Reactive Magnesium Nanoparticles to Perform Reactions in Suspension

Zerovalent magnesium (Mg(0)) nanoparticles are prepared in the liquid phase (THF) by reduction of MgBr2 either with lithium naphthalenide ([LiNaph]) or lithium biphenyl ([LiBP]). [LiBP]-driven reduction results in smaller Mg(0) nanoparticles (10.3±1.7 nm) than [LiNaph]-driven reduction (28.5±4 nm). The as-prepared Mg(0) nanoparticles are monocrystalline (d101=245±5 pm) for both types of reduction. Their reactivity is probed by liquid-phase reaction (THF, toluene) in suspension near room temperature (20-120 °C) with 1-bromoadamantane (AdBr), chlortriphenylsilane (Ph3SiCl), trichlorphenylsilane (PhSiCl3), 9H-carbazole (Hcbz), 7-azaindole (Hai), 1,8-diaminonaphthalene (H4nda) and N,N'-bis(α-pyridyl)-2,6-diaminopyridine (H2tpda) as exemplary starting materials. The reactions result in the formation of 1,1'-biadamantane (1), [MgCl2(thf)2]×Ph6Si2 (2), [Mg9(thf)14Cl18] (3), [Mg(cbz)2(thf)3] (4), [Mg4O(ai)6]×1.5 C7H8 (5), [Mg4(H2nda)4(thf)4] (6) and [Mg3(tpda)3] (7) with 40-80 % yield. 1 and 2 show the reactivity of Mg(0) nanoparticles for C-C and Si-Si coupling reactions with sterically demanding starting materials. 3-7 represent new coordination compounds using sterically demanding N-H-acidic amines as starting materials. The formation of multinuclear Mg2+ complexes with multidentate ligands illustrates the potential of the oxidative approach to obtain novel compounds with Mg(0) nanoparticles in the liquid phase.

A new potassium-based intermediate and its role in the desorption properties of the K-Mg-N-H system

New insights into the reaction pathways of different potassium/magnesium amide-hydride based systems are discussed. In situ SR-PXD experiments were for the first time performed in order to reveal the evolution of the phases connected with the hydrogen releasing processes. Evidence of a new K-N-H intermediate is shown and discussed with particular focus on structural modification. Based on these results, a new reaction mechanism of amide-hydride anionic exchange is proposed.

KNH2–KH: a metal amide–hydride solid solution

The addition of KH to KNH₂ provides the first metal amide–hydride solid solution by either mechanochemical or thermal input.

Ca6[Cr2N6]H, the first quaternary nitride-hydride

The novel quaternary nitride-hydride Ca(6)[Cr(2)N(6)]H was synthesized at 1000 degrees C in sealed niobium or stainless steel tubes. It crystallizes in the space group R3 (No. 148, Z = 3) with lattice constants (A) a = 9.0042(2) and c = 9.1898(3) and contains the complex anion [Cr(2)N(6)](11)(-) with a short chromium-chromium bond length of 2.26 A. To our knowledge, this is the first example of a non-nitrogen-bridged chromium-chromium dimer in an extended structure compound. Magnetic susceptibility measurements reveal the compound to be paramagnetic at room temperature and with a broad antiferromagnetic ordering centered around 55 K.