Discrete cobalt(II) and nickel(II) complexes of type ML (where L is a bis(2,4-pentanedionate) derivative incorporating a –SCH₂CH₂S– bridge between the γ-carbons of respective β-diketone units) have been synthesised and represent the first examples in which a γ-substituted, thioether-containing β-diketone ligand coordinates via a sulfur and oxygen donor in preference to the classical coordination mode involving both β-diketonate oxygens.