Photochemical Synthesis of cis,trans,cis‐1,2,3,4‐Tetrakis(diphenylphosphanyl)buta‐1,3‐diene and Its Metal Coordination

Abstract

The new bis(bidentate) tetraphosphane cis,trans,cis‐1,2,3,4‐tetrakis(diphenylphosphanyl)buta‐1,3‐diene (dppbd) (7) was obtained by applying a photochemical synthetic protocol. The key step of the photochemical reaction consisted of an intramolecular [2+2] cycloaddition involving a C–C double and triple bond of the Pt‐dimer species of the formula [Pt2Cl4(dppa)(trans‐dppen)] (2) {dppa = 1,2‐bis(diphenylphosphanyl)acetylene and dppen = 1,2‐bis(diphenylphosphanyl)ethene} leading to [Pt2Cl4(dppbd)] (5). The asymmetrically bridged precursor complex 2 was obtained by combinatorial chemistry. Single crystal X‐ray structure analyses of 2 and 5 proved that the intramolecular photochemical reaction occurred. Cyanolysis of 5 gave 7, which was oxidized to dppbdO4 (8). Compounds 7, 8, and the PdII dimer complex [Pd2Cl4(dppbd)] (9) were characterized in the solid state by a single‐crystal X‐ray structure analysis. Interesting photophysial properties emerged from the UV/Vis spectra acquired for 7 and the dimer Os complexes meso‐Δ,Λ/Λ,Δ‐[Os2(bpy)4(dppbd)](PF6)4 (10) and rac‐Δ,Δ/Λ,Λ‐[Os2(bpy)4(dppbd)](PF6)4 (11).

Phosphines in artificial photosynthesis: considering different aspects such as chromophores, water reduction catalysts (WRCs), water oxidation catalysts (WOCs), and dyads

“…Moreover, the new bis(bidentate)tetraphosphine cis , trans , cis -1,2,3,4-tetrakis(diphenylphosphanyl)buta-1,3-diene 72 (dppbd) complexed in the form [Os 2 (bpy) 4 (dppbd)](PF 6 ) 4 generated a TON of up to 1500. 73 Since this TON was achieved with a Pd@(BiPy–PEG–OMe) nanoparticle WRC, and we focus on molecular homogeneous catalysis in this review, it is only mentioned to illustrate the stabilization effect of the tetraphosphine ligand on the Os-chromophore.…”

“…13, left, where this photosensitizer has already been successfully applied in a photocatalytic system. 72 As mentioned above, the efficiency of Cu( i ) chromophores strongly depends on the steric pressure induced by the ligands and this can be directly measured by calculating the intramolecular contact distances. These considerations will be published elsewhere.…”