Tetracopper σ‐Bound μ‐Acetylide and ‐Diyne Units Stabilized by a Naphthyridine‐based Dinucleating Ligand

Abstract

Reactions of a dicopper(I) tert‐butoxide complex with alkynes possessing boryl or silyl capping groups resulted in formation of unprecedented tetracopper(I) µ‐acetylide/diyne complexes that were characterized by NMR and UV‐Vis spectroscopy, mass spectrometry and single‐crystal X‐ray diffraction. These compounds possess an unusual µ4‐η1:η1:η1:η1 coordination mode for the bridging organic fragment, enforced by the rigid and dinucleating nature of the ligand utilized. Thus, the central π system remains unperturbed and accessible for subsequent reactivity and modification. This has been corroborated by addition of a fifth copper atom, giving rise to a pentacopper acetylide complex. This work may provide a new approach by which metal‐metal cooperativity can be exploited in the transformation of acetylide and diyne groups to a variety of substrates, or as a starting point for the controlled synthesis of copper(I) alkyne‐containing clusters.

Diborane Reductions of CO2 and CS2 Mediated by Dicopper μ-Boryl Complexes of a Robust Bis(phosphino)-1,8-naphthyridine Ligand

“…Previous studies on related dicopper systems have demonstrated the utility and versatility of a dicopper tert -butoxide fragment as a useful precursor to other dicopper complexes, ,, and therefore [(PNNP Flu )Cu 2 (μ-O t Bu)][NTf 2 ] ( 3 ) was targeted as a starting material to provide access to new [(PNNP Flu )Cu 2 ] 2+ complexes. Monitoring the reaction by 1 H NMR spectroscopy indicated that 3 was generated quantitatively following addition of one equivalent of KO t Bu to a THF solution of 1 (Scheme ; 71% isolated yield), as evidenced by the appearance of a singlet at 1.69 ppm in THF- d 8 (Figure S12).…”