The nickel, copper and zinc complexes of potentially heptadentate nitrogen–sulfur donor ligands

The multidentate compound, tris-(o-butylthiobenzyl)- aminoethylamine (L), which contains four nitrogen and three sulfur donors has been synthesised by combining 2-amino-methyl-1,3-diamino-propane (tren) with o-butylthiobenzaldehyde. L has been reacted with the nitrate salts of nickel, copper and zinc to give a series of L M(NO) complexes which were crystallographically characterised. In all cases the metal binds to the N motif proffered by the tren moiety. The nickel complex achieves a hexacoordinate geometry by ligating with a didentate (-O,O′) nitrate. Copper and zinc both produced five coordinate species by ligating with a unidentate nitrate. None of the species reported include the thio-ethers in the coordination sphere of the metal. Replacing nitrate with nitrite in the copper system allows the synthesis of a five coordinate unidentate, oxygen bound, nitrite complex. A number of unsuccessful attempts have been made, using Cd, Pb and Au, to assemble the three thioethers groups into a secondary coordination motif for metals. These reactions produce a series of LM-halide complexes which have again been crystallographically characterised.