The reactions of ruthenium(II) complexes, [RuHCl(CO)(PPh3)2(B)] [B = PPh3, pyridine (py) or piperidine (pip)], with bidentate Schiff base ligands derived by condensing salicylaldehyde with aniline, o-, m- or p-toluidine have been carried out. The products were characterised by analytical, i.r., electronic, 1H-n.m.r. and 31P-n.m.r. spectral studies and are formulated as [RuCl(CO)(L)(PPh3)(B)] (L = Schiff base anion; B = PPh3, py or pip). An octahedral structure has been tentatively proposed for the new complexes. The Schiff bases and the new complexes were tested in vitro to evaluate their activity against the fungus Aspergillus flavus.

Ruthenium(II) complexes containing bidentate Schiff bases and their antifungal activity

Cd(II) and Cu(II) complexes of polydentate Schiff base ligands: synthesis, characterization, properties and biological activity

Synthesis, structure and biological activity of cobalt(II) and copper(II) complexes of valine-derived schiff bases.

A series of dinuclear complexes [{(L1–4)ClRuII}2(μ-tppz)][ClO4]2
{[1](ClO4)2 to [4](ClO4)2} has been prepared, in which two {RuII(L1–4)Cl}+ fragments [L = a 2-arylazopyridine ligand of the type 2-(C5H4N)–NN–C6H4R; for L1, R = H; L2, R =
p-Me; L3, R =
p-Cl; L4, R =
m-Me] are linked by the bridging ligand tppz [2,3,5,6-tetrakis(2-pyridyl)pyrazine]. A single isomer forms during the synthesis in each case, and the crystal structure of [4](ClO4)2 shows it to be a twofold-symmetric isomer with each ligand L arranged such that its pyridine donor is on the long axis of the molecule (trans to the pyrazine ring of tppz) and the azo donor is trans to one of the pyridyl donors of tppz. This allows the peripheral aryl ring attached to the azo unit of each ligand L to be oriented over either face of the bridging ligand giving a three-layer π-stacked (aryl–pyrazine–aryl) sandwich. Electrochemical studies revealed (i) separations of 190–250 mV (depending on the aryl substituent of L) between the successive Ru(II)/Ru(III) couples, indicative of a significant inter-metallic electronic coupling, and (ii) several ligand-based reductions of the π-acceptor pyrazine and arylazopyridine ligands. A UV/Vis/NIR spectroelectrochemical study showed the presence of an IVCT transition at ca. 1900 nm in MeCN for the Ru(II)–Ru(III) mixed-valence states, whose narrowness is indicative of borderline class III behaviour. Several reduced forms of the complexes were also spectroscopically characterised.

Dinuclear ruthenium(II) complexes [{(L)ClRuII}2(μ-tppz)]2+ (L = an arylazopyridine ligand) incorporating tetrakis(2-pyridyl)pyrazine (tppz) bridging ligand: synthesis, structure and spectroelectrochemical properties

Synthesis, characterization, electro chemistry, catalytic and biological activities of ruthenium(III) complexes with bidentate N, O/S donor ligands.

New salicylaldimine chelates of divalent and trivalent ruthenium have been synthesized from RuCl2(PPh3)3. The RuII complex trans- Ru(salen)(PPh3)2 is stable in the solid but very unstable to oxidation in solution. The RuIII derivative, Ru(salen)Cl(PPh3), displays magnetic and e.s.r. properties consistent with a low-spin d5 system under a ligand-field of rhombic symmetry.

den Bergen Am Van

Papers

Ruthenium complexes with a tetradentate salicylaldimine Schiff base