Dinuclear complexes with a μ-cyano ligand. Part X. Synthesis and characterization of several derivatives of cis-diaquaamminecobalt(III) complexes. Influence of pH

Six new dinuclear complexes, derived from cis-[Co(H₂O)₂(NH₃)₄]³⁺, cis-[Co(H₂O)₂(en)₂]³⁺ and [M(CN)₄^2? (M = Ni, Pd, Pt) were prepared and characterized by means of chemical analysis, electronic and IR measurements. The influence of the pH on the rate of the reaction was studied for the two derivatives of [Pd(CN)₄]^2?, showing that the best conditions to obtain the dinuclear compounds are at pH near 6, where the predominant species are cis-[Co(OH)(H₂O)(amine)₂]²⁺. The [Pt(CN)₄]^2? derivatives show PtPt interactions both in the solid state and in solution.     

Preparation of heterocyclic thialato ligands and their Copper(II) complexes

A number of different heterocyclic aldehydes substituted in the β-position with the t-butylthio moiety were converted into new S₂N₂ ligands containing protected thiol groups. Reaction of the protected ligands 2 with copper(II) salts resulted in elimination of isobutene and formation of copper(II) complexes of mercaptoimines 3.     

Five-coordinated metal complexes of bis(2-hydroxy-1-naphthylideneimine-3-propyl)amine and their reactivity towards dioxygen. Part I. An electrochemical investigation on manganese(II), iron(II), cobalt(II), nickel(II) and copper(II) complexes

The electrochemical behaviour in aprotic solvent of the complexes {M[bis-(2-hydroxy-l-naphthylideneimine-3-propyl)amine]}, where M = Mn(II), Co(II), Fe(II), Ni(II) and Cu(II) is reported. The complexes were prepared and characterized by elemental analysis, infrared and visible spectroscopy and magnetic susceptibility measurements. In addition the reactivity towards dioxygen of the Mn(II), Fe(II) and Co(II) derivatives was investigated, mainly by cyclic voltammetry and gas-volumetric uptake measurements. The results indicate that the Co(II) complexes are able to add dioxygen reversibly, while Mn(II) and Fe(II) compounds undergo an irreversible oxygenation process. The pathway of the dioxygenation processes is tentatively interpreted on the basis of the electrochemical responses. The results confirm that the location of the oxidation potential allows one to predict whether a compound is able to react with dioxygen, but it is not sufficient to predict whether the dioxygenation reaction proceeds reversibly.     

Stereochemistry and fungitoxicity of complexes of p-anisaldehydethiosemicarbazone with Mn(II), Fe(II), Co(II) and Ni(II)

The complexes of p-Anisaldehydethiosemicarbazone (PAT) with Mn(II), Fe(II), Co(II) and Ni(II) have been isolated and characterised on the basis of elemental analyses, molar conductance, magnetic moment and spectral studies. Fungicidal activity has been evaluated against Alternaria (Sp.), Paecilomyces (Sp.) and Pestalotia (Sp.).     

Manganese(II), iron(II) and nickel(II) chloride complexes with monodeprotonated anionic guanine

Upon refluxing 2:1 mixtures of guanine (guH) and MnCl₂, FeCl₂ or NiCl₂ in a 7:3 (v/v) mixture of ethanol and triethyl orthoformate for 1–2 weeks, partial substitution of gu^? for Cl^? groups occurs, and solid complexes of the M(gu)Cl·2ROH (R = C₂H₅ for M = Mn; R = H for M = Fe, Ni) type are obtained. The new complexes are pentacoordinated and appear to be linear chainlike polymeric species, involving a single-bridged

_n backbone. Coordination number five is attained by the presence of one terminal chloro and two terminal ROH ligands per metal ion. Most probable binding sites of bidentate bridging gu^? are the N(7) and N(9) imidazole ring nitrogens. IR evidence rules out the possibility of coordination of gu^? through any of the exocyclic potential ligand sites (O(6) oxygen or N(2) nitrogen) [1].     

