J. Marthinus Janse van Rensburg

Tricarbonyl(ŋ6-4′,7-dimethoxyiso-flavone) chromium(0)

The metal atom of the Cr(CO)3 unit of the title compound, [Cr(C17H14O4)(CO)3], is coordinated to the methoxyphenyl ring of the isoflavone ligand; the Cr(CO)3 unit exhibits a three-legged piano-stool conformation. The aromatic ring of the methoxyphenyl group is twisted by 42.49 (9)° with respect to the γ-pyrone ring. In the fused-ring, the dihedral angle between the phenylene and γ-pyrone rings is 3.08 (13)°.

Tricarbonyl(η6-4′,7-dimethoxyisoflavone)chromium(0)

The metal atom of the Cr(CO)3 unit of the title compound, [Cr(C17H14O4)(CO)3], is coordinated to the methoxyphenyl ring of the isoflavone ligand; the Cr(CO)3 unit exhibits a three-legged piano-stool conformation. The aromatic ring of the methoxyphenyl group is twisted by 42.49 (9)° with respect to the γ-pyrone ring. In the fused-ring, the dihedral angle between the phenylene and γ-pyrone rings is 3.08 (13)°.

cis-trans Isomers of PtX4L2 (X=halogen and L=neutral ligand): trans -bis(dimethyl sulfide)tetraiodidoplatinum(IV)

The octahedral title complex, [PtI4(C2H6S)2] or trans-PtI4(dms)2 (dms is dimethyl sulfide), crystallizes in the monoclinic space group P2(1)/n (Z = 2), with molecular symmetry C(i), which is the most frequently occurring point group for trans-PtX4L2 {56%, 28 structures in the Cambridge Structural Database (CSD) [Allen (2002). Acta Cryst. B58, 380-388]}, followed by C(1) (22%, 11 structures). The complexes form a puckered pseudo-hexagonal layer in the (10(1)) plane, and the layers are stacked with an interplanar distance of 7.10 A. Density functional theory (DFT) calculations on an isolated complex with the observed parameters as a starting structure converged to C(2h). Constraints to C(i) on the observed geometry give 3-4 kJ mol(-1) higher energy compared with C(2h). DFT calculations on [PtCl4(PzH)2] (PzH is pyrazole), reported in the CSD in both the cis and trans forms, show an energy difference of 21 kJ mol(-1) in favour of the trans complex. A CSD search for PtX4L2-type complexes, where X is a halogen and L is a ligand with a donor atom from group 14, 15 or 16, indicated a preferred trans geometrical arrangement, with a total fraction of 68%. The dominating crystal packing operators for the trans complexes are an inversion centre combined with a screw axis/glide plane (48%), followed by an inversion centre alone (28%).