A stannide can refer to an
intermetallic
An intermetallic (also called intermetallic compound, intermetallic alloy, ordered intermetallic alloy, long-range-ordered alloy) is a type of metallic alloy that forms an ordered solid-state compound between two or more metallic elements. Inte ...
compound containing
tin
Tin is a chemical element; it has symbol Sn () and atomic number 50. A silvery-colored metal, tin is soft enough to be cut with little force, and a bar of tin can be bent by hand with little effort. When bent, a bar of tin makes a sound, the ...
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 the Arabic word , ) is a basic 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 soluble base has a pH greater than 7.0. The a ...
or
alkaline earth
The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).. The elements have very similar properties: they are al ...
metal some of the compounds formed have ionic structures containing monatomic or polyatomic tin anions (
Zintl ions), 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".
There are multiple
rare earth stannides, including
with dysprosium and
yttrium
Yttrium is a chemical element; it has Symbol (chemistry), symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost a ...
.
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
In chemistry the polyhedral skeletal electron pair theory (PSEPT) provides electron counting rules useful for predicting the structures of clusters such as borane and carborane clusters. The electron counting rules were originally formulated by ...
(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
A silicide is a type of chemical compound that combines silicon and a usually more electropositive element.
Silicon is more electropositive than carbon. In terms of their physical properties, silicides are structurally closer to borides than t ...
and
plumbide 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 chemistry the polyhedral skeletal electron pair theory (PSEPT) provides electron counting rules useful for predicting the structures of clusters such as borane and carborane clusters. The electron counting rules were originally formulated by ...
, 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
In chemistry the polyhedral skeletal electron pair theory (PSEPT) provides electron counting rules useful for predicting the structures of clusters such as borane and carborane clusters. The electron counting rules were originally formulated by ...
.
* polymeric two-dimensional anion in Na
7Sn
12[.]
References
{{Monatomic anion compounds
Tin
Intermetallics
Anions
Cluster chemistry