Non‐Identical Stepwise Reversible Double‐Redox Coupled Bond Activation Reactions

This work presents a stepwise reversible two‐electron transfer induced hydrogen shift leading to the conversion of a bis‐pyrrolinium cation to an E ‐diaminoalkene and vice versa. Remarkably, the forward and the reverse reaction, which are both reversible, follow two completely different reaction pathways. Establishing such unprecedented property in this type of processes was possible by developing a novel synthetic route towards the starting dication. All intermediates involved in both the forward and the backward reactions were comprehensively characterized by a combination of spectroscopic, crystallographic, electrochemical, spectroelectrochemical, and theoretical methods. The presented synthetic route opens up new possibilities for the generation of multi‐pyrrolinium cation scaffold‐based organic redox systems, which constitute decidedly sought‐after molecules in contemporary chemistry

Organostannoxane-supported Pd(0) nanoparticles as an efficient catalytic system for alkyne dimerization

1066-1071An organostannoxane cage, [<i style="mso-bidi-font-style: normal">n-BuSn(O)OC(O)R]6 [R = -C6H4-p-PPh2] (SnP), has been utilised to stabilise palladium(0) nanoparticles (SnPPd). The latter is shown to efficiently catalyse the alkyne dimerisation reactions under mild reaction conditions. </span

Pyridyloxy Cyclophosphazenes and Carbophosphazenes: Inorganic Ring-Supported Coordination Platforms

This review deals with the utility of cyclophosphazenes and carbophosphazenes as supports for the construction of multi-site coordination platforms. The rich nucleophilic substitution chemistry of the chlorocyclophosphazenes and the analogous carbocyclophosphazenes can be utilized to replace chlorine atoms from these inorganic rings with coordinating side arms. This leads to the assembly of interesting compounds that have the capability to bind to multiple transition metal ions. Using this strategy several coordination ligands have been constructed. After a brief introduction to such ligands, this review deals with pyridyloxy cyclophosphazenes and carbophosphazenes. These ligands, in addition to possessing multiple coordinating arms, are also considered to be structurally flexible systems. This is because the pyridyl substituents are connected to the inorganic ring skeleton through flexible oxygen spacer atoms. The coordination chemistry of these pyridyloxy systems is discussed particularly in light of the work that has emanated from our laboratories in India

Organostannoxane-supported palladium nanoparticles. Highly efficient catalysts for Suzuki-coupling reactions

A phosphine-rich hexameric organostannoxanne, [n-BuSn(O)COOL]6 (PDrum; L = p-PPh2-C6H4-), has been synthesized by a 6:6 reaction between [n-BuSn(O)OH]n and p-Ph2PC6H4COOH. 119Sn{1H} NMR of PDrum revealed a single resonance at -481.0 ppm, indicating that it possesses the characteristic drum structure that is well-known among organostannoxanes. Reduction of PdCl2 with NaBH4 in the presence of PDrum afforded a palladium nanocomposite, NP-1. HRTEM of NP-1 indicates that the average nanoparticle size is about 3 nm. The latter has been shown to be very effective in mediating Suzuki-coupling reactions involving a number of different substrates. NP-1 can be recycled, and HRTEM analysis of the used catalyst reveals some agglomeration. Treatment of NP-1 with n-hexane and cooling to -25 &#176; C afforded another palladium nanocomposite, NP-2. The latter also is very effective in catalyzing the Suzuki-coupling reaction. HRTEM of NP-2 shows an average nanoparticle size of about 4.3 nm, which remains nearly unchanged even after catalysis. NP-2 is a composite also containing some amounts of SnO2

Self-assembly of organostannoxanes: formation of gels in aromatic solvents

Organostannoxane drums [n-BuSn(O)O2C-C6H4-4-OR]6 [R = -CH3 (1); -C9H19 (2); -C11H23 (3)] and [n-BuSn(O)O2C-C6H3-3,5-(OR)2]6 [R = -CH3 (4); -C9H19 (5)] were synthesized by the reaction of n-BuSn(O)(OH) with the corresponding carboxylic acid in a 1:1 stoichiometry. Analogous reactions involving [n-Bu2SnO]n in a 1:1 stoichiometry afforded the diorganostannoxane ladders {[n-Bu2SnO2C-C6H4-4-OR]2O}2 [R = -CH3 (6); -C9H19 (7); -C11H23 (8)] and {[n-Bu2SnO2C-C6H3-3,5-(OR)2]2O}2 [R = -CH3 (9) and -C9H19 (10)]. Compounds 1-10 could also be prepared by a solventless methodology, which involved grinding the reactants together in a mortar and pestle at room temperature. Compounds 1-10 exhibit gelation behavior in aromatic solvents. In contrast, in aliphatic solvents gelation behavior was not observed. Among the organostannoxanes reported here, 2, 3, 5, and 8 were found to be extremely efficient gelators based on their critical gelation concentration values. The microstructure of the organometallic gels, investigated by optical and scanning electron microscopy, reveals the presence of cross-linked network structures. The gels formed from 2and 3 can be converted into xerogels by removal of solvent. The latter can be reconverted into the original gels by treatment with aromatic solvents

Reactions of 4-diphenylphosphino benzoic acid with organotin oxides and -oxy-hydroxide

