2-Azabutadiene complexes of rhenium( i ): S , N -chelated species with photophysical properties heavily governed by the ligand hidden traits

Adrien Schlachter (1) , Frank Juvenal (1) , Rodolphe Kinghat Tangou (2) , Abderrahim Khatyr (2) , Fabrice Guyon (2) , Paul-Ludovic Karsenti (1) , Carsten Strohmann (3) , Marek Kubicki (4) , Yoann Rousselin (4) , Pierre Harvey (1) , Michael Knorr (2)

1 UdeS - Département de chimie [Sherbrooke]
2 UTINAM - Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213)
3 TU - Technische Universität Dortmund [Dortmund]
4 ICMUB - Institut de Chimie Moléculaire de l'Université de Bourgogne [Dijon]

The reaction of [Re(CO)3(THF)(μ-Br)]2 or [Re(CO)5X] (X = Cl, Br, I) with the diaryl-2-azabutadienes [(RS)2C[double bond, length as m-dash]C(H)–N[double bond, length as m-dash]CAr2] containing two thioether arms at the 4,4-position forms the luminescent S,N-chelate complexes fac-[(OC)3ReX{(RS)2C[double bond, length as m-dash]C(H)–N[double bond, length as m-dash]CAr2}] (1a–h). The halide abstraction by silver triflate converts [(OC)3ReCl{(PhS)2C[double bond, length as m-dash]C(H)–N[double bond, length as m-dash]CPh2}] (1c) to [(OC)3Re(OS([double bond, length as m-dash]O)2CF3){(PhS)2C[double bond, length as m-dash]C(H)–N[double bond, length as m-dash]CPh2}] (1j) bearing a covalently bound triflate ligand. The cyclic voltammograms reveal reversible S^N ligand-centred reduction and irreversible oxidation waves for all complexes. The crystal structures of nine octahedral complexes have been determined along with that of (NaphtylS)2C[double bond, length as m-dash]C(H)–N[double bond, length as m-dash]CPh2 (L6). A rich system of weak non-covalent intermolecular secondary interactions through CH⋯X(Cl, Br)Re, CH⋯O, CO⋯π(Ph), CH⋯πCO, CH⋯O and CH⋯S contacts has been evidenced. The photophysical properties have been investigated by steady-state and time-resolved absorption (fs transient absorption, fs-TAS) and emission (ns-TCSPC and ps-Streak camera) spectroscopy in 2-MeTHF solution at 298 and 77 K. The emission bands are composed of either singlet (450 < λmax < 535 nm) and/or triplet emissions (at 77 K only, λmax < 640 nm, or appearing as a tail at λ > 600 nm), which decay in a multiexponential manner for the fluorescence (short ps (i.e.

Domaines: Chimie

Adrien Schlachter, Frank Juvenal, Rodolphe Kinghat Tangou, Abderrahim Khatyr, Fabrice Guyon, et al.. 2-Azabutadiene complexes of rhenium( i ): S , N -chelated species with photophysical properties heavily governed by the ligand hidden traits. Dalton Transactions, 2021, 50 (8), pp.2945-2963. ⟨10.1039/d0dt04183a⟩. ⟨hal-03139731⟩