The Structure Chemistry of Boron-Rich Solids of the Alkali Metals

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

“…Dieser Strukturtyp ist seit 1932 bekannt, [264] weitere Literatur hierzu ist in Lit. [125] referiert. Von ihm ableitbar ist die Struktur der Metallcarbapentaboride MB 5 C (M = Na, K), in denen eines der sechs Boratome durch ein Kohlenstoffatom ersetzt ist, [265,266] umionen ist dieses Hexaborid dasjenige mit den längsten interikosaedrischen B-B-Bindungen.…”

Synthesis and Crystal Structure of Cesium Hexamminesodium Decahydro‐closo‐decaborate‐Ammonia(1/1), Cs[Na(NH3)6][B10H10]·NH3

“…We had earlier investigated the synthesis and crystal structure of alkali metal and alkylammonium closo-hydroborates with undistorted boron atom polyhedra [1,2], in order to compare them with typical building units found in boronrich borides [3]. Of the alkali metal hydroborates, only M 2 B 6 H 6 (M ϭ K, Cs), Rb 2 B 9 H 9 and M 2 B 12 H 12 , (M ϭ K, Rb, Cs) have been structurally characterised in the solid state [4Ϫ8].…”

“…Our first step was to crystallize alkylammonium-, ammonium-, alkali metal-or alkali earth metal hydroborates as ammoniates. Later, a gentle removal of NH 3 of novel solvent-free, crystalline hydroborates or new solvent-free modifications of known compounds. Surprisingly, we obtained a hydroborate containing two different alkali metal cations.…”

New route toward nanosized crystalline metal borides with tuneable stoichiometry and variable morphologies

“…B-terminated facets are indeed expected from the excess of boron source introduced. Although the consideration of relative surface energies requires confirmation by first principle calculations, it is consistent with the high strength of the B-B bonds in such compounds and with the high stability of B 6 clusters in borides, 39 which suggest that the boron covalent framework should drive the relative surface energies, so that the role of the metal atoms would be secondary. Noteworthy, the largest facets in bulk tetraboride grown by a metal flux method are also {110}, 40 confirming their low surface energy.…”