Photophysical Properties and Kinetic Studies of 2-Vinylpyridine-Based Cycloplatinated(II) Complexes Containing Various Phosphine Ligands.

A series of cycloplatinated(II) complexes with general formula of [PtMe(Vpy)(PR3)], Vpy = 2-vinylpyridine and PR3 = PPh3 (1a); PPh2Me (1b); PPhMe2 (1c), were synthesized and characterized by means of spectroscopic methods. These cycloplatinated(II) complexes were luminescent at room temperature in the yellow-orange region's structured bands. The PPhMe2 derivative was the strongest emissive among the complexes, and the complex with PPh3 was the weakest one. Similar to many luminescent cycloplatinated(II) complexes, the emission was mainly localized on the Vpy cyclometalated ligand as the main chromophoric moiety. The present cycloplatinated(II) complexes were oxidatively reacted with MeI to yield the corresponding cycloplatinated(IV) complexes. The kinetic studies of the reaction point out to an SN2 mechanism. The complex with PPhMe2 ligand exhibited the fastest oxidative addition reaction due to the most electron-rich Pt(II) center in its structure, whereas the PPh3 derivative showed the slowest one. Interestingly, for the PPhMe2 analog, the trans isomer was stable and could be isolated as both kinetic and thermodynamic product, while the other two underwent trans to cis isomerization.

Synthesis of polycyclic N-heterocyclic compounds via one-pot three-component cyclization strategy.

Reported herein is an unprecedented and sequential three-component synthetic strategy for the preparation of polycyclic N-heterocyclic compounds. This synthetic protocol enabled the preparation of a series of novel nitrogen-containing pentacyclic compound under convenient conditions in excellent yields and short reaction time. The synthesized products were characterized by IR, 1H NMR, 13C NMR and mass spectra. Furthermore, the definitive structure of target compounds was confirmed by X-ray analysis.

PtSn Nanoalloy Thin Films as Anode Catalysts in Methanol Fuel Cells.

Reactions of SnX2 (X = Cl, Br) with [PtMe2(bipy)], 1, (bipy = 2,2'-bipyridine), followed by NaBH4 reduction at the toluene/water interface in the presence or absence of graphene oxide support rendered PtSn nanoalloy thin films. They were characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The electrocatalytical activity of the PtSn thin films was investigated in the methanol oxidation reaction. Our studies showed that the PtSn/reduced-graphene oxide (RGO) thin film gave better catalytic results for MOR in comparison to bare PtSn or Pt thin films. A maximum jf/jb ratio (jf and jb are the maximum current densities in the forward and backward scans, respectively) of 6.77 was obtained for the PtSn/RGO thin film deriving from the 1 + SnBr2 + NaBH4 sequence.

A synthesis of functionalized arylthio-acrylates, benzo[b][1,4]thiazines and benzo[4,5]thiazolo[3,2-a]azepines from 2-methylbenzothiazole and acetylenic esters in aqueous media.

Alkyl (Z)-3-((2-(N-((E)-3-methoxy-3-oxoprop-1-en-1-yl)acetamido)phenyl)thio)acrylates are obtained from the reaction between 2-methylbenzothiazole and alkyl propiolates in 70% aqueous alcohol, in moderate yields. When dialkyl acetylenedicarboxylates were used under similar conditions, tetra-alkyl 9,10-dihydrobenzo[4,5]thiazolo[3,2-a]azepine-7,8,9,10-tetracarboxylates, together with dialkyl 4-acetyl-3,4-dihydro-2H-benzo[b][1,4]thiazine-2,3-dicarboxylates were obtained in about 4:1 ratios. The stereochemistry of these products has been confirmed by X-ray diffraction.

Iodine-mediated sp³ C-H functionalization of methyl ketones: a one-pot synthesis of functionalized indolizines via the 1,3-dipolar cycloaddition reaction between pyridinium ylides and ynones.

An efficient transition-metal-free approach toward C-H bond activation by using molecular [Formula: see text]-mediated [Formula: see text] C-H bond functionalization for the synthesis of indolizine derivatives via 1,3-dipolar cycloaddition reaction of nitrogen ylides with ynones is described.

Hydroxo-bridged dicopper(II,III) and -(III,III) complexes: models for putative intermediates in oxidation catalysis.

A macrocyclic ligand (L(4-)) comprising two pyridine(dicarboxamide) donors was used to target reactive copper species relevant to proposed intermediates in catalytic hydrocarbon oxidations by particulate methane monooxygenase and heterogeneous zeolite systems. Treatment of LH4 with base and Cu(OAc)2·H2O yielded (Me4N)2[L2Cu4(µ4-O)] (1) or (Me4N)[LCu2(µ-OH)] (2), depending on conditions. Complex 2 was found to undergo two reversible 1-electron oxidations via cyclic voltammetry and low-temperature chemical reactions. On the basis of spectroscopy and theory, the oxidation products were identified as novel hydroxo-bridged mixed-valent Cu(II)Cu(III) and symmetric Cu(III)2 species, respectively, that provide the first precedence for such moieties as oxidation catalysis intermediates.

Isolation of a 2-hydroxytetrahydrofuran complex from copper-promoted hydroxylation of THF.

