Plumbide is an anion oflead atoms. There are three plumbide anions, written as Pb−, Pb2− and Pb4− with 3oxidation states, -1, -2 and -4, respectively.Aplumbide can refer to one of two things: anintermetallic compound that containslead, or aZintl phase compound with lead as the anion.
Plumbides can be formed when lead forms a Zintl phase compound with a more metallic element. One salt that can be formed this way is whencryptand reacts withsodium and lead inethylenediamine (en) to produce[Na(crypt)]+
2[Pb5]2−, which is red in solution.[1]Lead can also create anions withtin, in a series of anions with the formula [Sn9−xPbx]4−.
Lead can also form the [Pb9]4− anion, which is emerald green in solution.[2]
An example of a plumbide is CeRhPb. The lead atom has acoordination number of 12 in the crystal structure of this compound. It is bound to fourrhodiums, sixceriums, and two other lead atoms in the crystal structure of the chemical.[3]
Several other plumbides are the M2Pd2Pb plumbides, where M is arare-earth element, and the intermetallic additionally contains apalladium. These plumbides tend to exhibit antiferromagnetism, and all of them are conductors.[4]
A third plumbide is Ti6Pb4.8. Like the above plumbides, it is an intermetallic, but it only containstitanium as the other metal, and not any rare earths.[5]
Plumbides can also beZintl phase compounds, such as [K(18-crown-6)]2K2Pb9·(en)1.5. This is not a simple Zintl compound, but rather contains the organic molecules18-crown-6 andethylenediamine (en) in order to stabilize the crystal structure.[6]