Effect of a (hetero)aromatic spacer on the direction of cyclopalladation in ditopic pincer ligands with thione sulfur donors

3-Diphenylthiophosphorylaniline and isophthalic or 2,6-pyridinedicarboxylic acids were used as key precursors for the synthesis of ditopic pincer ligands bearing thioamide and thiophosphoryl donor groups. Depending on the nature of a (hetero)aromatic spacer (meta-functionalized phenylene or pyridine rings), the ligands derived underwent coordination either at the lateral or central pincer units, selectively affording binuclear (in the case of phenylene-based ligand) or mononuclear (in the case of pyridine-based derivative) Pd(II) pincer complexes. The mononuclear pyridine-based palladacycle is prone to deprotonation of the secondary thioamide groups, resulting in sulfide clusters. A structure of the tetramer obtained was elucidated by single-crystal XRD.