Synthesis and structure of ruthenium(IV) complexes featuring N-heterocyclic ligands with an N-H group as the hydrogen-bond donor: hydrogen interactions in solution and in the solid state

The synthesis and characterization of novel ruthenium(IV) complexes [Ru(η(3):η(3)-C(10)H(16))Cl(2)L] [L = 3-methylpyrazole (2b), 3,5-dimethylpyrazole (2c), 3-methyl-5-phenylpyrazole (2d), 2-(1H-pyrazol-5-yl)phenol (2e), 6-azauracile (3), and 1H-indazol-3-ol (4)] are reported. Complex 2e is converted to the chelated complex [Ru(η(3):η(3)-C(10)H(16))Cl(κ(2)-N,O-2-(1H-pyrazol-3-yl)phenoxy)] (5) by treatment with an excess of NaOH. All of the ligands feature N-H, O-H, or C═O as the potential hydrogen-bonding group. The structures of complexes 2a-2c, 2e, 3, and 5 in the solid state have been determined by X-ray diffraction. Complexes 2a-2c and 3, which contain the pyrazole N-H group, exhibit intra- and intermolecular hydrogen bonds with chloride ligands [N-H···Cl distances (?): intramolecular, 2.30-2.78; intermolecular, 2.59-2.77]. Complexes 2e and 3 bearing respectively O-H and C═O groups also feature N-H···O interactions [intramolecular (2e), 2.27 ?; intermolecular (3), 2.00 ?]. Chelated complex 5, lacking the O-H group, only shows an intramolecular N-H···Cl hydrogen bonding of 2.42 ?. The structure of complex 3, which turns out to be a dimer in the solid state through a double intermolecular N-H···O hydrogen bonding, has also been investigated in solution (CD(2)Cl(2)) by NMR diffusion studies. Diffusion-ordered spectroscopy experiments reveal an equilibrium between monomer and dimer species in solution whose extension depends on the temperature, concentration, and coordinating properties of the solvent. Preliminary catalytic studies show that complex 3 is highly active in the redox isomerization of the allylic alcohols in an aqueous medium under very mild reaction conditions (35 °C) and in the absence of a base.     

New palladium-catalyzed cross-coupling routes to carbon functionalized metallatricarbadecaboranes

A general method for the synthesis of cage-carbon-functionalized cyclopentadienyl iron and cyclopentadienyl ruthenium tricarbadecaboranyl complexes has been developed that employs palladium-catalyzed Sonogashira, Heck, and Stille cross-coupling reactions directed at a cage-carbon haloaryl substituent. The key Li(+)[6-(p-XC(6)H(4))-nido-5,6,9-C(3)B(7)H(9)(-)] (X = I (1), Br (2), Cl (3)) haloaryl-tricarbadecaboranyl anionic ligands were synthesized in high yields via the reaction of the arachno-4,6-C(2)B(7)H(12)(-) anion with the corresponding p-halobenzonitriles (p-XC(6)H(4)-CN). The reactions of the salts 1-3 with (η(5)-C(5)H(5))Fe(CO)(2)I and (η(5)-C(5)H(5))Ru(CH(3)CN)(3)PF(6) were then used to produce the haloaryl complexes 1-(η(5)-C(5)H(5))-2-(p-XC(6)H(4))-closo-1,2,3,4-MC(3)B(7)H(9) (M = Fe, X = I (4), Br (5), Cl (6) and M = Ru, X = I (7), Br (8), Cl (9)). The sonication-promoted Sonogashira coupling reactions of 4 with terminal alkynes catalyzed by Pd(dppf)(2)Cl(2)/CuI yielded the alkynyl-linked derivatives 1-(η(5)-C(5)H(5))-2-p-RC(6)H(4)-closo-1,2,3,4-FeC(3)B(7)H(9) (R = (PhC≡C)- (10), (CH(3)CH(2)C(O)OCH(2)C≡C)- (11), ((η(5)-C(5)H(5))Fe(η(5)-C(5)H(4)C≡C))- (12)). Heck reactions of 4 with terminal alkenes catalyzed by Pd(OAc)(2) yielded the alkene-functionalized products 1-(η(5)-C(5)H(5))-2-p-RC(6)H(4)-closo-1,2,3,4-FeC(3)B(7)H(9) (R = (PhCH(2)CH═CH)- (13), (CH(3)(CH(2))(2)CH═CH)- (14)), while the Stille cross-coupling reactions of 4 with organotin compounds catalyzed by Pd(PPh(3))(2)Cl(2) afforded the complexes 1-(η(5)-C(5)H(5))-2-p-RC(6)H(4)-closo-1,2,3,4-FeC(3)B(7)H(9) (R = Ph- (15), (CH(2)═CH)- (16), (CH(2)═CHCH(2))- (17)). These reactions thus provide facile and systematic access to a wide variety of new types of functionalized metallatricarbadecaboranyl complexes with substituents needed for potential metallocene-like biomedical and/or optoelectronic applications.     

