Chelating Diamine Research Articles

Heteroleptic Ni(II) complexes containing chelating benzoato ligand with sharp bite angle: syntheses, crystal structures, and magnetism

From the system Ni(OH)2 – 4,4′-dmbpy – HBz (HBz = benzoic acid; 4,4′-dmbpy = 4,4′-dimethyl-2,2′-bipyridine) under various experimental conditions three complexes were isolated, namely light blue [Ni(4,4′-dmbpy)(Bz)2(H2O)] (1), violet [Ni(4,4′-dmbpy)2(Bz)](Bz)·2HBz (2), and pink microcrystalline product [Ni(4,4′-dmbpy)3](Bz)2·3.5H2O (3). The crystal structures of 1 and 2 were determined, that of 2 at two temperatures (100 and 277 K). The crystal structure of 1 is formed of neutral molecules, in which the Ni(II) central atom is hexa-coordinated by one chelating diamine ligand, one chelating and one monodentate benzoato ligands, and one aqua ligand. The crystal structure of 2 is ionic and in the complex cation the Ni(II) atom is hexa-coordinated by two chelating diamine ligands and one chelating benzoato ligand. The positive charge of the complex cation is counterbalanced by a benzoate anion, and two additional molecules of benzoic acid are present in the asymmetric unit. Magnetic properties of 1 and 2 were studied in the temperature range 1.8 – 300 K and confirmed strong axial single-ion anisotropy (D/kB = -7.78 K for 1, D/kB = -6.52 K for 2) of the Ni(II) ions in line with the deformed coordination spheres of the central atoms. In addition, antiferromagnetic spin dimers of Ni(II) ions mediated by hydrogen bonds are present in 1 with exchange coupling J/kB = -2.19 K. The obtained experimental results were supported by ab initio and DFT calculations.

Theoretical investigation into the mechanism of copper-catalyzed Sonogashira coupling using trans-1,2-diamino cyclohexane ligand

The mechanism of copper-catalyzed Sonogashira coupling reaction employing trans-1,2-diamino cyclohexane ligand have been investigated with Density Functional Theory (DFT) method augmented with Conductor-like Polarizable Continuum Model (CPCM) solvation model. The cross-coupling reactions could be accelerated by employing chelating diamine ligands. Thus, we considered trans-1,2-diamino cyclohexane as the ligand for our study. These coupling reactions find its applicability in the synthesis of aryl acetylenes, the precursors for the various benzofuran derivatives which are present in many biologically important compounds. Considering various reaction pathways possible, it was found that diamine ligated copper (I) acetylide was the active state of the catalyst, which on further reaction with aryl halide undergoes a concerted oxidative addition – reductive elimination process giving the cross-coupled product aryl acetylene while regenerating the active catalytic species. Unlike the Pd-catalyzed Sonogashira cross-coupling, there occurs a concerted mechanism owing to the ease of bond formation between Csp2-Csp carbon atoms and instability of a Cu (III) metal center. This shows the mechanism of copper-catalyzed cross-couplings are quite different from that of Pd catalyzed reactions. The latter usually involves individual process involving oxidative addition and reductive elimination. The presences of various functional groups on the substrate molecules have a crucial role in determining the feasibility of the reaction. Henceforth, we have investigated the electronic effects of various functional groups in the substrate molecule on the activation barrier of the cross-coupling reaction.

Two new end-on cyanato copper(II) complexes; synthesis, characterization, solvatochromism, magnetic investigation and quantum study

The present paper deals with magnetic interactions, solvatochromism and DFT calculations of two new end-on cyanato-bridged dinuclear copper(II) complexes with the formula [L(OCN)Cu(μN,N-OCN)]2, 1 and 2, where L1 = N,N-dimethyl,-N′-benzyl-ethylenediamine (1) and L2 = N,N-diethyl,-N′-benzyl-ethylenediamine (2). Both complexes were characterized on the basis of physicochemical and spectroscopic methods. X-ray crystallography of complex 2 showed a dinuclear nature with terminal and bridging cyanate groups. Each copper atom achieves a distorted square-pyramidal environment that is built up by five nitrogen atoms, with two nitrogen atoms coming from two N-bonded cyanato ligands that link two copper ions in an end-on fashion, one nitrogen atom from another cyanato ligand that acts as an N-bonded terminal ligand and the final two nitrogen atoms are from a chelating diamine ligand. The interaction between the two metal ions was investigated by magnetic measurements from 2 to 300 K. The variable temperature magnetic susceptibility data showed a weak ferromagnetic interaction with J values of 1.8 cm−1 for 1 and 7.7 cm−1 for 2. DFT computational results buttressed the experimental observations. The positive solvatochromic behaviors of the compounds were investigated in some organic solvents. The spectral shifts of these solutes were correlated with Kamlet and Taft parameters (α, β and π∗) using linear solvation energy relationships (LSEC). The multi-parametric analysis indicates that both the polarity/polarizability parameters (π∗) and the hydrogen bond donating ability (β) of the solvents play an important role in the absorption maxima of the compounds.

