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Novel platinum(II) and palladium(II) chlorido complexes with tetrazole derivatives 1-(2-hydroxyethyl)tetrazole (het) and 1-[tris(hydroxymethyl)methyl]tetrazole (thm), viz. cis-[Pt(het)2Cl2], trans-[Pt(het)2Cl2], trans-[Pt(thm)2Cl2], trans-[Pd(het)2Cl2], and trans-[Pd(thm)2Cl2], were synthesized. The compounds were characterized by elemental and high-resolution electrospray ionization (HRESI) mass spectrometry, high-performance liquid chromatography (HPLC), 1H, 13C and 195Pt nuclear magnetic resonance (NMR) spectroscopy, thermal analyses, and Infrared (IR) spectroscopy. Molecular and crystal structures of trans-[PdL2Cl2] and trans-[PtL2Cl2] (L = het, thm) were established by single-crystal X-ray analysis. The complex cis-[Pt(het)2Cl2] was found to undergo cis–to–trans isomerization upon heating in acetonitrile solution and in the solid state. The synthesized complexes show rather high water solubility lying in the range of 2–10 mg/L. [ABSTRACT FROM AUTHOR]

Novel platinum(II) and palladium(II) chlorido complexes with tetrazole derivatives 1-(2-hydroxyethyl)tetrazole (het) and 1-[tris(hydroxymethyl)methyl]tetrazole (thm), viz. cis-[Pt(het)2Cl2], trans-[Pt(het)2Cl2], trans-[Pt(thm)2Cl2], trans-[Pd(het)2Cl2], and trans-[Pd(thm)2Cl2], were synthesized. The compounds were characterized by elemental and high-resolution electrospray ionization (HRESI) mass spectrometry, high-performance liquid chromatography (HPLC), 1H, 13C and 195Pt nuclear magnetic resonance (NMR) spectroscopy, thermal analyses, and Infrared (IR) spectroscopy. Molecular and crystal structures of trans-[PdL2Cl2] and trans-[PtL2Cl2] (L = het, thm) were established by single-crystal X-ray analysis. The complex cis-[Pt(het)2Cl2] was found to undergo cis–to–trans isomerization upon heating in acetonitrile solution and in the solid state. The synthesized complexes show rather high water solubility lying in the range of 2–10 mg/L. [ABSTRACT FROM AUTHOR]

Bis-ADC complexes cis-[Pd{C(NHC6H4NH2)N(H)R}2]Cl2 (R = Xyl 4a, Cy 4b, C6H4-4-F 4c) and cis-[Pt{C(NHC6H4NH2)N(H)R}2]Cl2 (R = Xyl 5a, Cy 5b, C6H4-4-F 5c) were synthesized via the metal-mediated coupling of two isocyanide ligands in cis-[MCl2(CNR)2] (M = Pd, Pt; R = Xyl, Cy, C6H4-4-F) and 1,2-diaminobenzene. New compounds 4c and 5a–c were characterized by HR ESI+-MS, IR, and 1H, 13C{1H} and 195Pt{1H} NMR spectroscopy; the structures of 4a and 5a were elucidated by single-crystal X-ray diffraction. The stability of the ADC complexes in aqueous media (5 mM NaCl) was monitored by UV absorption spectroscopy, HR ESI+ mass spectrometry, and 195Pt{1H} NMR spectroscopy (for 5a). Molar conductivity measurements in MeOH (ΛM = 167–173 Ω−1 mol−1 cm2) indicate that, in this solvent, the ADC complexes exist as dicationic species of [A][Q]2 type. The ADC complexes binding to CT DNA was investigated by means of spectroscopic and hydrodynamic techniques including UV absorption and circular dichroism spectroscopy, fluorescence spectroscopy, low-gradient viscometry, flow birefringence, and AFM imaging. As a result, complexes 4a and 5a were shown to bind double-stranded DNA predominantly via the formation of monofunctional adducts in the major groove of the macromolecule. Binding of the ADC complexes also provokes the formation of a large number of intermolecular DNA–DNA contacts in solution. The antiproliferative activity of all prepared ADC complexes 4a–c and 5a–c was evaluated in vitro against three human carcinoma cell lines (HT-29, MDA-MB-231, and MCF-7) and two non-tumorigenic cell lines (L929 and RC-124) and compared to that of cisplatin. Among the compounds studied, complexes 4a and 5a appeared to be the most active species with IC50 values in MCF-7 cells of about 10 μM. [ABSTRACT FROM AUTHOR]

