Synthesis and characterization of the first carbene derivative of a polyoxometalate

Reaction of the Keggin-type polyanion [PW11O39]7- with the tetrakis-carbene ruthenium precursor [RuLMe4Cl2] (LMe = 1,3-dimethylimidazolidine-2-ylidene), in water, results in the formation of Na4K9[(PW9O34)2(cis-WO2)(cis-RuLMe2)].23H2O, which is the first carbene derivative of a polyoxometalate. The oxidation state of the ruthenium is confirmed by XANES experiments.     

The role of cation-cation interactions in a neptunyl chloride hydrate and topological aspects of neptunyl structural units

The compound K₄(NpO₂)₃Cl₇(H₂O)₄ was synthesized by evaporation of a Np⁵⁺-bearing solution. The crystal structure was determined by single crystal X-ray diffraction and refined to R₁=0.0374. The compound is triclinic, P−1, a=8.882(1) Å, b=12.082(2) Å, c=12.403(2) Å, α=65.855(2)°, β=69.604(2)°, γ=74.432(2)°, V=1126.0(3) Å³, and Z=2. The structure contains dimers of edge sharing Np⁵⁺ pentagonal bipyramids that are linked into infinite chains through cation-cation interactions with an additional Np⁵⁺ pentagonal bipyramid. The structural units are linked through bonds to interstitial K cations and by H bonding. A graphical representation for neptunyl structural units including cation-cation interactions is introduced.     

The first structural characterization of a rare earth ethanesulfonate

The crystal structure of catena‐poly[[triaquabis(ethanesulfonato‐κO)europium(III)]‐μ‐ethanesulfonato‐κ²O:O′], [Eu(C₂H₅SO₃)₃(H₂O)₃]_n, is the first reported determination of a rare earth ethanesulfonate and also of any hydrated binary metal ethanesulfonate. Two of the three ethanesulfonate anions act as bidentate bridging ligands and connect the single [Eu(C₂H₅SO₃)₃(H₂O)₃] building blocks into infinite chains along the [010] direction. Hydrogen bonds between the water molecules of one chain and sulfonate anions and water molecules of adjacent chains associate the chains into a two‐dimensional supramolecular network. In the third direction, only van der Waals forces between the alkyl groups are observed.     

Luminescent logic function of a surfactant-encapsulated polyoxometalate complex

We have fabricated a novel organic/inorganic hybrid material consisting of multifunctional surfactant-encapsulated polyoxometalloeuropate which functions as a luminescent logic gate with dual output operated by light and metal ion as inputs.     

Synthesis,spectroscopic and structural characterization of new complex of ruthenium(II) with Hmtpo ligand

The [(PPh₃)₂RuHCl(CO)(Hmtpo)] complex has been prepared and studied by IR, NMR, UV–VIS spectroscopy and X-ray crystallography. The complex was prepared in reactions of [RuHCl(CO)(PPh₃)₃] with 7-hydroxy-5-methyl[1,2,4]triazolo[1,5-a]pyrimidine in methanol. The electronic structure and UV–Vis spectrum of the obtained compound have been calculated using the TD–DFT method.     

Synthesis and characterization of a new dimeric polyoxometalate based on Anderson-type polyoxoanions and a trinuclear lanthanide coordination complex

An unusual compound, H₅[(C₆NO₂H₄)₄(H₂O)₁₅Nd₃][IMo₆O₂₄]₂·13.5H₂O (1) has been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), and single crystal X-ray diffraction. Compound 1 consists of two [IMo₆O₂₄]^5? units joined by a trinuclear neodymium-pyridine-4-carboxylic acid complex, resulting in a dimeric polyoxometalate, which further interact via weak intermolecular interactions to form a three-dimensional supramolecular framework with channels. To the best of our knowledge, no analogous dimeric polyoxometalate structure composed of an Anderson-type polyoxometalate has been reported in the literature.     

Structural and spectroscopic characterization of a charge-separated uranium benzophenone ketyl radical complex

The reaction of [((t-Bu)ArO) 3tacn)U (III)] ( 1) with 4,4'-di- tert-butylbenzophenone affords a unique isolable U(IV) ketyl radical species [((t-Bu)ArO) 3tacn)U (IV)(OC* (t-Bu)Ph 2)] (2) supported by XRD data, magnetization measurements, and DFT calculations. Isolation and full characterization of the corresponding diphenyl methoxide complex [((t-Bu)ArO) 3tacn)U (IV)(OCH ( t-Bu )Ph 2)] (3) is also presented. The one-electron reduction of benzophenone by [((Ad)ArO) 3tacn)U (III)] (4) leads to a purple U(IV) ketyl radical intermediate [((Ad)ArO) 3tacn)U (IV)(OC*Ph 2)] (5). This species is highly reactive, and attempts at isolation were unsuccessful and resulted in methoxide complex [((Ad)ArO) 3tacn)U (IV)(OCHPh 2)] (6) from H abstraction and dinuclear para-coupled complex [((Ad)ArO) 3tacn)U (IV)(OCPhPhCPh 2O)U (IV)((Ad)ArO) 3tacn)] (7).     

