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 an alternative name for such a compound is stannanide.)
Binary alkali and alkaline earth stannides
When tin is combined with an
alkali
In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...
or
alkaline earth metal some of the compounds formed have ionic structures containing monatomic or polyatomic tin anions (
Zintl ions
Nanoclusters are atomically precise, crystalline materials most often existing on the 0-2 nanometer scale. They are often considered kinetically stable intermediates that form during the synthesis of comparatively larger materials such as semico ...
), such as Sn
4− in Mg
2Sn
[S.M. Kauzlarich,(1994), Zintl Compounds, Encyclopedia of Inorganic Chemistry, John Wiley & sons, ] or in K
4Sn
9.
Even with these metals not all of the compounds formed can be considered to be ionic with localised bonding, for example Sr
3Sn
5, a metallic compound, contains square pyramidal units.
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. LiRh
3Sn
5 and MgRuSn
4) have been investigated.
Other metal stannides
Binary (involving one other metal) and ternary (involving two other metals) intermetallic stannides have been investigated.
Niobium stannide, Nb
3Sn is perhaps the best known superconducting tin intermetallics. This is more commonly called "niobium-tin".
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
A plumbide can refer to one of two things: an intermetallic compound that contains lead, or a Zintl phase compound with lead as the anion.
Zintl phase
Plumbides can be formed when lead forms a Zintl phase compound with a more metallic element. O ...
ions with similar structures, for example tetrahedral , the chain anion (Si
2−)
''n'', and .
*Sn
4− found for example in Mg
2Sn.
*, tetrahedral with 2c-2e bonds e.g. in CsSn.
*, tetrahedral ''closo''-cluster with 10 electrons (2''n'' + 2).
*(Sn
2−)
''n'' zig-zag chain polymeric anion with 2c-2e bonds found for example in BaSn.
* ''closo''-cluster, 12 electrons (2''n'' + 2), (i.e. trigonal bipyramidal) in (2,2,2-crypt-Na)
2Sn
5.
* polymeric two-dimensional anion in NaSn
2.
* ''nido''-cluster 22 electrons (2''n'' + 4), capped square antiprismatic with as per
polyhedral skeletal electron pair theory, in the intermetallic K
4Sn
9,
and a distorted ion in the salt Na
4Sn
9·7
en.
* a paramagnetic, 21 electrons, ''closo''- cluster anion (D
3h symmetry), 1 more electron than the 20 (2''n'' + 2) predicted by
polyhedral skeletal electron pair theory.
* polymeric two-dimensional anion in Na
7Sn
12[.]
References
{{reflist, 30em
Tin
Intermetallics
Anions
Cluster chemistry