Die Kristallstrukturen von Kalium‐, Rubidium‐ und Cäsium‐trifluororthocarbonat mit einer Bemerkung zum Bariumsulfat‐Typ¹

Abstract

The Crystal Structures of Potassium, Rubidium, and Cesium Trifluororthocarbonate and a Remark Concerning the Barium Sulfate Type'' Crystals of potassium, rubidium, and cesium trifluorortho-monoclinic, completely ordered low-temperature form, which carbonate (9a. 9 b, and 9c) have been grown by Ostwald rip-has been refined for 9c. The C -0 bond seems to be shortened ening in CH3CN applying a COFz pressure of 3 bar. Accord-by polar interactions. The results obtained with 9a, 9b, and ing to X-ray single-crystal structure analysis, 9a, 9b, and 9c 9c at room temperature indicate that the type of disorder belong to the baryte-structure family with an pseudotetrahed-found in 9 might be generally present in baryte-type comral anion being dynamically disordered at room temperature. pounds. All of the title compounds undergo a phase transition into a Seit den Untersuchungen Zintls sind die Salze Na3N03 (1) und Na3N04 (2) in Substanz bekannt*). Man hielt sie zunachst fur Salze der hypothetischen Orthosalpetrigen Saure bzw. Ortho~alpetersaure~,~). Die Aufklarung ihrer Konstitution rnit Rontgenbeugungsmethoden zeigte jedoch, daB nur 2 tetraedrische Ortho-Anionen enthalt 5,6), wahrend 1 als Oxidnitrit Na30(NOz) zu formulieren ist 7,8). Fur 2 wurden N -0-Bindungslangen groBer als 150 pm, also in der GroBenordnung der P -0-Abstande in Orthophosphaten, prognostiziert 9), was qualitativ plausibel erscheint, weil Stickstoff keine d-Orbitaie geeigneter Energie fur die Verstarkung der N-0-Bindungen zur Verfugung stellt. Gemessen an dieser Erwartung wurden die N -0-Abstande rnit 138 pm unerwartet kurz gefunden. In Konsequenz dieses Befundes mussen die Verkurzungen, die bei P(Si,S,Cl) -0-Bindungen gefunden wurden, nicht notwendigerweise auf pn: -dn-Mehrfachbindungsanteile lo) zuriickgefuhrt werden. Sie konnen -wie im Falle von Stickstoff nicht anders moglich -auch durch uberlagerung mit polaren Bindungsanteilen erklart werden. Fur die ahnlich gelagerten Falle der Aminoxide und Phosphanoxide wird diese Auffassung in einer inzwischen erschienen ausfuhrlichen theoretischen Arbeit ebenfalls vertreten"). Wegen der allgemeinen Bedeutung fur das Verstandnis der Bindungsverhaltnisse in tetraedrischen 0x0-Salzen der Nichtmetalle schien es wunschenswert, die Abmessungen weiterer isoelektronischer Spezies 3 -6 der zweiten Periode zur Verfugung zu haben.

Possible Existence of Alkali Metal Orthocarbonates at High Pressure

“…The adjustment of the size of the building unit occurred by alternating empirical‐potential global optimizations and ab initio level local optimizations for the structure candidates found in the global optimization step. The final C–O distance of d (CO)=1.42 Å is in satisfactory agreement with those experimentally determined for molecules containing a COF 3 unit 5…”

“…3 The existence of these esters led to expectations that its salts, the orthocarbonates, should also be accessible 4. Successful synthesis of the potassium, rubidium, and cesium trifluororthocarbonates ACOF 3 (A=K, Rb, Cs) by Ostwald ripening in CH 3 CN applying a COF 2 pressure of 3 bar5 support our idea that alkali metal orthocarbonates should also exist. Such compounds are of interest not only because they would fill a gap in the chemical systematics, but also because of the role they might play in the mineral forming processes in the Earth's crust and mantle at high pressure and temperature conditions.…”

Li2B6O9F2, a New Acentric Fluorooxoborate

“…Since F – is a very much weaker base than O 2– , one needs to apply stronger Lewis acids when using the former. Indeed, COF 2 can be reacted with CsF at very mild conditions to form CsCOF 3 1 or various alkali metal fluorides with SeO 2 or TeO 2 , yielding fluorooxoselenates(IV)2 or ‐tellurates(IV),3 respectively.…”

Synthetic Approaches to Trifluoromethoxy‐Substituted Compounds

“…Whereas the crystal structures of several alkali-metalbased trifluoromethanolate complexes (MOCF 3 , M = K, Rb, Cs) have been known for many years, [56] the first crystal structures of discrete copper or gold analogues were only reported in 2012 by Vicic and Zhang. [57] These authors also highlighted the high sensitivity of the complexes towards oxygen as well as their thermal sensitivity.…”