Synthesis, DNA Cleavage Activity, Cytotoxicity, Acetylcholinesterase Inhibition, and Acute Murine Toxicity of Redox-Active Ruthenium(II) Polypyridyl Complexes.

Four mononuclear [(L-L)2 Ru(tatpp)]2+ and two dinuclear [(L-L)2 Ru(tatpp)Ru(L-L)2 ]4+ ruthenium(II) polypyridyl complexes (RPCs) containing the 9,11,20,22-tetraazatetrapyrido[3,2-a:2',3'-c:3'',2''-l:2''',3'''-n]pentacene (tatpp) ligand were synthesized, in which L-L is a chelating diamine ligand such as 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4 phen) or 4,7-diphenyl-1,10-phenanthroline (Ph2 phen). These Ru-tatpp analogues all undergo reduction reactions with modest reducing agents, such as glutathione (GSH), at pH 7. These, plus several structurally related but non-redox-active RPCs, were screened for DNA cleavage activity, cytotoxicity, acetylcholinesterase (AChE) inhibition, and acute mouse toxicity, and their activities were examined with respect to redox activity and lipophilicity. All of the redox-active RPCs show single-strand DNA cleavage in the presence of GSH, whereas none of the non-redox-active RPCs do. Low-micromolar cytotoxicity (IC50 ) against malignant H358, CCL228, and MCF7 cultured cell lines was mainly restricted to the redox-active RPCs; however, they were substantially less toxic toward nonmalignant MCF10 cells. The IC50 values for AChE inhibition in cell-free assays and the acute toxicity of RPCs in mice revealed that whereas most RPCs show potent inhibitory action against AChE (IC50 values <15 μm), Ru-tatpp complexes as a class are surprisingly well tolerated in animals relative to other RPCs.

Crystal structure of 2-azido-1,3-bis-(2,6-diiso-propyl-phen-yl)-1,3,2-di-aza-phospho-lidine.

The title compound, C26H38N5P, was synthesized by reacting 2-chloro-1,3-bis-(2,6-diiso-propyl-phen-yl)-1,3,2-di-aza-phospho-lidine with sodium azide and a catalytic amount of lithium chloride in tetra-hydro-furan. The title compound is the first structurally characterized 2-azido-1,3,2-di-aza-phospho-lidine and exhibits a P atom in a trigonal pyramidal geometry. The azide P-N bond length of 1.8547 (16) Å is significantly longer than the P-N separations for the chelating di-amine [P-N = 1.6680 (15) and 1.6684 (14) Å]. The sterically hindered 2,6-diiso-propyl-phenyl groups twist away from the central heterocycle, with dihedral angles between the central heteocyclic ring and benzene rings of 76.17 (10) and 79.74 (9)°. In the crystal, a weak C-H⋯N link to the terminal N atom of the azide group leads to [100] chains.

Crystal structure of 2-chloro-1,3-bis-(2,6-diiso-propyl-phen-yl)-1,3,2-di-aza-phospho-lidine 2-oxide.

The title compound, C26H38ClN2OP, was synthesized by reacting phosphoryl chloride with N,N'-bis-(2,6-diiso-propyl-phen-yl)ethane-1,2-di-amine in the presence of N-methyl-morpholine which acted as an auxilliary base to quench the HCl released as a by-product. The resultant N-heterocyclic phosphine five-membered ring adopts a half-chair conformation and features a tetra-coordinate P atom ligated by the chelating di-amine [P-N = 1.6348 (14) and 1.6192 (14) Å], one double-bonded O atom [P1-O1 = 1.4652 (12) Å] and one Cl atom [P1-Cl1 = 2.0592 (7) Å]. The sterically hindered 2,6-diiso-propyl-phenyl (Dipp) groups twist away from the central heterocycle, with torsion angles of -75.66 (19) and 83.39 (19)° for the P-N-Car-Car links. A number of intra-molecular C-H⋯N, C-H⋯O and C-H⋯Cl close contacts occur. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds to generate [010] chains. C-H⋯π inter-actions are also observed.

