Copper(i) complexes based on ligand systems with two different binding sites: synthesis, structures and reaction with...

Area of Science:

• Coordination Chemistry
• Organometallic Chemistry
• Bioinorganic Chemistry

Background:

• Dibenzofuran-based ligands with N3-binding sites are valuable in coordination chemistry.
• Copper(I) complexes are known for their diverse reactivity and catalytic applications.

Purpose of the Study:

• To synthesize and characterize novel dicopper complexes using dibenzofuran-linked N3-donor ligands (L1 and L2).
• To investigate the coordination behavior of these ligands with various copper(I) precursors.
• To explore the reactivity of the resulting copper complexes, particularly their interaction with molecular oxygen.

Main Methods:

• Ligand synthesis and characterization.
• Coordination of ligands with copper(I) halides and salts of weakly coordinating anions.
• Isolation and structural elucidation of various copper complexes.
• Spectroscopic studies (UV/Vis, Raman) and kinetic investigations of oxygen adduct formation.
• Reactivity studies of oxygen adducts with substrates.

Main Results:

• Successful synthesis of dicopper complexes [(L1)(CuCl)2] (1), metallodimers (2, 3), and polymeric {[Cu(L2)Cl2]}n (8).
• Formation of discrete dicopper complexes with weakly coordinating anions, such as [(L1)(Cu(NCCH3))2](BF4)2 (4), [(L1)(Cu(NCCH3))(Cu(Y))](Y) (5, 6), [(L1)(Cudppe)](PF6)2 (7), [(L2)(Cu(NCCH3))2](Z)2 (9, 10), and [(L2)(Cudppe)](PF6)2 (11).
• Complexes 4-6, 9, and 10 rapidly form metastable O2 adducts at -90 °C, with O2 bridging the two copper centers.
• The O2 adducts exhibit dual reactivity, acting as both electrophiles and nucleophiles.

Conclusions:

• The dibenzofuran-based ligands L1 and L2 effectively support the formation of diverse dicopper complexes with copper(I).
• The synthesized dicopper complexes can reversibly bind molecular oxygen, forming metastable adducts.
• These oxygen adducts display interesting reactivity, highlighting their potential in oxidation catalysis.