Photochemical Synthesis of ,,-1,2,3,4-Tetrakis(diphenylphosphanyl)buta-1,3-diene and Its Metal Coordination.

The new bis(bidentate) tetraphosphane ,,-1,2,3,4-tetrakis(diphenylphosphanyl)buta-1,3-diene (dppbd) () 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 [PtCl(dppa)(-dppen)] () {dppa = 1,2-bis(diphenylphosphanyl)acetylene and dppen = 1,2-bis(diphenylphosphanyl)ethene} leading to [PtCl(dppbd)] (). The asymmetrically bridged precursor complex was obtained by combinatorial chemistry. Single crystal X-ray structure analyses of and proved that the intramolecular photochemical reaction occurred. Cyanolysis of gave , which was oxidized to dppbdO4 (). Compounds , , and the Pd dimer complex [PdCl(dppbd)] () 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 and the dimer Os complexes -Δ,Λ/Λ,Δ-[Os(bpy)(dppbd)](PF) () and -Δ,Δ/Λ,Λ-[Os(bpy)(dppbd)](PF) ().