Redetermination of the crystal structure of di-methyl-bis-[2,4-penta-nedionato(1-)-κ(2)O(2),O(4)]tin(IV).

The redetermination of the title compound, [Sn(CH3)2(C5H7O2)2] or SnMe2(acac)2, from CCD data recorded at 100 K basically confirms the previous study based on integrated film data recorded at room temperature [Miller & Schlemper (1972 ▸). Inorg. Chem.12, 677-681], but reveals a remarkable shrinkage of the a axis [7.12 (1) > 6.7694 (4) Å]. The mol-ecule belongs to point group Ci with the Sn(IV) atom on a centre of inversion. The Sn(IV) atom shows a slightly distorted octa-hedral coordination sphere with the methyl groups in trans positions and a Sn-C bond length of 2.115 (2) Å which may serve as a standard value for an Sn-CH3 bond of an octa-hedrally coordinated Sn(IV) atom. The Sn-O bonds involving the two carbonyl groups of the acetyl-acetonate ligand are of equal length [2.180 (1) and 2.183 (1) Å], as are the C=O [1.273 (1) and 1.274 (1) Å] and C-C bond lengths [1.393 (2) and 1.400 (2) Å]. The acetyl-acetonate ligand deviates considerably from planarity, with a dihedral angle of 5.57 (9)° between the least-squares planes of the two acetone moieties. The four O atoms of the two symmetry-related acetyl-acetonate ligands are arranged in a nearly quadratic rectangle. Weak C-H⋯O inter-actions consolidate the crystal packing.