MoV2O42+ Directs the Formation and Subsequent Linking of Potential Building Blocks under Different Boundary Conditions: A Related Set of Novel Cyclic Polyoxomolybdates

Microporosity and Catalytic Activity for Hydrodesulfurization of Pharmacosiderite Mo4P3O16 Synthesized at a Moderate Temperature

Pharmacosiderite Mo4P3O16 (Pharma-MoPO) consists of [Mo4O4] cubane unit and [PO4] tetrahedral to form an open framework with a microporous structure similar to that of LTA-type zeolite. Although attractive applications are expected due to its microporous structure and redox-active components, its physicochemical properties have been poorly investigated due to the specificity of its synthesis, which requires a high hydrothermal synthesis temperature of 360 °C. In this study, we succeeded in synthesizing Pharma-MoPO by hydrothermal synthesis at 230 °C, which can be applied using a commercially available autoclave by changing the metal source. Through the study of the solids and liquids obtained after hydrothermal syntheses, the formation process of Pharma-MoPO under our studied synthesis conditions was proposed. Advanced characterizations provided detailed structural information on Pharma-MoPO, including the location site of a countercation NH4+. Pharma-MoPO could adsorb CO2 with the amount close to the number of cages without removing NH4+. Pharma-MoPO exhibited stable catalytic activity for the hydrodesulfurization of thiophene while maintaining its crystal structure, except for the introduction of sulfide by replacing lattice oxygens. Pharmacosiderite Mo4P3O16 was successfully obtained by hydrothermal synthesis at a moderate temperature, and its microporosity for CO2 adsorption and catalytic properties for hydrodesulfurization were discovered.

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.

Reactions of a {Mo16}-type polyoxometalate cluster with electrophiles: a synthetic, theoretical and magnetic investigation

A medium-nuclearity mixed-valence polyoxomolybdate [H2Mo16O52]10-={Mo16}(1a) was synthesized using an approach that employed protonated hexamethylenetetramine (HMTAH+) as counter ion and yielded (HMTAH)10 1a.34 H2O (1). The {Mo16} cluster anion exhibits significant nucleophilicity and traps electrophiles such as divalent transition metal ions, resulting in a family of isostructural compounds based on {Mo16M2}-type anions [M(H2O)8H2Mo16O52]6- (M=FeII (2), MnII (3), CoII (4)). The highly reactive nature of the {Mo16} system is also revealed by rearrangement and decomposition reactions of to either slowly form a sodium-bridged heptamolybdate-based chain compound (5) when left in the reaction solution or, in the presence of very high concentrations of electrophiles, to heptamolybdate-based cluster compounds [M2(H2O)9Mo7O24]2- of the {M2Mo7}-type (M=FeII (6), MnII (7)). Compounds were characterised by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, magnetic susceptibility measurements, and density functional theory calculations.

A new two-dimensional molybdenum(V) nickel phosphate built up of [H18(Mo16O32)Ni16(PO4)26(OH)6(H2O)8]18- wheels

The new molybdenum(V) nickel phosphate Na(6)Ni(6)[(Mo(2)O(4))(8)Ni(16)(H(2)PO(4))(4)(HPO(4))(10)(PO(4))(12)(OH)(6)(H(2)O)(8)].66H(2)O (1) was synthesized hydrothermally. The structure (orthorhombic, space group Cccm; a = 23.999(4), b = 36.595(6), c = 20.445(4) A) was solved from single-crystal data. The framework structure of 1 consists of anionic inorganic sheets formed by the linkages of large polyoxomolybdate rings via nickel(II) octahedra. Charge-compensating sodium atoms are interleaved between the sheets. Magnetic studies of compound 1 revealed that among the 22 nickel(II) centers, 10 are interacting. The chi(M)T = f(T) curve can be fitted using the dinuclear expression appropriate to the HDVV isotropic exchange Hamiltonian H = -2JS(1).S(2), with S(1) = S(2) = 1 and J = -24.1 cm(-)(1), showing that nickel is antiferromagnetically coupled within Ni(2) pairs.