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Driven by the growing threat of cancer, many research efforts are directed at developing new chemotherapeutic agents, where the central role is played by transition metal complexes. The proper ligand design serves as a key factor to unlock the anticancer potential of a particular metal center. Following a recent trend, we have prepared unsymmetrical pincer ligands that combine benzothiazole and thiocarbamate donor groups. These compounds are shown to readily undergo direct cyclopalladation, affording the target S,C,N-type Pd(II) pincer complexes both in solution and in the absence of a solvent. The solid-phase strategy provided the complexes in an efficient and ecologically friendly manner. The resulting palladacycles are fully characterized using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy and, in one case, by single-crystal X-ray diffraction (XRD). The solvent-free reactions are additionally analyzed by powder XRD. The pincer complexes exhibit remarkable cytotoxicity against several solid and blood cancer cell lines, including human colorectal carcinoma (HCT116), breast cancer (MCF7), prostate adenocarcinoma (PC3), chronic myelogenous leukemia (K562), multiple plasmacytoma (AMO1), and acute lymphoblastic leukemia (H9), with the dimethylamino-substituted derivative being particularly effective. The latter also induced an appreciable level of apoptosis in both parental and doxorubicin-resistant cells K562 and K562/iS9, vindicating the high anticancer potential of this type of palladacycles. [ABSTRACT FROM AUTHOR]

[Display omitted] In response to rising environmental concerns, chemistry is experiencing a considerable change in both concepts and practices to adopt more efficient and sustainable technologies. One of the alternative technologies that offer many advantages over the conventional solution-based techniques is mechanochemistry which utilizes mechanical energy to induce chemical reactions. Despite the fact that mechanochemistry has reached high significance in the creation of advanced materials, such as alloys, ceramics, electrode materials, and nanocomposites, in the field of small molecule synthesis its potential remains largely untapped. This review highlights the opportunities and prospects of different mechanochemical tools in the synthesis of organometallic compounds, including transition metal complexes with N-heterocyclic carbene, arene, and cyclopentadienyl ligands, monometallacyclic and pincer derivatives, as well as main group metal compounds (e.g. , allyl complexes and the Grignard reagents). Many important organometallic transformations such as C–H bond metalation, transmetalation, and oxidative addition can be successfully implemented under mechanochemical conditions in a highly productive and energy-saving manner. Furthermore, the postmodification of metal-containing species upon grinding or milling is shown to be a powerful route to both new discrete metal complexes and different supramolecular architectures (metal-containing organic cages, macrocylces, networks). [ABSTRACT FROM AUTHOR]

Abstract: P(X)-functionalized enaminoketones (X = O, S) 1a,b have been readily obtained by the condensation of o-(thio)phosphorylated anilines with sodium salt of benzoylacetaldehyde. The ligands derived exist in solution in the expected ketamino tautomeric form, but, unlike typical enaminoketones, tend to exist as cis-isomers in polar media, favored by the formation of the strong P O…HN intramolecular hydrogen bond. This six-membered hydrogen-bonded ring is also observed in the solid structure of 1a, which, nevertheless, features a trans-configuration of the enaminoketone fragment. Independent from the isomeric composition, the ligands obtained readily form κ3-X,N,O (X = O, S) complexes with a range of transition metal ions (Re(I), Pd(II), Cu(II), and Ni(II)) adopting in all cases the cis-configuration. The structures of the novel compounds are confirmed using multinuclear NMR and IR spectroscopy as well as X-ray crystallography. [Copyright &y& Elsevier]

A series of novel oligodentate ligands has been designed by the modular assembly of ortho-(thio)phosphorylated anilines with a range of commercially available carbonyl compounds. The new ligands readily form complexes with a series of metal ions (Pd(II), Cu(II), Ni(II), and Re(I)) both in neutral and deprotonated forms, providing OO, SN, ONO, SNO, SNS, SNN, and ONN donor sets. The structure and composition of the resulting complexes depend on the nature and mutual disposition of the donating groups as well as on the reaction conditions. [ABSTRACT FROM PUBLISHER]

The synthetic approaches to novel families of SCE (E = S',N,O) hybrid pincer-type ligands bearing thophosphoryl, thiophosphoryloxy, and thiophosphorylamino groups in various combinations with thiophosphoryl-, thiocarbamoyl-, and imine- (including that of benzothiazole ring) donating functions have been developed. All of the ligands readily undergo direct cyclometallation (metal = Pd(II), Pt(II)) to afford 5,5- or 5,6-membered pincer complexes. Palladium complexes displayed from high to excellent catalytic performance in the Suzuki cross-coupling reaction of aryl bromides and phenylboronic acid and the higher asymmetry for a complex served as a factor of its higher catalytic activity. [ABSTRACT FROM AUTHOR]