Formation of a dinuclear imido complex from the reaction of a ruthenium(VI) nitride with a ruthenium(II) hydride

The treatment of [Ru(L(OEt))(N)Cl(2)] (1; L(OEt)(-) = [Co(η(5)-C(5)H(5)){P(O)(OEt)(2)}(3)](-)) with Et(3)SiH affords [Ru(L(OEt))Cl(2)(NH(3))] (2), whereas that with [Ru(L(OEt))(H)(CO)(PPh(3))] (3) gives the dinuclear imido complex [(L(OEt))Cl(2)Ru(μ-NH)Ru(CO)(PPh(3))(L(OEt))] (4). The imido group in 4 binds to the two ruthenium atoms unsymmetrically with Ru-N distances of 1.818(6) and 1.952(6) ?. The reaction between 1 and 3 at 25 °C in a toluene solution is first order in both complexes with a second-order rate constant determined to be (7.2 ± 0.4) × 10(-5) M(-1) s(-1).     

Hydride ion transfer from ruthenium(II) complexes in water: kinetics and mechanism

Reactions of hydride complexes of ruthenium(II) with hydride acceptors have been examined for Ru(terpy)(bpy)H(+), Ru(terpy)(dmb)H(+), and Ru(η(6)-C(6)Me(6))(bpy)(H)(+) in aqueous media at 25 °C (terpy = 2,2';6',2'-terpyridine, bpy = 2,2'-bipyridine, dmb = 4,4'-dimethyl-2,2'-bipyridine). The acceptors include CO(2), CO, CH(2)O, and H(3)O(+). CO reacts with Ru(terpy)(dmb)H(+) with a rate constant of 1.2 (0.2) × 10(1) M(-1) s(-1), but for Ru(η(6)-C(6)Me(6))(bpy)(H)(+), the reaction was very slow, k ≤ 0.1 M(-1) s(-1). Ru(terpy)(bpy)H(+) and Ru(η(6)-C(6)Me(6))(bpy)(H)(+) react with CH(2)O with rate constants of (6 ± 4) × 10(6) and 1.1 × 10(3) M(-1) s(-1), respectively. The reaction of Ru(η(6)-C(6)Me(6))(bpy)(H)(+) with acid exhibits straightforward, second-order kinetics, with the rate proportional to [Ru(η(6)-C(6)Me(6))(bpy)(H)(+)] and [H(3)O(+)] and k = 2.2 × 10(1) M(-1) s(-1) (μ = 0.1 M, Na(2)SO(4) medium). However, for the case of Ru(terpy)(bpy)H(+), the protonation step is very rapid, and only the formation of the product Ru(terpy)(bpy)(H(2)O)(2+) (presumably via a dihydrogen or dihydride complex) is observed with a k(obs) of ca. 4 s(-1). The hydricities of HCO(2)(-), HCO(-), and H(3)CO(-) in water are estimated as +1.48, -0.76, and +1.57 eV/molecule (+34, -17.5, +36 kcal/mol), respectively. Theoretical studies of the reactions with CO(2) reveal a "product-like" transition state with short C-H and long M-H distances. (Reactant) Ru-H stretched 0.68 ?; (product) C-H stretched only 0.04 ?. The role of water solvent was explored by including one, two, or three water molecules in the calculation.     

Highly Efficient Redox Isomerisation of Allylic Alcohols Catalysed by Pyrazole‐Based Ruthenium(IV) Complexes in Water: Mechanisms of Bifunctional Catalysis in Water

