The photodecomposition product μ‐oxalato‐1κ 2 O , O ′:2κ 2 O ′′, O ′′′‐bis{bis[2‐(2‐pyridyl)phenyl‐κ 2 C , N ]iridium(III)}–acetone (1/1.974)

An attempt to grow crystals of [Ir(ppy) 2 (vacac)], (I), from an acetone‐ d 6 solution formed instead crystals of [{Ir(ppy) 2 } 2 (μ‐oxalato)] acetone solvate, (II), [Ir 2 (C 11 H 8 N) 4 (C 2 O 4 )]·1.974C 3 H 6 O, where ppy is the phenylpyridine anion and vacac is vinylacetylacetonate. Each Ir III ion in (II) is in a pseudo‐octahedral coordination environment, where the pyridine N atoms are trans to each other and the phenyl C atoms are trans to the O atoms of the oxalate bridging ligand. There are two crystallographically independent dimer molecules, each lying on an inversion centre. It is suggested that the oxalate ligand is formed in a series of steps initiated by the aldol condensation of acetone with vacac.