Synthesis, characterization and antibacterial activity of palladium(II) bromide complexes of thioamides; X-ray structure of [Pd(tetramethylthiourea)4]Br2

Abstract

Palladium(II) bromide complexes of thioamides having the general formulae [PdL 2 Br 2 ] and [PdL 4 ]Br 2where L = Thiourea (Tu), Methylthiourea (Metu), Dimethylthiourea (Dmtu), Tetramethylthiourea (Tmtu), Imidazolidine-2-thione (Imt), Mercaptopyridine (Mpy), Mercaptopyrimidine (Mpm) and Thionicotinamide (Tna) were prepared by reacting K 2 [PdCl 4 ] with KBr and the corresponding thioamides. The complexes were characterized by elemental analysis, IR and NMR spectroscopy, and one of them, [Pd(Tmtu) 4 ]Br 2 (1) by X-ray crystallography. The crystal structure of 1 shows a square-planar coordination environment around the Pd(II) atoms with the average cis and trans S-Pd-S bond angles of 90.0°and 180.0°, respectively. The synthesized complexes were screened for antibacterial effects, and the results showed that the complexes exhibit significant activities against both gram positive and gram negative bacteria.

Synthesis, Characterization and Cytotoxicity Evaluation of New Biimidazole Palladium(II) Complexes with Thioureas

“…Secondly, it was noticed a shift of the νCS band to lower frequency [2 (709 cm -1 ), 3 (767 cm -1 ), 4 (751 cm -1 ), 5 (718 cm -1 ) and 6 (906 cm -1 )] when compared with that of the free ligands [tu (730 cm -1 ), mtu (776 cm -1 ), ptu (811 cm -1 ), dmtu (725 cm -1 ) and dptu (933 cm -1 )]. [30][31][32][33][34][35] These spectroscopic modifications clearly indicated an increase of the double bond character of the CN bond and a weakening of the C=S bond, being consistent with S-bonding of thiourea-type ligands in 2-6. 36 According to the literature, 15 one singlet at 2.19 ppm is observed in the 1 H NMR spectrum of the free tmbiimH 2 .…”

“…Among the physical techniques employed to evidence the coordination mode of thiourea-type ligands, IR spectroscopy is one of the most widely used method. [27][28][29][30] The shift of νCN and νCS absorptions is frequently used as diagnosis for S-coordination. Firstly, the intense νCN absorption at 1475 cm -1 (tu), 1556 cm -1 (mtu), 1463 cm -1 (ptu), 1560 cm -1 (dmtu) and 1326 cm -1 (dptu) observable in the IR spectra of the ligands, [30][31][32][33][34][35] decreased in intensity and shifted to 1504 cm -1 (2), 1576 cm -1 (3), 1448 cm -1 (4), 1593 cm -1 (5) after coordination.…”

Pd‐Catalyzed Z‐Selective Semihydrogenation of Alkynes: Determining the Type of Active Species

“…Its strong p-acceptor properties combined with its strong sdonor properties originate from its resonance structures, which make it as trongly binding ligand for low-valent as well as high-valent complexes (Figure 1). [70] Thioureas have been exploited as ligands for Pd-complexes, [71][72][73] Pd-catalyzed reactions, [74][75][76] the removal of trace metal salts from aqueous solutions [77] andt he preparation of coordination polymers. [78] TMTU possesses qualities that are advantageousf or poison ligands.…”

Cross‐Linked Thiazolidine Network as Support for Palladium: A New Catalyst for Suzuki and Heck Reactions

“…In Scheme is reported a tentative picture of the obtained material. Very likely, Pd species can be stabilized through the sulfur atoms of the heterocyclic ligand to give complexes of type PdL 2 Br 2 22. The high‐resolution S 2p core‐level XPS spectrum of material 6 (Figure S6 in the Supporting Information) shows the presence of a broad peak indicating the presence of different sulfur moieties.…”