The catalytic activity of ruthenium(IV) ([Ru(η³:η³‐C₁₀H₁₆)Cl₂L]; C₁₀H₁₆=2,7‐dimethylocta‐2,6‐diene‐1,8‐diyl, L=pyrazole, 3‐methylpyrazole, 3,5‐dimethylpyrazole, 3‐methyl‐5‐phenylpyrazole, 2‐(1H‐pyrazol‐3‐yl)phenol or indazole) and ruthenium(II) complexes ([Ru(η⁶‐arene)Cl₂(3,5‐dimethylpyrazole)]; arene=C₆H₆, p‐cymene or C₆Me₆) in the redox isomerisation of allylic alcohols into carbonyl compounds in water is reported. The former show much higher catalytic activity than ruthenium(II) complexes. In particular, a variety of allylic alcohols have been quantitatively isomerised by using [Ru(η³:η³‐C₁₀H₁₆)Cl₂(pyrazole)] as a catalyst; the reactions proceeded faster in water than in THF, and in the absence of base. The isomerisations of monosubstituted alcohols take place rapidly (10–60 min, turn‐over frequency=750–3000 h^?1) and, in some cases, at 35 °C in 60 min. The nature of the aqueous species formed in water by this complex has been analysed by ESI‐MS. To analyse how an aqueous medium can influence the mechanism of the bifunctional catalytic process, DFT calculations (B3LYP) including one or two explicit water molecules and using the polarisable continuum model have been carried out and provide a valuable insight into the role of water on the activity of the bifunctional catalyst. Several mechanisms have been considered and imply the formation of aqua complexes and their deprotonated species generated from [Ru(η³:η³‐C₁₀H₁₆)Cl₂(pyrazole)]. Different competitive pathways based on outer‐sphere mechanisms, which imply hydrogen‐transfer processes, have been analysed. The overall isomerisation implies two hydrogen‐transfer steps from the substrate to the catalyst and subsequent transfer back to the substrate. In addition to the conventional Noyori outer‐sphere mechanism, which involves the pyrazolide ligand, a new mechanism with a hydroxopyrazole complex as the active species can be at work in water. The possibility of formation of an enol, which isomerises easily to the keto form in water, also contributes to the efficiency in water.     

Controlled assembly of ruthenium complexes through ortho-carborane dithiolate and polysulfide ligands

Treatment of ortho-carborane, n-butyl lithium, sulfur, and [(p-cymene)RuCl(2)](2) in varying ratio led to four new compounds (p-cymene)Ru[S(3)(C(2)B(10)H(10))(2)] (3), [(p-cymene)Ru(2)(μ(2)-S(2)C(2)B(10)H(9))(μ(3)-S(2)C(2)B(10)H(10))](2) (4), [(p-cymene)Ru](2)Ru(μ(2)-η(2):η(2)-S(2)) (μ(2)-η(2):η(1)-S(2)Cl)(μ(2)-S(2)C(2)B(10)H(10))(2) (5), and [(p-cymene)Ru](2)Ru(μ(2)-η(1):η(1)-S(2))(μ(3)-η(2):η(2)-S(4)) (μ(2)-S(2)C(2)B(10)H(10))(2) (6), respectively. In 3, the ruthenium atom is coordinated by three S atoms from a in situ generated tridentate [S(3)(C(2)B(10)H(10))(2)](2-) ligand. 4 consists of two identical dinuclear (p-cymene)Ru(2)(μ(2)-S(2)C(2)B(10)H(9))(μ(3)-S(2)C(2)B(10)H(10)) subunits which connect to each other via the Ru-Ru bond and two bridging o-carborane-1,2-dithiolate ligands. In 4, a Ru-B bond is present. 5 contains a Ru(3)(μ(2)-S)(2)(μ(2)-S(2))(μ(2)-S(2)Cl) core, and the central ruthenium atom is coordinated by seven S atoms in a distorted pentagonal bipyramidal geometry. In 5, a S-Cl bond is generated. 6 has a novel Ru(3)(μ(2)-S)(2)(μ(2)-S(2))(μ(3)-S(4)) core, and the three ruthenium atoms are connected through the two terminal sulfur atoms of the S-S-S-S chain in a μ(3) binding fashion. All the four complexes have been characterized by elemental analysis, mass, NMR, and X-ray crystallography.     

Bis(allyl)-ruthenium(IV) complexes as highly efficient catalysts for the redox isomerization of allylic alcohols into carbonyl compounds in organic and aqueous media: scope, limitations, and theoretical analysis of the mechanism

The catalytic activity of the bis(allyl)-ruthenium(IV) dimer [[Ru(eta(3):eta(3)-C(10)H(16))(mu-Cl)Cl](2)] (C(10)H(16) = 2,7-dimethylocta-2,6-diene-1,8-diyl) (1), and that of its mononuclear derivatives [Ru(eta(3):eta(3)-C(10)H(16))Cl(2)(L)] (L = CO, PR(3), CNR, NCR) (2) and [Ru(eta(3):eta(3)-C(10)H(16))Cl(NCMe)(2)][SbF(6)] (3), in the redox isomerization of allylic alcohols into carbonyl compounds, both in tetrahydrofuran and in water, is reported. In particular, a variety of allylic alcohols have been quantitatively isomerized using [[Ru(eta(3):eta(3)-C(10)H(16))(mu-Cl)Cl](2)] (1) as catalyst, the reactions proceeding in all cases faster in water. Remarkably, complex 1 has been found to be the most efficient catalyst reported to date for this particular transformation, leading to TOF and TON values up to 62,500 h(-1) and 1 500,000, respectively. Moreover, catalyst 1 can be recycled and is capable of performing allylic alcohol isomerizations even in the presence of conjugated dienes, which are known to be strong poisons in isomerization catalysis. On the basis of both experimental data and theoretical calculations (DFT), a complete catalytic cycle for the isomerization of 2-propen-1-ol into propenal is described. The potential energy surfaces of the cycle have been explored at the B3LYP/6-311 + G(d,p)//B3LYP/6-31G(d,p) + LAN2DZ level. The proposed mechanism involves the coordination of the oxygen atom of the allylic alcohol to the metal. The DFT energy profile is consistent with the experimental observation that the reaction only proceeds under heating. Calculations predict the catalytic cycle to be strongly exergonic, in full agreement with the high yields experimentally observed.     

