The molecular mobility of a MOF-5 metal-organic framework was investigated by broadband dielectric spectroscopy. Three relaxation processes were revealed. The temperature dependence of their relaxation rates follows an Arrhenius law. The process observed at lower temperatures is attributed to bending fluctuations of the edges of the cages involving the Zn-O clusters. The processes ("region II") at higher temperatures were assigned to fluctuations of phenyl rings in agreement with the NMR data found by Gould et al. (J. Am. Chem. Soc. 2008, 130, 3246). The carboxylate groups might also be involved. The rotational fluctuations of the phenyl rings leading to the low frequency part of relaxation region II might be hindered either by some solvent molecules entrapped in the cages or by an interpenetrated structure and have a broad distribution of activation energies. The high frequency part of region II corresponds nearly to a Debye-like process: This is explained by a well-defined structure of empty pores.

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The heavy pnictogen tricyanides, E(CN) (E=Sb, Bi), were synthesized from EF and Me SiCN in ionic liquids, for example, 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIm][OTf]), which prevents the oligomerization of the molecular E(CN) species by formation of [BMIm][E(CN) (OTf)] salts in solution. Recrystallization of [BMIm][E(CN) (OTf)] from THF led to the isolation and full characterization of the molecular species E(CN) ⋅2 THF.

The catalytic reduction of carbon À heteroatom multiple bonds under mild conditions constitutes an important transformation in organic synthesis and the pharmaceutical as well as agrochemical industry. [1] Obviously, high selectivity and broad tolerance towards functional groups are key factors for the acceptance and application of novel methodologies. In addition to molecular hydrogen and hydrogen transfer reagents, [2] hydrosilanes are commonly used as reducing agents. [3] Since the early reports three decades ago, [4] the asymmetric and non-asymmetric hydrosilylations of prochiral ketones relied mainly on precious-metal-based catalysts, such as rhodium, [5] ruthenium, [6] and iridium. [7] However, less-expensive metals, such as titanium, [8] tin, [9] and copper [10] were explored, too. [11] More recently, efforts have been devoted to the development of more-benign and available bio-relevant metal catalysts based on iron [12] and zinc complexes. [13] Notably, silanes have also been used as reducing reagents in the presence of acid, [14] fluoride ions, [15] or base, [14a, 15b, 16] although in many cases harsh reaction conditions and large amounts of salt or base were required. Clearly, each of these procedures has its merits as well as limitations. Either the cost of the metal catalyst, toxicity of the residual metal in the product, operational difficulties (such as low temperature À50 to À70 8C), or the use of complex ligand systems limit their applications. Hence, the development of novel catalysts continues to attract academic and industrial interest.Based on the recent work of groups including ourselves on iron-, zinc-, and copper-catalyzed reductions, [17, 18] we started a joint program to explore the catalytic performance of heterogeneous catalysts for the hydrosilylation of ketones. [19] In particular, we were attracted by the use of socalled metal-organic frameworks (MOFs), an important class of porous crystalline materials. [20] Because of their high porosity and surface area, these materials may also find applications in catalysis. [21] At the starting point of our investigations, we used the known {Cu 3 A C H T U N G T R E N N U N G (BTC) 2 } (BTC = 1,3,5-benzenetricarboxylate) material ( Figure 1) [22] in the hydrosilylation of acetophenone. To the best of our knowledge, this and similar MOFs have not been applied in such reductions. [23] In exploratory experiments, the variation of the reaction temperature and solvent were performed in the presence of different silanes. To determine product yields conveniently by GC, NaOH (1 m) in methanol was added after 16 hours to hydrolyze the corresponding silyl ether to 1-phenylethanol. Selected catalytic results are shown in Table 1. Whilst