Mo₂B₄O₉—Connecting Borate and Metal‐Cluster Chemistry

Abstract

We report on the first thoroughly characterized molybdenum borate, which was synthesized in a high-pressure/high-temperature experiment at 12.3 GPa/1300 °C using a Walker-type multianvil apparatus. Mo B O incorporates tetrahedral molybdenum clusters into an anionic borate crystal structure-a structural motif that has never been observed before in the wide field of borate crystal chemistry. The six bonding molecular orbitals of the [Mo ] tetrahedron are completely filled with 12 electrons, which are fully delocalized over the four molybdenum atoms. This finding is in agreement with the results of the magnetic measurements, which confirmed the diamagnetic character of Mo B O . The two four-coordinated boron sites can be differentiated in the B MAS-NMR spectrum because of the strongly different degrees of local distortions. Experimentally obtained IR and Raman bands were assigned to vibrational modes based on DFT calculations.

From LiB3O5 to NaRbB6O9F2: Fluorine‐Directed Evolution of Structural Chemistry

“…In order to enrich the structuralc hemistry of borates,s everal design strategies have been put forward. For example, introducing cations with lone-pair electrons, [2b, 4, 8, 16-19] d 0 , [20,21] or d 10 [9,[22][23][24] transition metals into borates is regardeda st he effective approach to adjust crystal structures and properties. Introducing the isolated BÀOg roups is also especially worth noting to design compounds with variouss tructures, such as BaB 2 O 4 ,w ith isolated [B 3 O 6 ]r ings, crystallizes in two different space groups.…”

Molybdenum imidazole citrate and bipyridine homocitrate in different oxidation states – balance between coordinated α-hydroxy and α-alkoxy groups

“…S23 and S24 † respectively. [92][93][94] IR and UV-visible spectra 1-4 were also characterized by IR and UV-Vis spectroscopies respectively. Based on the IR spectra shown in Fig.…”

The First High‐Pressure Chromium Oxonitridoborate CrB4O6N—an Unexpected Link to Nitridosilicate Chemistry

“…Over the past two decades, a main aspect of our research has been the high‐pressure synthesis of new borate materials. Astounding results in this field could be discovered, for example, the structural motive of edge‐sharing BO 4 tetrahedra in centrosymmetric Dy 4 B 6 O 15 [1] and non‐centrosymmetric La 3 B 6 O 13 (OH), [2] the discovery of an synthetic access to the substance class of ammine borates (Cd(NH 3 ) 2 [B 3 O 5 (NH 3 )] 2 ), [3] or unexpected Mo 4 ‐clusters in the borate framework of Mo 2 B 4 O 9 [4] …”

“…Later on, additional nitridosilicate representatives of this structure type were found. [16] A fourfold connected carbon atom C [4] ,s imilar to the central nitrogen atom of the starlike-shaped entities,can be found in the isostructural phases RE 2 Si 4 N 6 C( RE = Y, La, Tb,H o) [17] and YScSi 4 N 6 C. [18] Examples of oxonitridosilicates of this structure type could not be found up to now.P orob et al [19] claimed the existence of both oxygen and nitrogen in SrScSi 4 (O,N) 7 due to the blue shift of the Eu 2+ activated material in comparison to the isostructural nitride phosphor. However,t he successful insertion of oxygen into this framework is possible with simultaneous substitution of silicon by aluminum, as presented for example in the sialons (oxonitridoalumosilicates) MLnSi 4Àx Al x O x N 1Àx (M = Sr, Ba, Eu; Ln = Ho-Yb) [20] and SrYSi 4Àx Al x O x N 1Àx .…”