A new sterically loaded pentadentate N3S2 ligand and its zinc complexes

In quest of complexes having [MN3S2] cores in the monomeric form and trans-thiolate donor atoms, the new pentadentate thiolate amine pytBuN2H2S2–H2 [=pytBuN2H2S22-=2,6-bis(2-mercapto-3,5-di-tert-butylphenylaminomethyl)pyridine(2-)] has been synthesized.The template condensation reaction of bis(2-mercapto-3,5-di-tert-butylaniline)zinc (II)[Zn(tBu2ma)2] and pyridine-2,6-dicarbaldehyde in methanol at 40 °C leads to the formation of imine zinc complex [Zn(pytBuN2S2)] (7), which is very unstable and decomposes to give thiazole 5. However, if the template condensation is followed by in situ reduction with an excess of NaBH4, the stable saturated amine complex [Zn(pytBuN2H2S2)] (8) is formed. Demetallation of zinc complex 8 under acidic conditions leads to the formation of the desired dithiolate pytBuN2H2S2–H2 ligand (9).

A new sterically demanding pentadentate thiolate-amine ligand pytBuN2S2–H2 [=pytBuN2H2S22-=2,6-bis(2-mercapto-3,5-di-tert-butylphenylaminomethyl)pyridine(2-)] and its zinc complexes were synthesized.Template condensation of bis(2-mercapto-3,5-di-tert-butylaniline)zinc [Zn(tBu2ma)2] and pyridine-2,6-dicarbaldehyde followed by in situ reduction with NaBH4 leads to the formation of [Zn(pytBuN2H2S2)].Demetallation of the zinc complex [Zn(pytBuN2H2S2)] under acidic conditions leads to the formation of the desired dithiolate pytBuN2H2S2–H2 ligand.Figure optionsDownload as PowerPoint slide