Plumbane

Chembox new
Name = Plumbane
ImageFile = Plumbane-2D.png ImageSize = 120
IUPACName = Plumbane
OtherNames = Plumbane, lead tetrahydride, tetrahydridolead, lead(IV) hydride
Section1 = Chembox Identifiers
CASNo = 15875-18-0
Section2 = Chembox Properties
Formula = PbH₄
MolarMass = 211.23 g/mol
BoilingPt = -13 °C

Plumbane, PbH₄, is a metal hydride comprised of lead and hydrogen. [Porritt, C. J. "Chem. Ind-London." 1975, "9", 398] Plumbane is not well-characterized or well-known, and it is thermodynamically unstable with respect to the loss of a hydrogen atom.Hein, T. A.; Thiel, W. "J. Phys. Chem." 1993, "97", 4381] Derivatives of plumbane include lead tetrafluoride, PbF₄ and tetra-ethyl lead, (CH₃CH₂)₄Pb.

History

Until recently, it was uncertain whether plumbane had ever actually been synthesized; [Cotton, F. A.; Wilkinson, G.; Murillo, C. A.; Bochman, M. "Advanced Inorganic Chemistry." Wiley: New York, 1999] although, in 1963, Saalfeld and Svec reported the observation of PbH₄⁺ by mass spectrometry.Saalfeld, F. E.; Svec, H. "Inorg. Chem." 1963, "2", 46.] 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. [Pyykkö, P.; Desclaux, J. P. "Chem. Phys. Lett." 1974, "29", 534] [Pyykkö, P.; Desclaux, J. P. "Nature." 1977, "266", 366]

Properties

Plumbane is an unstable colorless gas and is the heaviest group IV hydride. [ [http://www.hbcpnetbase.com/ CRC Handbook of Chemistry and Physics, Online Edition.] ] Furthermore, plumbane has a tetrahedral (T_d) structure with an equilibrium bond distance of 1.73 Å. [Visser, O.; Visscher, L.; Aerts, P. J. C.; Nieuwpoort, W. C. "Theor. Chem. Acc." 1991, "81", 405] By weight percent, the composition of plumbane is 1.91% hydrogen and 98.09% lead. In plumbane, the formal oxidation states of hydrogen and lead are -1 and +4, respectively. The stability of metal hydrides with the formula MH₄ (M = Si-Pb) decreases as the atomic number of M increases.

Preparation

In general, metal hydrides are formed when hydrogen gas is allowed to react with metals. They can serve to store hydrogen gas, which is highly flammable.

Early studies of PbH₄ revealed that the molecule is unstable as compared to its lighter congeners (silane, germane, and stannane). [Malli, G. L.; Siegert, M.; Turner, D. P. "Int. J. Quantum. Chem." 2004, "99", 940] It cannot be made by methods used to synthesize GeH₄ or SnH₄.

Recently, plumbane has been synthesized from lead(II) nitrate, Pb(NO₃)₂, and sodium borohydride, NaBH₄. [Krivtsun, V. M.; Kuritsyn, Y. A.; Snegirev, E. P. "Opt. Spectrosc." 1999, "86", 686] Additionally, a non-nascent mechanism for plumbane synthesis has been developed. [Yan, Z.; et al. "Guangpuxue Yu Guangpu Fenxi." 2005, "25", 1720]

In 2002, Wang, X. et al. carefully studied the preparation of PbH₄ by laser ablation and additionally identified the infrared (IR) bands. [Wang, X.; Andrews, J. "J. Am. Chem. Soc." 2002, "125", 6581]

Congeners

* Methane CH₄
* Silane SiH₄
* Germane GeH₄
* Stannane SnH₄

References