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The First Boroselenates as new Silicate Analogues
Author(s) -
Daub Michael,
Hillebrecht Harald
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201404100
Subject(s) - orthorhombic crystal system , monoclinic crystal system , triclinic crystal system , crystallography , chemistry , boron , stereochemistry , crystal structure , alkali metal , organic chemistry
The first boroselenates were obtained as single crystals by the reaction of selenic acid with boron acid and the corresponding alkali carbonates. The structure determinations showed a far‐reaching analogy to very recently described borosulfates and the borophosphates, that is, tetrahedral BO 4 and SeO 4 units linked by common corners. In each case, the BO 4 tetrahedra are surrounded by SeO 4 tetrahedra. As a function of the B/Se ratio, this results in chains (1:3; Cs 3 [B(SeO 4 ) 3 ], Rb 3 [B(SeO 4 ) 3 ]), isolated pentamers (1:4; HK 4 [(B(SeO 4 ) 4 ]), or pentamers with additional isolated SeO 4 tetrahedra (1:5; (H 3 O)Na 6 [B(SeO 4 ) 4 ](SeO 4 ). Compound Rb 3 [B(SeO 4 ) 3 ] (orthorhombic, Ibca , Z =8, a =7.508(2), b =15.249(3), c =23.454(5) Å) is isotypic to Rb 3 [B(SO 4 ) 3 ]) and Ba 3 [B(PO 4 ) 3 ]. Compound Cs 3 [B(SeO 4 ) 3 ] (monoclinic, P 2 1 / c , Z =4, a =11.3552(4), b =7.9893(3), c =15.7692(6) Å, β =101.013(1)°) represents a distorted variant of Rb 3 [B(SeO 4 ) 3 ]. The isolated pentamers in HK 4 [(B(SeO 4 ) 4 ]) (triclinic, P $\bar 1$ , Z =6, a =7.5303(1), b =7.5380(1), c =42.3659(4) Å, α =88.740(1), β =89.971(1), γ =89.971(1)°) were also found in K 5 [(B(SO 4 ) 4 ] and Na 5 [(B(SO 4 ) 4 ]. Compound (H 3 O)Na 6 [B(SeO 4 ) 4 ](SeO 4 ) (tetragonal, I $\bar 4$ , a =9.9796(1), c =18.2614(2) Å) is a super structure of the borophosphates Sr 6 [B(PO 4 ) 4 ](PO 4 ) and Pb 6 [B(PO 4 ) 4 ](PO 4 ). Because the tetrahedra are only connected through apices, there are topological analogies to silicates. Therefore, boroselenates may have a similar variability of crystal structures, such as borosulfates and borophosphates.