On the bridging mode in tetrahedral tetralead(II) hydroxocomplexes

Using Hartree-Fock, B3LYP and MP2 treatments, the optimal geometries and corresponding electronic structures of tetrahedral [Pb4(μ3-OH)4]4+, [Pb4O(μ3-OH)4]2+, [Pb4(μ2-OH)6]2+ and [Pb4O(μ2-OH)4] complexes are investigated. All these complexes of Td symmetry are stable. Direct Pb-Pb and O-O interactions are weakly antibonding in all the systems under study. The clusters are held together exclusively by relatively weak Pb-O(OH) and Pb-O bonds, which are stronger in μ2-OH bridged complexes (despite longer Pb-Pb distances). The non-existence of [Pb4(μ2-OH)6]2+ and [Pb4O(μ2-OH)6] complexes in real solutions/solids might be explained by their high reactivity and/or solvent/solid state effects of polar environment.