Synthesis, characterization, thermal, electrochemical, and DFT studies of mononuclear cyclopalladated complexes containing bidentate phosphine ligands and their biological evaluation as antioxidant and antibacterial agents

Abstract

The non-symmetric phosphorus ylides and their Pd(II) complexes have been synthesized as potential antioxidant and antibacterial compounds and their structures were elucidated using a variety of physicochemical techniques. The reaction of 1 equiv non-symmetric phosphorus ylides, Ph 2 PCH 2 PPh 2 C(H)C(O)PhX (X = Br (Y 1 ), Cl (Y 2 ), NO 2 (Y 3 ), OCH 3 (Y 4 )) with [Pd(dppe)Cl 2 ] (M 1 ), followed by treatment with 2 equiv AgOTf led to monomeric chelate complexes, [(dppe)Pd(Ph 2 PCH 2 PPh 2 C(H)C(O)PhX)] (OSO 2 CF 3 ) 2 (X = Br (C 1 ), Cl (C 2 ), NO 2 (C 3 ), OCH 3 (C 4 )), which contain a five-membered P,P chelate ring in one side and a five-membered P,C chelate ring in the other side. Palladium ion complexes were synthesized and investigated by cyclic voltammetry, FT-IR, UV-visible, multinuclear ( 1 H, 31 P and 19 F) NMR, thermal analysis and ESI-mass spectroscopic studies. Some complexes and ligands have been studied by powder XRD and single crystal X-ray diffraction techniques. FT-IR and 31 P NMR studies revealed that the ylides Y are coordinated to the metal ions via the terminal phosphorus (P c ) of the ylides and methene group (CH). The proposed coordination geometry around the Pd atom in these complexes is defined as slightly distorted square planar by UV-Visible and DFT studies. Thermal stability of all complexes was also shown by TG/DTG methods. Furthermore, the electrochemical behavior of the complexes was investigated by cyclic voltammetry. The results indicate that all complexes are successfully synthesized from the initial ligands. All complexes were analyzed for their antioxidant properties by DPPH free radical scavenging assay. In addition, the antibacterial effects of the hexane-solved complexes were investigated by disc diffusion method against four Gram positive and negative bacteria. All complexes represented antibacterial activity against bacteria tested especially on Gram positive ones. A theoretical study on the structure, 1 H and 31 P NMR chemical shifts and the interaction energy between the Pd 2+ ion and ligands dppe and ylide Y is also reported.

A palladium–phosphine catalytic system as an active and recycable precatalyst for Suzuki coupling in water

“…A single anodic peak (A L1 ) was observed on the reverse scan. This behavior is similar to that reported previously by Champness et al [37], Batchelor et al [38], Downard et al [39] and our group [40][41][42] in cyclic voltammetric studies of various types of Pd(II) complexes The cathodic peak C M1 at 1.05 V versus the Ag/AgCl reference electrode can be assigned to the formation of a Pd(0) center with a coordination number between 2 and 4 [or alternatively to an equilibrium mixture of several Pd(0) species] [39,[43][44][45]. There are some examples of stable Pd(0) complexes; particularly relevant is [Pd(L) 2 ] 0 (L = 1,2-bis(dimethylarsino)benzene), which is sufficiently stable to be isolated as a solid [46].…”

Seven-membered Pd(II) complexes containing symmetric phosphorus ylides: Synthesis, characterization and high catalytic activity toward Suzuki cross-coupling reactions

“…IR spectra were recorded on a Shimadzu 435-U-04 spectrophotometer from KBr pellets. 1 H, 13 C and 31 P NMR spectra were recorded on 400 MHz Bruker and 90 MHz Jeol spectrometer in DMSO-d 6 or CDCl 3 as the solvent at 25 8C. Chemical shifts (ppm) are reported according to internal TMS and external 85% phosphoric acid.…”

“…Resonance-stabilized phosphorous ylides, particularly the keto ylides, are used as important ligands in organometallic and coordination chemistry [5][6][7][8][9]. This delocalization also makes these ligands weak nucleophiles, but this does not reduce their interest as ligands.…”

“…Phosphorus ylides of the type Ph 2 P(CH 2 ) n PPh 2 (CHC(O)R) (n = 1, or 2; R = Me, Ph or -OMe), containing phosphine and keto-stabilized phosphorus ylide moieties are also known, and their transition metal complexes are mostly confined to palladium and, to a The reaction of 1,2-bis(diphenylphosphino)ethane (dppe) with various ketones in acetone produces the new phosphonium salts [RC(O)CH 2 PPh 2 (CH 2 ) 2 PPh 2 CH 2 C(O)R]X 2 (R = 2-naphtyl, X = Br (1); R = 2,4-dichlorophenyl, X = Cl (2); R = 3-nitrophenyl, X = Br (3)). Further treatment with a base gives the symmetrical phosphorus ylides, RC(O)CH5PPh 2 (CH 2 ) 2 PPh 2 5CHC(O)R (R = 2-naphtyl (4), 2,4-dichlorophenyl (5), 3-nitrophenyl (6)). These ligands react with Pd(II) chloride to form C,C-chelated complexes with the composition [RC(O)CH5PPh 2 (CH 2 ) 2 PPh 2 5CHC(O)R]PdCl 2 , where R = 2-naphtyl (7), 2,4-dichlorophenyl (8), 3-nitrophenyl (9).…”

Synthesis and Characterisation of Hg(II) Complexes Including Bidentate Phosphorus Ylides

“…Coordination of ligands towards Hg(II) has assumed importance since, in mercury's detoxification process, the initial Hg-C bond cleavage involves the increase in the coordination number around Hg. [26][27][28][29][30][31][32][33][34][35] In the present work, a series of Hg(II) complexes with ligand systems were prepared and their antibacterial activities were screened. 25 Here, we report the synthesis and characterisation of Hg(II) complexes with new asymmetrical phosphorus ylides derived from bis(diphenylphosphino) methane.…”