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

Abstract

The synthesis, crystal structures, magnetic properties, and single molecular conductances of two linear trinickel string complexes, [Ni3(mpta)4(NCS)2] (2) and [Ni3(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].

Applications of Palladium-Catalyzed C–N Cross-Coupling Reactions

“…Given the importance of 1D metal string complexes as molecular wires, Peng and co-workers synthesized and studied a new class of linear trinickel compounds 621 ( Scheme 149 ). 504 The chelating ligand present in this complex, 4-methylpyridylthiazolylamine (Hmpta), was accessed by coupling 2-bromothiazole and 2-amino-4-methylpyridine using an L6 -based catalyst (41% yield). Together with cyanide ligands, the resulting tridentate structures were successfully combined with a nickel source to yield air- and moisture-stable complexes.…”

Revisit of trinickel metal string complexes [Ni3L4X2] (L = dipyridylamido, diazaphenoxazine; X = NCS, CN) for quantum transport

“…Reported metal string complexes include those with the metal atoms composed of the same element, defected atom chains where one of the metal centers is missing from the 1‐D coordination sites, and mixed elements in which the positions of the metal elements can be designated . A range of coordinating groups (e.g., amido, pyridyl, naphthyridyl, anthyridinyl, and thiophenyl) are formulated as the equatorial ligands . Their electronegativity and rigidity exhibit significant effects on the oxidation number of the metal center and the metal–metal distance associated with the ligand–metal–metal–ligand torsion angle .…”

“…A range of coordinating groups (e.g., amido, pyridyl, naphthyridyl, anthyridinyl, and thiophenyl) are formulated as the equatorial ligands . Their electronegativity and rigidity exhibit significant effects on the oxidation number of the metal center and the metal–metal distance associated with the ligand–metal–metal–ligand torsion angle . The equatorial and axial ligands have a significant influence of metal string complexes on the spin multiplicity and magnetism .…”

Buchwald‐Hartwig Amination of Coordinating Heterocycles Enabled by Large‐but‐Flexible Pd‐BIAN‐NHC Catalysts**

“…To our delight, a broad range of aryl and heteroaryl chlorides bearing electronically diverse substituents could be readily cross‐coupled by using this catalyst system ( 6 a – 6 x ). It is noteworthy that N ‐(pyridin‐2‐yl)thiazol‐2‐amine ( 6 d ), the key ligand in the construction of coordination polymers, [18] could be obtained by this protocol. Furthermore, heterocycles such as 1 H ‐pyrrole and 1 H ‐indole are well tolerated, affording the products ( 6 k – 6 l ) in nearly quantitative yields.…”