RbCrIII(C2O4)2·2H2O,Cs2Mg(C2O4)2·4H2O and Rb2CuII(C2O4)2·2H2O: three new complex oxalate hydrates |
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Authors: | Uwe Kolitsch |
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Abstract: | Rubidium chromium(III) dioxalate dihydrate [diaquabis(μ‐oxalato)chromium(III)rubidium(I)], [RbCr(C2O4)2(H2O)2], (I), and dicaesium magnesium dioxalate tetrahydrate [tetraaquabis(μ‐oxalato)magnesium(II)dicaesium(I)], [Cs2Mg(C2O4)2(H2O)4], (II), have layered structures which are new among double‐metal oxalates. In (I), the Rb and Cr atoms lie on sites with imposed 2/m symmetry and the unique water molecule lies on a mirror plane; in (II), the Mg atom lies on a twofold axis. The two non‐equivalent Cr and Mg atoms both show octahedral coordination, with a mean Cr—O distance of 1.966 Å and a mean Mg—O distance of 2.066 Å. Dirubidium copper(II) dioxalate dihydrate [diaquabis(μ‐oxalato)copper(II)dirubidium(I)], [Rb2Cu(C2O4)2(H2O)2], (III), is also layered and is isotypic with the previously described K2‐ and (NH4)2CuII(C2O4)2·2H2O compounds. The two non‐equivalent Cu atoms lie on inversion centres and are both (4+2)‐coordinated. Hydrogen bonds are medium‐strong to weak in the three compounds. The oxalate groups are slightly non‐planar only in the Cs–Mg compound, (II), and are more distinctly non‐planar in the K–Cu compound, (III). |
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