Unreported coordination behaviour of a bis(semicarbazone) ligand in a lead(II) complex

Abstract A novel lead(II) complex with the Schiff base benzil bis(semicarbazone), [Pb(LH 2 ) 2 (NO 3 )]NO 3  · 1/2H 2 O, has been synthesised and structurally characterized as well as the free ligand. The coordination number of Pb(II) is seven provided by two neutral ligand molecules and one nitrato group. The most interesting characteristic of this complex is the different behaviour observed in the two bis(semicarbazone) molecules. One of them is a N 2 O 2 chelate ligand, whereas the other one is bonded to the lead ion only through one of the semicarbazone branches. The seventh position in the lead coordination sphere is provided by one oxygen atom from a nitrato ligand.