Ruthenium piano-stool complexes bearing imidazole-based PN ligands

A variety of piano-stool complexes of cyclopentadienyl ruthenium(II) with imidazole-based PN ligands have been synthesized starting from the precursor complexes CpRu(C10H8)]PF6, CpRu(NCMe)(3)]PF6 and CpRu(PPh3)(2)Cl]. PN ligands used are imidazol-2-yl, -4-yl and -5-yl phosphines. Depending on the ligand and precursor different types of coordination modes were observed; in the case of polyimidazolyl PN ligands these were kappa P-1-monodentate, kappa P-2,N-, kappa N-2,N- and kappa N-3,N,N-chelating and mu-kappa P:kappa N-2,N-brigding. The solid-state structures of CpRu(1a)(2)Cl]center dot H2O (5 center dot H2O) and {CpRu(mu-kappa(2)-N,N-kappa('1)-P-2b)}(2)](C6H5PO3H)(2)(C6H5PO3H2)( 2), a hydrolysis product of the as well determined {CpRu(2b)} (2)](PF6)(2)center dot 2CH(3)CN (7b center dot 2CH(3)CN) were determined (1a = imidazol-2-yldiphenyl phosphine, 2b = bis(1-methylimidazol-2-yl) phenyl phosphine, 3a = tris(imidazol-2-yl) phosphine). Furthermore, the complexes CpRu(L)(2)]PF6 (L = imidazol-2-yl or imidazol-4-yl phosphine) have been screened for their catalytic activity in the hydration of 1-octyne. (C) 2011 Elsevier B. V. All rights reserved

Designing organometallic compounds for catalysis and therapy

Bioorganometallic chemistry is a rapidly developing area of research. In recent years organometallic compounds have provided a rich platform for the design of effective catalysts, e.g. for olefin metathesis and transfer hydrogenation. Electronic and steric effects are used to control both the thermodynamics and kinetics of ligand substitution and redox reactions of metal ions, especially Ru II. Can similar features be incorporated into the design of targeted organometallic drugs? Such complexes offer potential for novel mechanisms of drug action through incorporation of outer-sphere recognition of targets and controlled activation features based on ligand substitution as well as metal- and ligand-based redox processes. We focus here on η 6-arene, η 5-cyclopentadienyl sandwich and half-sandwich complexes of Fe II, Ru II, Os II and Ir III with promising activity towards cancer, malaria, and other conditions. © 2012 The Royal Society of Chemistry

Novel multitopic diphos-type ligands

Seven novel imidazole and thiazole derivatives of diphos-type ligands are presented. They are of the general structure R2P(CH2)(2)PR2, where R is imidazol-2-yl (1), 1-methylimidazol-2-yl (2), 1-methyl-benzimidazol-2-yl (3), 1-methylimidazol-5-yl (4), 2-isopropylimidazol-4(5)-yl (5), thiazol-2-yl (6), benzothiazol-2-yl (7), thiazol-4-yl (8) or thiazol-5-yl (9). Syntheses involved direct metallation or halogen-metal exchange reactions. Their solubility, especially in aqueous solution, is strongly dependent on the nature of the substituents as is their partition coefficient log D. The crystal structures of compounds 2, 3, 7a and 9 as well as the structure of the rhodium complex (2)(2)Rh2Cl2]Cl-2 (10) have been determined. (C) 2010 Elsevier B. V. All rights reserved

Synthesis, X-ray crystal structure and cytotoxicity of a new tetranuclear ruthenium arene complex

The tetranuclear ruthenium arene compound [(cym)4Ru4(2)Cl6]Cl2 (3) (cym = η6-p-cymene, 2 = 1,2-bis(di-N-methylimidazol-2-ylphosphino)ethane) was prepared and characterised by one- and two-dimensional NMR techniques. Its cytotoxicity against four different cell lines was determined and, with an approximate IC50 of >100 μM 3 can be regarded as non-toxic. Its partition coefficient in n-octanol/water (log D7.4) was also determined. The structures of complex 3 as well as of the related compound [(cym)2Ru2(4)Cl2]Cl2 (5) (4 = 1,2-bis(di-N-methylimidazol-2-ylphosphino)ethane dioxide) were determined by single crystal structure analysis. Upon oxidation in protic solvents, ligand 2 shows P–C bond cleavage reactions to yield P,P′-bis(N-methylimidazol-2-yl)ethylene diphosphinic acid (6)