Transfer hydrogenation reactions catalyzed by chiral half-sandwich Ruthenium complexes derived from Proline

Chiral ruthenium half-sandwich complexes were prepared using a chelating diamine made from proline with a phenyl, ethyl, or benzyl group, instead of hydrogen on one of the coordinating arms. Three of these complexes were obtained as single diastereoisomers and their configuration identified by X-ray crystallography. The complexes are recyclable catalysts for the reduction of ketones to chiral alcohols in water. A ruthenium hydride species is identified as the active species by NMR spectroscopy and isotopic labelling experiments. Maximum enantio-selectivity was attained when a phenyl group was directly attached to the primary amine on the diamine ligand derived from proline. Transfer hydrogenation of ketones in water can be carried out using water soluble half-sandwich complexes of ruthenium with chiral ligands derived from proline with better enantioselectivity when phenyl groups are on the proline based chiral ligand.

Synthesis, Crystal Structure, and Characterization of Ternary Copper(II) Complex Derived from N-(salicylidene)-L-valine

Ternary Schiff base copper(II) complex [CuL(tmpda)] (where H2L is N-(salicylidene)-L-valine; tmpda is N,N,N′,N′-tetramethyl-1,3-propanediamine) has been characterized by UV-Vis., FTIR, and single crystal XRD. The crystal structure displays a distorted square pyramidal geometry in which Schiff base is bonded to the Cu(II) ion via phenolate oxygen, imine nitrogen, and an oxygen atom of the carboxylate group through the basal plane and the chelating diamine, N,N,N′,N′-tetramethyl-1,3-propanediamine, displays an axial and equatorial mode of binding via NN-donor atoms.

Theoretical study on the degree of delocalization of unpaired spin in two mixed valence copper(II/I) complexes with isomeric chelating diamines and iodide

Two new mixed valence copper(II)–copper(I) complexes, [Cu(L1)2CuI3] (1) and [Cu(L2)2]2 [Cu(L2)2(Cu2I5)2]·2CH3CN (2) where L1=N,N-dimethylethane-1,2-diamine and L2=N-ethylethane-1,2-diamine, have been synthesized using isomeric chelating diamines and iodide. Complexes are characterized by elemental analyses, IR and UV–Vis spectroscopy. Single crystal X-ray diffraction studies confirm their structures. The degree of delocalization of the unpaired spin has been investigated by computing the spin density using the crystallographic coordinates. Interestingly, it can be observed from that the unpaired electron is delocalized between both copper centers in complex 1, whereas complex 2 is a completely localized mixed valence complex.

Synthesis, crystal structures, spectroscopic characterization and in vitro antidiabetic studies of new Schiff base Copper(II) complexes

Two new Schiff base copper(II) complexes, [CuL1(tmen)] (1) and [Cu $_{\mathrm {2}}\mathrm {L}_{\text {2}}^{\text {2}}$ (tmen)] (2) {where, H $_{\mathrm {2}}\textit {L}^{\mathrm {1}}=$ N-(salicylidene)-L-valine, H $_{\mathrm {2}}\textit {L}^{\mathrm {2}}=$ N-(3,5-dichlorosalicylidene)-L-valine and tmen = N,N,N $^{\prime }$ ,N $^{\prime }$ -tetramethylethylene-1,2-diamine} have been synthesized and characterized by molar conductance, elemental analyses, VSM-RT, UV-Vis, FTIR, EPR, and CD spectra. Both the complexes were structurally characterized by single crystal XRD. The crystal structure of complex 1 displays a distorted square pyramidal geometry in which Schiff base is coordinated to the Cu(II) ion via ONO-donor in the axial mode, whereas, the chelating diamine displays axial and equatorial mode of binding via NN-donor atoms. The crystal structure of the complex 2 reveals a syn-anti mode of carboxylate bridged dinuclear complex, in which, the coordination geometry around Cu(1) is square pyramid and distorted square planar around Cu(2). The target complexes were screened for in vitro antidiabetic activity. Both the complexes showed good inhibitory activity for α-amylase and α-glucosidase.