Coordination chemistry of 4-methyl-2,6,7-trioxa-1-phosphabicyclo[2,2,1]heptane: preparation and characterization of Ru(II) complexes

The complexes TpRu[P(OCH(2))(2)(OCCH(3)](PPh(3))Cl (2) [Tp = hydridotris(pyrazolyl)borate; P(OCH(2))(2)(OCCH(3)) (1) = (4-methyl-2,6,7-trioxa-1-phosphabicyclo[2,2,1]heptane] and TpRu(L)(PPh(3))Cl [L = P(OCH(2))(3)CEt (3), PMe(3) (4) or P(OMe)(3) (5)], (η(6)-C(6)H(6))Ru(L)Cl(2) [L = PPh(3) (6), P(OMe)(3) (7), PMe(3) (8), P(OCH(2))(3)CEt (9), CO (10) or P(OCH(2))(2)(OCCH(3)) (11)] and (η(6)-p-cymene)Ru(L)Cl(2) [L = P(OCH(2))(3)CEt (12), P(OCH(2))(2)(OCCH(3))P(OCH(2))(2)(OCCH(3)) (13), P(OMe)(3) (14) or PPh(3) (15)] have been synthesized, isolated, and characterized by NMR spectroscopy, cyclic voltammetry, mass spectrometry, and, for some complexes, single crystal X-ray diffraction. Data from cyclic voltammetry and solid-state structures have been used to compare the properties of (1) with other phosphorus-based ligands as well as carbon monoxide. Data from the solid-state structures of Ru(II) complexes show that P(OCH(2))(2)(OCCH(3)) has a cone angle of 104°. Cyclic voltammetry data reveal that the Ru(II) complexes bearing P(OCH(2))(2)(OCCH(3)) have more positive Ru(III/II) redox potentials than analogous complexes with the other phosphorus ligands; however, the Ru(III/II) potential for (η(6)-C(6)H(6))Ru[P(OCH(2))(2)(OCCH(3))]Cl(2) is more negative compared to the Ru(III/II) potential for the CO complex (η(6)-C(6)H(6))Ru(CO)Cl(2). For the Ru(II) complexes studied herein, these data are consistent with the overall donor ability of 1 being less than other common phosphines (e.g., PMe(3) or PPh(3)) or phosphites [e.g., P(OCH(2))(3)CEt or P(OMe)(3)] but greater than carbon monoxide.     

Aminocyclopentadienyl ruthenium complexes as racemization catalysts for dynamic kinetic resolution of secondary alcohols at ambient temperature

Aminocyclopentadienyl ruthenium complexes, which can be used as room-temperature racemization catalysts with lipases in the dynamic kinetic resolution (DKR) of secondary alcohols, were synthesized from cyclopenta-2,4-dienimines, Ru(3)(CO)(12), and CHCl(3): [2,3,4,5-Ph(4)(eta(5)-C(4)CNHR)]Ru(CO)(2)Cl (4: R = i-Pr; 5: R = n-Pr; 6: R = t-Bu), [2,5-Me(2)-3,4-Ph(2)(eta(5)-C(4)CNHR)]Ru(CO)(2)Cl (7: R = i-Pr; 8: R = Ph), and [2,3,4,5-Ph(4)(eta(5)-C(4)CNHAr)]Ru(CO)(2)Cl (9: Ar = p-NO(2)C(6)H(4); 10: Ar = p-ClC(6)H(4); 11: Ar = Ph; 12: Ar = p-OMeC(6)H(4); 13: Ar = p-NMe(2)C(6)H(4)). The tests in the racemization of (S)-4-phenyl-2-butanol showed that 7 is the most active catalyst, although the difference decreased in the DKR. Complex 4 was used in the DKR of various alcohols; at room temperature, not only simple alcohols but also functionalized ones such as allylic alcohols, alkynyl alcohols, diols, hydroxyl esters, and chlorohydrins were successfully transformed to chiral acetates. In mechanistic studies for the catalytic racemization, ruthenium hydride 14 appeared to be a key species. It was the major organometallic species in the racemization of (S)-1-phenylethanol with 4 and potassium tert-butoxide. In a separate experiment, (S)-1-phenylethanol was racemized catalytically by 14 in the presence of acetophenone.     