Complexes [Cu 2 L 2 Cl 4 ], [NiL 2 Cl 2 ], [PdLCl 2 ], and [PtLCl 2 ], where L is a novel ligand from the series of 2-subsituted 5-(α-aminoalkyl)tetrazoles, namely 5-( N , N -dimethylaminomethyl)-2- tert -butyltetrazole, have been synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray analysis. The complexes reported show different coordination geometries of the metals, viz. octahedral for Ni, square pyramidal for Cu, and square planar for Pt and Pd complexes. At the same time, the ligand L demonstrates the same coordination mode in all the complexes. It acts as a chelating ligand coordinated to the metal via two nitrogen atoms, namely the tetrazole ring N 4 and the dimethylamino N atoms. Complex [PtLCl 2 ] was found to have promising antiproliferative activity against human cervical carcinoma cells, with IC 50 value being average between those of cisplatin and carboplatin. The temperature-dependent magnetic susceptibility measurements of complex [Cu 2 L 2 Cl 4 ] revealed that the copper(II) ions were weakly antiferromagnetically coupled showing a coupling constant J of −2 cm −1 . [ABSTRACT FROM AUTHOR]

2-R-2 H-Tetrazol-5-ylacetic acids (abbreviated as 2-R-taa; R = Me, iPr, tBu) react with K2[PtCl4] in 1 m HCl in H2O at r.t. furnishing trans-platinum(II) complexes trans-[PtCl2(2-R-taa)2] ( 1- 3), whereas cis-isomeric species cis-[PtCl2(2-R-taa)2] (R = iPr, 4; tBu, 5) are isolated at lower temperature (4-6 °C). In the presence of EtOH in the reaction mixture, esterification of the tetrazol-5-ylacetoxy group of 2- tBu-taa leads to trans-[PtCl2(ethyl 2- tert-butyl-2 H-tetrazol-5-ylacetate)2] ( 6). Complexes 1- 6 were characterized by elemental analyses (CHN), HRESI+-MS, 1H, 13C{1H}, 195Pt{1H} NMR and IR spectroscopy, differential scanning calorimetry/thermogravimetry (DSC/TG), and X-ray diffraction (for 1·H2O, 2, 3·2H2O, 4, 5·2H2O, and 6). The generation of the tetrazole-based complexes in solution (1 m DCl in D2O, 25 °C) was studied by 1H NMR spectroscopy and HPLC-MS. The obtained data indicate the initial formation of anionic [PtCl3(2-R-taa)]- complexes that are subsequently converted into disubstituted isomeric platinum(II) species cis- and trans-[PtCl2(2-R-taa)2]. By contrast to cis- and trans-[PtCl2(2-R-taa)2] that were inactive in two human cancer models in vitro (IC50 > 100 µ m), complex 6 demonstrated noticeable antiproliferative effects in HT-29 colon and MCF-7 breast carcinoma cell lines with IC50 values of 14.2 ± 1.1 and 5.8 ± 1.2 µ m, respectively. [ABSTRACT FROM AUTHOR]

One of two PtIV-activated propanenitriles in trans-[PtCl4(EtCN)2] is involved in platinum(iv)-mediated nitrile–imine coupling with the platinum(ii)-based metallacycles [PtCl2{NH=C(NR2)N(Ph)C(=NH)N(Ph)C(NR2)=NH}] [R2 = Me2 (1a), C5H10 (1b)] yielding diplatinum products, whose structures depend on molar ratios between the reactants. At a 1 : 1 ratio, the mixed-valence platinum(ii)/platinum(iv) species [PtCl4{NH=C(NR2)N(Ph)C{=[(N(Et)C=NH)PtCl2(EtCN)]}N(Ph)C(NR2)=NH}] [R2 = Me2 (2a), (CH2)5 (2b)] were generated, whereas at a 1 : 2 ratio the dinuclear platinum(ii)/platinum(ii) complexes [PtCl2{NH=C(NR2)N(Ph)C{=[(N(Et)C=NH)PtCl2(EtCN)]}N(Ph)C(NR2)=NH}] [R2 = Me2 (3a), (CH2)5 (3b)] were obtained. In contrast to the nitrile–imine coupling observed for the platinum(iv) dinitrile complex, the reaction between the platinum(ii) congener trans-[PtCl2(EtCN)2] and any one of 1a,b gives exclusively the substituted dimetallic platinum(ii)/platinum(ii) products [PtCl2{NH=C(NR2)N(Ph)C{=[(NH)PtCl2(EtCN)]}N(Ph)C(NR2)=NH}] [R2 = Me2 (6a), (CH2)5 (6b)] featuring platinum-containing guanidine 1 as one of the ligands. Complexes 2a,b, 3a,b, and 6a,b were characterized by elemental analyses (C, H, N), HRESI-MS, IR, 1H NMR spectroscopy, and DTA/TG. The molecular and crystal structure of 2a·2CDCl3 was additionally studied by single-crystal X-ray diffraction. Complexes 2a,b undergo further redox transformation in solutions, and single crystals of [PtCl2{NH=C(NMe2)N(Ph)C{=[(N(Et)C=NH)PtCl2(MeCN)]}N(Ph)C(NMe2)=NH}]·2CH2Cl2 (3′a·2CH2Cl2) were obtained from 2a in a CH2Cl2–MeCN–C2H4Cl2 mixture and studied by X-ray crystallography. The driving forces for the generation of diplatinum products 2 and 3 were elucidated based on a quantum-chemical study. [ABSTRACT FROM AUTHOR]

