Na5AuSe12-the first selenoaurate(III) with discrete complex anions
1998; Elsevier BV; Volume: 269; Issue: 1-2 Linguagem: Inglês
10.1016/s0925-8388(98)00002-4
ISSN1873-4669
AutoresKurt O. Klepp, C. Weithaler, Martin Sing,
Tópico(s)Organometallic Compounds Synthesis and Characterization
ResumoThe novel polyselenoaurate(III) Na5AuSe12 was prepared by reacting a stoichiometric mixture of Na2Se, Au and Se at 345°C followed by slow cooling. Na5AuSe12 forms transparent red crystals of lamellar habit. It is monoclinic, mP36, s.g. P21, with a=7.145(1) Å, b=16.790(6) Å, c=8.291(1) Å, β=107.13(1)°, Z=2. The crystal structure was determined from diffractometer data and refined to a conventional R of 0.032 (3830 Fo's, 163 variables). Na5AuSe12 contains discrete mononuclear anions [AuSe12]5− which are formed by four triselenide chains in end-on coordination with the central atom. The Au-atom is in an almost undistorted square planar coordination through Se. The mean Au–Se bond length is 2.500 Å, Se–Se bond lengths in the Se3−chains are in the range of 2.346–2.363 Å. The shortest intra-anionic Se–Se-contacts are in the range of 3.19–3.27 Å. In the crystal structure the [AuSe12]5− anions are stacked in columns along [100]. Together with three of the five crystallographically independent Na+-ions the columns are arranged in slabs parallel to (010)-plane which are separated by layers of the remaining Na+-ions. Na5AuSe12 is the first alkali selenoaurate(III) containing molecular anions. It undergoes peritectic decomposition at 275°C and is soluble in dimethylformamide.
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