Mono and dinuclear arene ruthenium(II) triazoles by 1,3-dipolar cycloadditions to a coordinated azide in ruthenium(II) compounds

The dimeric η(6)-hexamethylbenzene ruthenium(II) triazole compounds of formulation [{(η(6)-C(6)Me(6))Ru(N(3)C(2)(CO(2)R)(2))}(2)(μC(2)O(4))] have been synthesized by 1,3-diploar cycloadditions of coordinated azido compound [{(η(6)-C(6)Me(6))Ru(L(1))N(3)}] (1) with substituted acetylene, RO(2)CC(2)CO(2)R via unexpected oxidation of the coordinated ligand to oxalate (where; L(1) = 5-hydroxy-2-(hydroxymethyl)-4-pyrone; R = Me, 3 or Et, 4). In contrast, a similar 1,3-dipolar cycloaddition reaction of [{(η(6)-C(6)Me(6))Ru(L(2))N(3)}] (2) (where; L(2) = tropolone) with acetylene yielded the monomeric triazole compound [(η(6)-C(6)Me(6))Ru(L(2)){N(3)C(2)(CO(2)R)(2)}] (where; R = Me, 5; Et, 6). The compounds were characterized by spectroscopy and the structures of representative compounds 4 and 6 have been determined by single crystal X-ray diffraction. The two ruthenium centres in the compound 4, are linked by a tetra-dentate oxalate group. Both compounds, 4 and 6, crystallized in a triclinic space group P-1.     

Ruthenium(II) and ruthenium(IV) complexes containing kappa1-P-, kappa2-P,O-, and kappa3-P,N,O-iminophosphorane-phosphine ligands Ph2PCH2P[=NP(=O)(OR)2]Ph2 (R = Et,Ph): synthesis,reactivity, theoretical studies,and catalytic activity in transfer hydrogenation of cyclohexanone

[(Ru(eta(6)-p-cymene)(mu-Cl)Cl)(2)] and [(Ru(eta(3):eta(3)-C(10)H(16))(mu-Cl)Cl)(2)] react with Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2) (R = Et (1a), Ph (1b)) affording complexes [Ru(eta(6)-p-cymene)Cl(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et (2a), Ph (2b)) and [Ru(eta(3):eta(3)-C(10)H(16))Cl(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et (6a), Ph (6b)). While treatment of 2a with 1 equiv of AgSbF(6) yields a mixture of [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OEt)(2)]Ph(2))][SbF(6)] (3a) and [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,N-Ph(2)PCH(2)P[=NP(=O)(OEt)(2)]Ph(2))][SbF(6)] (4a), [Ru(eta(6)-p-cymene)Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OPh)(2)]Ph(2))][SbF(6)] (3b) and [Ru(eta(3):eta(3)-C(10)H(16))Cl(kappa(2)-P,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)] (R = Et (7a), Ph (7b)) are selectively formed from 2b and 6a,b. Complexes [Ru(eta(6)-p-cymene)(kappa(3)-P,N,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)](2) (R = Et (5a), Ph (5b)) and [Ru(eta(3):eta(3)-C(10)H(16))(kappa(3)-P,N,O-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))][SbF(6)](2) (R = Et (8a), Ph (8b)) have been prepared using 2 equiv of AgSbF(6). The reactivity of 3-5a,b has been explored allowing the synthesis of [Ru(eta(6)-p-cymene)X(2)(kappa(1)-P-Ph(2)PCH(2)P[=NP(=O)(OR)(2)]Ph(2))] (R = Et, Ph; X = Br, I, N(3), NCO (9-12a,b)). The catalytic activity of 2-8a,b in transfer hydrogenation of cyclohexanone, as well as theoretical calculations on the models [Ru(eta(6)-C(6)H(6))Cl(kappa(2)-P,N-H(2)PCH(2)P[=NP(=O)(OH)(2)]H(2))]+ and [Ru(eta(6)-C(6)H(6))Cl(kappa(2)-P,O-H(2)PCH(2)P[=NP(=O)(OH)(2)]H(2))]+, has been also studied.     

