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Interconversion between CO2 + H2 and FA/formate is the most promising strategy for the fixation of carbon dioxide and reversible hydrogen storage; however, FA dehydrogenation and CO2 hydrogenation are usually studied separately using different catalysts for each reaction. This report describes of the catalysis of [Cp*Ir(N∧N)(X)]n+ (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl; X = Cl, n = 0; X = H2O, n = 1) bearing a proton-responsive N∧N pyridylpyrrole ligand for both reactions. Complex 2-H2O catalyzes FA dehydrogenation at 90 °C with a TOFmax of 45 900 h-1. Its catalysis is more active in aqueous solution than in neat solution under base-free conditions. These complexes also catalyze CO2 hydrogenation in the presence of base to formate under atmospheric pressure (CO2/H2 = 0.05 MPa/0.05 MPa) at 25 °C with a TOF value of 4.5 h-1 in aqueous solution and with a TOF value of 29 h-1 in a methanol/H2O mixture solvent. The possible mechanism is proposed by intermediate characterization and KIE experiments. The extraordinary activity of these complexes are mainly attributed to the metal-ligand cooperative effect of the the pyrrole group to accept a proton in the dehydrogenation of formic acid and assist cooperative heterolytic H-H bond cleavage in CO2 hydrogenation.

Spurred by the rapid growth of Ru-based complexes as molecular water oxidation catalysts (WOCs), we propose novel ruthenium(II) complexes bearing pyridylpyrrole-carboxylate (H2ppc) ligands as members of the WOC family. The structure of these complexes has 4-picoline (pic)/dimethyl sulfoxide (DMSO) in [Ru(ppc)(pic)2(dmso)] and pic/pic in [Ru(ppc)(pic)3] as axial ligands. Another ppc2- ligand and one pic ligand are located at the equatorial positions. [Ru(ppc)(pic)2(dmso)] behaves as a WOC as determined by electrochemical measurement and has an ultrahigh electrocatalytic current density of 8.17 mA cm-2 at 1.55 V (vs NHE) with a low onset potential of 0.352 V (vs NHE), a turnover number of 241, a turnover frequency of 203.39 s-1, and kcat of 16.34 s-1 under neutral conditions. The H2O/pic exchange of the complexes accompanied by oxidation of a ruthenium center is the initial step in the catalytic cycle. The cyclic voltametric measurements of [Ru(ppc)(pic)2(dmso)] at various scan rates, Pourbaix diagrams (plots of E vs pH), and kinetic studies suggested a water nucleophilic attack mechanism. HPO42- in a phosphate buffer solution is invoked in water oxidation as the proton acceptor.

Seven three dimensional (3D) uranyl organic frameworks (UOFs), formulated as [NH4 ][(UO2 )3 (HTTDS)(H2 O)] (1), [(UO2 )4 (HTTDS)2 ](HIM)6 (2, IM=imidazole), [(UO2 )4 (TTDS)(H2 O)2 (Phen)2 ] (3, Phen=1,10-phenanthroline), [Zn(H2 O)4 ]0.5 [(UO2 )3 (HTTDS)(H2 O)4 ] (4), and {(UO2 )2 [Zn(H2 O)3 ]2 (TTDS)} (5), {Zn(UO2 )2 (H2 O)(Dib)0.5 (HDib)(HTTDS)} (6, Dib=1,4-di(1H-imidazol-1-yl)benzene) and [Na]{(UO2 )4 [Cu3 (u3 -OH)(H2 O)7 ](TTDS)2 } (7) have been hydrothermally prepared using a rigid octadentate carboxylate ligand, tetrakis(3,5-dicarboxyphenyl)silicon(H8 TTDS). These UOFs have different 3D self-assembled structures as a function of co-ligands, structure-directing agents and transition metals. The structure of 1 has an infinite ribbon formed by the UO7 pentagonal bipyramid bridged by carboxylate groups. With further introduction of auxiliary N-donor ligands, different structure of 2 and 3 are formed, in 2 the imidazole serves as space filler, while in 3 the Phen are bound to [UO2 ]2+ units as co-ligands. The second metal centers were introduced in the syntheses of 4-7, and in all cases, they are part of the final structures, either as a counterion (4) or as a component of framework (5-7). Interesting, in 7, a rare polyoxometalate [Cu3 (μ3 -OH)O7 (O2 CR)4 ] cluster was found in the structure. It acts as an inorganic building unit together with the dimer [(UO2 )2 (O2 CR)4 ] unit. Those uranyl carboxylates were sufficiently determined by single crystal X-ray diffraction, and their topological structures and luminescence properties were analyzed in detail.

To explore structure-activity relationships with respect to light-harvesting behavior, a family of neutral iridium complexes [Ir(ppy)2(LR)] 1-4 (where ppy = 2-phenylpyridine, and NN = 2-(1H-pyrrol-2-yl)pyridine and its functionalized derivatives) were designed and synthesized. The structural modifications in metal complexes are accomplished through the attributions of electron-donating CH3 in 2, OCH3 in 3, and electron-withdrawing CF3 in 4. The structural analysis displays that the pyridylpyrrole acts as one-negative charged bidentated ligand to chelate the iridium center. The electrochemical and photophysical properties of these complexes were systematically studied. The neutral 1-4 as well as the ionic structurally analogous [Ir(ppy)2(bpy)](PF6) (5) were utilized as PSs in photocatalytic hydrogen generation from water with [Co(bpy)3](PF6)2 as catalyst and triethanolamine (TEOA) as electron sacrificial agent in the presence of salt LiCl. Complex 1 maintains activity for more than 144 h under irradiation, and the total turnover number is up to 1768. The electrochemical properties and the quenching reaction indicate the H2 generation by neutral complexes 1-4 is involved exclusively in the oxidative quenching process.

Energetic metal–organic frameworks (EMOFs) have witnessed increasing development and been proved as promising candidates for new high energy density materials (HEDMs). Here, three metal energetic complexes based on 3,4-diaminofurazan (DAF) and 3-amino-1H-1,2,4-triazole (Hatz) ligands have been synthesized via a routine method and fully characterized by IR, 1H NMR, 13C NMR spectroscopy, X-ray single-crystal diffraction and DSC-TG techniques. The standard heats of combustion were obtained by an oxygen bomb calorimeter, and the detonation performance was calculated using the EXPLO5 program. Crystal structure determinations reveal that 1 shows a one-dimensional zigzag chain structure consisting of Zn(II) and bidentate DAF, ultimately producing a 2D MOF through extensive hydrogen bond interactions. The crystal densities of these complexes are up to 1.9 g cm−3 at 298 K. The thermal analyses from the DSC-TG test show that most of them have good thermal stability with the highest decomposition temperature of 241 °C. The as-synthesized compounds possess highly positive heats of formation with values for 2 and 3 of 2329.30 kJ mol−1 and 3261.57 kJ mol−1, respectively, and high heats of detonation with value for 2 of 10231 kJ kg−1, superior to that of HMX and RDX, which are most powerful organic explosives in use today. Expectedly, they exhibit excellent detonation performance, of which 2 has the best detonation velocity (9405 m s−1) and detonation pressure (46.64 GPa), and thus shows a great promise for potential applications as a high-energy density material. In addition, DFT calculations were performed in order to investigate the electronic properties based on the structures. This study highlights the great potential of nitrogen-rich group containing EMOFs (or complexes) for new eco-friendly energetic materials.