Gold(I) complexes with phosphane and thiotetrazolate ligands were prepared and investigated as a new type of bioactive gold metallodrugs. The complexes triggered very efficient inhibition of the enzyme thioredoxin reductase (TrxR), which is an important molecular target for gold species. Strong cytotoxic effects were observed in MDA-MB-231 breast adenocarcinoma and HT-29 colon carcinoma cells, and the complexes also caused strong effects in vincristine resistant Nalm-6 leukemia cells. Cellular uptake studies showed elevated cellular gold levels for complexes containing a triphenylphosphane ligand, whereas trifurylphosphane analogues accumulated at significantly lower cellular concentrations. [ABSTRACT FROM AUTHOR]

Abstract: Two series of tetrazole-containing platinum(II) and palladium(II) chlorido complexes, trans-[ML2Cl2] (M=Pt, Pd) and cis-[PtL2Cl2]·nH2O (n =0, 1), where L is 1- or 2-substituted 5-aminotetrazole, have been synthesized and thoroughly characterized. Configuration of platinum(II) complexes obtained from the reaction of 5-aminotetrazoles with K2PtCl4 has been found to vary depending on the nature of tetrazole derivatives and reaction conditions. According to in vitro cytotoxic evaluation, only platinum complexes display noticeable antiproliferative effect, and their cytotoxicity depends strongly on their geometry and hydrophobicity of the carrier ligands. The most promising complexes are cis-[Pt(1-apt)2Cl2]·H2O and cis-[Pt(2-abt)2Cl2]·H2O, where 1-apt is 5-amino-1-phenyltetrazole and 2-abt is 5-amino-2-tert-butyltetrazole. In comparison with cisplatin, they show comparable cytotoxic potency against cisplatin-sensitive human cancer cell lines, cis-[Pt(2-abt)2Cl2]·H2O performing substantially higher activity against cisplatin-resistant cell lines. Cell cycle studies in H1299 cell line indicated that cis-[Pt(2-abt)2Cl2]·H2O induced apoptosis launched from G2 accumulations. The DNA interaction with cis-[Pt(1-apt)2Cl2]·H2O was followed by UV spectroscopy, circular dichroism, hydrodynamic and electrophoretic mobility studies. Both cis-[Pt(1-apt)2Cl2]·H2O and cis-[Pt(2-abt)2Cl2]·H2O complexes appeared to be significantly less toxic than cisplatin in mice, while only compound cis-[Pt(1-apt)2Cl2]·H2O displayed noticeable efficacy in vivo. [Copyright &y& Elsevier]

Abstract: Complexes ML1 2 and ML2 2, with M=FeII, CoII, NiII, and 1,3-bis(2-R-tetrazol-5-yl)triazenide ligands L1 (R=Me) and L2 (R= tBu), have been synthesized by the reaction of corresponding 1,3-bis(2-R-tetrazol-5-yl)triazenes with metal(II) salts in basic media and characterized by IR, UV–Vis spectroscopy, thermal and X-ray diffraction analyses. Both 1,3-bis(2-R-tetrazol-5-yl)triazenes were found to deprotonate on coordination and act as tridentate chelating ligands forming distorted MN6 octahedra around metal(II) cations. [ABSTRACT FROM AUTHOR]

Abstract: Complexes CuL3Cl2, PdL2Cl2 and PtL2Cl2, where L is a novel ligand from the series of 2-substituted 5-aminotetrazoles, namely 5-amino-2-tert-butyltetrazole (1), have been synthesized by the reaction of metal(II) chlorides with 1 and characterized by IR spectroscopy, thermal and X-ray analyses. The crystallographic structural analysis of these complexes revealed that 1 acts as a monodentate ligand coordinated to the metal via endocyclic N4 atom. Platinum complex demonstrates promising cytotoxicity against human cervical carcinoma cells with IC50 value average between those of cisplatin and carboplatin. [Copyright &y& Elsevier]

Hydrolytically stable PdII and PtII complexes supported by acyclic diaminocarbene ligands represent a novel class of structural organometallic anticancer agents exhibiting nanomolar antiproliferative activity in a panel of cancer cell lines (IC50 0.07–0.81 μM) and up to 300‐fold selectivity for cancer cells over normal primary fibroblasts. The lead drug candidate was 300 times more potent than cisplatin in vitro and showed higher efficacy in reducing the growth of aggressive MDA‐MB‐231 xenograft tumors in mice. [ABSTRACT FROM AUTHOR]

