the first phase, which ceases after the enzymatic reduction of Ru^III to the Ru^II species, the latter behaving similarly to 1a as the inhibitor of the enzyme.     

Novel alkyl alkanethiolsulfonate sulfhydryl reagents. Modification of derivatives ofl-cysteine

A simple, general scheme for the synthesis of sulfhydryl-specific alkyl alkanethiolsulfonate (RSSO₂R′) reagents where R′ is methyl, has been developed. Two new reagents, methyl aminoethanethiolsulfonate (2) and methyl benzylthiolsulfonate (3) were synthesized. These were used to modify stoichiometrically and selectively under mild conditions the sulfhydryl groups ofN-acetyl-l-cysteine ethyl ester (4),N-acetyl-l-cysteinep-nitroanilide (7), glutathione, and the A chain of bovine insulin. The corresponding β-S-(β-aminoethanethiol) and β-S-(benzylthiol) derivatives ofl-cysteine and of the peptides were afforded. The characteristics and significance of these reactions and products are discussed.     

Reactivity of a low-valent chromium dinitrogen complex

(Nn^iPrCr)₂(μ₂-κ²:κ²-N₂) (1, Nn^iPr = bis(2,6-diisopropylphenyl)pentane-2,4-ketiminato), formally a chromium(I) complex, was exposed to a variety of small molecules possessing hetero- or homo-atomic single, double, or triple bonds. Reaction of 1 with adamantyl azide yielded complexes in various higher oxidation states, such as (Nn^iPrCr^II)₂(μ₂-NAd) (2), Nn^iPrCr^III(κ²-N₄Ad₂) (3), or Nn^iPrCr^V(NAd)₂ (4). Compound 1 was found to reductively couple 3-pentanone to form Nn^iPrCr(κ²-O₂C₂Et₄) (5) and reductively couple benzylidene aniline to form both Nn^iPrCr^III(cis-κ²-C₂₈H₂₂N₂) (6a) an Nn^iPrCr^III(trans-κ²-C₂₈H₂₂N₂) (6b). Reaction with a stochiometric amount of benzylidene aniline yielded the imine complex Nn^iPrCr(η²-NPhCHPh) (7). Exposure of 1 to a bulky isocyanide formed the octahedral Nn^iPrCr^I[CN(C₆H₄(Me)₂]₄ (9). Complex 1 was also found to break the O-O, NO, and S-S bonds in various small molecules to form Nn^iPrCr^II(OCMe₃) (11), Nn^iPrCr^V(O)(NPh) (8), and [Nn^iPrCr^II(μ-SPh)]₂ (10).     

Two novel hydroperoxylated products of 20(S)-protopanaxadiol produced by Mucor racemosus and their cytotoxic activities against human prostate cancer cells

Microbial transformation of 20(S)-protopanaxadiol (1) by Mucor racemosus AS 3.205 yielded two novel hydroperoxylated metabolites and three known hydroxylated metabolites. The structures of the metabolites were identified as 26-hydroxyl-20(S)-protopanaxadiol (2), 23,24-en-25-hydroxyl-20(S)-protopanaxadiol (3), 25,26-en-24(R)-hydroperoxyl-20(S)-protopanaxadiol (4), 23,24-en-25-hydroperoxyl-20(S)-protopanaxadiol (5), and 25-hydroxyl-20(S)-protopanaxadiol (6). 4 and 5 are new compounds. Metabolites 2, 4, and 5 showed the more potent inhibitory effects against DU-145 and PC-3 cell lines than the substrate.     

3D hydrogen bonded heteronuclear Co, Ni, Cu and Zn aqua complexes derived from dipicolinic acid

The heteronuclear water-soluble and air-stable compounds [M(H₂O)₅M′(dipic)₂] · mH₂O (M/M′ = Cu^II/Co^II (1), Cu^II/Ni^II (2), Cu^II/Zn^II (3), Zn^II/Co^II (4), Ni^II/Co^II (5), m = 2-3; H₂dipic = dipicolinic acid) have been prepared by self-assembly synthesis in aqueous solution at room temperature, and characterized by IR, UV-Vis and atomic absorption spectroscopies, elemental and X-ray diffraction single crystal (for 1 and 2) analyses. 1-5 represent the first examples of heteronuclear dipicolinate compounds with 3d metals. Extensive H-bonding interactions involving all aqua ligands, dipicolinate oxygens and lattice water molecules further stabilize the dimetallic units by linking them to form three-dimensional polymeric networks.     