Treatment of [Ir(PPh3)3Cl] with 2-[5-(pyridin-2-yl)-1H-pyrrol-2-yl]pyridine (Hdpp) in refluxing toluene affords an unexpected pyrrole-metalated iridium(III) hydride complex, [Ir(K2C,N-dpp)(H)(Cl)(PPh3)2] (1), via Cpyrrole-H activation, while the presence of the base KOtBu as the deprotonation reagent produces a pyridine-metalated iridium(III) hydride complex, [Ir(K3C,N,N-dpp)(H)(PPh3)2] (2), via Cpyridine-H activation. Treatment of [Ir(PPh3)3Cl] prepared by a convenient method with Hdpp in the presence of KOtBu under the refluxing mixture solvent toluene/methanol (2:1, v/v) generates the N,N-chelating complex [Ir(K2N,N-dpp)(H)(Cl)(PPh3)2] (3) together with 1 and the N,N-chelating dihydride complex [Ir(K2N,N-dpp)(H)2(PPh3)2] (4). Complex 4 is also readily produced by the reaction of [Ir(PPh3)3Cl] and Hdpp in the presence of KOtBu under refluxing methanol or by the reaction of IrCl3 and PPh3 in refluxing 2-ethoxyethanol. Complexes 1-4 are fully characterized by NMR, IR, and UV-vis spectroscopy and X-ray diffraction analysis. The dpp-/dpp2- ligand shows rich coordination capability, of which pyridine- and pyrrole-cyclometalated coordination modes are first reported. The formation of structural isomers 1 and 3 involved the selective activation of the C-H and N-H bonds of Hdpp is rationalized by theoretical calculations.

New dipyridylpyrrole N-oxide ligands HL1 and HL2 are designed and synthesized via oxidation of 2-(5-(pyridin-2-yl)-1H-pyrrol-2-yl)pyridine (Hdpp) by using 3-chloroperbenzoic acid (m-CPBA) in CH2Cl2. The treatment of ZnEt2 with two equiv. of HL1 and HL2 affords [Zn(L1)2] and [Zn(L2)2] in medium yield, respectively. These ligands and zinc complexes are fully characterized by NMR, IR, UV-vis and ESI-MS spectroscopy and X-ray diffraction analysis. The structure of HL1 and HL2 shows a planar geometry. The intramolecular hydrogen-bond interactions between the imino hydrogen and N-oxide oxygen atom are observed. In [Zn(L1)2] and [Zn(L2)2], two ligands chelate to the zinc metal with a cross perpendicular geometry. The zinc complexes were employed as a highly efficient catalyst for the thiol-Michael addition of thiols to α,β-unsaturated ketones in EtOH at room temperature. The loading of the catalyst is lowered to 0.01 mol%. The catalytic mechanism was proposed based on NMR and ESI-MS experiments.

A family of Ru2dimers, [Ru2(μ-κ2N,N′:κ2N′,N′′-dpp)2(μ-X)(X)2]q+(X = Cl, Br,q= 0 and X = I,q= 1) is synthesized from a [Ru2(OAc)4Cl] paddlewheel starting material. The neutral products are mixed-valence Ru25+dimers with a Ru–Ru bond order of 0.5, while the cationic iodide is a Ru26+dimer with formal bond order of 1.0. The Ru–Ru distance is strikingly independent of the identity of the halide and the oxidation state of ruthenium, most likely a consequence of the small bridging nitrogen which constrains the geometry. The spectroscopic properties (EPR, UV/Vis) of the Br complex are consistent with a large σ–σ* splitting in [Ru2(μ-κ2N,N′:κ2N′,N′′-dpp)2(μ-Br)(Br)2].

Four novel polyoxouranium-based uranyl carboxylates have been constructed by using a combination of three silicon-centered carboxylate ligands and polyoxouranium building blocks. Interesting oligomerization of the uranyl groups from three types of tetrameric units in 1 and 2 to octameric [(UO2)8(μ3-OH)6(μ2-OH)2(H2O)4]8+ in 3 and ultimately infinite polyoxouranium chains in 4 was observed. The 3D structure of 2 contains two different linear tetramers, whose structures are totally different from seven types of tetranuclear motifs previously observed in uranyl carboxylates. Compound 3 displays a rare octanuclear polyoxouranium brick; it is fabricated by the association of eight uranyl units in pentagonal-bipyramidal geometry that involves the edge-sharing polyhedral connection mode, which are further linked by four isolated UO7 pentagonal bipyramids to create a complicated 3D framework. These newly synthesized hybrid materials were extensively characterized by single crystal analysis, thermogravimetric analysis (TG) and different spectroscopic techniques (IR, UV-vis, and luminescence spectroscopy), which show well-resolved characteristic "five-finger" emission of the uranyl ions under excitation at 420 nm. Relativistic density functional theory (DFT) was used to explore five model compounds that theoretically simulate experimental real compounds. Experimental spectroscopy was rationalized by electronic-structure analysis.

Treatment of [Ru 3 (CO) 12 ] with 2,5-di(2-pyridyl)pyrrole (HL1) and 2,5-di(2-(5-bromopyridyl)pyrrole (HL2) in refluxing toluene afforded the dinuclear Ru(I) carbonyl complexes [Ru 2 (CO) 4 (L)] (L = L1 ( 1 ), L2 ( 3 ), respectively). Alternatively, 1 along with a minor mononuclear product [Ru(CO) 2 (L1) 2 ] ( 2 ) was synthesized from reaction of [Ru(CO) 2 Cl 2 ] n with HL1 in methanol in the presence of triethylamine. Complexes 1 – 3 have been fully characterized by NMR, IR, UV–vis, ESI-MS, and elementary analysis. Single-crystal X-ray diffraction indicates that both 1 and 3 feature a Ru–Ru single bond and the di(pyridyl)pyrrolide ligands bind to the two Ru(I) centers in a μ-κ 2 N,N’ :κ 1 N” chelating-bridging mode. Complex 2 is mononuclear Ru(II) complex with two κ 2 N , N ’ di(pyridyl)pyrrolide ligand. The spectroscopic and electrochemical properties of 1 and 3 were also explored.

The treatment of 2-(5-(pyridin-2-yl)-1H-pyrrol-2-yl)pyridine (HL1) and PhICl2 as halogenation reagent generated monochloro-pyrrole HL2, dichloro-pyrrole HL3 and penta-chloro L4. The reaction of HL3 with [Ru(CO)2Cl2]n gave diruthenium(I) complex [Ru2(μ-κ2N,N′:κ1N″-L3)2(CO)4] (1) and monoruthenium(II) complex [Ru(κ3N,N′,N‴-L3)(κ2N,N′-L3)(CO)] (2). All these newly synthesized compounds were fully characterized by 1H NMR, IR, UV–Vis spectra, elemental analyses and X-ray diffraction study. The structural analysis shows that dichloro-pyrrole L3− acts as chelating and bridging ligand to coordinate two ruthenium atoms in 1, and acts as bidentated and tridentated ligand in 2.

Image-guided photodynamic therapy (PDT) has received growing attention due to its non-invasiveness and precise controllability. However, the PDT efficiency of most photosensitizers are decreased in living system due to the aggregation-caused singlet oxygen (1 O2 ) generation decreasing. Herein, we present an Iridium (III) pyridylpyrrole complex (Ir-1) featuring of aggregation-induced emission (AIE) and 1 O2 generation characteristics for image-guided PDT of cancer. Ir-1 aqueous solution exhibits bright red phosphorescence peaked at 630 nm, large Stokes shift of 227 nm, and good 1 O2 generation ability. The 1 O2 generating rate of Ir-1 in EtOH/water mixture solution is 2.3 times higher than that of Rose Bengal. In vitro experimental results revealed that Ir-1 has better biocompatibility and higher phototoxicity compared with clinically used photosensitizers (Rose Bengal and Ce6), suggesting that Ir-1 can serve as a photosensitizer for image-guided PDT of cancer.

