The first examples of triply bonded dirhenium(II) complexes that contain β-diketonate ligands

The reaction of Re2Cl4(μ-dppm)2 (dppm=Ph2PCH2PPh2) with Tl(acac) affords the bis-acetylacetonate complex Re2Cl2(acac)2(μ-dppm)2 (1) via the intermediacy of Re2Cl3(acac)(μ-dppm)2 (2). These are the first examples of β-diketonate complexes of the electron-rich triple bond. Solutions of 1 in non-aqueous solvents slowly convert to 2, which in the presence of an oxygen source decomposes to Re2(μ-O)(O)2Cl4(μ-dppm)2 and Re2(μ-O)2(O)2Cl4(μ-dppm)2 (3). The single crystal X-ray structures of 1–3 have been determined; the Re–Re distances (in Å) are 2.2968(3), 2.2542(5) and 3.1415(7), respectively.