Group IB organometallic chemistry : XXXVII. Complex forming reactions of polynuclear arylcopper compounds: CalkP bond cleavage in 1,2-bis(diphenylphosphino)ethane (diphos) by (2-Me2NCH2C6H4)4Cu4 and crystal structure of [(C6H5)2PCu · diphos]2 · 2 C6H6

Molecular weight measurements and microwave titrations indicate that no interaction occurs between tetrameric 2-Me₂NCH₂C₆H₄Cu (Ar₄Cu₄) and the monodentate ligands PPh₃, CH₃CN or pyridine. However, the tetrameric structure Ar₄Cu₄ breaks down upon interaction (1/1 molar ratio ArCu/L) with the bidentate ligands (L) Diphos or cis-DPPEE to give the monomeric 1/1 complexes ArCu · L.Addition of Diphos to ArCu · Diphos or conducting the reaction of Ar₄Cu₄ with Diphos in a 1/2 ratio (ArCu/Diphos) gives rise to a C_alkP bond cleavage reaction resulting in the formation of dimeric (Ph₂PCu · Diphos)₂ · 2 C₆H₆, ArH and Ph₂PCHCH₂.The molecular structure of (Ph₂PCu · Diphos)₂ · 2 C₆H₆, has been determined by a single-crystal X-ray diffraction study. Crystals are monoclinic, space group P2₁/c and have Z  2 in a unit cell of dimensions a  12.997(6), b  12.669(7), c  22.839(9) Å and β  94.48(4)°. The structure was refined to R  0.048 for 3048 independent reflections. The four copper atoms in the dimer are held together by two Ph₂P bridges. The bonding in the dimer is discussed.