The diethylphosphonate ligand HL 1 substituted pyridylpyrrole was synthesized by treatment of 2-bromo-6-(1H'-pyrrol-2-yl)pyridine and diethylphosphite in presence of base triethylamine and catalyst Pd(PPh 3 ) 4 under refluxing toluene conditions. The HL 1 ligand was treated with bromotrimethylsilane and followed hydrolysis by methanol to afford diphosphonic acid ligand H 3 L 2 . Treatment of H 3 L 2 with [Ru(NO)Cl 3 ] in presence of triethylamine in refluxing thf was generated diruthenium nitrosyl complex [Ru(L 2 )(NO)(Cl)] 2 ·(Et 3 NH) 2 ([ 1 ]·(Et 3 NH) 2 ), which is water soluble. The ligands and metal complex were fully characterized by NMR, IR, ESI-MS and single crystal X-ray diffraction technology. The solid state structure analysis displays 1 2- is dinuclear species, of which two ruthenium atoms are linked by two PO 3 2- groups. Photorelease of nitric oxide from 1 2- was monitored by UV-Vis spectra and the amount of the NO was determined by Griess reaction and DPPH radical scavenging reaction.

A well structure-defined dinuclear silver complex [Ag2(PDP)]OTf, where HPDP—bispyridylpyrrole ligand, OTf−—triflato, was used as catalyst for coupling of CO2 with epoxides to generate exclusive cyclic carbonates. Yield up to 87% was obtained for various substrates at a low loading of 0.1 mol%, at ambient temperature and pressure under solvent-free condition. The catalytic reusability of 1·OTf was also studied. Although coupling reaction of CO2 with epoxides can be catalyzed by dinuclear silver complexes with low catalyst loading at ambient temperature and pressure, the experiment of reusability of catalyst displays the dinuclear silver complex is decomposed due to the excess Br− in co-catalyst TBAB. The formed silver triphenylphosphine complex or inorganic silver materials provide real catalytic reactivity to the coupling reaction.

N,N′-diisobutyloxycarbonyl-N″,N‴-(1,3-propylene)-bisthiourea ( L ) and its silver(I) and gold(I) complexes were designed and synthesized. Treatment of 1,3-propanediamine with the isothiocyanate i PrCH 2 OC(O)NCS yielded bisthiourea L with over 90% yield. Treatment of L with AgNO 3 in CH 3 CN afforded coordination polymer {[Ag( L )(NO 3 )·CH 3 CN]} n ( 1 ) with layer structure, while with HAuCl 4 in CH 3 CN resulted in reduction of Au 3+ to Au + to yield molecular [Au( L )Cl] ( 2 ). Ligand L and complexes 1 and 2 were fully characterized by IR, 1 H NMR, UV–Vis, cyclic voltammetry and element analysis. The X-ray diffraction analysis displays that the bisthiourea L behaves as sulfur donor to coordinate to Ag and Au atom with μ 3- (S, μ 2 -S′,S′) and μ 2 -S, S′ coordination mode in 1 and 2 , respectively.

Nitrogen donor ligands HL1, HL3, HL4 and their silver complexes 1·OTf–4·OTf are prepared and fully characterized. Treatment of HL1-HL4 with AgOTf (OTf− = triflato) in presence of base Et3N and co-ligand PPh3 affords dinuclear Ag(I) complexes [Ag2(L)(PPh3)2]·OTf (L = L1−, 1·OTf; L = L2−, 2·OTf; L = L3−, 3·OTf; L = L4−, 4·OTf), respectively. The solid structure displays L acts as bis(bidentate) ligand, bridging between two Ag(I) centres. The Ag⋯Ag interaction as well as other weak interactions, such as Ag⋯Brintermolecular for 1+, Ag⋯Brintramolecular for 2+, Ag⋯S for 3+ are observed. These complexes are applied in the A3-coupling reaction of aldehydes, alkynes and amines under mild conditions, and showed excellent catalytic efficiency and recyclability. 1 mol% catalyst loading gives 99% yield of propargylamines product in 0.15 h at 35 °C in open air atmosphere. 1·OTf can be recycled six times without noticeable less of the catalyst activity.

Treatment of [Ir(PPh3)3Cl] with the 2-(1H-pyrrol-2-yl)pyridine (Hpp) ligand under refluxing toluene affords the iridium(III) hydride complex [Ir(H)Cl(pp)(PPh3)2] (1), whereas in the simultaneous presence of KOtBu the reaction gives iridium(III) hydride isomers, namely ortho-metallated triphenylphosphine cis-(P,P)-[Ir(H)(pp)(PPh3){K2C,P-PPh2(C6H4)}] (2) and trans-(P,P)-[Ir(H)(pp)(PPh3){K2C,P-PPh2(C6H4)}] (3). Complexes 1–3 are fully characterized by 1H NMR, 31P NMR, IR and UV–vis spectroscopy, together with single crystal X-ray diffraction analysis.

Five mononuclear copper(I) complexes and one dinuclear silver(I) phosphine complex containing the bispyridylpyrrole ligand were synthesized and structurally characterized. Treatment of CuCl and the deprotonated bispyridylpyrrole ligand with bis(phosphine) ligands afforded the copper(I) complexes [(PDPH)Cu(XANTPhos)] (1), [(PDPH)Cu(DPEPhos)] (2), [(PDPBr)Cu(XANTPhos)] (3) and [(PDPBr)Cu(DPEPhos)] (4), while addition of two equivalences of PPh3 gave [(PDPBr)Cu(PPh3)2] (5), where PDPH− = 2,5-bis(2-pyridyl)pyrrole, PDPBr− = 2,5-bis(6′-bromo-2′-pyridyl)-pyrrole, XANTPhos = 9,9-di-methyl-4,5-bis(diphenylphosphino)xanthene, DPEPhos = oxydi-2,1-phenylene)bis-diphenylphosphine. Reaction of PDPBr− with AgOTf and DPEPhos yielded the dinuclear silver(I) complex [(PDPBr)Ag2(DPEPhos)](OTf) (6). All of these complexes were fully characterized on the basis of IR spectra, 1H and 31P NMR spectra, elements analysis, UV–Vis spectra and X-ray single crystal diffraction analysis. The photophysical properties of these complexes were also studied.

A new class of neutral dicopper(I)–halide complexes with {Cu2(μ-X)} (X = Cl, Br and I) core supported by bispyridylpyrrole ligand have been synthesized and characterized. Replacements of chloride ligand in [Cu2(μ-X)2(PPh3)3] (X = Cl, Br, I) by the anionic PDPH− (PDPH− = 2,5-bis(2′-pyridyl)pyrrole) or PDPBr− (PDPBr− = 2,5-bis(6′-bromo-2′-pyridyl)-pyrrole) ligand gives complexes 1–6. They are [(PDPH)Cu2(μ-X)(PPh3)2] (X = Cl (1); Br (2); I (3)) and [(PDPBr)Cu2(μ-X)(PPh3)2] (X = Cl (4); Br (5); I (6)). The X-ray crystallographic studies reveal these complexes are isostructural. Two phosphine–copper(I) units are linked by one halogen atom and one nitrogen atom from bridging bispyridylpyrrole ligand to form 4-membered Cu2XN core. Each copper atom is located in the center of distorted tetrahedral geometry. The PDPH− and PDPBr− ligands display μ2-κ2(N,N′), κ2(N′,N″) bonding mode. The separation of Cu⋯Cu in 1–6 is in the range of 2.6708(15)–2.7959(6) A. The photophysical properties of 1–6 are described.

