Phosphoester bond cleavage of para-nitrophenylphosphate (pNPP), a commonly used model substrate, is accelerated by using the complex MoO(2)Cl(2)(DMF)(2) (1) (DMF = dimethylformamide) as a hydrolysis promoting agent, even when catalytic amounts of 1 (10 mol% relative to pNPP) are used. The reactions were performed under mild conditions (37-75 °C) and followed by (1)H NMR spectroscopy. For assays performed with high amounts of 1 (1000 mol% relative to pNPP), a white solid (2) precipitates during the initial stages of the reaction, which subsequently dissolves, leading eventually to the precipitation of a less soluble yellow solid (3). Taken together, the characterization data for 2 (FT-IR spectroscopy, elemental analysis, (1)H and (13)C NMR, and electrospray ionization mass spectrometry) indicate that it is a polymeric material with the formula Mo(2)O(6)(DMF)(n) and a structure comprising infinite isopolyoxomolybdate chains built up from edge-shared {MoO(6)} octahedra. Compound 3 was identified as the Keggin-type phosphomolybdate [(CH(3))(2)NH(2)](3)PMo(12)O(40). The formation of 3 is explained by the reaction of inorganic phosphate ions with isopolymolybdate species derived from 2, with dimethylammonium ions arising from the degradation of DMF. Both 2 and 3 are active for phosphoester bond hydrolysis with conversion profiles comparable to the ones obtained with the precursor 1.

The reaction of [MoO(2)Cl(2)(di-tBu-bipy)] (1) (di-tBu-bipy = 4,4'-di-tert-butyl-2,2'-bipyridine) with water at 100-120 °C in a Teflon-lined stainless steel autoclave, in an open reflux system, or in a microwave synthesis system gave the octanuclear complex [Mo(8)O(22)(OH)(4)(di-tBu-bipy)(4)] (2) as a microcrystalline powder in good yields. Single crystals of 2 suitable for X-ray diffraction were obtained by the reaction of MoO(3) and di-tBu-bipy in water at 160 °C for 3 days. The molecular structure of 2 comprises a purely inorganic core, Mo(4)O(8)(μ(3)-OH)(2)(μ(2)-O)(2), attached to two peripheral oxo-bridged binuclear units, Mo(2)O(4)(μ(2)-O)(2)(OH)(di-tBu-bipy)(2). The inorganic core is composed of a unique assembly of four {MoO(5)} distorted square pyramids connected to each other via edge-sharing. Overall, the octanuclear complex adopts a highly distorted form strongly resembling an "S"-shaped molecular unit. Complex 2 was applied in the catalytic epoxidation of the biorenewable olefins DL-limonene (Lim) and methyl oleate (Ole), using tert-butylhydroperoxide (TBHP) as an oxygen donor, under mild reaction conditions (55 °C, air). The reactions of Lim and Ole gave the respective epoxide monomers in fairly high selectivities at high conversions (89% 1,2-epoxy-p-menth-8-ene selectivity at 96% Lim conversion; 99% methyl 9,10-epoxystearate selectivity at 94% Ole conversion, reached within 24 h reaction). Iodometric titrations revealed no measurable "non-productive" decomposition of TBHP.

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