The reactions of p-diphenylphosphinobenzoic acid (LCOOH) with various organotin precursors have been carried out. Accordingly, the reaction of with LCOOH afforded the hexameric compound, — (1). On the other hand, the reaction of LCOOH with gave the tetrameric compound — (2). The 1-D coordination polymers —, (3), (4)] were prepared in the reaction of or with LCOOH. The compounds 1-4 were structurally characterized by multinuclear NMR spectroscopic and single crystal X-ray diffraction studies. SYNOPSIS The reactions of p-diphenylphosphinobenzoic acid with various organotin precursors have been shown to afford hexameric compound 1, tetrameric compound 2 and 1-D polymeric compounds 3 and 4. The compounds 1-4 were structurally characterized by multinuclear NMR spectroscopic and single crystal X-ray diffraction methods

Heterometallic trinuclear {CoIII2LnIII} (Ln = Gd, Tb, Ho and Er) complexes in a bent geometry. Field-induced single-ion magnetic behavior of the ErIIIand TbIIIanalogues

Through the use of a multi-site compartmental ligand, 2-methoxy-6-[{2-(2-hydroxyethylamino)ethylimino}methyl]phenol (LH3), the family of heterometallic, trinuclear complexes of the formula [CoIII2Ln(L)2(μ-O2CCH3)2(H2O)3]·NO3·xMeOH·yH2O has been expanded beyond Ln = DyIII to include GdIII (1), TbIII (2), HoIII (3) and ErIII (4) for 1, 3 and 4 (x = 1; y = 1) and for 2 (x = 0; y = 2). The metallic core of these complexes consists of a (CoIII–LnIII–CoIII) motif bridged in a bent geometry resulting in six-coordinated distorted CoIII octahedra and nine-coordinated LnIII monocapped square-antiprisms. The magnetic characterization of these compounds reveals the erbium and terbium analogues to display a field induced single-ion magnetic behavior similar to the dysprosium analogue but at lower temperatures. The energy barrier for the reversal of the magnetization of the CoIII2TbIII analogue is Ueff ≥ 15.6(4) K, while for the CoIII2ErIII analogue Ueff ≥ 9.9(8) K. The magnetic properties are discussed in terms of distortions of the 4f electron cloud

Data for Heterometallic trinuclear {CoIIILnIII} (Ln = Gd, Tb, Ho and Er) complexes in a bent geometry. Field-induced single-ion magnetic behavior of the ErIII and TbIII analogues

Through the use of a multi-site compartmental ligand, 2-methoxy-6-[{2-(2-hydroxyethylamino)ethylimino}methyl]phenol (LH3), the family of heterometallic, trinuclear complexes of the formula [CoIII2Ln(L)2(μ-O2CCH3)2(H2O)3]·NO3·xMeOH·yH2O has been expanded beyond Ln = DyIII to include GdIII (1), TbIII (2), HoIII (3) and ErIII (4) for 1, 3 and 4 (x = 1; y = 1) and for 2 (x = 0; y = 2). The metallic core of these complexes consists of a (CoIII–LnIII–CoIII) motif bridged in a bent geometry resulting in six-coordinated distorted CoIII octahedra and nine-coordinated LnIII monocapped square-antiprisms. The magnetic characterization of these compounds reveals the erbium and terbium analogues to display a field induced single-ion magnetic behavior similar to the dysprosium analogue but at lower temperatures. The energy barrier for the reversal of the magnetization of the CoIII2TbIII analogue is Ueff ≥ 15.6(4) K, while for the CoIII2ErIII analogue Ueff ≥ 9.9(8) K. The magnetic properties are discussed in terms of distortions of the 4f electron cloud

N , N′ ‐Ethylene‐Bridged Bis‐2‐Aryl‐Pyrrolinium Cations to E ‐Diaminoalkenes: Non‐Identical Stepwise Reversible Double‐Redox Coupled Bond Activation Reactions

We present here a stepwise reversible two-electrontransfer induced hydrogen shift leading to the conversion of a bis-pyrrolinium cation to an E-diaminoalkene and vice versa.Remarkably, the forward and the reverse reaction, which are bothreversible, follow two completely different reaction pathways.Establishing such unprecedented property in this type of processeswas possible by developing of a novel synthetic route towards thestarting dication. All intermediates involved in both the forward andthe backward reactions were comprehensively characterized by acombination of spectroscopic, crystallographic, electrochemical,spectroelectrochemical, and theoretical methods. The presentedsynthetic route opens up new possibilities for the generation of multi-pyrrolinium cation scaffold-based organic redox systems, whichconstitute decidedly sought-after molecules in contemporarychemistry.Fil: Nayak, Mithilesh Kumar. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; EspañaFil: Stubbe, Jessica. Freie Universität Berlin.; AlemaniaFil: Neuman, Nicolás Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Narayanan, Ramakirushnan Suriya. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; EspañaFil: Maji, Sandipan. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; EspañaFil: Schulzke, Carola. ERNST MORITZ ARNDT UNIVERSITÄT GREIFSWALD (UG);Fil: Chandrasekhar, Vadapalli. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; EspañaFil: Sarkar, Biprajit. Freie Universität Berlin.; AlemaniaFil: Jana, Anukul. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; Españ