Abstract: Tetrazol-2-ylacetic acid (2-TzaH) was found to react with CuCl2, PdCl2, and K2PtCl4 in water giving Cu(2-Tza)2, PdCl2(2-TzaH)2·2H2O and PtCl2(2-TzaH)2, correspondingly. Obtained complexes, being the first reported examples of coordination compounds derived from 2-TzaH, have been characterized by IR spectroscopy, thermal and X-ray diffraction methods. 2-TzaH was found to act as a monodentate ligand coordinated to the metal ion via N4 atom of heteroring in palladium complex and as tridentate bridging ligand coordinated via N4 atom and two oxygen atoms in copper complex. Cu(2-Tza)2 presents 2D coordination polymer, whereas PdCl2(2-TzaH)2·2H2O is molecular complex. [Copyright &y& Elsevier]

While bis(1-methyl-1 H-tetra­zol-5-yl)diazene, C4H6N10, (I), has no crystallographically imposed symmetry, in the two title chloro­copper(I) complexes, [Cu2Cl2(C4H6N10)] n, (II), and [CuCl(C4H6N10)] n, (III), the organic ligands lie across centres of inversion; in (III), the Cu and Cl atoms additionally lie about a twofold rotation axis in the space group P2/ c. Complex (II) forms a two-dimensional coordination polymer containing tetra­hedrally coordinated CuI atoms, and complex (III) forms a one-dimensional coordination polymer containing five-coordinate square-pyramidal CuI atoms. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue are Tatiyana Serebryanskaya, Mikhail Kinzhalov and co‐workers at St. Petersburg State University, the Research Institute for Physical Chemical Problems, Belarusian State University, Togliatti State University and Blokhin National Medical Research Center of Oncology. The image depicts the shield of Pallas Athena with the structure of a palladium carbene complex that protects against triple‐negative breast cancer. Read the full text of the article at 10.1002/chem.202400101. [ABSTRACT FROM AUTHOR]

The article titled "Metal-(Acyclic Diaminocarbene) Complexes Demonstrate Nanomolar Antiproliferative Activity against Triple-Negative Breast Cancer" discusses the use of a palladium compound to target aggressive tumors while sparing normal cells and tissues. The authors draw inspiration from the protective figure of Pallas Athena, which symbolizes the original meaning of the word "palladium." The research article provides more detailed information on this topic and can be accessed using the provided DOI. [Extracted from the article]

Abstract A synthesis of the PdII and PtII N , N -diaryldiazabutadiene complexes and their self-assembly into infinite 1-dimensional chains in the solid state via rare C (sp2)–H ... Hal hydrogen bonding is reported. All the new compounds were characterized using elemental analyses (C, H, N), ESI-MS, IR, 1H and 13C NMR techniques and X-ray diffraction analysis. The nature and energies of intermolecular non-covalent interactions, which are responsible for the supramolecular polymerization, were studied theoretically using DFT calculations and topological analysis of the electron density distribution within the formalism of Bader's theory (QTAIM method). While chloro-complexes, which feature a relatively stronger C (sp2)–H ... Hal hydrogen bonding, form supramolecular polymers, the iodo-derivative does not self-assemble into 1-D chains due to the dominance of other crystal packing forces over the potential H⋯I contacts. Thus, the C (sp2)–H ... Hal HB can dictate a packing preference in the solid state and serve as a useful tool for supramolecular engineers. Graphical abstract Image 1 Highlights • Synthesis of the new PdII and PtII N , N -diaryldiazabutadiene complexes. • Self-assembly of the new complexes into 1-dimensional chains in the solid state via C (sp2)–H ... Hal hydrogen bonding. • X-ray diffraction analysis of the new materials. • Theoretical study of the nature and energies of intermolecular non-covalent interactions. [ABSTRACT FROM AUTHOR]

The synthesis of 2-pyridyltellurenyl bromide via Br2 oxidative cleavage of the Te–Te bond of dipyridylditelluride is reported. Single-crystal X-ray diffraction analysis of 2-pyridyltellurenyl bromide demonstrated that the Te atom of 2-pyridyltellurenyl bromide was involved in four different noncovalent contacts: Te⋯Te interactions, two Te⋯Br ChB, and one Te⋯N ChB contact forming 3D supramolecular symmetrical framework. In contrast to 2-pyridylselenenyl halides, the Te congener does not react with nitriles furnishing cyclization products. 2-Pyridylselenenyl chloride was demonstrated to easily form the corresponding adduct with benzonitrile. The cyclization product was studied by the single-crystal X-ray diffraction analysis, which revealed that in contrast to earlier studied cationic 1,2,4-selenadiazoles, here we observed that the adduct with benzonitrile formed supramolecular dimers via Se⋯Se interactions in the solid state, which were never observed before for 1,2,4-selenadiazoles. [ABSTRACT FROM AUTHOR]