o-Semiquinolato complexes of palladium and platinum with arylazoaryl ligands

Spin-labelled cyclometallated palladium complexes. EPR study of dynamic processes in coordination sphere

“…1) is singlet (g i = 2.0040) with palladium satellites ( 105 Pd, 22.2%, S = 5/2, g N = À0.26), a Pd = 1.35G. Hyperfine splitting on azophenyl nitrogens ( 14 N, 99.96%, S = 1, g N = 0.40) is not observed, similarly to 1b [9]. So, 1c should have similar square-planar structure.…”

“…The value of a N = 0.85G is typical for compounds with nitrogen atom in apical position relatively to o-semiquinonato plane [11]. The phosphorous constant value a P = 3.15G is close to that one in 1bÁPPh 3 (a P = 3.7G) [9]. This value is typical for complexes with phosphorous nuclear being in the plane of semiquinonato ligand.…”

“…But although corresponding o-semiquinonato (like 1a and 1b) [9] derivatives were obtained several decades earlier, their reactivity has not been studied in details. It was found only that complex 1b reacts with PPh 3 forming four-coordinated square-planar product 1bÁPPh 3 (Scheme 2) [9] whereas its acetylacetonato analog 1d forms a row of unstable adducts with PPh 3 [10].…”

“…Complex 1a was obtained [9] but it was not investigated in details. Moreover, strong trans-effect of PdAC bond in the complex 1d was found.…”

“…Moreover, strong trans-effect of PdAC bond in the complex 1d was found. It results in the difference of NMR chemical shifts of acetilacetonato groups: ACH 3 ( 1 H, d 1.99 and 2.12 ppm, 13 C, d 27.6 and 28.1 ppm) and C@O ( 13 C, d 186.3 and 188.5 ppm) [10], but it was not found in 1a [9].…”