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Addition of two or more equivalents of LiPPhH to [N3N]MCl ([N3N]3- = [(Me3SiNCH2CH2)3N]3-; M = Mo or W) produced [N3N]M⋮P complexes via intermediate [N3N]M(PPhH) complexes. The reaction between [N3N]MoCl and 2 equiv of LiAsPhH in the absence of light gave a mixture of [N3N]Mo⋮As (∼30% yield) and [N3N]MoPh. [N3N]Mo⋮N and [N3N]W⋮N were both prepared via decomposition of intermediate azide complexes. Tungsten nitrido, phosphido, or arsenido complexes react readily with methyl triflate in toluene to give the cationic methyl imido, methyl phosphinidene, and methyl arsinidene complexes, respectively. Addition of methyl triflate or trimethylsilyl triflate to [N3N]Mo⋮N yields the cationic imido complexes {[N3N]MoNMe}OTf and {[N3N]MoNSiMe3}OTf, respectively, but {[N3N]Mo=PMe}OTf is not stable in solution at room temperature for more than 1−2 h. The reaction between “[Rh(CO)2(CH3CN)2]PF6” and 2 equiv of [N3N]Mo⋮P or [N3N]W⋮P gave red, crystalline adducts that contain two [N3N]M⋮P “ligands”, e.g., [Rh{[N3N]W⋮P}2(CO)(CH3CN)]+, while red, crystalline [Rh{[N3N]W⋮As}2(CO)(CH3CN)]PF6 could be prepared by an analogous route. {[N3N]MoNSiMe3}OTf could be reduced to “19-electron” [N3N]MoNSiMe3, while addition of MeMgCl to {[N3N]MoNSiMe3}OTf or {[N3N]MoNMe}OTf yielded complexes of the type [N3N]Mo(NR)(Me). The complex in which R = Me was unstable with respect to loss of methane and formation of the iminato complex, [N3N]Mo(NCH2). Both [N3NF]W(PPhH) and [N3NF]Mo(PPhH) ([N3NF]3- = [(C6F5NCH2CH2)3N]3-) could be prepared readily, but all attempts to prepare [N3NF]W⋮P failed. X-ray studies of [N3N]W⋮P, [N3N]Mo(PPhH), [N3N]Mo⋮As, {[N3N]WAsMe}OTf, [Rh{[N3N]W⋮P}2(CO)(CH3CN)]+, and [N3N]Mo=NSiMe3 are presented and discussed.

Ethane oxidative dehydrogenation (ODH) is an alternative route for ethene production. Crystalline M1 phase of Mo-V mixed metal oxide is an excellent catalyst for this reaction. Here we show a hydrothermal synthesis method that generates M1 phases with high surface areas starting from poorly soluble metal oxides. Use of organic additives allows control of the concentration of metals in aqueous suspension. Reactions leading to crystalline M1 take place at 190 °C, i.e., approximately 400 °C lower than under current synthesis conditions. The evolution of solvated polyoxometalate ions and crystalline phases in the solid is monitored by spectroscopies. Catalysts prepared by this route show higher ODH activity compared to conventionally prepared catalysts. The higher activity is due not only to the high specific surface area but also to the corrugated lateral termination of the M1 crystals, as seen by atomic resolution electron microscopy, exposing a high concentration of catalytically active sites.

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