Tetrahedral 1:1 adducts of guanine with cobalt(II), copper(II) and zinc(II) chlorides

Adducts of the M(guH)Cl₂ type were prepared by refluxing 2:1 molar mixtures of guanine (guH) and MCl₂ (M = Co, Cu, Zn) in ethanol-triethyl orthoformate for 2–3 days. Characterization studies suggest that all three new complexes involve distorted tetrahedral configurations. A linear chainlike polymeric structural type with a single-bridged (-MguH-)_n backbone and two terminal chloro ligands per metal ion (MN₂Cl₂ chromophore) is proposed for these compounds, in view of their poor solubility in organic media, their stoichiometry in conjunction with their tetrahedral symmetry, and the reported crystal structures of 9-methyladenine analogs (M = Co, Zn), which are polymeric with single bridges of the adenine derivative between adjacent metal ions. Bidentate bridging guH coordinates exclusively through ring nitrogens, and is most probably N(7), N(9)-bonded. The possibility of use of exocyclic potential ligand sites of guH (CO oxygen or NH₂ nitrogen) in coordination is ruled out by the infrared evidence [1].     

Chromium(III) complexes and their relationship to the glucose tolerance factor. Part II. Structure and biological activity of amino acid complexes

A number of octahedral chromium complexes with amino acids are ligands have been prepared and their structures assigned on the basis of their chromatographic and spectral properties. These include complexes with the general structure Cr(AA)₂(H₂O)₂ where the amino acids glycine, glutamic acid and glutamine act as bidentate ligands. The analogous compound with cysteine as ligand is stable at low pH, but at high pH a terdentate cysteine complex, Cr(cysteine)₂^?, is formed. These complexes, as well as a solution of monodentate glycine aquo complexes, and Cr-nicotinic acid-glycine and Cr-nicotinic acid-cysteine complexes of undetermined structure, have been assayed for glucose tolerance factor activity using a yeast assay. Only Cr(glutamine)₂- (H₂O)₂⁺, Cr-nicotinic acid-glycine and the mixture of complexes Cr(glycine)_n(H₂O)_6-n⁺³ showed significant activity. It is proposed that a trans arrangement of the non-coordinated nitrogen atoms in the ligands of these complexes can mimic the structural features of the glucose tolerance factor which are essential for biological activity.     

Heterocyclic amine adducts of bis(2-thiopyridine N-oxide)nickel(II)

Heterocyclic amine adducts of bis(2-thiopyridine N-oxide)nickel(II), Ni(OS)₂·B (B = pyridine, piperidine, pyrazine and 3,4-lutidine) and Ni(OS)₂·2B (B = 3-picoline, 4-picoline and 3,4-lutidine). In addition, a stable 1:1 adduct was formed with piperazine as well as a thermally unstable 2:1 adduct. The thermal decomposition enthalpies of these adducts and their infrared and electronic spectra are discussed.     

Circularly polarized luminescence studies of the adducts formed with Eu(III) β-diketone complexes and (—)-sparteine

The optical activity resulting from the complexation of (—)-sparteine by a series of Eu(III) β-diketone compounds has been studied by means of circularly polarized luminescence spectroscopy. It was found that the presence of at least one perfluoro group was necessary for the formation of an adduct complex. With Eu(III) complexes containing achiral β-diketone ligands, it was found that the observed chirality could be considered to result from a combination of vicinal and conformational effects. With Eu(III) complexes containing chiral β-diketone ligands, the optical activity was found to be dominated by confïgurational effects.     

Copper(II) halide complexes of 2-aminobenzophenone. Crystal and molecular structure of bis(2-aminobenzophenone)dichlorocopper(II)

The complexes CuX₂L₂ (X = Cl, Br; L = 2-aminobenzophenone) were prepared and characterized by means of magnetic and spectroscopic measurements. For the Cl compound the crystal structure was also determined. Crystals are triclinic, space group P$\text{1}$, with a = 13.397(3), b = 10.752(2), c = 9.205(2) Å, α = 72.26(1)°, β = 91.58(1)°, γ = 106.86(1)°, and Z = 2. The structure was solved by the heavy-atom method and refined by least-squares calculations to R = 0.034 for 2581 counter data. It consists of discrete CuX₂L₂ monomers showing distorted trigonal bipyramidal coordination geometry about the copper ion. The amino nitrogens are axial ligands, with the equatorial positions occupied by two chlorine atoms and a carbonyl oxygen from one L molecule acting as a bidentate ligand. Infrared and ligand field spectroscopies and magnetic measurements, interpreted on the basis of the known crystal structure, also suggest a similar structure for the related Br compound.     

