Triplet Metallovinylidenes of Palladium and Platinum Based on a Chelating P Diazoalkene Ligand

Abstract

Triplet carbenes featuring a metal adjacent to the carbene center metallocarbenes; R amp; 9472;C amp; 9472;M are an emerging class of diradicals within the field of reactive intermediates. Here, we report the synthesis of the first spectroscopically characterized triplet metallovinylidenes R amp; 9472;C amp; 8594;M; M Pt, Pd . The synthetic access is based on a rigid P C chelating diazoalkene ligand and its coordination to Pt and Pd. The C P chelating ligand geometrically constrains the R amp; 9472;C amp; 8594;M angle and inhibits free bending. Irradiation of the free diazoalkene ligand generates a triplet vinylidene, characterized by Q band electron paramagnetic resonance EPR spectroscopy. Irradiation of the metal coordination complexes Pt and Pd affords triplet metallovinylidenes, which were characterized at low temperatures including photochemically triggered in crystallo X ray diffraction. Combined FD FT THz EPR spectroscopy and SQUID measurements allowed the determination of the large triplet zero field splitting ZFS with D values of 124.5 cm amp; 8722;1 Pt and 8.0 cm amp; 8722;1 Pd in excellent agreement with the electronic structure obtained by high level quantum chemical calculation