Dismutation of Tricyanoboryllead Compounds: The Homoleptic Tetrakis(tricyanoboryl)plumbate Tetraanion.

A series of unprecedently air-stable (tricyanoboryl)plumbate anions was obtained by the reaction of the boron-centered nucleophile B(CN) 3 2- with triorganyllead halides. Salts of the anions [R 3 PbB(CN) 3 ] - (R=Ph, Et) were isolated and found to be stable in air at room temperature. In the case of Me 3 PbHal (Hal=Cl, Br), a mixture of the anions [Me 4-n Pb{B(CN) 3 } n ] n- (n=1, 2) was obtained. The [Et 3 PbB(CN) 3 ] - ion undergoes stepwise dismutation in aqueous solution to yield the plumbate anions [Et 4-n Pb{B(CN) 3 } n ] n- (n=1-4) and PbEt 4 as by-product. The reaction rate increases with decreasing pH value of the aqueous solution or by bubbling O 2 through the reaction mixture. Adjustment of the conditions allowed the selective formation and isolation of salts of all anions of the series [Et 4-n Pb{B(CN) 3 } n ] n- (n=2-4) including the homoleptic tetraanion [Pb{B(CN) 3 } 4 ] 4- .