Ruthenium(II) polypyridyl complexes: potential precursors, metalloligands, and topo II inhibitors

Neutral and cationic mononuclear complexes containing both group 15 and polypyridyl ligands [Ru(kappa3-tptz)(PPh3)Cl2] [1; tptz=2,4,6-tris(2-pyridyl)-1,3,5-triazine], [Ru(kappa3-tptz)(kappa2-dppm)Cl]BF4 [2; dppm=bis(diphenylphosphino)methane], [Ru(kappa3-tptz)(PPh3)(pa)]Cl (3; pa=phenylalanine), [Ru(kappa3-tptz)(PPh3)(dtc)]Cl (4; dtc=diethyldithiocarbamate), [Ru(kappa3-tptz)(PPh3)(SCN)2] (5) and [Ru(kappa3-tptz)(PPh3)(N3)2] (6) have been synthesized. Complex 1 has been used as a metalloligand in the synthesis of homo- and heterodinuclear complexes [Cl2(PPh3)Ru(micro-tptz)Ru(eta6-C6H6)Cl]BF4 (7), [Cl2(PPh3)Ru(mu-tptz)Ru(eta6-C10H14)Cl]PF6 (8), and [Cl2(PPh3)Ru(micro-tptz)Rh(eta5-C5Me5)Cl]BF4 (9). Complexes 7-9 present examples of homo- and heterodinuclear complexes in which a typical organometallic moiety [(eta6-C6H6)RuCl]+, [(eta6-C10H14)RuCl]+, or [(eta5-C5Me5)RhCl]+ is bonded to a ruthenium(II) polypyridine moiety. The complexes have been fully characterized by elemental analyses, fast-atom-bombardment mass spectroscopy, NMR (1H and 31P), and electronic spectral studies. Molecular structures of 1-3, 8, and 9 have been determined by single-crystal X-ray diffraction analyses. Complex 1 functions as a good precursor in the synthesis of other ruthenium(II) complexes and as a metalloligand. All of the complexes under study exhibit inhibitory effects on the Topoisomerase II-DNA activity of filarial parasite Setaria cervi and beta-hematin/hemozoin formation in the presence of Plasmodium yoelii lysate.     

Cellular delivery of pyrenyl-arene ruthenium complexes by a water-soluble arene ruthenium metalla-cage

Three pyrenyl-arene ruthenium complexes (M(1)-M(3)) of the general formula [Ru(η(6)-arene-pyrenyl)Cl(2)(pta)] (pta = 1,3,5-triaza-7-phosphaadamantane) have been synthesised and characterised. Prior to the coordination to ruthenium, pyrene was connected to the arene ligand via an alkane chain containing different functional groups: ester (L(1)), ether (L(2)) and amide (L(3)), respectively. Furthermore, the pyrenyl moieties of the M(n) complexes were encapsulated within the hydrophobic cavity of the water soluble metalla-cage, [Ru(6)(η(6)-p-cymene)(6)(tpt)(2)(donq)(3)](6+) (tpt = 2,4,6-tri-(pyridin-4-yl)-1,3,5-triazine; donq = 5,8-dioxydo-1,4-naphthoquinonato), while the arene ruthenium end was pointing out of the cage, thus giving rise to the corresponding host-guest systems [M(n)?Ru(6)(η(6)-p-cymene)(6)(tpt)(2)(donq)(3)](6+) ([M(n)?cage](6+)). The antitumor activity of the pyrenyl-arene ruthenium complexes (M(n)) and the corresponding host-guest systems [M(n)?cage][CF(3)SO(3)](6) were evaluated in vitro in different types of human cancer cell lines (A549, A2780, A2780cisR, Me300 and HeLa). Complex M(2), which contains an ether group within the alkane chain, demonstrated at least a 10 times higher cytotoxicity than the reference compound [Ru(η(6)-p-cymene)Cl(2)(pta)] (RAPTA-C). All host-guest systems [M(n)?cage](6+) showed good anticancer activity with IC(50) values ranging from 2 to 8 μM after 72 h exposure. The fluorescence of the pyrenyl moiety allowed the monitoring of the cellular uptake and revealed an increase of uptake by a factor two of the M(2) complex when encapsulated in the metalla-cage [Ru(6)(η(6)-p-cymene)(6)(tpt)(2)(donq)(3)](6+).     

NN型双齿半夹心Ru(Ⅱ)化合物:无受体脱氢环化合成喹啉和吡咯衍生物的催化剂

四个含NN型双齿配体的半夹心(η^6-p-cymene)Ru(II)化合物被成功制备.这四个化合物分别为(η^6-p-cymene)-Ru(C5H4N-C5H3N-OH)(1),(η^6-p-cymene)Ru(C5H4N-CH2-C5H4N)(2),(η^6-p-cymene)Ru(C5H4N-CH2-C5H3N-OH)(3)和(η^6-p-cymene)Ru(C5H4N-CH2-C5H3N-OCH3)(4).这些化合物通过核磁氢谱、碳谱和元素分析等手段表征,化合物2的结构被X射线单晶衍射证实.将这些化合物应用于催化氨醇与酮的环化反应,其中3的催化效率最高.在0.5mol%化合物3的存在下,制备了一系列喹啉和吡啶衍生物.     