A copper-bispyridylpyrrolide complex [Cu(PDPH)Cl] (PDPH = 2,5-bis(2′-pyridyl)pyrrole) was synthesized and characterized. The complex crystallizes in the orthorhombic system with space group Pccn, a = 0.9016(3) nm, b = 1.0931(4) nm, c = 2.5319(8) nm, and V = 2.4951(15) nm3. The copper center is situated in a square planar geometry. The interaction of the copper(II) complex with calf thymus DNA (CT-DNA) was investigated by electronic absorption, circular dichroism (CD) and fluorescence spectra. It is proposed that the complex binds to CT-DNA through groove binding mode. Nuclease activity of the complex was also studied by gel electrophoresis method. The complex can efficiently cleave supercoiled pBR322 DNA in the presence of ascorbate (H2A) via oxidative pathway. The preliminary mechanism of DNA cleavage by the complex with different inhibiting reagents indicates that the hydroxyl radicals were involved as the active species in the DNA cleavage process.

The treatment of [Ce(LOEt)2(NO3)2] (LOEt– = [Co(η5-C5H5){P(O)(OEt)2}3]–) with KMnO4 in water afforded a diamagnetic purple solid 1, which is tentatively formulated as a CeIV permanganate complex, “[Ce(LOEt)2(MnO4)2]”. The ZrIV analogue, [Zr(LOEt)2(MnO4)2] (2), has been prepared similarly from [Zr(LOEt)2(NO3)2] and KMnO4. The recrystallization of 1 from CH2Cl2/hexanes at –18 °C led to the isolation of dinuclear [(CeLOEt)2(μ-LOEt′)2][MnO4]2 (3), which contains the dianionic tripodal ligand [LOEt′]2– ([(η5-C5H5)Co{P(O)(OEt)2}2{P(O)2(OEt)}]2–). The reactions of 1 with K[ReO4] and [NH4][OsO3N] afforded the heterodimetallic complexes [Ce(LOEt)2(ReO4)2] (4) and [Ce(LOEt)2(NOsO3)2] (5), respectively. The crystal structures of 3 and 5 have been determined. Freshly prepared 1 can oxidize alkylbenzenes such as toluene, ethylbenzene, and cumene at room temperature to give the corresponding ketone and/or alcohol products. Ce–LOEt complexes are efficient promoters of the aerobic oxidation of alkylbenzenes by a radical mechanism. For example, cumene in the presence of [Ce(LOEt)2(H2O)2]Cl (1 mM) in air at 100 °C for 10 h afforded a ca. 6:1 mixture of 2-phenyl-2-propanol and acetophenone with a total turnover number of 6810.

Reaction of deprotonated 2,5-bis(2'-pyridyl)pyrrole (HPDPH) with AgOTf (where OTf(-) = triflato) in THF readily yields a yellow triangular Ag3 complex [(PDPH)Ag]3 (1), of which the av. AgAg distance is 2.902 Å. A mixture of HPDPH and AgOTf reacts with PPh3 to afford a linear Ag3 complex [Ag{(PDPH)Ag(PPh3)}2](OTf) (2·OTf), whereas it reacts with diethyl phosphite in the presence of Li[N(SiMe3)2] to yield a di-nuclear complex Li2[(PDPH)Ag2{P(O)(OEt)2}2](OTf) (Li2·3·OTf). In 2, the terminal Ag atoms are three coordinate containing one phosphorous atom from PPh3 and two nitrogen atoms of the PDPH ligand. The center Ag atom is only two coordinate, binding to the residued pyridyl N atom of the PDPH ligand. In 3, two silver atoms are bridged by one PDPH ligand. Treatment of PDPH with CuCl in the presence of NaH afforded a heterobimetallic copper-sodium complex [Cu(PDPH)2Na(thf)2] (4). The PDPH ligand in 1-4 is nonplanar, with torsion angles between pyridine and pyrrole rings in the range of 15.8-38.3°. The argentophilic interactions, π∙∙∙π stacking, and weak interaction of Ag∙∙∙C(aromatic) are observed in these complexes. Interestingly, treatment of the analogous 2,5-bis(6'-bromo-2'-pyridyl)pyrrole (HPDPBr) with AgOTf affords a di-nuclear complex [(HPDPBr)Ag]2(OTf)2 (5·(OTf)2). Its HPDPBr ligands coordinate to Ag atoms in a head-to-head fashion, and two protonated pyrrole linkages reside in the anti-parallel direction and are non-coordinating. Short AgBr distances of 3.255-3.390 Å are observed.

Two cobalt(II) complexes [Co(QCT)2]·Cl·1.5H2O (1) (QCT = quinoline-2-carboxaldehyde thiosemicarbazone) and [Co(QCMT)(CH3OH)Cl2] (2) (QCMT = quinoline-2-carboxaldehyde N4-methyl-thiosemicarbazone) have been synthesized and structurally characterized. Complex 1 crystallizes in a triclinic system with space group P–1 and complex 2 crystallizes in a monoclinic system with space group P2(1)/n. In both complexes the cobalt(II) center is six coordinated with distorted octahedral geometry. The interactions of two complexes with CT-DNA were investigated by electronic absorption spectra, circular dichroism (CD) spectra and fluorescence spectra. Results suggest that the complexes bind to DNA via groove binding mode, and complex 2 has stronger binding ability than complex 1. The in vitro cytotoxicity has been tested against the human lung adenocarcinoma cell line A-549, cisplatin-resistant cell line A-549/CDDP, and human breast adenocarcinoma cell line MCF-7. Complex 2 is more cytotoxic than complex 1, and both of th...

Heteropolymetallic complexes [(salen)Ti(ReO 4 ) 2 ] ( 1 ) and [{(salen)Ti(ReO 4 )} 2 (μ-O)] ( 2 ) are easily obtained in high yields via reaction of [(salen)TiCl 2 ] and [{(salen)TiCl 2 } 2 (μ-O)] with (Me 3 SiO)ReO 3 , respectively (where, salen = (S,S)- N , N ′-bis(3,5-di- tert -butylsalicylidene)cyclohexane-1,2-diamine dianion). The structure of complex 2 was established by single-crystal X-ray diffraction. The tetrahedral geometry of the ReO 4 − anion links the dititanium unit of {(salen)Ti} 2 (μ-O) in the axial positions. The Re–O–Ti bridge angles range from 146.1(2) to 162.6(2) with a Re⋯Ti separation of 3.780 A. Complexes 1 and 2 are capable of catalytic oxidation of sulfides with t BuOOH.

Ruthenium(VI) complexes with a sterically bulky bidentate Schiff base ligand, 2-[(2,6-diisopropylphenyl)imino]methyl-4,6-dibromophenolate (L−), have been synthesized and their reactivity studied. Treatment of [Bun4N][Ru(N)Cl4] in tetrahydrofuran with 2 equivalents of NaL afforded cis-[Ru(N)Cl(L)2] (1) that reacted with Ag(OTf) (OTf− = triflate) in acetone to give trans-[Ru(N)(H2O)L2][OTf] (2). Reactions of complex 1 with Me3NO and elemental sulfur afforded cis-[Ru(NO)(Cl)L2] (3) and cis-[Ru(NS)(Cl)L2] (4), respectively. Reaction of complex 1 with Me3SiN3 in MeCN afforded [Ru(MeCN)(Cl)L2], which could alternatively be prepared by photolysis of complex 3 in CH2Cl2–MeCN with UV light. The crystal structures of complexes 1 and 2 have been determined.

