Stannide Explained

A stannide can refer to an intermetallic compound containing tin combined with one or more other metals; an anion consisting solely of tin atoms or a compound containing such an anion, or, in the field of organometallic chemistry an ionic compound containing an organotin anion (e.g.see ^[1] an alternative name for such a compound is stannanide.)

Binary alkali and alkaline earth stannides

When tin is combined with an alkali or alkaline earth metal some of the compounds formed have ionic structures containing monatomic or polyatomic tin anions (Zintl ions), such as Sn⁴⁻ in Mg₂Sn^[2] or in K₄Sn₉.^[3] Even with these metals not all of the compounds formed can be considered to be ionic with localised bonding, for example Sr₃Sn₅, a metallic compound, contains square pyramidal units.^[4]

Ternary alkali and alkaline earth stannides

Ternary (where there is an alkali or alkaline earth metal, a transition metal as well as tin e.g. LiRh₃Sn₅^[5] and MgRuSn₄^[6]) have been investigated.

Other metal stannides

Binary (involving one other metal) and ternary (involving two other metals) intermetallic stannides have been investigated. Niobium stannide, Nb₃Sn is perhaps the best known superconducting tin intermetallics. This is more commonly called "niobium-tin".

There are multiple rare earth stannides, including with dysprosium and yttrium.

Stannide ions,

Some examples of stannide Zintl ions are listed below. Some of them contain 2-centre 2-electron bonds (2c-2e), others are "electron deficient" and bonding sometimes can be described using polyhedral skeletal electron pair theory (Wade's rules) where the number of valence electrons contributed by each tin atom is considered to be 2 (the s electrons do not contribute). There are some examples of silicide and plumbide ions with similar structures, for example tetrahedral, the chain anion (Si²⁻)_n, and .^{[2] [7]}

• Sn⁴⁻ found for example in Mg₂Sn.^[2]
• , tetrahedral with 2c-2e bonds e.g. in CsSn.^[2]
• , tetrahedral closo-cluster with 10 electrons (2n + 2).^[8]
• (Sn²⁻)_n zig-zag chain polymeric anion with 2c-2e bonds found for example in BaSn.^[2]
• closo-cluster, 12 electrons (2n + 2), (i.e. trigonal bipyramidal) in (2,2,2-crypt-Na)₂Sn₅.^[9]
• polymeric two-dimensional anion in NaSn₂.^[10]
• nido-cluster 22 electrons (2n + 4), capped square antiprismatic with as per polyhedral skeletal electron pair theory, in the intermetallic K₄Sn₉,^[3] and a distorted ion in the salt Na₄Sn₉·7 en.^[11]
• a paramagnetic, 21 electrons, closo- cluster anion (D_3h symmetry), 1 more electron than the 20 (2n + 2) predicted by polyhedral skeletal electron pair theory.^[12]
• polymeric two-dimensional anion in Na₇Sn₁₂^[13]

Notes and References

1. Flacke . F. . Jacobs . H. . 1997 . [Li(NH₃)₄] [Sn(SnPh₃)₃].C₆H₆, Crystal structure of a stannide with trigonal pyramidal tin skeleton . European Journal of Solid State and Inorganic Chemistry . 34 . 5. 495–501 .
2. S.M. Kauzlarich,(1994), Zintl Compounds, Encyclopedia of Inorganic Chemistry, John Wiley & sons,
3. Hoch . C. . Wendorff . M. . Röhr . C. . 2002 . Tetrapotassium nonastannide, K₄Sn₉ . Acta Crystallogr C . 58 . 4. i45–i46 . 10.1107/S0108270102002032 . 11932511 . 2002AcCrC..58I..45H .
4. Klem . M. T. . Vaughey . J. T. . Harp . J G. . Corbett . J D. . 2001 . A₃Tt₅ Phases Sr₃Sn₅, Ba₃Pb₅, and La₃Sn₅. Structure and Bonding in a Series of Isotypic Metallic Compounds with Increased Electron Count and Their Comparison with the Nominal Zintl Phase La₃In₅ . Inorg. Chem. . 40 . 27. 7020–7026 . 10.1021/ic010804v . 11754285 .
5. Sreeraj . P . Johrendt . D. . Müller . H. . Hoffmann . R.-D. . Wu . Zhiyun . Pöttgen . R. . 2005 . The stannide LiRh₃Sn₅: Synthesis, structure, and chemical bonding . Zeitschrift für Naturforschung B . 60 . 9. 933–939 . 10.1515/znb-2005-0904 . 197000256 . free .
6. Schlüter . M. . Kunst . A. . Pöttgen . R. . 2002. The Ternary Stannides MgRuSn₄ and Mg_xRh₃Sn_7−x (x = 0.98–1.55) . Zeitschrift für anorganische und allgemeine Chemie . 628 . 12. 2641–2646 . 10.1002/1521-3749(200212)628:12<2641::aid-zaac2641>3.0.co;2-y.
7. Yong . Li . Stephan D. Hoffmann . Thomas F. Fässler . A low-dimensional arrangement of [Pb₉]⁴⁻ clusters in [K(18-crown-6)]₂K₂Pb₉·(en)_1.5 . Inorganica Chimica Acta . 359 . 15 . 4774–4778 . Elsevier . 1 December 2006 . 10.1016/j.ica.2006.04.017 .
8. Critchlow . S. C. . Corbett . J. D. . 1981. Stable homopolyatomic anions: the tetrastannide (2–) and tetragermanide(2–) anions, and X-ray crystal structure of . ethylenediamine . J. Chem. Soc. Chem. Commun.. 1981 . 5. 236–237 . 10.1039/C39810000236 .
9. Edwards . P. A. . Corbett . J. D. . 1977 . Stable homopolyatomic anions. Synthesis and crystal structures of salts containing the pentaplumbide(2−) and pentastannide(2−) anions . Inorg. Chem. . 16 . 4. 903–907 . 10.1021/ic50170a036 .
10. Dubois . F. . Schreyer . M. . Fässler . T. F. . 2005 . NaSn₂: A Novel Binary Zintl Phase with 2D Polyanions of Realgar-Type Units [Sn₈]⁴⁻ . Inorg. Chem. . 44 . 3. 477–479 . 10.1021/ic048770p . 15679372 .
11. Diehl . L. . Khodadadeh . K. . Kummer . D. . Strähle . J. . 1976 . Anorganische Polyederverbindungen, III. Zintl's Polyanionige Salze: Darstellung und Eigenschaften der kristallinen Verbindungen [Na₄·7 en]Sn₉, [Na₄·5 en]Ge₉ und [Na₃·4 en]Sb₇ und ihrer Lösungen Die Kristallstruktur von [Na₄·7 en]Sn₉ . Chemische Berichte . 109 . 100. 3404–3418 . 10.1002/cber.19761091018 .
12. Critchlow . S. C. . Corbett . J. D. . 1983 . Homopolyatomic anions. The synthesis and characterization of the novel paramagnetic nonastannide(3−) anion, a D_3h cluster with 21 skeletal electrons . J. Am. Chem. Soc. . 105 . 17. 5715–5716 . 10.1021/ja00355a045 .
13. .Fässler . T.F. . Hoffmann . S. . 2003 . Na₇Sn₁₂: A Binary Zintl Phase with a Two-Dimensional Covalently Bonded Tin Framework . Inorg. Chem. . 42 . 18. 5474–5476 . 10.1021/ic030148u . 12950190 .