Complexation between vanadium(V) and citrate: spectroscopic and structural characterization of a dinuclear vanadium(V) complex

Investigation of the aqueous coordination chemistry for citrate and vanadium(V) resulted in the isolation and characterization of a dinuclear vanadium(V) citrato complex (1) Na₂K₂[VO2(Hcit)]₂ · 9H₂O. Complex (1) is an intermediate between the fully deprotonated and diprotonated citrate vanadate. It may represent an early mobilized precursor in the biosynthesis of FeV-co, as well as a relevant model in the proton transport relay process between P-cluster pair to M-cluster pair. The complex has been characterized by elemental analyses and i.r. spectroscopy. Its i.r. spectra are consistent with a oxo-bridged dinuclear structure as revealed by a single crystal X-ray diffraction study.     

Hydrothermal synthesis and characterization of a new Anderson-type polyoxometalate

A new compound based on Anderson-type polyoxometalate, [Cu(phen)H₂O]₂[CrH₅Mo₆O₂₄]?·5H₂O (1) (phen?=?1,10-phenanthroline), has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectrum, and thermal gravimetric analysis. Luminescent, electrochemical, and electroactivity properties of 1 have been studied.     

The first structural characterization and determination of the isomerization activation parameters of a chiral phosphatitanocene

The activation parameters (delta G++298 = 11.5 (+/- 1.0) kcal mol-1, delta H++ = 16.3 (+/- 3.0) kcal mol-1, delta S++ = 16 (+/- 11) cal mol-1 K-1) have been determined for the rac to meso isomerization of a phosphametallocene, bis(3,4-dimethyl-2-phenylphospholyl)titanium dichloride, 2, which has been structurally characterized.     

Structural and spectroscopic characterization of an electrophilic iron nitrido complex

We have isolated and structurally characterized a terminal iron nitrido complex supported by a bulky tris(carbene)borate ligand. The electronic structure of this complex reveals that the a1 LUMO (formerly Fe(dz2)) is strongly stabilized by reduced antibonding interactions with the carbene sigma-donor ligands and configurational mixing (hybridization) with higher lying Fe 4s and 4p atomic orbitals. This unusual bonding interaction results in a low-lying Fe nitrido acceptor orbital (LUMO) that possesses electrophilic character. Reaction with PPh3 results in nitrogen atom transfer to the phosphine, supporting a reaction mechanism involving nucleophilic attack of the triphenylphosphine HOMO at the electrophilic LUMO of the iron nitrido complex.     

A surfactant-encapsulated polyoxometalate complex towards a thermotropic liquid crystal

A novel surfactant-encapsulated terbium-substituted heteropolyoxotungstate complex [L1]13[Tb(SiW11O39)2].30H2O (SEC-1) bearing mesomorphous groups was successfully prepared by the ionic self-assembling route, exhibiting characteristic thermotropic liquid-crystalline behavior.     

Isolation and structural characterization of the first thermally robust and air stable Cr(4+) bent-metallocene complex

The first thermally robust and air stable bent-sandwich chromocene complex with chromium in the +4 oxidation state has been isolated and fully characterized.     

The synthesis, structural, and spectroscopic characterization of uranium(IV) perrhenate complexes

We report the synthesis, structural, and spectroscopic characterization of a series of uranium(IV)-perrhenato complexes. Three isostructural complexes with general formula [U(ReO4)4(L)4] (where L = tri-n-butylphosphine oxide/TBPO (2), triethyl phosphate/TEP (3), or tri-iso-butyl phosphate/TiBP (4)), have been synthesized, both through the photoreduction of ethanolic {UO2}2+ solutions and also via a novel U(IV) starting material, U(ReO4)4.5H2O (1). Compound 1 has also been used in the preparation of [U(ReO4)4(TPPO)3(CH3CN)].2CH3CN (5) and [U(ReO4)(DPPMO2)3(OH)][ReO4]2.2CH3CN (6), where TPPO represents triphenylphosphine oxide and DPPMO2 represents bis(diphenylphosphino)methane dioxide. All six complexes have been spectroscopically characterized using NMR, UV-vis-NIR, and IR techniques, with 2, 3, 5, and 6 also fully structurally characterized. The U atoms in compounds 2-6 all exhibit eight-coordinate geometry with up to four perrhenate groups in addition to three (DPPMO2 and TPPO) or four (TEP, TiBP, TBPO) coordinated organic ligands. In the case of compounds 5 and 6, the coordination of eight ligands to the U(IV) center is completed by the binding of a solvent molecule (CH3CN) and OH-, respectively. Solid-state physical analysis (elemental and thermogravimetric) and infrared spectroscopy are in agreement with the structural studies. The crystallographic data suggest that the strength of the U(IV)-O-donor ligand bonds decreases across the series R3PO > [ReO4]- > (RO)3PO. Solution-state IR and 31P NMR spectroscopy appear to be in agreement with these solid-state results.     