Treatment of the 2,5-bis(2′-pyridyl)pyrrolato (PDP−) anion with {Ru(COD)Cl2}n in THF readily yielded [Ru(PDP)(COD)Cl] (1) in almost quantitative yield. Anion metathesis of 1 in organic solvent by NO3− and OTf− (OTf− = triflato) gave [Ru(PDP)(COD)(NO3)] (2) and [Ru(PDP)(COD)(OTf)] (3), and in aqueous solution by BF4− and PF6− afforded aqueous complexes [Ru(PDP)(COD)(H2O)](BF4) (4+·BF4−) and [Ru(PDP)(COD)(H2O)](PF6) (4+·PF6−), respectively. Treatment of 1 with PhICl2 in CH2Cl2 afforded 5 with halogenated pyrrole. These complexes exhibit similar structure, including one Ru(II) atom, one 2,5-bis(2′-pyridyl)pyrrole and one monodentate anion or aqua ligand. Each Ru(II) tightly binds to three adjacent coplanar sites of PDP− ligand to form a meridional configuration. Complex 1 with NaIO4 as the oxidant in EtOAc–CH3CN–H2O (ratio = 3 : 1 : 2) proved to be highly effective in the catalytic oxidation of olefins to carbonyl products.

Dinuclear ruthenium nitrido complexes supported by the Kläui's tripodal ligand [CpCo{P(O)(OEt)(2)}(3)](-) (L(OEt)(-)) have been synthesized starting from the ruthenium(VI) nitrido precursor [L(OEt)Ru(VI)(N)Cl(2)] (1). Heating a solution of 1 in CCl(4) at reflux, followed by recrystallization from hexane under nitrogen, afforded the mixed-valence ruthenium(V)-ruthenium(IV) μ-nitrido complex [L(OEt)Cl(2)Ru(V)(μ-N)Ru(IV)Cl(2)L(OEt)] (2). The cyclic voltammogram of 2 exhibited reversible couples at 0.19 and 1.13 V versus Cp(2)Fe(+/0), which are assigned as the Ru(V)-Ru(IV)/Ru(IV)-Ru(IV) and Ru(V)-Ru(V)/Ru(V)-Ru(IV) couples, respectively. Recrystallization of 2 from Et(2)O/heptane in air yielded the diamagnetic Ru(IV)-Ru(IV) complex [H(13)O(6)][{L(OEt)Ru(IV)Cl(2)}(2)(μ-N)] ([H(13)O(6)][2]), which underwent cation exchange with n-Bu(4)NOH to give [n-Bu(4)N][2]. X-ray diffraction revealed that the complex anions in [H(13)O(6)][2] and [n-Bu(4)N][2] contain linear, symmetric Ru-N-Ru bridges. Treatment of 1 with [(η(6)-p-cymene)Ru(II)Cl(2)](2) in benzene afforded the tetranuclear ruthenium(IV) complex [L(OEt)Cl(2)Ru(IV)(μ-N)Ru(IV)(H(2)O)Cl(2)](2) (3) containing symmetric Ru(IV)-N-Ru(IV) bridges. The reaction of 1 with [Ru(II)(H)(Cl)(CO)(PCy(3))(2)] (Cy = cyclohexyl) gave the ruthenium(VI)-ruthenium(II) nitrido complex [L(OEt)Cl(2)Ru(VI)(μ-N)Ru(II)(H)Cl(CO)(PCy(3))(2)] (4). The observed short Ru(II)-N bond distance [1.915(5) Å] and high C-O stretching frequency (1985 cm(-1)) in 4 are suggestive of π interaction between Ru(II) and the nitride.

Treatment of [Ru( CHR)Cl2(PCy3)2] (Cy = cyclohexyl) with Tl[N(Pr2iPO)2] and AgLOEt (LOEt− = [CpCo{P(O)(OEt)2}3]−) afforded the Ru carbene complexes [Ru( CHPh)(PCy3)Cl{N(Pr2iPO)2}] (1) and [LOEtRu( CHR)(PCy3)Cl] (2), respectively. Chloride abstraction of complex 2 with TlPF6 in MeCN afforded [LOEtRu( CHPh)(PCy3)(MeCN)][PF6] (3). Complexes 1 and 2 are capable of catalyzing ring-closing metathesis of diethyl 1,2-diallylmalonate. The crystal structure of complex 2 has been determined.

Bismuth(III) compounds containing the Klaui's oxygen tripodal ligand [CpCo{P(O)(OEt)(2)}(3)](-) (L(OEt)(-)) have been synthesized, and their interactions with dichromate in aqueous media were studied. The treatment of Bi(5)O(OH)(9)(NO(3))(4) with NaL(OEt) in water afforded [L(OEt)Bi(NO(3))(2)](2) (1), whereas that of BiCl(3) with NaL(OEt) in CH(2)Cl(2) yielded L(OEt)BiCl(2) (2). Chloride abstraction of 2 with AgX afforded [L(OEt)BiX(2)](2) [X(-) = triflate (OTf(-)) (3), tosylate (OTs(-)) (4)]. In aqueous solutions at pH > 4, 4 underwent ligand redistribution to give the bis(tripod) complex [(L(OEt))(2)Bi(H(2)O)][OTs] (5). The treatment of 4 with Na(2)Cr(2)O(7) in acetone/water afforded the Bi(III)/Cr(VI) oxo cluster [(L(OEt))(4)Bi(4)(μ(3)-CrO(4))(2)(μ(3)-Cr(2)O(7))(2)] (6) containing a unique Bi(4)Cr(4)O(12) oxometallic core. Compound 6 oxidized benzyl alcohol to give ca. 6 equiv of benzaldehyde. The reaction between 2 and CrO(3) yielded [L(OEt)Bi(OCrO(2)Cl)](2)(μ-Cl)(2) (7). The crystal structures of complexes 4-7 have been determined.

Two dimensional layered like coordination polymer [Co(2,4'-bpdc)(H2O)]n containing one-dimensional double-stranded left-handed helical channels from achiral building block 2,4'-biphenyldicarboxylic acid (2,4'-H2bpdc) was reported. The resultant crystals were not racemic as evidenced by the observation of strong signals in vibrational circular dichroism (VCD) and circular dichroism (CD) spectra

A new pillar-layered coordination framework [Er(H2O)(C5H2N2O4)(TA)0.5]n (1) has been hydrothermally synthesized by employing imidazole-4,5-dicarboxlylate (H3IDC) and terephthalate (H2TA) and structurally characterized. Single crystal X-ray diffraction analysis reveals that compound 1 exhibits the 2D pillar-layered coordination framework with meso-helical character constructed from auxiliary ligand TA2− (that is, pillar) bridging two [Er(HIDC2−)]n layers (namely, Δ- and Λ-layers), which is the first example of lanthanide coordination framework including imidazole-4,5-dicarboxlylate and terephthalate. Meanwhile, the thermogravimetric analysis shows compound 1 has high thermal stability.

