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A synthetic route to the preparation of cobalt(III) complexes coordinated by bidentate phenylthioether ligands is described. Complexes of the type ((2-(X-phenylthio)ethylamine)- N , S)bis(ethylenediamine)cobalt(III) perchlorate, [(en)2Co(S (X-phenyl)CH2CH2 N H2)](ClO4)3, where X = 4-methoxy (2a), 4-methyl (2b), 3-methyl (2c), nothing (2d), 3-methoxy (2e), 4-bromo (2f) and 3-bromo (2g) were prepared. The synthetic route involves reaction of trans -dichloridobis(ethylenediamine)cobalt(III) chloride with NH2CH2CH2SC6H4X to produce cis -[(en)2CoCl(N H2CH2CH2SC6H4X)]Cl2 (1a – g). Formation of the Co–S bond, completing the ring closure, is then accomplished by removing the coordinated chlorido by addition of AgClO4 in sulfolane. Complexes were characterized by 1H and 13C NMR spectroscopy, UV-Vis spectroscopy and elemental analysis. In addition, the solid-state structure (X-ray) of the monohydrate of 2d confirms the coordination mode of the ligand. Preliminary kinetic investigations in basic solution show that the Co–S bond is broken resulting in the formation of [(en)2Co(OH)(N H2CH2CH2SC6H4X)]2+. At 15.0°C, a Hammett Plot is linear (r 2 = 0.981) with ρ = 2.24 ± 0.13. We have prepared a series of cobalt(III) complexes coordinated in a κ 2N,S manner by substituted phenylthioether ligands. The preparation is a two-step process starting with trans- dichloridobis(ethylenediamine)cobalt(III) chloride. NMR spectroscopy was used to characterize the complexes. In addition, the presence of an intense ligand-to-metal charge-transfer transition in the UV region confirms that a sulfur atom is bonded to the cobalt(III) center. In basic solution, the Co–S bond is broken, presumably by the classical SN1CB mechanism. The rate of the cleavage reaction increases as the electron-withdrawing ability of the phenyl substituent increases. (Image credit: Lee Roecker.) [ABSTRACT FROM AUTHOR]

Towards the goal of generating new stabilized gold complexes as potent anticancer agents, we report here a novel class of Au(I) agents from Au(III)-mediated C aryl -P bond formation captured within the same complex by reacting a C^N cyclometalated Au(III) complex with bisphosphines. Cyclometalated Au(III) complexes of the type [Au(C^N)Cl 2 ], where C^N represent different aryl pyridine framework reacted with bis(2-diphenylphosphino)phenyl ether in refluxing methanol to access an unsymmetrical gold complex featuring C-P coupling and Au(I)-phosphine. The complexes were characterized by 1 H-NMR, 13 C-NMR, and 31 P-NMR and mass spectrometry. The structures of the complexes were characterized by X-ray crystallography and purity ascertained by HPLC and elemental analysis. The complexes demonstrate promising anticancer activity in a broad panel of cancer cell lines of different tumor origin. Mechanistically, the complexes induce apoptosis, generate mitochondrial ROS, depolarize mitochondrial membrane potential and modulate mitochondrial respiration in cancer cells. Overall, we developed a new structural class of Au(I) complexes with promising anticancer potential with potential utility in other applications.

The synthesis, crystal structure, and a Hirshfeld surface analysis of tris-{ N , N -diethyl- N '-[(4-nitro-phen-yl)(oxo)meth-yl]carbamimido-thio-ato}cobalt(III) conducted at 180 K are presented. The complex consists of three N , N -diethyl- N '-[(4-nitro-benzene)(oxo)meth-yl]carbamimido-thio-ato ligands, threefold sym-metric-ally bonded about the Co III ion, in approximately octa-hedral coordination, which generates a triple of individually near planar metallacyclic (Co-S-C-N-C-O) rings. The overall geometry of the complex is determined by the mutual orientation of each metallacycle about the crystallographically imposed threefold axis [dihedral angles = 81.70 (2)°] and by the dihedral angles between the various planar groups within each asymmetric unit [metallacycle to benzene ring = 13.83 (7)°; benzene ring to nitro group = 17.494 (8)°]. The complexes stack in anti-parallel columns about the axis of the space group ( P ), generating solvent-accessible channels along [001]. These channels contain ill-defined, multiply disordered, partial-occupancy solvent. Atom-atom contacts in the crystal packing predominantly (∼96%) involve hydrogen, the most abundant types being H⋯H (36.6%), H⋯O (31.0%), H⋯C (19.2%), H⋯N (4.8%), and H⋯S (4.4%)., (© Roecker and Parkin 2024.)

Syntheses of the acyclic amidinium salts, morpholino-formamidinium hexa-fluorido-phosphate [OC 4 H 8 N-CH=NH 2 ]PF 6 or C 5 H 11 N 2 O + ·PF 6 - , 1 , and pyrrolidinoformamidinium hexa-fluorido-phosphate [C 4 H 8 N-CH= NH 2 ]PF 6 or C 5 H 11 N 2 + ·PF 6 - , 2 , were carried out by heating either morpholine or pyrrolidine with triethyl orthoformate and ammonium hexa-fluorido-phosphate. Crystals of 1 obtained directly from the reaction mixture contain one cation and one anion in the asymmetric unit. The structure involves cations linked in chains parallel to the b axis by N-H⋯O hydrogen bonds in space group Pbca , with glide-related chains pointing in opposite directions. Crystals of 1 obtained by recrystallization from ethanol, however, showed a similar unit cell and the same basic structure, but unexpectedly, there was positional disorder [occupancy ratio 0.639 (4):0.361 (4)] in one of the cation chains, which lowered the crystal symmetry to the non-centrosymmetric space group Pca2 1 , with two cations and anions in the asymmetric unit. In the pyrrolidino compound, 2 , cations and anions are ordered and are stacked separately, with zigzag N-H⋯F hydrogen-bonding between stacks, forming ribbons parallel to (101), extended along the b -axis direction. Slight differences in the delocalized C=N distances between the two cations may reflect the inductive effect of the oxygen atom in the morpholino compound., (© Neary et al. 2024.)