Dimers of oxocentred [OCu₄]⁶⁺ tetrahedra in two novel copper selenite chlorides, K[Cu₃O](SeO₃)₂Cl and Na₂[Cu₇O₂] (SeO₃)₄Cl₄, and related minerals and inorganic compounds

Abstract

Two novel copper selenite chlorides, K[Cu3O](SeO3)2Cl (I) and Na2[Cu7O2](SeO3)4Cl4 (II), have been synthesized by the CVT method. Their crystal structures have been solved by direct methods and refined by least-squares techniques. I is triclinic, space group P1̄, a = 7.6821(5), b = 8.1179(5), c = 8.7836(6) Å, α = 113.193(3), β = 108.735(4), γ = 98.245(4)°, V = 453.32(5) Å3, R1 = 0.0481 for 1210 unique reflections with F≥4σ(F); II is triclinic, space group P1̄,a = 7.4362(6), b = 8.3361(7), c = 9.1343(11) Å,α = 110.277(6), β = 106.212(6), γ = 105.158(4)°, V = 467.94(8) Å3, R1 = 0.0265 for 2498 unique reflections with F≥4σ(F). The structures of I and II can be described in terms of dimers of copper oxocentred tetrahedra. In I, two (OCu4)6+ tetrahedra share a common Cu···Cu edge to form the [O2Cu6]8+ dimer, whereas the structure of II is based upon two (OCu4)6+ tetrahedra linked together by one common Cu atom resulting in the formation of the [O2Cu7]10+ dimer. A comparison with related minerals and inorganic compounds is given.

Se–Cl Interactions in Selenite Chlorides: A Theoretical Study

“…By analogy with Cu 5 O 2 (SeO 3 ) 2 Cl 2 polymorphs, its crystal structure contains additional O atoms tetrahedrally coordinated by four Cu atoms [48]. Two (OCu 4 ) tetrahedra share a common Cu atom to form a [O 2 Cu 7 ] dimer ( Figure 8a) similar to those recently observed in the crystal structure of Na 2 Cu 7 O 2 (SeO 3 ) 4 Cl 4 [72,73].…”

Oxocentered Units in Three Novel Rb‐Containing Copper Compounds Prepared by CVT Reaction Method

“…Compound II is isotypic to the previously reported KCu 3 O(SeO 3 ) 2 Cl and contains one symmetrically independent O 2– anion non‐bonded to Se and tetrahedrally coordinated by four Cu atoms to form oxocentered [OCu 4 ] 6+ tetrahedra [O7–Cu = 1.888(6)–1.945(7) Å]. Two [OCu 4 ] 6+ tetrahedra share a common Cu3 ··· Cu3 [O7–Cu3 = 1.934(7)–1.945(7) Å] edge to form a [O 2 Cu 6 ] 8+ dimer.…”

“…The structure of II is the Rb analogue of previously reported KCu 3 O(SeO 3 ) 2 Cl . The a and c parameters are the most seriously influenced by the increased size of an alkali metal atom: it enlarges by 0.174 Å from 7.682 in K to 7.856 Å in Rb and by 0.156 from 8.784 for K to 8.940 Å in Rb, respectively, whereas the b parameter does not experience significant changes (Δ = 0.044 Å).…”

“…The presence of oxocentered tetrahedral units in the crystal structures of I – III provides an indirect evidence that polynuclear Cu‐based oxoclusters may serve as forms of Cu transportation in the gaseous phase in CVT reactions, which would explain their occurrence in the crystal structures of phases formed in dry natural and synthetic environments , …”

The crystal structure of the first synthetic copper(II) tellurite arsenate, CuII 5(TeIVO3)2(AsVO4)2

“…No volcano has been more prolific at producing unique minerals than the Tolbachik Volcano on Russia's Kamchatka peninsula (Pekov et al, 2018a). The synthesis of compounds by chemical vapour transport (CVT) using Cl 2 gas as a transport agent mimics the conditions under which many fumarole minerals are crystallized (Kovrugin et al, 2015(Kovrugin et al, , 2016, and CVT has been used to synthesize four new Cu-containing tellurites (Markovski et al, 2016;Zinyakhina et al, 2016). Te is generally enriched by up to four orders of magnitude in volcanic vents, with an average Te concentration of 50 p.p.m.…”