Structure-Directing Forces in Intercluster Compounds of Cationic [Ag14(C[TRIPLE BOND]CtBu)12Cl]+ Building Blocks and Polyoxometalates: Long-Range versus Short-Range Bonding Interactions

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Abstract

Crystallization of [Ag14(C[TRIPLE BOND]CtBu)12Cl][BF4] and different polyoxometalates in organic solvents yields a series of new intercluster compounds: [Ag14(C[TRIPLE BOND]CtBu)12Cl(CH3CN)]2[W6O19] (1), (nBu4N)[Ag14(C[TRIPLE BOND]CtBu)12Cl(CH3CN)]2[PW12O40] (2), and [Ag14(C[TRIPLE BOND]CtBu)12Cl]2[Ag14(C[TRIPLE BOND]CtBu)12Cl(CH3CN)]2[SiMo12O40] (3). Applying the same technique to a system starting from polymeric {[Ag3(C[TRIPLE BOND]CtBu)2][BF4]⋅0.6 H2O}n and the polyoxometalate (nBu4N)2[W6O19] results in the formation of [Ag14(C[TRIPLE BOND]CtBu)12(CH3CN)2][W6O19] (4). Here, the Ag14 cluster is generated from polymeric {[Ag3(C[TRIPLE BOND]CtBu)2][BF4]⋅0.6 H2O}n during crystallization. In a similar way, [Ag15(C[TRIPLE BOND]CtBu)12(CH3CN)5][PW12O40] (5) has been obtained from {[Ag3(C[TRIPLE BOND]CtBu)2][BF4]⋅0.6 H2O}n and (nBu4N)3[PW12O40]. The use of charged building blocks was intentional, because at these conditions the contribution of long-range Coulomb interactions would benefit most from full periodicity of the intercluster compound, thus favoring formation of well-crystalline materials. The latter has been achieved, indeed. However, as a most conspicuous feature, equally charged species aggregate, which demonstrates that the short-range interactions between the “surfaces” of the clusters represent the more powerful structure direction forces than the long-range Coulomb bonding. This observation is of significant importance for understanding the mechanisms underlying self-organization of monodisperse and structurally well-defined particles of nanometer size.

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