• T Arumuganathan

      Articles written in Journal of Chemical Sciences

    • Two different zinc(II)-aqua complexes held up by a metal-oxide based support: Synthesis, crystal structure and catalytic activity of [HMTAH]2[{Zn(H2O)5}{Zn(H2O)4}{Mo7O24}].2H2O (HMTAH = protonated hexamethylenetetramine)

      T Arumuganathan A Srinivasarao T Vijay Kumar Samar K Das

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      An inorganic−organic hybrid material, [HMTAH]2[{Zn(H2O)5}{Zn(H2O)4}{Mo7O24}].2H2O (1) (where HMTAH = protonated hxamethylenetetramine) has been synthesized and structurally characterized. The compound 1 crystallizes in a monoclinic space group $C2/c$. The crystal data of 1: 𝑎 = 43.12(3), 𝑏 = 12.399(10), 𝑐 = 16.285(13), 𝛽 = 111.131(11), 𝑍 = 8. Its crystal structure shows that two different Zn(II)-aqua complexes, [Zn(H2O)5]2+ and [Zn(H2O)4]2+ are covalently coordinated to a heptamolybdateanion [Mo7O24]6- resulting in an anionic species of polyoxometalate supported zinc-aqua complexes, [{Zn(H2O)}{Zn(H2O)4}{Mo7O24}]2-, that is stabilized with two protonated hexamethylenetetramine cations in the title compound 1. In the crystal structure, both lattice water molecules are found to interact with the heptamolybdate cluster anion and the protonated hexamethylenetetramine cation resulting in an intricate three-dimensional hydrogen bonding network. Interestingly, compound 1 exhibits catalytic activity towards oxidation of some primary alcohols.

    • Non-covalent O$\cdots$O interactions among isopolyanions using a cis-{MoO2} moiety by the assistance of N-H$\cdots$O hydrogen bonds

      T Arumuganathan A Srinivasa Rao Samar K Das

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      An inorganic-organic hybrid material, [2-AmpH]4[Mo8O26] (1) has been isolated by the reaction of Na2MoO$_4·2$H2O with 2-aminopyrimidine (2-Amp) from an acidic aqueous medium. In this low pH synthesis, the organic molecule (2-Amp) gets mono-protonated (2-AmpH+) and acts as the cation in stabilizing the octamolybdate anion in 1. Compound 1 crystallizes in the triclinic space group 𝑃-1 with 𝑎 = 9.925(3), 𝑏 = 10.020(3), 𝑐 = 10.414(3) Å, 𝛼 = 88.811(4), 𝛽 = 64.907(4), 𝛾 = 89.506(4)°, 𝑍 = 1. An interesting three-dimensional supramolecular structure, having well-defined channels, is formed through N-H$\cdots$O and C-H$\cdots$O hydrogen bonds, in which the protonated organic cation plays a significant role. The crystal structure also reveals an unusual cluster-cluster (non-covalent O$\cdots$O) interaction using cis-(MoO2} moieties of the isopolyanion. N-H$\cdots$O hydrogen bonds, originated from pyridimidinium cation and isopolyanion, are found to influence to attain such non-covalent O$\cdots$O interactions among polyoxometalate anions. An interesting helical arrangement, formed from isopolyanion and organic cation, is observed.

    • Polyoxometalates: Toward new materials

      A Srinivasa Rao T Arumuganathan Vaddypally Shivaiah Samar K Das

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      This article describes an account of some of our polyoxometalate (POM)-based research, we have been doing in our laboratory last several years. There are several well-defined POM cluster anions, that are structurally characterized. We have chosen Anderson-type of heteropolyanion [Al(OH)6Mo6O18]$^{3−}$ and explored its linking propensity in different dimensions using `s', `d' and `f' block elements as linkers.We have demonstrated how a lanthanide linker provides a new pathway in forming a two-dimensional linked {As8V14} system [{Ln(H2O)6}2As8V14O42(SO3)]$_n$.8nH2O, that is derived from discrete {As8V14} cluster containing compound (NH4)6[As8V14O42(SO3)]. A polyoxometalate compound has been described in which a reduced tungstovanadate-heteropolyanion clusters get linked via capped V = O groups into one-dimensional chains. All these systems have already been reported elsewhere. The last portion of this article will be described by a new system [3-ampH]6[V10O28]$\cdot$2H2O having discrete molecular structure and extended supramolecular structure.

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