The insertion of 1,1-diphenylethylene into the Mg-Mg bond of two magnesium(I) dimers, [(Nacnac)Mg-] (Ar = CHMe-2,4,6 (Mes); CHEt-2,6 (Dep)), yielding 1,2-dimagnesioethane products, [{(Nacnac)Mg}(μ-CHCPh)], is described. These reactions are readily reversible at room temperature and thus represent the first examples of room-temperature reversible redox processes for s-block metal complexes. The 1,2-dimagnesioethane products are highly activated magnesium alkyls and show unprecedented, uncatalyzed reactivity toward H, CO, and ethylene. Computational studies have investigated the mechanisms of all presented reaction types.
The first scandium phosphinoalkylidene complex was synthesized and structurally characterized. The complex has the shortest Sc-C bond lengths reported to date (2.089(3) Å). DFT calculations reveal the presence of a three center π interaction in the complex. This scandium phosphinoalkylidene complex undergoes intermolecular C-H bond activation of pyridine, 4-dimethylamino pyridine and 1,3-dimethylpyrazole at room temperature. Furthermore, the complex rapidly activates H under mild conditions. DFT calculations also demonstrate that the C-H activation of 1,3-dimethylpyrazole is selective for thermodynamic reasons and the relatively slow reaction is due to the need of fully breaking the chelating effect of the phosphino group to undergo the reaction whereas this is not the case for H.
Two extremely bulky amidinate ligands, [RC{N(Dip)}{N(Ar)}] (Dip = 2,6-diisopropylphenyl; Ar = CH{C(H)Ph}Pr-2,6,4; R = 1-adamantyl (L), tert-butyl (L)) have been developed and utilised for the kinetic stabilisation of the strontium and magnesium hydride complexes, [LSr(μ-H)] and [LMg(μ-H)] (R = Ad or Bu). The former represents the missing link in the series of dimeric systems, [LAe(μ-H)] (Ae = alkaline earth metal). The structure and bonding of the complexes have been studied by crystallographic, spectroscopic and computational techniques.
We report the synthesis and characterization of terminal uranium(iv) hydrosulfido and sulfido complexes, supported by the hexadentate, tacn-based ligand (Ad,MeArO)3tacn3–.
Travel behavior is becoming inherently dynamic and socially connected because of the increasing use of mobile technologies; as such, the concept of context is becoming increasingly important in travel and tourism and particularly within today's technology-supported mobile environment. This article builds upon existing literature describing recent developments in context-aware system design with the aim of defining the notion of context as it relates to the mobile technological environment for tourism. As part of this effort, a conceptual framework is proposed to describe the structure and fundamental properties of context, and several implications are discussed for tourism research and the design of mobile systems.
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