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Mononuclear and dinuclear Ru(II) complexes cis -[Ru(κ 2 -dppm)(bpy)Cl 2 ] ( 1 ), cis -[Ru(κ 2 -dppe)(bpy)Cl 2 ] ( 2 ) and [Ru 2 (bpy) 2 (μ-dpam) 2 (μ-Cl) 2 ](Cl) 2 ([ 3 ](Cl) 2 ) were prepared from the reactions between cis (Cl), cis (S)-[Ru(bpy)(dmso- S ) 2 Cl 2 ] and diphosphine/diarsine ligands (bpy = 2,2'-bipyridine; dppm = 1,1-bis(diphenylphosphino)methane; dppe = 1,2-bis(diphenylphosphino)ethane; dpam = 1,1-bis(diphenylarsino)methane). While methoxy-substituted ruthenafuran [Ru(bpy)(κ 2 -dppe)(C^O)] + ([ 7 ] + ; C^O = anionic bidentate [ C (OMe)CHC(Ph) O ] - chelate) was obtained as the only product in the reaction between 2 and phenyl ynone HC≡C(C=O)Ph in MeOH, replacing 2 with 1 led to the formation of both methoxy-substituted ruthenafuran [Ru(bpy)(κ 2 -dppm)(C^O)] + ([ 4 ] + ) and phosphonium-ring-fused bicyclic ruthenafuran [Ru(bpy)(P^C^O)Cl] + ([ 5 ] + ; P^C^O = neutral tridentate [(Ph) 2 P CH 2 P(Ph) 2 C CHC(Ph) O ] chelate). All of these aforementioned metallafuran complexes were derived from Ru(II)-vinylidene intermediates. The potential applications of these metallafuran complexes as anticancer agents were evaluated by in vitro cytotoxicity studies against cervical carcinoma (HeLa) cancer cell line. All the ruthenafuran complexes were found to be one order of magnitude more cytotoxic than cisplatin, which is one of the metal-based anticancer agents being widely used currently.

A novel approach to design bimetallic anticancer drug candidates with the capability to combat both drug resistance and tumor metastasis is reported. These water-soluble bifunctional Pt(iv)-Ru(ii) heterodinuclear complexes with a unique mode of action display up to 2-orders of magnitude enhanced cytotoxicity in cisplatin-resistant cells and significantly impede cancer cell migration.

Polypyridyl and related ligands have been widely used for the development of water oxidation catalysts. Supposedly these ligands are oxidation-resistant and can stabilize high-oxidation-state intermediates. In this work a series of ruthenium(II) complexes [Ru(qpy)(L)2 ](2+) (qpy=2,2':6',2'':6'',2'''-quaterpyridine; L=substituted pyridine) have been synthesized and found to catalyze Ce(IV) -driven water oxidation, with turnover numbers of up to 2100. However, these ruthenium complexes are found to function only as precatalysts; first, they have to be oxidized to the qpy-N,N'''-dioxide (ONNO) complexes [Ru(ONNO)(L)2 ](3+) which are the real catalysts for water oxidation., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Small-molecule inhibitors of poly(ADP-ribose) polymerase-1 (PARP-1) have currently drawn much attention as promising chemotherapeutic drug candidates, and there is a need to develop more potent PARP inhibitors with improved bioavailability. Here we report a strategy to improve the cytotoxicity of PARP inhibitors by conjugation with organometallic ruthenium(II)-arene compounds. We also report a systematic study to reveal the mechanism of action of these ruthenium-PARP inhibitor conjugates. The complexes have been synthesized and characterized spectroscopically. The improved antiproliferative activity from the as-prepared complexes in four human cancer cell lines has indicated their potential for further development as antitumor drugs. Cellular uptake study reveals that the most active complex 3 easily entered into cells. Target validation assays show that the complexes inhibited PARP-1 slightly better than the original PARP inhibitors, that complex 3 strongly bound to DNA and inhibited transcription, and that this complex arrested the cell cycle at the G0/G1 stage. This type of information could shed light on the design of the next generation of more active ruthenium-PARP inhibitor conjugates., (© 2013.)