Expeditious entry to novel 2-methylene-2,3-dihydrofuro[3,2-c] chromen-2-ones from 6-chloro-4-hydroxychromen-2-one and propargylic alcohols

A catalytic system consisting of the ruthenium(II) complex [Ru(η3-2-C3H4Me)(CO)(dppf)][SbF6] (dppf=1,1'-bis(diphenylphosphino)ferrocene) and trifluoroacetic acid has been used to promote the coupling of secondary propargylic alcohols with 6-chloro-4-hydroxychromen-2-one. The reactions afforded unusual 2-methylene-2,3-dihydrofuro[3,2-c]chromen-2-ones in good yields.     

Effect of chelating ring size in catalytic ketone hydrogenation: facile synthesis of ruthenium(II) precatalysts containing an N-heterocyclic carbene with a primary amine donor for ketone hydrogenation and a DFT study of mechanisms

A half-sandwich ruthenium(II) complex, [Ru(η(6)-p-cymene)(C-NH(2))Cl]PF(6) (4·PF(6)), containing an N-heterocyclic carbene (NHC) with a primary amine donor (C-NH(2)) which chelates through the carbene carbon and the amine nitrogen to form a 6-membered ring was synthesized in a one-pot reaction starting from a primary-amine functionalized imidazolium salt 2. Complex 4·PF(6) catalyzed the hydrogenation of ketones using 2-propanol or H(2) as the reductant. A maximum turnover frequency of 1062 h(-1) and a turnover number of 1140 at 5 h were achieved for the transfer hydrogenation of 3'-chloroacetophenone in 2-propanol at 75 °C. A cationic hydride-amine complex 5, [Ru(η(6)-p-cymene)(C-NH(2))H]PF(6), was synthesized, and this reacted very slowly with acetophenone unless first activated by an alkoxide base. Computational studies by DFT methods suggested that the poor reactivity of the hydride-amine complex 5 was attributed to a large barrier for the transfer of its H(+)/H(-) couple to a ketone for bifunctional catalysis. An inner-sphere mechanism, which involves a decoordinated amine group of the C-NH(2) ligand, was computed to be a feasible energetic pathway in comparison to the computed outer-sphere bifunctional mechanism. This explains the catalytic activity and selectivity that is observed for the newly synthesized ruthenium(II) catalysts.     

Electron-rich iron/ruthenium arylalkynyl complexes for third-order nonlinear optics: redox-switching between three states

The new [(η(2)-dppe)(η(5)-C(5)Me(5))Fe(C≡C-1,4-C(6)H(4)C≡C)Ru(η(2) -dppe)(2) C≡C(C(6)H(5))] complex (3-H) and its hexanuclear relative [{(η(2)-dppe)(η(5)-C(5) Me(5))Fe(C≡C-1,4-C(6)H(4)-C≡C)Ru(η(2)-dppe)(2)(C≡C-1,4-C(6)H(4)C≡C)(3)(1,3,5-C(6)H(3))] (4) have been synthesized and characterized. The linear and cubic nonlinear optical properties of these compounds in their various redox states have been studied along with those of the analogous complexes [(η(2)-dppe)(η(5)-C(5)Me(5))Fe(C≡C-1,4-C(6)H(4)C≡C)Ru(η(2)-dppe)(2)R][PF(6)](n) (n=0-2; R=Cl, 2-Cl; R=C≡C(4-C(6)H(4)NO(2)),3-NO(2)). We show that molecules exhibiting large third-order nonlinearities can be obtained by assembling such dinuclear Fe/Ru units around a central 1,3,5-substituted C(6)H(3) core. These data are discussed with a particular emphasis on the large changes in their nonlinear (third-order) optical properties brought about by oxidation. Experimental and computational (DFT) evidence for the electronic structures of these compounds in their various redox states is presented using 3-H(n+) as a prototypical model. Single crystals of this complex in its mono-oxidized state (3-H[PF(6)]) provide the first structural data for such carbon-rich Fe(III) /Ru(II) heteronuclear mixed-valent (MV) systems. Although experimental evidence for the structure of the dioxidized states was more difficult to obtain, the theoretical study reveals that 3-H(2+) can be considered to have a biradical structure with two independent spins. The low-lying absorptions that appear in the near-infrared (NIR) range for all these compounds following oxidation correspond to intervalence charge-transfer (IVCT) bands for the mono-oxidized states and to ligand-to-metal charge-transfer (LMCT) transitions for the dioxidized states. These play a crucial role in the strong optical modulation achieved. The possibility of accessing additional states with distinct linear or nonlinear optical properties is also briefly discussed.     