Theoretical investigation into optical and electronic properties of 1,8-naphthalimide derivatives

A series of 1,8-naphthalimide derivatives has been designed to explore their optical, electronic, and charge transport properties as charge transport and/or luminescent materials for organic light-emitting diodes (OLEDs). The frontier molecular orbitals (FMOs) analysis have shown that the vertical electronic transitions of absorption and emission are characterized as intramolecular charge transfer (ICT) for electron-donating and aromatic groups substituted derivatives. However, the ICT character of the electron-withdrawing substituted derivatives is not significant. The calculated results show that their optical and electronic properties are affected by the substituent groups in 4-position of 1,8-naphthalimide. Our results suggest that 1,8-naphthalimide derivatives with electron-donating ?OCH₃ and ?N(CH₃)₂ (1 and 2), electron-withdrawing ?CN and?COCH₃ (3 and 4), 2-(thiophen-2-yl)thiophene (5), 2,3-dihydrothieno[3,4-b][1, 4]dioxine (6), 2-phenyl-1,3,4-oxadiazole (7), and benzo[c][1,2,5]thiadiazole (8) fragments are expected to be promising candidates for luminescent materials for OLEDs, particularly for 5 and 7. In addition, 3 and 7 can be used as promising hole transport materials for OLEDs. This study should be helpful in further theoretical investigations on such kind of systems and also to the experimental study for charge transport and/or luminescent materials for OLEDs.

Nickel(II) and iron(II) mononuclear complexes with 1-methylimidazole-2-aldoximate: New building units for molecule-assembled magnetic materials

A new class of mononuclear metal complexes with 1-methylimidazole-2-aldoximate (miao) has been synthesized and characterized: trans-Ni^II(Cl)₂(Hmiao)₂ (1), trans-Ni^II(miao)₂(py)₂ (2), NO-trans-Ni^II(miao)₂(phen) (3), and NO-trans-Fe^II(miao)₂(phen) (4). The crystal structures of 2, 3, and 4 have been determined by single-crystal X-ray crystallography. Compound 1 having the protonated miao ligand (i.e., Hmiao) is a precursor for synthesizing 2 and 3. Compound 2 is an octahedral Ni^II complex surrounded by two miao bidentate ligands and two monodentate ligands of pyridine in a trans-arrangement. Compound 3 is a cis-type octahedral Ni^II complex with two miao ligands and a bidentate ligand of 1,10-phenanthroline, in which the ligand arrangement around Ni^II center is found in an NO-trans form. Compound 4 is an isostructural Fe^II derivative of 3. Compounds 1, 2, and 3 exhibit paramagnetic nature with an S = 1 spin and a positive zero-field splitting, among which it for 3 is overlapped with intermolecular ferromagnetic interaction (zJ/k_B = +0.16 K). Compound 4 is diamagnetic due to the existence of low-spin Fe^II ion.     

Characterization of bio-related vanadium and zinc complexes containing tetradentate dithiolate-disulfide, -diamine and -amine-amide ligands

The reaction of [VCl₃(PMe₂Ph)₃] _{with HSS′S′SH (where the HS are thiophenolate and the S′ thioether functions, respectively), H2–1, yields [VCl(μ-SS′S′S)]2 (3) with one of the thiolate groups of each of the two ligands in the bridging mode. Reaction of Na2–1 with [VOCl2(thf)2] leads to a polymeric product of composition [VO(SS′S′S)]x (4). The products obtained from the reaction between [VOCl2(thf)2] and NaSNNSNa, Na2–2, (S is thiophenolate, N the amine function) depend on subtle changes in the diamine backbone of this ligand: If the amine functions are linked by -CH2CH2– (2a), the tetranuclear V^IV complex [V(SNNS)μ-O]4 (5) is formed alongside the V^III complex [VCl(SNNS)]. If the backbone is -CH(Me)CH(Me)- (2b), [VO(SNNS)] (7) and the dinuclear, asymmetrically oxo-bridged V^IV complex [{(SNN ^– S)(thf)V}μ-O{V(SNN ^– S)}] (8) are obtained. In 8, one amine of each of the two ligands is deprotonated to the amide group. In either case, the complexation is accompanied by oxidation of the thiolates to disulfides, leading to the generation of teraazatetrathio-cycloeicosanes (6a/b). Compounds 5 and 8·2THF have been structurally characterized by X-ray analyses. The connectivities have further been established for 3·2CH2Cl2 and for 6b, which exhibits the same conformation as formally characterized 6a. The cluster compound 5 is stabilized by an extended intramolecular N-H...O and N-H...S) hydrogen-bonding network. In 7·2THF, one of the THFs of crystallization is hydrogen-bonded to the NH of the penta-coordinated {VO(SNN ^– S)} moiety; further, there is an intramolecular hydrogen bond between one of the thiolates of this tetragonal-pyramidal half of the molecule and the NH of the octahedral {VO(SNN ^– S)thf} half. The generation of the ligand 2b from its precursor compound, the zinc complex [Zn(SNNS)] (9) leads to the structural characterization of 9·CH3OH with a large SZnS bite angle and a strong hydrogen bond between the methanolic OH and one of the thiolate sulfurs. The relevance of these compounds in biological systems is discussed.}