Systematic investigations on the reactions between cis‐[M(dppm)2Cl2] (M=Ru/Os; dppm=1,1‐bis(diphenylphosphino)methane) and pyridine/quinoline substituted homopropargylic alcohols uncovered the diverse Ru(II)/Os(II)‐induced alkyne activation pathways. The alkynes underwent cyclization on M via a "non‐vinylidene" pathway at lower temperatures, resulting in alkenyl intermediates which might further metallacyclize to give metallapyrroloindolizines. Conversely, reactions at higher temperatures induced alkyne cyclization on M via a "vinylidene" pathway, affording cyclic oxacarbene complexes. Additionally, a rare decyclization mechanism was observed during the transformation of a metallacyclization‐resistant alkenyl complex into a cyclic oxacarbene complex. DFT calculations were employed to validate the experimental findings. Overall, these results not only provide insights into controlling alkyne activation pathways, but also offer new strategies for preparing metalated heterocyclic and metallacyclic complexes. [ABSTRACT FROM AUTHOR]

We report the first example of oxidative cleavage of the strong C–N bonds of primary amines by a ruthenium(VI) nitrido complex. The driving force for this very fast C–N cleavage reaction comes from the formation of stable N≡N after the initial coupling of the amine N and the nitrido ligand. [ABSTRACT FROM AUTHOR]

Oxidative degradation and transformation of catalysts are commonly observed in water oxidation by molecular catalysts, especially when a highly oxidizing reagent such as (NH4)2[Ce(NO3)6] [Ce(IV)] is used. We report herein the synthesis of a ruthenium(III) complex bearing an oxidative resistant bipyridine-bis(alkoxide) ligand, [Ru(bdalk)(pic)2]+ (1, H2bdalk = 2,2′-([2,2′-bipyridine]-6,6′-diyl)bis(propan-2-ol), pic = 4-picoline) as a water oxidation catalyst (WOC). A ruthenium(II) nitrosyl complex [Ru(Hbdalk)(NO)(pic)2]2+ (3) was also formed during the water oxidation process by 1/Ce(IV), and was isolated and structurally characterized. Complex 3 was found to be an active WOC, with the nitrosyl group remaining intact during water oxidation. [ABSTRACT FROM AUTHOR]

Metallafuran complexes with a fused five‐membered phosphonium ring were synthesized from reactions between terminal ynones HC≡C(C=O)R and cis‐[Ru/Os(dppm)2Cl2] (dppm=1,1‐bis(diphenylphosphino)methane). A metal–vinylidene‐involving pathway was found to be an energetically feasible formation mechanism for these complexes. These phosphonium‐containing metallafurans, like many phosphonium‐functionalized drugs, have the ability to induce mitochondrial dysfunction. They also exhibit stronger cytotoxicity against several human cancer cell lines in comparison with their metal precursors and the classic anticancer drug cisplatin. Overall, this work provides structural and mechanistic insights for the rational design of functional metallacycles via activation of alkynes by RuII and OsII centers. [ABSTRACT FROM AUTHOR]

The two series of ruthenium–indolizinone complexes prepared by Ru-mediated cyclization of pyridine-tethered alkynes represent the first examples of metalated indolizinone complexes. Joint experimental–theoretical investigation suggests an unconventional 5-endo-dig cyclization pathway as their formation mechanism. They also exhibit moderate cytotoxicity against several human cancer cell lines. [ABSTRACT FROM AUTHOR]

Water‐oxidation catalysts (WOCs) based on transition‐metal complexes often undergo oxidative degradation of the ligands, which leads to unidentifiable products. We report herein the use of a ruthenium(III) complex bearing a 2,2′‐bipyridyl (bpy)–bis(phenoxy) ligand, [Ru(L)(pic)2]+ [1, H2L=6,6′‐bis(2‐hydroxyphenyl)‐2,2′‐bipyridine, pic=4‐picoline] as a WOC. The phenoxy‐type ligand in 1 is readily oxidized by CeIV in aqueous acidic medium to give a ruthenium bpy–dicarboxylate complex ([Ru(bda)(pic)2]+, H2bda=2,2′‐bipyridine‐6,6′‐dicarboxylic acid) via ruthenium bpy–phenoxybenzoquinone (1′) and ruthenium bpy–bis(benzoquinone) (1′′) intermediates. All four ruthenium species can oxidize water; however, 1 and 1′ are rapidly oxidized to 1′′ by CeIV. On the other hand, 1′′ is robust enough that it is responsible for the initial phase of O2 evolution before it is finally oxidized to CO2 and [Ru(bda)(pic)2]+, which is a highly active WOC. [ABSTRACT FROM AUTHOR]

Hydroquinone is readily oxidized by a (salen)ruthenium(vi) nitrido complex in the presence of pyridine to give benzoquinone. Experimental and computational studies suggest that the reaction occurs via a novel mechanism that involves an initial electrophilic attack at the aromatic ring of the hydroquinone by the nitrido ligand. [ABSTRACT FROM AUTHOR]

