Copper Complexes of the Tetradentate N,N′ ‐Bis(2‐amino‐3,5‐di‐ tert ‐butylphenyl)‐2,2′‐diaminobiphenyl Ligand
Résumé
Abstract The ligand N,N′‐ bis(2‐amino‐3,5‐di‐ tert ‐butylphenyl)‐2,2′‐diaminobiphenyl was synthesized and coordinated to copper. Complex 1 + was structurally characterized, showing two deprotonated diiminobenzoquinone ligands coordinated to a single Cu(I) center. The paramagnetic complexes 1 and 1 2+ were generated and characterized by EPR and Vis‐NIR spectroscopy. Complex 1 exhibits an isotropic resonance at g=2.00, which is reminiscent of Cu(I) diiminosemiquinone species. The dication 1 2+ exhibits a metal‐based ground spin state and hence is described as a Cu(II) diiminobenzoquinone complex. Both 1 and 1 + show a NIR band (954, 980 nm) of high intensity (>20 mM −1 cm −1 ) assigned to ligand‐based charge transfer transitions.