Synthesis, structure and supramolecular assembly in the crystalline state of a bifunctionalized arylimido derivative of hexamolybdate

Insights into organic-inorganic hybrid molecular materials: organoimido functionalized polyoxomolybdates

Polyoxometalates (POMs) are polyatomic anions that comprise transition metal group 5 (V, Nb, Ta) or group 6 (Mo, W) oxyanions connected together by shared oxygen atoms. POMs are fascinating because of their exclusive and remarkable characteristics. One of the most interesting features of POMs is their capability to function as an electron relay by performing stepwise multi-electron redox reactions while maintaining their structural integrity. Functionalization of POMs with amino organic compounds results in organoimido derivatives of polyoxometalates, which have aroused interest due to augmentation of their properties. Comprehensive study has shown that the synthesis methodologies to obtain desired organoimido derivatives of POMs by employing various imido-releasing reagents have progressed drastically in recent decades, particularly the innovative DCC-dehydrating technique. These organoimido functionalized POMs have been used as major building blocks to develop unique nanostructured organic-inorganic hybrid molecular materials. Many conventional organic synthesis processes such as Pd-catalyzed carbon-carbon coupling and esterification reactions have been performed with organoimido functionalized POMs where the presence of POM triggered the reaction process. Thus, investigation of the reactivity of organoimido derivatives of POMs foreshadows the intriguing future of POMs chemistry.

New sterically encumbered arylimido hexamolybdates for organic oxidation reactions

Surface modification of the parent hexamolybdate by aryl amines results in useful catalysts for the oxidation of cyclohexene to cyclohexene epoxide and benzyl alcohol to benzaldehyde and benzoic acid.

An organic-inorganic hybrid semiconductor material based on Lindqvist polyoxomolybdate and a tetra-nuclear copper complex containing two different ligands

A 3D organic-inorganic hybrid compound based on the Lindqvist-type polyoxometalate, [{Cu(phen)}3{Cu(μ2-ox)3}{Mo6O19}] (1) (phen = 1,10-phenanthroline, ox = oxalate), has been synthesized under hydrothermal conditions and structurally characterized by elemental analysis, IR, TG, PXRD, XPS, UV-vis, and single-crystal X-ray diffraction. In compound 1, three C2O4(2-) ligands bridge one Cu atom and three Cu(phen) fragments to form a tetra-nuclear copper(II) coordination complex [{Cu(phen)}3{Cu(μ2-ox)3}](2+) unit. The six-node [Mo6O19](2-) clusters are interweaved by the 6-connected tetranuclear copper(II) complex units into an intricate 3D network structure, exhibiting a 4(12)·6(3)-nbo (sodium chloride-type) topology. Compound 1 exhibits the highest connectivity of Lindqvist-type POM hybrid materials. The electrochemical behavior of 1-CPE has been investigated in detail. Furthermore, a diffuse reflectivity spectrum of 1 reveals the presence of an optical band gap and the nature of semiconductivity with a large energy gap. A magnetic susceptibility study reveals predominant antiferromagnetic interactions between the Cu(II) bridge units.

A new mono-functionalized organoimido hexa-molybdate derivative: bis-(tetra-n-butyl-ammonium) (5-chloro-2-methyl-phenyl-imido)-μ(6)-oxido-dodeca-μ(2)-oxido-penta-oxidohexa-molybdate(VI)

The title complex, [(C(4)H(9))(4)N](2)[Mo(6)(C(7)H(6)ClN)O(18)], was prepared by the reaction of (Bu(4)N)(4)[α-Mo(8)O(26)] and 2-methyl-5-chloro-aniline hydro-chloride with N,N'-dicyclo-hexyl-carbodiimide as dehydrating agent in dry acetonitrile solution. The aryl-imido ligand is linked to an Mo atom of the Lindqvist-type hexamolybdate anion by an Mo N triple bond, with a bond length of 1.732 (4) Å and an Mo N-C bond angle of 169.1 (4)°, typical for monodentate imido groups in such hybrid complexes. Due to the inter-action between one H atom in the aryl group and an O atom of a symmetry-related hexa-molybdate cluster, the anions form centrosymmetric dimers in the crystal structure. Weak C-H⋯O contacts are observed between the cations and anions. Unresolved disorder in some of the butyl chains of the ammonium cation is noted.

A Kinetically Controlled Trans Bifunctionalized Organoimido Derivative of the Lindqvist-Type Hexamolybdate: Synthesis, Spectroscopic Characterization, and Crystal Structure of (n-Bu4N)2{trans-[Mo6O17(NAr)2]} (Ar = 2,6-dimethylphenyl)

A kinetically controlled trans bifunctionalized organoimido derivative of hexamolybdate, (n-Bu(4)N)(2){trans-[Mo(6)O(17)(NAr)(2)]} (Ar = 2,6-dimethylphenyl) 1, in which the two 2,6-dimethylphenylimido groups are bonded to hexamolybdate at the trans positions, has been successfully synthesized in ca. 60% yield under mild reaction conditions. Its trans structure has been confirmed by a single-crystal X-ray diffraction study. In the crystals, cluster anions of 1 self-assemble into a 3D netlike structure via two different kinds of C-H...O hydrogen bondings, in which 1D supramolecular rectangular channels containing tetrabutylammonium cations form along the a axis. Compound 1 has also been characterized by (1)H NMR, IR, and UV-vis spectroscopic studies. UV-vis-near-IR reflectance spectroscopy measurements reveal the compound's nature of semiconductivity with an optical energy gap of 2.55 eV.

A trifluoromethyl substituted organoimido derivative of the hexametalate cluster: Synthesis, crystal structure and bioactivity of [Mo6O17(NAr)2]2− (Ar=o-CF3C6H4)

The hexamolybdate cluster has been functionalized with fluorine-containing aromatic amine by the DCC (N,N'-dicyclohexylcarbodiimide) dehydrating protocol and a novel bifunctionalized arylimido derivative of hexamolybdate bearing the electron-withdrawing trifluoromethyl group, (Bu(4)N)(2)[Mo(6)O(17)(NAr)(2)] (Ar=o-CF(3)C(6)H(4)), has been prepared. Complete assignments were achieved for the title compound by elemental analysis, IR, (1)H NMR, UV/visible and single-crystal X-ray diffraction analyses. The preliminary agricultural biological activity test indicated that it has some herbicidal and insecticidal activities.