A recent X-ray crystal structure from our group (Figure 1), shows a dicopper(I,I) core bridged by benzyl mercaptides within a 1,8-naphthyridine-2,7-diimine tetradentate ligand, a benzyl-substituted diimine, and an unusual planar mercaptide-bridged Cu<sub>4</sub> subunit displaying terminal iodo ligands. Significantly, the copper(I)-copper(I) distance within the napthyridine chelate is ca. 2.7 Å – comparable with the distance reported for the copper A dinuclear site. Of further interest, this complex showed <sup>1</sup>H-NMR signals from the mercaptide benzylic and phenyl ring protons that are substantially shielded (ca. 1 ppm) relative to uncomplexed mercaptan. Subsequently, we have isolated green crystalline complexes of an analogous R = phenyl substituted diimine, in the absence of halide ligands, that show similar shielding shifts for the mercaptide benzylic and phenyl hydrogens, peak areas consistent with disubstitution, and naphthyridine signals consistent with symmetrical substitution. Thus, we propose that a new bridged dicopper(I,I)-bis-mercaptide complex has formed. Structural and spectroscopic data supporting our proposal will be presented.

Dicopper(I,I)-naphthyridinediimine-bis-mercaptides as model complexes of reduced copper A

256th National Meeting (2018)

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