Arene-ruthenium complexes of an acyclic thiolate-thioether and tridentate thioether derivatives resulting from ring-closure reactions

The reaction of [(eta(6)-arene)RuCl(2)](2) (arene = C(6)Me(6), 1,4-MeC(6)H(4)CHMe(2)) with a large excess of the dianion of bis(2-mercaptoethyl) sulfide, (HSCH(2)CH(2))(2)S, obtained from deprotonation of the dithiol with freshly prepared NaOMe, gives the deep red, monomeric complexes [(eta(6)-arene)Ru(eta(3)-C(4)H(8)S(3))] (arene = C(6)Me(6) (5), 1,4-MeC(6)H(4)CHMe(2) (6)) in which the dianion is bound to the metal atom through one thioether and two thiolate sulfur atoms. Complex 5 reacts with [(eta(6)-C(6)Me(6))RuCl(2)](2) (4) in a 2:1 mole ratio to give a quantitative yield of the chloride salt of a binuclear cation [((eta(6)-C(6)Me(6))Ru)(2)Cl(mu(2)-eta(2):eta(3)-C(4)H(8)S(3))](+) (7) in which the thiolate sulfur atoms of the [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(8)S(3))] group bridge to a (eta(6)-C(6)Me(6))RuCl unit. This compound is also obtained directly from the reaction of 4 with the dithiolate, if the Ru dimer is used in large excess. The binuclear complex [((eta(6)-C(6)Me(6))Ru)(2)(MeCN)(mu(2)-eta(2):eta(3)-C(4)H(8)S(3))](PF(6))(2).MeCN, (9)(PF(6))(2).MeCN, is obtained by treatment of (7)Cl with NH(4)PF(6) in acetonitrile. Protonation of 5 with HCl gave the mono- and diprotonated derivatives viz. [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(9)S(3))]Cl, (8)Cl, and [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(10)S(3))]Cl(2), (10)Cl(2), respectively. The reaction of 5 with methyl iodide gives both the mono- and di-S-methylated derivatives. Treatment of 5 with dibromoalkanes, Br(CH(2))(n)Br (n = 1-5), effects ring closure to give the (eta(6)-C(6)Me(6))Ru dications containing the trithia mesocyclic zS3 (z = 8-12) ligands, isolated as their PF(6) salts. The X-ray crystal structures of 5, 6, the solvates of (7)Cl and (9)(PF(6))(2), and the trithia mesocyclic Ru complexes (eta(6)-C(6)Me(6))Ru(zS3)(PF(6))(2) (z = 8-11) are reported.     

Tetradentate selenium ligand as a building block for homodinuclear complexes of Pd(II) and Ru(II) having seven membered rings or bis-pincer coordination mode: high catalytic activity of Pd-complexes for Heck reaction

1,2,4,5-Tetrakis(phenyselenomethyl)benzene (L) has been synthesized by reaction of in situ generated PhSe(-) with 1,2,4,5-tetrakis(bromomethyl)benzene in N(2) atmosphere. Its first bimetallic complexes and a bis-pincer complex having compositions [(η(3)-C(3)H(5))(2)Pd(2)(L)][ClO(4)](2) (1) [Pd(2)(C(5)H(5)N)(2)(L)][BF(4)](2) (2) and [(η(6)-C(6)H(6))(2)Ru(2)(L)Cl(2)][PF(6)](2) (3) have been synthesized by reacting L with [Pd(η(3)-C(3)H(5))Cl](2), [Pd(CH(3)CN)(4)][BF(4)](2) and [(η(6)-C(6)H(6))(2)RuCl(2)](2) respectively. The structures of ligand L and its all three complexes have been determined by X-ray crystallography. In 1 and 3, ligand L forms with two organometallic species seven membered chelate rings whereas in 2 it ligates in a bis-pincer coordination mode. The geometry around Pd in 1 or 2 is close to square planar whereas in 3, Ru has pseudo-octahedral half sandwich "Piano-Stool" geometry. The Pd-Se bond distances are in the ranges 2.4004(9)-2.4627(14) ? and follow the order 1 > 2, whereas Ru-Se bond lengths are between 2.4945(16) and 2.5157(17) ?. The 1 and 2 have been found efficient catalysts for Heck reaction of aryl halides with styrene and methyl acrylate. The 2 is superior to 1. The TON and TOF values (per Pd) are up to ~47500 and ~2639 h(-1) respectively.