Polypyridyl and related ligands have been widely used for the development of water oxidation catalysts. Supposedly these ligands are oxidation-resistant and can stabilize high-oxidation-state intermediates. In this work a series of ruthenium(II) complexes [Ru(qpy)(L)2]2+ (qpy=2,2′:6′,2′′:6′′,2′′′-quaterpyridine; L=substituted pyridine) have been synthesized and found to catalyze CeIV-driven water oxidation, with turnover numbers of up to 2100. However, these ruthenium complexes are found to function only as precatalysts; first, they have to be oxidized to the qpy- N, N′′′-dioxide (ONNO) complexes [Ru(ONNO)(L)2]3+ which are the real catalysts for water oxidation. [ABSTRACT FROM AUTHOR]

Exploring new reactivity of metal nitrides is of great interest because it can give insights to N2 fixation chemistry and provide new methods for nitrogenation of organic substrates. In this work, reaction of a (salen)ruthenium(VI) nitrido complex with various alkynes results in the formation of novel (salen)ruthenium(III) imine complexes. Kinetic and computational studies suggest that the reactions go through an initial ruthenium(IV) aziro intermediate, followed by addition of nucleophiles to give the (salen)ruthenium(III) imine complexes. These unprecedented reactions provide a new pathway for nitrogenation of alkynes based on a metal nitride. [ABSTRACT FROM AUTHOR]

To improve the emission and excited-state properties of luminescent cyanometalates, new classes of highly solvatochromic luminescent cyanoruthenium(II) and cyanoruthenate(II) complexes of the general formulae [Ru(PR3)2(CN)2( $\widehat{NN}$)] and K[Ru(PR3)(CN)3( $\widehat{NN}$)], respectively, were developed. These complexes could be readily synthesized through the ligand-substitution reaction of K2[Ru(CN)4(PR3)2] with a diimine ligand. The geometrical isomerism of these complexes was characterized by using various spectroscopic techniques. Their photophysical properties, solvatochromism, and electrochemistry have also been investigated. Our detailed study showed that many of these complexes exhibited extremely environmentally sensitive emissions and significantly improved emission quantum efficiencies and lifetimes compared with the well-studied tetracyanoruthenate systems. [ABSTRACT FROM AUTHOR]

The cyclization of heteroatom‐functionalized alkynes induced by d6‐transition‐metal centers has traditionally been associated with the vinylidene pathway. However, recent evidence suggests that d6‐transition‐metal centers can also activate alkynes through non‐vinylidene pathways. In this study, we conducted a comprehensive experimental and theoretical investigation into the reactions between the Ru(II) complex [Ru([9]aneS3)(bpy)(OH2)]2+ and 2‐alkynylanilines. Our study revealed that the selectivity between the vinylidene and non‐vinylidene pathways can be tuned by reaction temperature, substrate, and solvent polarity. This strategic control allows for the preferential formation of either C2‐ or C3‐metalated indole zwitterion complexes. Additionally, we identified a rare decyclization mechanism that enables the conversion of C2‐metalated indoles to C3‐metalated indoles, underscoring the significance of product stability in these pathways. Overall, this work demonstrates practical approaches to control the preference between vinylidene and non‐vinylidene pathways, which is crucial for the design of new catalysts and metalated heterocyclic complexes. [ABSTRACT FROM AUTHOR]

Highlights from the article: Keywords: alkyne activation; metallacycles; osmium; ruthenium B Reactions between terminal ynones b and ruthenium(II)/osmium(II) precursors with a 1,1-bis(diphenylphosphino)methane (dppm) auxiliary ligand produced metallafuran complexes with a fused five-membered phosphonium ring. Alkyne activation, metallacycles, osmium, ruthenium.

Abstract: Three new optically pure C 1-terpyridine ligands (L1–3) were prepared and the copper(II) complexes, of formula [Cu(L)Cl2], the rhodium(III) complexes, of formula [Rh(L)Cl3], and the ruthenium(II) complexes, of formula cis- or trans-[Ru(L)(X)Cl2] (X=DMSO or CO), were synthesized. Structures of a chiral C 1-ligand, a copper complex, a rhodium complex and a ruthenium DMSO complex were analysed using X-ray crystal structure analysis. The copper, rhodium and ruthenium complexes were shown to be precursors of catalysts for cyclopropanation. Reaction of [Cu(L)Cl2], [Rh(L)Cl3] or cis- or trans-[Ru(L)(X)Cl2] with AgOTf converted the complex to catalyst, which in the case of trans-[Ru(L)(CO)Cl2] gave enantioselectivities of up to 67% ee for the cis-isomers of styrene cyclopropanes with t-butyl diazoacetate. Comparisons with C 2-analog of copper, rhodium and ruthenium catalysts were made. [Copyright &y& Elsevier]