Interaction of Rh(I) with meso-arylsapphyrins and -rubyrins: first structural characterization of bimetallic hetero-rubyrin complex

The ligational behavior of meso-arylsapphyrins and rubyrins toward Rh(I) is investigated. Sapphyrins form monometallic complexes with coordination of one imine and amine type nitrogens of the bipyrrole unit in an eta2 fashion. The Rh(I) coordination is completed by the presence of two ancillary carbon monoxide ligands. Rubyrins form both monometallic and bimetallic complexes. Two types of bimetallic complexes have been isolated. In the first type, both rhodium atoms are projected above the mean rubyrin plane, while in the second type, one rhodium atom is projected above and the other below the mean plane. Detailed 1H and 2D NMR spectral analyses along with IR and UV-visible spectra of the complexes confirm the proposed binding modes for the rhodium complexes. Furthermore, the single-crystal X-ray analysis of one of the bimetallic complexes of rubyrin shows a bowl-shaped symmetric structure where both Rh(I) atoms are projected above the mean rubyrin plane at an angle of 71.73 degrees. The geometry around each rhodium center is approximately square planar [N1-Rh1-N2, 80.38(9) degrees; C15-Rh1-C16, 86.95(14) degrees; N1-Rh1-C15, 97.13(12) degrees; and N2-RH1-C16, 94.97(12) degrees ]. The omicronbserved distance of 4.313 A between the two rhodium centers reveals very little interaction between the two rhodium atoms. This type of metal binding is accompanied by a 180 degrees ring flip of the heterocyclic ring connecting the two bipyrrole units. In dioxarubyrin, where one of the pyrrole rings of the bipyrrole unit is inverted, Rh(I) binds at the periphery to the pyrrole nitrogen, leaving the rubyrin cavity empty. The absence of one amino and one imino nitrogen on the dipyrromethene subunits in the sapphyrins and rubyrins described here forces Rh(I) to bind to bipyrrole nitrogens.     

The first phosphite complex of a metalloporphyrin

(Di­phenyl phosphite‐κO)(5,10,15,20‐tetra­phenyl­porphyrinato‐κ⁴N)­manganese(III) hexa­fluoro­antimonate(V), [Mn(C₄₄H₂₈N₄)(C₁₂H₁₁O₃P)](SbF₆), is the first example of a structurally characterized di­aryl or di­alkyl phosphite complex of a metal–porphyrin ion. The axial phosphite ligand binds to the Mn^III ion via the P=O O atom, affording a nominally five‐coordinate complex with an Mn—O distance of 2.120 (4) Å. The mean porphyrin Mn—N distance is 2.000 (4) Å and the Mn^III ion is displaced from the 24‐atom porphyrin mean plane by 0.1548 (13) Å towards the axial O atom. The porphyrin adopts a marked saddle conformation, with a small domed component. The saddle distortion of the porphyrin ligand reflects the tight back‐to‐back dimers formed in the lattice by pairs of neighboring cations. The `non‐covalent' dimers in the lattice exhibit an unusual (weak) η²‐type coordination of a pyrrole C=C bond from a neighboring mol­ecule, with Mn^III⃛C distances of 3.697 (5) and 3.537 (5) Å.     

Synthesis, spectroscopic, and X-ray structural characterization of pharmacologically active substituted pyrazolyl-acetanilides

Five new pyrazole acetanilides were synthesized by N-alkylation of pyrazole and its derivatives with 4′-propionyl-2-iodoacetanilide. Compounds 1–5 were characterized by ¹H NMR, ¹³C NMR, IR, UV–Vis, MS, and elemental analysis. X-ray structures of representative compounds 1, 3, and 5 established their conformations and solid-state hydrogen bonding preferences. Acute toxicity, local anesthetic, and antiarrhythmic activities were assessed for compounds 1–5 using established protocols. Lower potencies and lower acute toxicities were recorded relative to lidocaine. Enhanced anesthetic activity of compound 3 was attributed to the presence of the propionyl group in the molecule. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis and structural characterization of a silver complex of a mixed-donor N-heterocyclic carbene linked cyclophane

The synthesis of a dicationic imidazolium-linked cyclophane and a dimeric silver-N-heterocyclic carbene complex, that is the first silver complex with a N-heterocyclic carbene ligand involved in a pi-bonding interaction, is reported.