Treatment of Ru(CO)(Cl)(H)(PPh3)3 with NaLOEt (LOEt − = [CpCo{P(O)(OEt)2}3]−) afforded the hydride complex (PPh3)(CO)-LOEtRu(H) (1), which has been characterized by X-ray crystallography. Similarly, the tricyclohexylphosphine analogue, (PCy3)(CO)LOEtRu(H) (2), was synthesized from Ru(CO)Cl(H)(PCy3)2 and NaLOEt. Treatment of complex 1 with R’sO2N3 afforded the (arylsulfonyl)amido complexes LOEtRu(CO)(PPh3)(NHSO2R) (R = 2,4,6-i-Pr3C6H2 (3), 4-t-BuC6H4 (4)). The crystal structure of complex 3 has been determined. The Ru-N distance and Ru-N-S angle in 3 are 2.076(3) A and 126.14(16)°, respectively. Reactions of complex 1 with acids have been studied.

Heating [Rh(dtbpy)(κ2-C,C′-CH2CMe2C6H4)(CH2CMe2Ph)] (1; dtbpy = 4,4′-di-tert-butyl-2,2′-bipyridyl) in p-xylene at 110 °C resulted in the formation of the 2-tert-butylphenyl complex [Rh(dtbpy)(κ2-C,C′-CH2CMe2C6H4)(C6H4tBu-2)] (3). Treatment of complex 1 with diethyl phosphite gave the phosphito-bridged dimer [Rh(dtbpy)(κ2-C,C′-CH2CMe2C6H4){P(O)(OEt)2}]2 (4). Refluxing [Ir(dtbpy)(κ2-C,C′-CH2CMe2C6H4)(C6H4tBu-2)] (2) with 2-phenylpyridine (ppyH) and 4-(2-pyridyl)benzaldehyde in toluene followed by column chromatography afforded [Ir(dtbpy)(CH2CMe2Ph)Cl(κ2-N,C-ppy)] (5) and the carbonyl complex [Ir(dtbpy)(CH2CMe2Ph)(CO)(R)] (6) [R = 4-(2-pyridyl)phenyl], respectively. Anion metathesis of [M(dtbpy)(CH2CMe2Ph)(H2O)(OTs)2] with NaBArF4 [ArF = 3,5-(CF3)2C6H3] afforded cationic [M(dtbpy)(CH2CMe2Ph)(H2O)(μ-OTs)]2[BArF4]2 [M = Rh (7), Ir (8)] that are capable of catalyzing H/D exchange of tetrahydrofuran by using D2O as the deuterium source. The crystal structures of complexes 4–7 were determined.

Treatment of [Cp∗Ir(ppy)Cl] (Cp∗ = η5-C5Me5, ppyH = 2-(2-pyridyl)phenyl) with Ag(OTf) (OTf− = triflate) in MeOH and MeCN gave the solvento complexes [Cp∗Ir(ppy)(solv)][OTf] (solv = MeOH (1) and MeCN (2)). Complex 1 is capable of catalyzing oxidation and azirdination of styrene with PhIO and PhINTs (Ts = tosyl), respectively. Treatment of 2 with a stoichiometric amount of PhINTs resulted in the insertion of the NTs group into the Ir–C(ppy) bond and formation of [Cp∗Ir(η2-ppy-NTs)(MeCN)][OTf] (3). Treatment of 1 with R2E2 afforded [Cp∗Ir(ppy)(η1-R2E2)][OTf] (E = S (4), Se (5), Te (6)). Reactions of 4 and 5 with Ag(OTf) resulted in cleavage of the E–E bond and insertion of an ER group into the Ir–C(ppy) bond. The crystal structures of complexes 2–6 and [Cp∗Ir(η2-ppy-S-p-tol)(H2O)][OTf]2 have been determined.

Treatment of Ru(═CHPh)Cl2(PCy3)2 (Cy = cyclohexyl) with K[N(i-Pr2PS)2] afforded a mixture of Ru(═CHPh)[N(i-Pr2PS)2](PCy3)Cl (1) and Ru(═CHPh)[N(i-Pr2PS)2]2 (2). Reaction of 1 with TlOPh gave Ru(═CHPh)[N(i-Pr2PS)2](PCy3)(OPh) (3), whereas that with NaOMe yielded the Ru(II) hydride compound Ru(H)[N(i-Pr2PS)2][PCy2(η2-C6H9)] (4), in which the dicyclohexyl(cyclohex-3-enyl)phosphine ligand binds to Ru via the phosphorus atom and the C═C bond of the cyclohex-3-enyl ring. The structures of complexes 3 and 4 have been established by X-ray crystallography.

Interaction of [LOEtZrF3] ( L OEt - = [Co(η5-C5H5){P(O)(OEt)2}3]−) (1) with 3 equivalents of bis(trimethylsilyl) sulfate afforded the ZrIV hydrogensulfato complex [(LOEt)2Zr2(SO4)2(HSO4)2] (2) that reacted with Et3N to give [Et3NH][LOEtZr(H2O)(SO4)2] (3). Treatment of complex 1 with 3 equivalents of trimethylsilyl acetate afforded [LOEtZr(OCOCH3)3] (4), whereas that with 1 and 2 equivalents of trimethylsilyl trimethylsiloxyacetate yielded [LOEtZrF(OCOCH2O)]2 (5) and [LOEtZr(OCOCH2OH)(OCOCH2O)]2 (6), respectively. The crystal structures of complexes 2 and 6 have been determined.

Self-assemblies of two unsymmetrical tridentate N2O/N2S donor Schiff base ligands, that is, 2-((2-(dimethylamino)ethylimino)methyl)phenol (HL1) and methyl-2-pyridylmethylidenehy-drazinecarbodithioate (HL2), with different cadmium salts have led to 11 anion-controlled complexes, namely, [Cd(Ln)2] [n = 1 for 1 and n = 2 for 2], [Cd(L1)(HL1)](ClO4) (3), [Cd(HL2)(L2)](ClO4)(H2O) (4), [Cd(L2)Cl2] (5), [Cd(L1)Cl]2 (6), [Cd(L1)(NO3)]2 (7), [Cd(L2)(NO3)(CH3OH)]2 (8), [Cd(L2)(NO3)(H2O)]2 (8a), [Cd2(L1)2(SCN)2]n (9), and [CdL2(SCN)2]n (10), respectively. Eleven compounds were characterized by elemental analyses, IR spectra, MS and thermogravimetric analyses, of which 10 structures 2, 3, 4, 5, 6, 7, 8, 8a, 9, and 10 were further determined by single-crystal X-ray diffraction analyses. The compounds 2, 3, and 4 are mononuclear, in which the neutral molecule unit CdII(L2)2 (in 2) as well as cation units [CdII(HL1−2)(L1−2)]+ (L1 for 3 and L2 for 4) are respectively connected by hydrogen bonds C−H···S, O−H···O, and C−H·...

The Klaui oxygen tripodal ligands [(η 5 -C 5 H 5 )Co{P(O)(OR) 2 } 3 ] − (L OR − where R = alkyl group), which have been recognized as oxygen analogues of cyclopentadienyl, can form stable complexes with a range of main group and transition metal ions. This review reports on the recent developments in the coordination and organometallic chemistry of the Klaui tripodal ligands. Special attention will be paid to polynuclear M-L OEt (M = Ti, Zr) oxo and hydroxo compounds that may serve as models for group 4 metal aqua ions.