Metal(II) complexes of 1-formylisoquinoline thiosemicarbazone: their preparation,characterization and antitumour activity

Complexes of Co(II), Ni(lI), Cu(II), Zn(II) and Pt(II) with 1-formylisoquinoline thiosemicarbazone (1-iqtsc-H) were prepared and characterized by elemental analyses, conductance measurement and spectral studies. On the basis of these studies a distorted octahedral structure for [Co(1-iqtsc)₂]·2H₂O, a distorted trigonal-bipyramidal structure for [Ni- (1-iqtsc-H)Cl₂], [Cu(1-iqtsc-H)Cl₂] and [Zn(1-iqtsc- H)(OAc)₂]·H₂O and a square-planar structure for [Pt(1-iqtsc)Cl] are suggested. All these metal(II) complexes were screened for their antitumour activity in the P388 lymphocytic leukaemia test system in mice. Except for Pt(Il), the complexes were found to possess significant activity; the Ni(II) complex showed a T/C value of 161 at the optimum dosage.     

Platinum(II) complexes of pyrimidine-derived ligands

A series of new Pt(II) complexes of hydrazinouracils were synthesized and studied. The complexes have the general formula [Pt₂L2^?Cl₂]nH₂O, where L^? is a deprotonated molecule of a ligand, n = 1?3 and there are two bridging chloride ions. The ligands are bonded through the amino group of the hydrazine residue and the nitrogen atom of the pyrimidine cycle. From ¹H NMR data it is concluded that the preferred type of coordination is Pt- N(3), hydrazine chelation, which is characteristic for solid complexes. Although the participation of the N(1) atom in formation on the polynuclear complexes is possible, it may be that N(1) coordination occurs only in solutions.     

The syntheses and properties of cobalt(II), nickel(II) and copper(II) complexes with some heterocyclic dithiocarbamates

New cobalt(II), Nickel(II) and copper(II) dithiocarbamato complexes of the type M(Rdtc)₂ (Rdtc = 4-phenylpiperidinedithiocarbamate and N-phenylpiperazinedithiocarbamate) have been prepared and characterized through elemental analyses, conductivity measurements, spectral (electronic and IR) studies, magnetic moment measurements at different temperatures, e.p.r. techniques and thermal analyses (TG and DTG). The dithioligands exhibit bidentate behaviour in all the complexes. The magnetic moments studies suggest that there is no significant interaction between copper ions, and the e.p.r. data provide parameters typical of sulphur coordination in planar CuS₄ chromophores.     

Antitumor activity and metal complexes of the first transition series. Trans-bis(salicylaldoximato)copper(II) and related copper(II) complexes,a novel group of potential antitumor agents

The antitumor activity of forty nine different metal complexes of the first transition series against mouse leukemia L 1210 cells and of two of the complexes against Ehrlich ascites carcinoma have been tested in vitro by the method described in this paper. Eight complexes showed a 50% inhibition of tumor cell division at concentration level 5–6 μg/ml of the complex for the former and two most effective complexes also for the latter. The trans-bis-(salicylaldoximato)copper(II) and trans-bis(resorcylaldoximato)copper(II) complexes were found to possess the highest antitumor activity.     

In vivo properties of some new cis-platinum complexes containing 7-azaindole ligands

Toxicity data and some preliminary antitumor testing results are reported for the new complexes cis-PtLX₂ (L = 1H-pyrrolo[2,3-b]pyridine, (7-azaindole); X₂ = Cl₂, I₂ oxalate). Although these complexes have the cis-PtN₂X₂ configuration recognised as desirable for effective antitumor behavior, no significant antitumor properties were observed against a number of primary screens; although interesting toxicity differences were observed between the three compounds.     

Dichloro(6-aminoethylaminopurine)platinum(II) and its hydroxy analogues: Synthesis and preliminary evaluation

The synthesis, chemical characterization and functional evaluation are reported for dichloro(6-aminoethylaminopurine)platinum(II) and dichloro(6-hydroxyethylaminopurine)platinum(II) and dichloro(6-hydroxyethylamethylaminopurine)platinum(II) (i.e. Pt(6-AEAP), Pt(6-HEAP) and Pt(6-MHEAP) new complexes of platinum(II). Certain reaction conditions favored the formation of the tripurine platinum complex, but the monopurine complex could be obtained either by hydrolysis of the tripurine or by reacting at reduced temperature and concentration. Although neither compound was as effective as cis-diamminedichloroplatinum(II) (i.e. DDP) at reducing tumor cell viability or proliferation, both were associated with much less renal toxicity than DDP in the mouse kidney (i.e. Pt(6-AEAP):～20 × less; Pt(6-MHEAP): ～100 × less).