Synthesis and Crystal Structure of CsCu₃O₂, Containing a New Type of Oxocuprate(I) Polyanion

Abstract

CsCu 3 O 2 was prepared via the azide route. Stoichiometric mixtures of the precursors (CsN 3 , Cu 2 O and CuO) were heated in a special regime up to 450°C and annealed at this temperature for 50 h in silver crucibles. Single crystals have been grown by subsequent annealing of as prepared powders at 450°C for 2000 h in silver crucibles, which were sealed in glass ampoules under dried Ar. According to the X-ray analysis of the crystal structure (P3m1, Alkalioxocuprates(I) are known to form three families of general compositions A 3 Cu 5 O 4 (A ϭ K [1, 2], Rb [3], Cs [2, 3]; K 2 RbCu 5 O 4 , KRb 2 Cu 5 O 4 [3]), ACuO (A ϭ Li [4Ϫ6], Na [6, 7], K [5, 6], Rb [6, 7] and Cs [8]), and A 3 CuO 2 (A ϭ K [9], Rb [10] and Na 2 KCuO 2 [11]). Their crystal structures are all dominated by the presence of linear units CuO 2 , in different connectivities, depending on the respective Cu/O-ratio. In spite of the fact that argentates(I) of the type AAg 3 O 2 (A ϭ Li [12], Na [13]) have been shown to exist, no copper analogue has been reported, so far. Here we present the synthesis and structure determination of CsCu 3 O 2 , a first representative.

The Azide/Nitrate Route, a Versatile and Prolific Procedure for the Synthesis of Alkali Oxometalates

“…Out of the multitude of poly oxometalate topologies two quite exotic ones appear worth to be mentioned. The two‐dimensionally infinite frameworks of Co 2 O 3 2– and Cu 3 O 2 – , as found in Rb 2 Co 2 O 3 38 and CsCu 3 O 2 ,52 respectively, adopt the basic topologies of the stable black phosphorus and grew arsenic modifications. Whereas in the cuprate(I) oxygen assumes the position of arsenic and copper mimics the As‐As bond, the functions are inverted in the cobaltate(II).…”