Treatment of [n-Bu4N][Ru(N)Cl4] with [AgL(OEt)] (L(OEt)- = [(eta5-C5H5)Co{P(O)(OEt)2}3]-) afforded the ruthenium(VI) nitrido complex [L(OEt)Ru(N)Cl2] (1), which reacted with PPh3 to give the ruthenium(IV) phosphiniminato complex [L(OEt)Ru(NPPh3)Cl2] (2). The cyclic voltammogram of 2 displays the RuIV/III couple at ca. 0 V vs ferrocenium/ferrocene. Treatment of 1 with Me3NO afforded [LOEtRu(NO)Cl2] (3), which reacted with Ag(OTf) (OTf- = triflate) to give the chloro-bridged tetranuclear ruthenium/silver complex [L(OEt)Ru(NO)Cl2]2[Ag(OTf)]2 (4). Treatment of 1 with Na2S2O3 gave the thionitrosyl complex [L(OEt)Ru(NS)Cl2] (5). The solid-state structures of 1-4 have been established by X-ray crystallography.

Treatment of [L OEt Ti(OTf) 3 ] ( L OEt − = [ CpCo { P ( O ) ( OEt ) 2 } 3 ] - , OTf − = triflate) with S -binapO 2 (binap = 2,2′-bis(diphenylphosphinoyl)-1,1′-binaphthyl) afforded the terminal hydroxo complex [L OEt Ti( S -binapO 2 )(OH)][OTf] 2 ( 1 ). Treatment of [L OEt Ti(OTf) 3 ] with K(tpip) (tpip − = [N(Ph 2 PO) 2 ] − ) afforded [L OEt Ti(tpip)(OTf)][OTf] ( 2 ) that reacted with CsOH to give [L OEt Ti(tpip)(OH)][OTf] ( 3 ). The structures of 1 and 2 have been determined.

Treatment of titanyl sulfate in about 60 mM sulfuric acid with NaL(OEt) (L(OEt) (-)=[(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)}(3)](-)) afforded the mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(2)(mu-SO(4))] (2). In more concentrated sulfuric acid (>1 M), the same reaction yielded the di-mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(mu-SO(4))(2)] (3). Reaction of 2 with HOTf (OTf=triflate, CF(3)SO(3)) gave the tris(triflato) complex [L(OEt)Ti(OTf)(3)] (4), whereas treatment of 2 with Ag(OTf) in CH(2)Cl(2) afforded the sulfato-capped trinuclear complex [{(L(OEt))(3)Ti(3)(mu-O)(3)}(mu(3)-SO(4)){Ag(OTf)}][OTf] (5), in which the Ag(OTf) moiety binds to a mu-oxo group in the Ti(3)(mu-O)(3) core. Reaction of 2 in H(2)O with Ba(NO(3))(2) afforded the tetranuclear complex (L(OEt))(4)Ti(4)(mu-O)(6) (6). Treatment of 2 with [{Rh(cod)Cl}(2)] (cod=1,5-cyclooctadiene), [Re(CO)(5)Cl], and [Ru(tBu(2)bpy)(PPh(3))(2)Cl(2)] (tBu(2)bpy=4,4'-di-tert-butyl-2,2'-dipyridyl) in the presence of Ag(OTf) afforded the heterometallic complexes [(L(OEt))(2)Ti(2)(O)(2)(SO(4)){Rh(cod)}(2)][OTf](2) (7), [(L(OEt))(2)Ti(O)(2)(SO(4)){Re(CO)(3)}][OTf] (8), and [{(L(OEt))(2)Ti(2)(mu-O)}(mu(3)-SO(4))(mu-O)(2){Ru(PPh(3))(tBu(2)bpy)}][OTf](2) (9), respectively. Complex 9 is paramagnetic with a measured magnetic moment of about 2.4 mu(B). Treatment of zirconyl nitrate with NaL(OEt) in 3.5 M sulfuric acid afforded [(L(OEt))(2)Zr(NO(3))][L(OEt)Zr(SO(4))(NO(3))] (10). Reaction of ZrCl(4) in 1.8 M sulfuric acid with NaL(OEt) in the presence Na(2)SO(4) gave the mu-sulfato-bridged complex [L(OEt)Zr(SO(4))(H(2)O)](2)(mu-SO(4)) (11). Treatment of 11 with triflic acid afforded [(L(OEt))(2)Zr][OTf](2) (12), whereas reaction of 11 with Ag(OTf) afforded a mixture of 12 and trinuclear [{L(OEt)Zr(SO(4))(H(2)O)}(3)(mu(3)-SO(4))][OTf] (13). The Zr(IV) triflato complex [L(OEt)Zr(OTf)(3)] (14) was prepared by reaction of L(OEt)ZrF(3) with Me(3)SiOTf. Complexes 4 and 14 can catalyze the Diels-Alder reaction of 1,3-cyclohexadiene with acrolein in good selectivity. Complexes 2-5, 9-11, and 13 have been characterized by X-ray crystallography.

This paper describes the syntheses and characterization of three novel phosphonate compounds M{(C5H4N)CH(OH)PO3}(H2O) [M = Mn (1), Fe (2), Co (3)] with isomorphous layered structures. Each {MO4N} trigonal bipyramid in the structure is corner-shared with three {CPO3} tetrahedra from three equivalent [hydroxy(4-pyridyl)methyl]phosphonate ligands, forming a one-dimensional inorganic double chain. These inorganic chains are linked together via the organic groups of the ligand, leading to a two-dimensional layer structure. The layers are further connected to each other through extensive hydrogen bonds, thus generating a three-dimensional supramolecular network. The magnetic properties show that weak antiferromagnetic interactions are mediated between the metal centers in all three compounds.

η(5)-η(1) ring slippage of [OsCp2] (Cp = η(5)-C5H5) and [Ru(η(5)-ind)2] (ind = indenyl) resulting from reaction with the ruthenium(VI) nitride [Ru(L(OEt))(N)Cl2] (1; L(OEt)(-) = [CoCp{P(O)(OEt)2}3](-)) is reported. The treatment of [OsCp2] or [Ru(η(5)-ind)2] with 1 resulted in η(5)-η(1) ring slippage of the cycloolefin ligands and formation of the trinuclear nitrido complexes [Cp(η(1)-C5H5)Os(NRuL(OEt)Cl2)2] (2) or [(η(5)-ind)(η(1)-ind)Ru(NRuL(OEt)Cl2)2] (3). No reactions were found between [OsCp2] and amines, such as pyridine and 2,2'-bipyridyl, or other metal nitrides, such as [Os(L(OEt))(N)Cl2], indicating that the electrophilic property of 1 is essential for ring slippage. The crystal structures of 2 and 3 have been determined. The short Os-N distances in 2 [1.833(5) and 1.817(5) A] and the (ind)Ru-N distances in 3 [1.827(5) and 1.852(5) A] are indicative of multiple bond character, consistent with density functional theory (DFT) calculations. Therefore, 2 and 3 may be described by two resonance forms: Ru(VI)-M(II)-Ru(VI) and Ru(IV)-M(VI)-Ru(IV) (M = Os, Ru). Also, DFT calculations indicate that for the reaction of 1 with [OsCp2] or [Ru(η(5)-ind)2], η(5)-η(1) ring slippage is energetically more favorable than the η(5)-η(3) counterpart. The driving force for η(5)-η(1) ring slippage is believed to be the formation of the strong M-N (M = Os, Ru) (multiple) bonds. By contrast, the same reaction with acetonitrile is energetically uphill, and thus no ring slippage occurs.

