The photodecomposition product μ-oxalato-1κ²O,O′:2κ²O′′,O′′′-bis{bis[2-(2-pyridyl)phenyl-κ²C,N]iridium(III)}–acetone (1/1.974)

An attempt to grow crystals of [Ir(ppy)₂(vacac)], (I), from an acetone-d₆ solution formed instead crystals of [{Ir(ppy)₂}₂(μ-oxalato)] acetone solvate, (II), [Ir₂(C₁₁H₈N)₄(C₂O₄)]·1.974C₃H₆O, 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.