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Hexacyanomanganate(III) mit Kryolithstruktur: Cs 2 NaMn(CN) 6 und Cs 2 KMn(CN) 6 / Hexacyanomanganates(III) with Cryolite Type Structure: Cs 2 NaMn(CN) 6 and Cs 2 KMn(CN) 6

1989; De Gruyter; Volume: 44; Issue: 8 Linguagem: Inglês

10.1515/znb-1989-0807

1865-7117

Bernd Ziegler, R. Haegele, D. Babel,

Inorganic Fluorides and Related Compounds

The crystal structures of the isotypic monoclinic cyano complexes Cs 2 NaMn(CN) 6 (a = 759.7(1), b = 780.6(1), c = 1095.0(1) pm, β = 90.07(1)°) and Cs 2 KMn(CN) 6 (a = 769.8(2), b = 820.4(1), c = 1120.7(2) pm, β = 90.25(1)°) have been refined from single crystal X-ray data in space group P2 1 /n, Z = 2 (wR = 0.039 and 0.027, resp., using 1639 and 1732 independent reflections). The compounds are isostructural with cryolite, Na 3 AlF 6 , showing quite similar position parameters and nearly regular octahedra (average Mn—C= 198.8/199.6pm, C—N = 114.7/114.4pm for Na/K compound, resp.). The tilting of octahedra [Mn(CN) 6 ] 3— , [NaN 6 ] (Na—N = 248.5 pm) and [KN 6 ] (K—N = 280.0 pm) is compared to that of other cyano-cryolites and rationalized using radius ratio arguments in the form of a tolerance factor relation.