A complex of a binucleating macrocyclic ligand comprising a [Cu(II)(µ-OH)Na](2+) core reacts with CuI in THF/CH3CN to yield a novel species with a deprotonated 2-hydroxytetrahydrofuran (THF-2-ol) bridging between Cu(II) and Na(I) ions. The complexes were characterized by X-ray crystallography, electron paramagnetic resonance spectroscopy, and electrospray ionization mass spectrometry. (18)O-labeling studies support incorporation of the O atom from µ-OH into the coordinated THF-2-ol ligand.

Copper-, palladium-, and platinum-containing complexes of an asymmetric dinucleating ligand.

The coordination chemistry of an asymmetric dinucleating hexadentate ligand LH(2) comprising neutral alkyltriamine and potentially dianionic dicarboxamido-pyridyl donor sets with copper, palladium, and platinum has been explored. Monometallic, dicopper, and heterodinuclear Cu-Pd and -Pt complexes have been prepared and characterized, including by NMR, EPR, UV-vis, and IR spectroscopy and X-ray crystallography. For example, the monometallic complexes [(LH(2))MCl]X (M = Cu, X = OTf; M = Pd or Pt, X = Cl) were prepared, wherein the metal(II) ions are coordinated to the triamine portion and the pyridyldicarboxamide is unperturbed. Treatment of LH(2) with [MesCu](x) (Mes = mesityl) provided a monocopper(I) complex, again with the metal coordinated only to the trialkylamine donor set. Reaction of [(LH(2))CuCl]OTf with NaOMe resulted in an unexpected migration of the copper(II)-chloride fragment to the pyridyldicarboxamide site to yield Na[LCuCl], from which a dicopper complex LCu(2)Cl(2) and mixed-metal complexes LCu(Cl)M(Cl) (M = Pd, Pt) were prepared by addition of CuCl(2) or MCl(2), respectively. The heterodinuclear complexes were also prepared by addition of CuCl(2) to [(LH(2))MCl]Cl.

Directed derivatization of organotin sulfide compounds: synthesis and self-assembly of an SnS backpack-like cage and a CuSnS ternary cluster.

The organic functionalized, ternary CuSnS cluster [R(N)(2){Sn(mu-S)(2)Cu(PPh(2)Me)}(4)] (3; R(N) = (CMe(2)CH(2)CMeNNH)(2)CO) was obtained by a two-step reaction, first derivatization of carbonyl functionalized double-decker-like cage [(R(1)Sn)(4)(mu-S)(6)] (R(1) = CMe(2)CH(2)COMe) using carbohydrazide, and ensuing reaction of the resulting hydrazone functionalized thiostannate [(R(N)Sn(2))(2)(mu-S)(6)] (1) with Na(2)S.9H(2)O and [CuCl(PPh(2)Me)(3)]; as confirmed by ESI mass spectrometry, the second step passes a thiostannate intermediate species, Na(2)[R(N)(SnS)(2)(mu-S)(2)] (2).

Directed formation of an organotin sulfide cavitand and its transformation into a rugby-ball-like capsule.

We report the systematic synthesis and thorough characterization of a discrete organotin sulfide cavitand, [R(B)(4)Sn(12)S(20)] {1, R(B) = 1,5-bis[(E)-2-(4-methylpentan-2-ylidene)hydrazinyl]naphthalene}, which readily undergoes a unique transformation into a stable, rugby-ball-like capsule, [R(B)(3)Sn(6)S(8)][(SnCl(3))(2)] (2), upon addition of a protic acid. DMF molecules are embedded within the cavities of both compounds by hydrogen-bonding interactions, spotlighting the title compounds with respect to molecular containment.

A heterocyclic organogallium peroxide with two dialkylgallium groups bridged by a peroxide dianion.

Treatment of Li[H2GaR2] [R=CH(SiMe3)2] with the hydrogen peroxide adduct (H2O2)2.DABCO (DABCO=diazabicyclooctane) afforded a heterocyclic digallium peroxide, [R2Ga(micro,eta1,eta1-O2)(micro-OH)GaR2]Li(DABCO) (2), in which two dialkylgallium groups are bridged by an oxidizing peroxo and a hydroxo ligand.

Facile access to the hydrazone functionalized PdGeS cluster [{R(N)Ge(mu-S)3}4Pd6] from the thiogermanate anion [{R(N)Ge}2(mu-S)2S2]2-.

The decanuclear ternary PdGeS cluster [{R(N)Ge(mu-S)(3)}(4)Pd(6)] x MeOH (2 x MeOH) has been obtained in high yield by a two-step reaction, involving the derivatization of the carbonyl functionalized adamantane-like [(R(1)Ge)(4)(mu-S)(6)] (R(1) = CMe(2)CH(2)COMe) with N(2)H(4) x H(2)O, and a subsequent reaction of the resulting hydrazone functionalized thiogermanate (NH(3)NH(2))(2)[(R(N)Ge)(2)(mu-S)(2)S(2)] (R(N) = CMe(2)CH(2)CMeNNH(2), 1) with an acidic solution of (N,N'-tmeda)Pd(NO(3))(2). Cluster 2 has an elegant molecular structure which can be viewed as an R(N) ligated ensemble of four edge-sharing [Pd(3)GeS(3)] defect hetercubanes that meet at an unoccupied center. Thus, the cluster consists of six square-planar coordinated Pd(II) ions at the vertices of a regular octahedron with four faces capped by four [R(N)GeS(3)](3-) units. The title compounds were structurally characterized by means of single-crystal X-ray diffraction as well as physical property measurements. Moreover, density functional theory calculations were performed to gain insight into the unique coordination situation of the hydrazone substituent.