Lead

Abstract

Lead has the largest atom of the Group IV elements, so the bonds that it forms are weaker than those formed by the other members of the group. Organolead compounds R₄Pb are therefore less thermally stable and more reactive than their tin analogues, and the Pb-Pb bond in the series R₆Pb₂ is relatively easily broken. Chain or ring compounds with several metal-metal links are unknown, although a few such links may be present in materials approximating in composition to (R₂Pb) _n , and the compound (Ph₃Pb)₄Pb is known. The few organolead hydrides that have been prepared decompose at or below room temperature. Many derivatives of the types R₃PbX and R₂PbX₂ have been described, where X is an electronegative group, and counterparts of the main types of organotin derivatives are known, although some areas remain relatively unexplored, particularly compounds with lead bonded to the heavier elements of Groups V and VI or to non-transition metals. Mixed organo derivatives of lead(IV) usually show a greater tendency to disproportionate than the corresponding compounds of other Group IV elements.