This paper reports the synthesis and crystal structure of a novel mixed valence ruthenium(II,III) compound, (NH(4))(3)Ru(2)(hedp)(2).2H(2)O (1), where hedp represents 1-hydroxyethylidenediphosphonate. It has a two-dimensional structure in which the paddlewheel diruthenium(II,III) units of Ru(2)(hedp)(2) are cross-linked through the phosphonate groups. The layers are stacked along the [100] direction with strong intra- and interlayer hydrogen bonds. Primary magnetic results are presented.

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) Å. 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).

The treatment of HfCl(4) with NaL(OEt) (L(OEt)(-) = [(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)}(3)](-)) in nitric acid afforded L(OEt)Hf(NO(3))(3) (1). Hydrolysis of 1 in acetone/water (4:1, v/v) yielded the hydroxy-bridged dimer [(L(OEt))(2)Hf(2)(H(2)O)(4)(mu-OH)(2)][NO(3)](4) (2). The treatment of (NH(4))(2)[Ce(NO(3))(6)] with 2 equiv of NaL(OEt) in water afforded (L(OEt))(2)Ce(NO(3))(2) (3), whereas that with 1 equiv of NaL(OEt) in CH(2)Cl(2) gave L(OEt)Ce(NO(3))(3) (4). While 4 is stable in organic solvents such as acetone, it was converted completely to 3 in acetone/water. The treatment of 3 with bis(p-nitrophenyl)phosphate (BNPP) afforded (L(OEt))(2)Ce[eta(1)-OPO(OR)(2)](2) (5; R = p-NO(2)C(6)H(4)), whereas the reaction of 4 with NaPO(2)(OR)(2) yielded dinuclear [L(OEt)Ce(NO(3))(2){mu-O(2)P(OR)(2)}](2) [R = p-NO(2)C(6)H(4) (6), Ph (7)]. The addition of 3 in acetone to an aqueous solution of NaH(2)PO(4) yielded the cerium(IV) dihydrogen phosphate complex (L(OEt))(2)Ce(PO(4)H(2))(2) (8). Complexes 1-5 and 7 have been characterized by X-ray crystallography. The hydrolysis of BNPP with L(OEt)M(NO(3))(3) (M = Zr, Hf, Ce) in acetone/water has been studied by (1)H NMR spectroscopy. At 25 degrees C, with [Ce] = 20[BNPP], in an acetone-d(6)/N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid (4:1, v/v) buffer solution (50 mM) (4:1, v/v), the hydrolysis of BNPP with 4 was found to exhibit first-order kinetics with a rate constant of (1.1 +/- 0.1) x 10(-3) s(-1).

In the presence of organic templates, six diruthenium diphosphonates, namely, [H3N(CH2)3NH3]2[Ru2(hedp)2] (1), [H3N(CH2)4NH3]2[Ru2(hedp)2].4H2O (2), [H3N(CH2)5NH3]2[Ru2(hedp)2].4H2O (3), [H3N(CH2)3NH3][Ru2(hedp)(hedpH)].H2O (4), [H3N(CH2)4NH3][Ru2(hedpH(0.5))2].2H2O (5), and [H3N(CH2)5NH3]2[Ru2(hedp)2][Ru2(hedpH)2]] (6) [hedp = 1-hydroxyethylidenediphosphonate, CH3C(OH)(PO3)2] have been synthesized under hydrothermal conditions. Compounds 1-3 contain homovalent paddlewheel cores of Ru2(II,II)(hedp)2(4-) that are connected through edge-sharing of the [RuO5Ru] octahedra, resulting in infinite linear chains. Compounds 4-6 contain mixed-valent diruthenium(II,III) phosphonate paddlewheel cores of Ru2(II,III)(hedpH(n))2(3-2n)- that are connected by phosphonate oxygen atoms, forming distorted square-grid layers in 4 and 6 or a kagomé lattice in 5. Both the templates and the pH values are found to play important roles in directing the final products with particular topologies and oxidation states of the diruthenium unit. The magnetic studies show that weak antiferromagentic interactions are propagated between the homovalent diruthenium units in compounds 1-3. For compounds 4-6, weak ferromagnetic interactions are observed.

Treatment of titanyl sulfate in dilute sulfuric acid with 1 equiv of NaL(OEt) (L(OEt)(-) = [(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)](3)](-)) in the presence of Na(3)PO(4) and Na(4)P(2)O(7) led to isolation of [(L(OEt)Ti)(3)(mu-O)(3)(mu(3-)PO(4))] (1) and [(L(OEt)Ti)(2)(mu-O)(mu-P(2)O(7))] (2), respectively. The structure of 1 consists of a Ti(3)O(3) core capped by a mu(3)-phosphato group. In 2, the [P(2)O(7)](4-) ligands binds to the two Ti's in a mu:eta(2),eta(2) fashion. Treatment of titanyl sulfate in dilute sulfuric acid with NaL(OEt) and 1.5 equiv of Na(2)Cr(2)O(7) gave [(L(OEt)Ti)(2)(mu-CrO(4))(3)] (3) that contains two L(OEt)Ti(3+) fragments bridged by three mu-CrO(4)(2-)-O,O' ligands. Complex 3 can act as a 6-electron oxidant and oxidize benzyl alcohol to give ca. 3 equiv of benzaldehyde. Treatment of [L(OEt)Ti(OTf)(3)] (OTf(-) = triflate) with [n-Bu(4)N][ReO(4)] afforded [[L(OEt)Ti(ReO(4))(2)](2)(mu-O)] (4). Treatment of [L(OEt)MF(3)] (M = Ti and Zr) with 3 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(3)] (5) and [L(OEt)Zr(ReO(4))(3)(H(2)O)] (6), respectively. Treatment of [L(OEt)MF(3)] with 2 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(2)F] (7) and [[L(OEt)Zr(ReO(4))(2)](2)(mu-F)(2)] (8), respectively, which reacted with Me(3)SiOTf to give [L(OEt)M(ReO(4))(2)(OTf)] (M = Ti (9), Zr (10)). Hydrolysis of [L(OEt)Zr(OTf)(3)] (11) with Na(2)WO(4).xH(2)O and wet CH(2)Cl(2) afforded the hydroxo-bridged complexes [[L(OEt)Zr(H(2)O)](3)(mu-OH)(3)(mu(3)-O)][OTf](4) (12) and [[L(OEt)Zr(H(2)O)(2)](2)(mu-OH)(2)][OTf](4) (13), respectively. The solid-state structures of 1-3, 6, and 11-13 have been established by X-ray crystallography. The L(OEt)Ti(IV) complexes can catalyze oxidation of methyl p-tolyl sulfide with tert-butyl hydroperoxide. The bimetallic Ti/ Re complexes 5 and 9 were found to be more active catalysts for the sulfide oxidation than other Ti(IV) complexes presumably because Re alkylperoxo species are involved as the reactive intermediates.

In the polymeric complex of the title compound, {[AgNi(C(5)H(3)N(2)O(2))(2)(H(2)O)(2)]NO(3)·2H(2)O}(n), the Ag(I) ion displays an angular coordination geometry with two N atoms from pyrazine-2-carboxyl-ate ligands, and the Ni(II) ion is hexa-coordinated by two O atoms from two water mol-ecules, two O and two N atoms from pyrazine-2-carboxyl-ate ligands in a distorted octa-hedral geometry. In the crystal, the Ag(I) and Ni(II) ions lie on a mirror plane and an inversion centre, respectively. The complex chains, the nitrate ions and the uncoordinated water mol-ecules are linked together through O-H⋯O hydrogen bonds and weak Ag⋯O inter-actions [2.619 (17)-2.749 (17) Å] into a three-dimensional network.