Plumbane, PbH₄, is a metal

hydride In chemistry, a hydride is formally the anion of hydrogen( H−). The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of ...

and

group 14 hydride Group 14 hydrides are chemical compounds composed of hydrogen atoms and group 14 atoms (the elements of group 14 are carbon, silicon, germanium, tin, lead and flerovium). Tetrahydrides The tetrahydride series has the chemical formula XH4, wi ...

composed of

lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate ...

and

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

. Plumbane is not well characterized or well known, and it is thermodynamically unstable with respect to the loss of a hydrogen atom. Derivatives of plumbane include lead tetrafluoride, PbF₄, and tetraethyllead, (CH₃CH₂)₄Pb.

History

Until recently, it was uncertain whether plumbane had ever actually been synthesized, although the first reports date back to the 1920s and in 1963, Saalfeld and Svec reported the observation of by mass spectrometry. Plumbane has repeatedly been the subject of Dirac– Hartree–Fock relativistic calculation studies, which investigate the stabilities, geometries, and relative energies of hydrides of the formula MH₄ or MH₂.

Properties

Plumbane is an unstable colorless gas and is the heaviest group IV hydride. Furthermore, plumbane has a tetrahedral (T_d) structure with an equilibrium distance between lead and hydrogen of 1.73 Å. By weight percent, the composition of plumbane is 1.91% hydrogen and 98.09% lead. In plumbane, the formal

oxidation states In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. ...

of hydrogen and lead are +1 and -4, respectively, because the

electronegativity Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the ...

of lead(IV) is higher than that of hydrogen. The stability of metal hydrides with the formula MH₄ (M = C–Pb) decreases as the atomic number of M increases.

Preparation

Early studies of PbH₄ revealed that the molecule is unstable as compared to its lighter congeners (

silane Silane is an inorganic compound with chemical formula, . It is a colourless, pyrophoric, toxic gas with a sharp, repulsive smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental silicon. Sila ...

, germane, and stannane). It cannot be made by methods used to synthesize GeH₄ or SnH₄. In 1999, plumbane was synthesized from lead(II) nitrate, Pb(NO₃)₂, and

sodium borohydride Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound with the formula Na BH4. This white solid, usually encountered as an aqueous basic solution, is a reducing agent that finds applic ...

, NaBH₄. A non-nascent mechanism for plumbane synthesis was reported in 2005. In 2003, Wang and Andrews carefully studied the preparation of PbH₄ by

laser ablation Laser ablation or photoablation (also called laser blasting) is the process of removing material from a solid (or occasionally liquid) surface by irradiating it with a laser beam. At low laser flux, the material is heated by the absorbed laser ...

and additionally identified the

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from aroun ...

(IR) bands.

Congeners

Congeners of plumbane include: *

Methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ear ...

, CH₄ *

Silane Silane is an inorganic compound with chemical formula, . It is a colourless, pyrophoric, toxic gas with a sharp, repulsive smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental silicon. Sila ...

, SiH₄ * Germane, GeH₄ * Stannane, SnH₄

References

{{Hydrides by group Metal hydrides Lead compounds