Interactions of nickel(II) ions in protic ionic liquids comprising N-hexyl(or N-2-ethtylhexyl)ethylenediamines

The interactions of nickel(II) ions in a protic ionic liquid (PIL) comprising monoprotic N-alkyl (alkyl=hexyl or 2-ethylhexyl)–ethylenediaminium ions (HHexen+ or HEthexen+, respectively) combined with bis(trifluoromethanesulfonyl)amide (Tf2N−) or trifluoroacetate (TFA−) ions were investigated using visible (VIS) electronic and extended X-ray absorption fine structure (EXAFS) spectroscopy. These were compared to the analogous nickel(II) complexes in molecular solvents, and copper(II) ion in the same PIL systems. A complete extraction of nickel(II) and copper(II) ions from the aqueous phase was achieved by using the above mentioned PILs with the Tf2N− counter anion. Absorption spectra were used to explore the interaction mode of the nickel(II) ions with the chelating diamine PIL by the addition of nickel(II) salts to the PIL. This demonstrated a dominant formation of the tris(alkyl-en) complex at lower nickel(II) concentrations and changes of the complex to a cis-aniono bis(alkyl-en) complex with the addition of the nickel(II) salts. The ethyl-branch in the cationic unit of the PIL was observed to have a larger effect on the solubility of the copper(II) salts than that of the nickel(II) salts. The EXAFS spectra analysis of the nickel(II) ions in the PILs gives the significant information on the fine structure around the nickel(II) ion coordinated by hexylethylenediamine (Hexen) in the PILs.

Asymmetric Ruthenium‐Catalyzed Hydrogenation of 2,6‐Disubstituted 1,5‐Naphthyridines: Access to Chiral 1,5‐Diaza‐cis‐Decalins

AbstractThe first asymmetric hydrogenation (AH) of 2,6‐disubstituted and 2,3,6‐trisubstituted 1,5‐naphthyridines, catalyzed by chiral cationic ruthenium diamine complexes, has been developed. A wide range of 1,5‐naphthyridine derivatives were efficiently hydrogenated to give 1,2,3,4‐tetrahydro‐1,5‐naphthyridines with up to 99 % ee and full conversions. This facile and green protocol is applicable to the scaled‐up synthesis of optically pure 1,5‐diaza‐cis‐decalins, which have been used as rigid chelating diamine ligands for asymmetric synthesis.

Asymmetric ruthenium-catalyzed hydrogenation of 2,6-disubstituted 1,5-naphthyridines: access to chiral 1,5-diaza-cis-decalins.

The first asymmetric hydrogenation (AH) of 2,6-disubstituted and 2,3,6-trisubstituted 1,5-naphthyridines, catalyzed by chiral cationic ruthenium diamine complexes, has been developed. A wide range of 1,5-naphthyridine derivatives were efficiently hydrogenated to give 1,2,3,4-tetrahydro-1,5-naphthyridines with up to 99 % ee and full conversions. This facile and green protocol is applicable to the scaled-up synthesis of optically pure 1,5-diaza-cis-decalins, which have been used as rigid chelating diamine ligands for asymmetric synthesis.

A novel class of bis- and tris-chelate diam(m)inebis(dicarboxylato)platinum(IV) complexes as potential anticancer prodrugs.

A novel class of platinum(IV) complexes of the type [Pt(Am)(R(COO)2)2], where Am is a chelating diamine or two monodentate am(m)ine ligands and R(COO)2 is a chelating dicarboxylato moiety, was synthesized. For this purpose, the reaction between the corresponding tetrahydroxidoplatinum(IV) precursors and various dicarboxylic acids, such as oxalic, malonic, 3-methylmalonic, and cyclobutanedicarboxylic acid, was utilized. All new compounds were characterized in detail, using 1D and 2D NMR techniques, ESI-MS, FTIR spectroscopy, elemental analysis, TGA, and X-ray diffraction. Their in vitro cytotoxicity was determined in a panel of human tumor cell lines (CH1, SW480 and A549) by means of the MTT colorimetric assay. Furthermore, the lipophilicity and redox properties of the novel complexes were evaluated in order to better understand their pharmacological behavior. The most promising drug candidate, 4b (Pt(DACH)(mal)2), demonstrated low in vivo toxicity but profound anticancer activity against both the L1210 leukemia and CT-26 colon carcinoma models.

