Syntheses, crystal structures and Raman spectra of Ba(BF4)(PF6), Ba(BF4)(AsF6) and Ba2(BF4)2(AsF6)(H3F4); the first examples of metal salts containing simultaneously tetrahedral BF4− and octahedral AF6− anions

✍ Scribed by Matic Lozinšek; Tina Bunič; Evgeny Goreshnik; Anton Meden; Melita Tramšek; Gašper Tavčar; Boris Žemva

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 583 KB
• Volume: 182
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2009.08.004

✦ Synopsis

In the system BaF 2 /BF 3 /PF 5 /anhydrous hydrogen fluoride (aHF) a compound Ba(BF 4 )(PF 6 ) was isolated and characterized by Raman spectroscopy and X-ray diffraction on the single crystal. Ba(BF 4 )(PF 6 ) crystallizes in a hexagonal P62m space group with a ¼ 10.2251(4) Å, c ¼ 6.1535(4) Å, V ¼ 557.17(5) Å3 at 200 K, and Z ¼ 3. Both crystallographically independent Ba atoms possess coordination polyhedra in the shape of tri-capped trigonal prisms, which include F atoms from BF 4 À and PF 6 À anions. In the analogous system with AsF 5 instead of PF 5 the compound Ba(BF 4 )(AsF 6 ) was isolated and characterized. It crystallizes in an orthorhombic Pnma space group with a ¼ 10.415(2) Å, b ¼ 6.325(3) Å, c ¼ 11.8297(17) Å, V ¼ 779.3(4) Å3 at 200 K, and Z ¼ 4. The coordination around Ba atom is in the shape of slightly distorted tri-capped trigonal prism which includes five F atoms from AsF 6

À and four F atoms from BF 4 À anions. When the system BaF 2 /BF 3 /AsF 5 /aHF is made basic with an extra addition of BaF 2 , the compound Ba 2 (BF 4 ) 2 (AsF 6 )(H 3 F 4 ) was obtained. It crystallizes in a hexagonal P6 3 /mmc space group with a ¼ 6.8709(9) Å, c ¼ 17.327(8) Å, V ¼ 708.4(4) Å3 at 200 K, and Z ¼ 2. The barium environment in the shape of tetra-capped distorted trigonal prism involves 10 F atoms from four BF 4 À , three AsF 6 À and three H 3 F 4 À anions. All F atoms, except the central atom in H 3 F 4 moiety, act as m 2 -bridges yielding a complex 3-D structural network.