Synthesis, Structure, Magnetism, and Single Molecular Conductance of Linear Trinickel String Complexes with Sulfur‐Containing Ligands

The synthesis, crystal structures, magnetic properties, and single molecular conductances of two linear trinickel string complexes, [Ni 3 (mpta) 4 (NCS) 2 ] ( 2 ) and [Ni 3 (mpta) 4 (CN) 2 ] ( 3 ), supported by sulfur‐containing Hmpta ( 1 ) ligands are presented (Hmpta = 4‐methylpyridylthiazolylamine). Compounds 2 and 3 possess a 1D trinickel backbone coordinated by four mpta – ligands. Within the trinickel framework, the two terminal high‐spin ( S = 1) Ni ions are strongly antiferromagnetically coupled ( J = –91 cm –1 in 2 and –79 cm –1 in 3 ). As the axial CN – ligand is very basic and strongly pulls the terminal Ni ions away from the central Ni ion, the Ni–Ni distances in 3 (ca. 2.52 Å) are longer than those in 2 (ca. 2.47 Å). The lengthening of the Ni–Ni bond lengths causes 3 to exhibit weaker antiferromagnetic interactions and lower single molecular conductance [ R = 7.1 (±1.5) MΩ for 2 and R = 11.1 (±3.9) MΩ for 3 ].