Rationalizing the formation and versatility of multinuclear metal complexes of bis(1-methyluracil-5-yl)methane as hybrids between classical calix[n]arenes and metallacalixaromatics

Metallacalix[n]arenes are a distinct class of metallacyclic compounds consisting of heteroaromatic rings L and square-planar cis-a2MII entities (M=Pt or Pd; a=NH3 or amine; or a2=chelating diamine) instead of methylene bridges as in the classic calix[n]arenes. Here a series of hybrid compounds is described, which simultaneously have bridging –CH2– as well as cis-a2MII units, and uracil containing ligands L. Specifically, L=bis(1-methyluracil-5-yl)methane (1) and in one case a derivative of it, bis(1-methyluracil-5-yl)methylbenzene (2), have been reacted with cis-[a2M(H2O)2]2+ (with a=NH3 or a2=2,2′-bipyridine or bis(pyrazloyl-1-yl)propane) in water and products were isolated. Altogether X-ray crystal structures of eight metallacycles (complexes 3–6, 8–11) of M2L2, M4L2, and M6L6 stoichiometries have been determined as well as a second modification of 1. In all closed metallacycles the 1-methyluracil entities are deprotonated with metals coordinating via N3 positions, and without exception the uracil rings adopt 1,3-alternate conformations. A special feature of ligand 1 in its twofold deprotonated form is its propensity to bind additional metal ions through its exocyclic oxygen functionalities. While O4 sites appear to be favored as secondary metal binding sites, linkage isomerism and involvement of O2 is likewise possible (compounds 4, 9, 10). On the basis of the X-ray crystal structures, a reaction scheme is proposed which accounts for the different stoichiometries observed.

Isotopically Enriched 13C Diffusion-Ordered NMR Spectroscopy: Analysis of Methyllithium

We report the development of isotopic-labeled (13)C diffusion-ordered NMR spectroscopy (DOSY) NMR with diffusion coefficient-formula weight (D-FW) analysis and its application in characterizing the aggregation state of methyllithium aggregates and complexes with several widely used diamines. Commercially available (13)C-labeled benzene and several easily synthesized (13)C-labeled compounds using (13)C-labeled iodomethane as the isotopic source are developed as internal references for diffusion-formula weight analysis (D-FW). The technique greatly expands the applicability of DOSY D-FW analysis to a much wider variety of compounds because of isotopic labeling. These results reveal that methyllithium exists as a tetrasolvated tetramer in diethyl ether and exclusively as bis-solvated dimers with chelating diamines.

Synthesis, Characterization, and Interaction with Biomolecules of Platinum(II) Complexes with Shikimic Acid-Based Ligands

Starting from the active ingredient shikimic acid (SA) of traditional Chinese medicine and NH2(CH2)nOH, (n = 2–6), we have synthesized a series of new water-soluble Pt(II) complexes PtLa–eCl2, where La–e are chelating diamine ligands with carbon chain covalently attached to SA (La–e = SA-NH(CH2)nNHCH2CH2NH2; La, n = 2; Lb, n = 3; Lc, n = 4; Ld, n = 5; Le, n = 6). The results of the elemental analysis, LC-MS, capillary electrophoresis, and 1H, 13C NMR indicated that there was only one product (isomer) formed under the present experimental conditions, in which the coordinate mode of PtLa–eCl2 was two-amine bidentate. Their in vitro cytotoxic activities were evaluated by MTT method, where these compounds only exhibited low cytotoxicity towards BEL7404, which should correlate their low lipophilicity. The interactions of the five Pt(II) complexes with DNA were investigated by agarose gel electrophoresis, which suggests that the Pt(II) complexes could induce DNA alteration. We also studied the interactions of the Pt(II) complexes with 5′-GMP with ESI-MS and 1H NMR and found that PtLbCl2, PtLcCl2, and PtLdCl2 could react with 5′-GMP to form mono-GMP and bis-GMP adducts. Furthermore, the cell-cycle analysis revealed that PtLbCl2, PtLcCl2 cause cell G2-phase arrest after incubation for 72 h. Overall, these water-soluble Pt(II) complexes interact with DNA mainly through covalent binding, which blocks the DNA synthesis and replication and thus induces cytotoxicity that weakens as the length of carbon chain increases.

