Thiosemicarbazones as co-ordinating agents. Part 2. Synthesis, spectroscopic characterization, and X-ray structure of aquachloro(pyridoxal thiosemicarbazone)manganese(II) chloride and aqua(pyridoxal thiosemicarbazonato)-copper(II) chloride monohydrate

Abstract

The chelating behaviour of neutral (H₂L) and deprotonated pyridoxal thiosemicarbazone has been investigated in two new complexes, [Mn(H₂L)(OH₂)Cl]Cl (1) and [Cu(HL)(OH₂)]Cl·H₂O (2). Both crystal structures have been determined using single-crystal X-ray diffraction methods. Compound (1) crystallizes in space group P2₁/n, with a= 13.902(4), b= 9.316(1), c= 11.982(3)Å, β= 107.61(2)° and Z= 4; compound (2) crystallizes in space group P, with a= 9.732(2), b= 9.491(3), c= 7.894(2)Å, α= 95.73(3), β= 101.65(3), γ= 79.30(2)°, and Z= 2. The structures were solved by the heavy-atom method and refined to R values of 0.057 and 0.044 respectively. The co-ordination geometry about the manganese(II) ion, in the monomer (1), is based on an uncommon distorted square pyramid, with H₂L together with the H₂O molecule forming the equatorial plane and the Cl atom occupying the axial position. The Cu^II ion, in compound (2), has a square-planar geometry with phenolic oxygen, imine nitrogen, sulphur, and a water molecule as the basal donors. A sulphur atom of a centrosymmetrically related molecule, occupying the axial position, serves as a bridging element to form a dimeric structure. Both compounds are paramagnetic and their effective magnetic moments are 4.37 for (1) and 1.81 for (2). The main vibrational bands are also reported and discussed.