Transfer Hydrogenation of Aryl Ketones with Half‐Sandwich RuII Complexes That Contain Chelating Diamines

AbstractIn a comparative study, half‐sandwich complexes of RuII (1) with pyridine‐based chelating diamine [NN = 2‐aminomethylpiperidine (ampi), a; 2‐aminomethylpyridine (ampy), b; 8‐aminoquaniline (aquan), c; 4,4′‐dimethyl‐2,2′‐bipyridine (dbipy), d; 2,2′‐bipyridine (bipy), e] or amine amide (Ts‐ampi, 2a) were synthesized by cleavage of [{(η6‐p‐cymene)Ru(μ‐Cl)Cl}2] dimer and the resulting complexes were screened for their efficiency in the transfer hydrogenation (TH) of acetophenone in 2‐propanol (IPA) at 82 °C or in water in HCOONa. Among the complexes, cationic 1a, neutral 2a, and 1b, which bear ampi and ampy, were the most effective in terms of catalyst performance (turnover frequency values: 198, 6000, 23 h–1, respectively).

Selective adsorption and separation of trace dissolved Fe(III) from natural water samples by double template imprinted sorbent with chelating diamines

A double template imprinted sorbent with chelating diamines was prepared by sol–gel process for the selective separation and enrichment of trace Fe(III) from natural water samples prior to its determination by flame atomic adsorption spectroscopy (FAAS). The resulting materials were characterized by SEM, FTIR, elemental analysis and nitrogen gas adsorption–desorption. Compared with the CTAB imprinted sorbent (CTAB-imp) and the Fe(III) imprinted sorbent (Fe-imp), the double template imprinted sorbent (Fe–CTAB-imp) had higher selectivity and adsorption capacity for Fe(III). In the presence of Cr(III) ion, selectivity coefficient of the Fe–CTAB-imp for Fe(III) were 261 and 267, respectively, which are much higher than that of CTAB-imp (1.61 and 1.32). The uptake capacities of the Fe–CTAB-imp were much higher than those of sorbents prepared without CTAB template. The relative selectivity coefficient of the Fe–CTAB-imp for Fe(III)/Cr(III) was 68.9 times greater than the Fe-imp. The sorption isotherms on the Fe–CTAB-imp conformed to the Langmuir equation, and the theoretical sorption capacity was 36.90±3.16mg/g. Furthermore, the Fe–CTAB-imp possessed fast sorption kinetics for Fe(III) from aqueous solution with a saturation time of less than 5min, and could be used repeatedly. Combined with FAAS, the method detection limit for Fe(III) could reach the level of 0.26ng/mL. This sorbent has been successfully applied to the separation and determination of trace Fe(III) in reference materials, artificial seawater, fresh water and nearshore seawater samples with satisfactory results.

Synthesis, characterization and cytotoxic activity of palladium (II) dithiocarbamate complexes with α,ω-diamines

The polymeric [PdCl(dithiocarbamate)]n complexes, in which the ligand ion is dimethyldithiocarbamate (DMDT), pyrrolidine dithiocarbamate (PyDT, (CH2)4NCS2−) and sarcosine ethyl ester dithiocarbamate (ESDT, EtO2CCH2N(CH3)CS2−), have been reacted with chelating diamines, like ethylenediamine (en) or 1,3-diaminopropane (dap) and long chain diamines, like 1,4-diaminobutane (dab) or 1,7-diaminoheptane (dah). The reaction products depend on either diamine chain length or molar ratio. By operating at PdCl(dithiocarbamate)/diamine molar ratio 1:1 chelating diamines yielded the ionic [Pd(dithiocarbamate)(diamine)]Cl species (diamine=en or dap), whereas with long chain diamines species of the type [Pd(dithiocarbamate)(diamine)]nCln (diamine=dab or dah) were obtained, in which each Pd(dithiocarbamate)+ unit binds to the NH2 group of two different molecules, in a network of bridging diamines. At molar ratio 1:0.5, the long chain diamines yielded the binuclear [Pd2Cl2(dithiocarbamate)2(diamine)] complexes (diamine=dab or dah), whereas exchange reactions take place generally in the presence of en or dap. The reaction trend is described on the basis of IR and proton NMR spectra. The new dithiocarbamate complexes were preliminarily tested for their cytotoxicity on human cancer cells.