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. Can. J. Chem. 53,2371Chem. 53, (1975. The molecular and crystal structure of cis-dichlorobis(dimethylsulfoxide)platinum(II), cis-[PtC12(DMSO)2], has been studied by X-ray diffraction. The compound belongs to the monoclinic P2Jc space group and the cell parameters are: a = 8.653, b = 13.580, c = 10.914 A, B = 123.43", and Z = 4. The refinement of the positional and anisotropic thermal parameters, carried out by full matrix least-squares calculations, converged to R = 0.029 and R, = 0.027.The coordination around the platinum atom is planar. As expected, the DMSO molecules are bonded to the platinum atom through sulfur. The bond distances found are: Pt-Cl = 2.306,2.312 A; Pt-S = 2.244,2.229 A; S-0 = 1.469, 1.454 A, and S-C = 1.77 to 1.79 A. IntroductionPtCl,(DMSO),, we have undertaken the study PtCl,(DMSO),, obtained as yellow crystals of the crystals by diffractionfrom the reaction between K,PtCl, and dimethylsulfoxide has variously been assigned the cis (1, 2) and the trans (3) configuration. The complex is not isomorphous with the corresponding Pd(I1) complex which is known, from X-ray diffraction studies, to have a trans configuration (4). Although the infrared spectrum indicates a cis configuration, the chemical behavior is more in keeping with a trans configuration (ref. 5, a note added in proof, confirmed the assignment of a cis configuration since the authors had just synthesized the trans isomer). There is general agreement that in the platinum-(11) complexes with one or two dimethylsulfoxide molecules, the ligands are bonded to platinum through sulfur. A strong peak around 1125 cm-' in the infrared spectrum has been assigned to the S-0 stretching vibration, indicating bonding through sulfur (6), since it is shifted to higher frequency than the corresponding vibration in the free ligand.Recently, we have decided to study the reactions between PtCl,(DMSO), and some nucleosides. In order to know the exact nature of Experimental SectionCrystal Data PtCl2C4H1zS2O2 f.w. Crystals of cis-dichlorobis(dimethylsulfoxide)platinum-(11) were obtained directly from the reaction of K2PtC14 in aqueous dimethylsulfoxide as previously described (1). A set of precession photographs indicated that the hOl, I = 2n + 1 and OkO, k = 2n + 1 reflections are systematic absences indicating the P2Jc space group. The cell parameters were calculated by least-squares refinement from the setting angles of 15 automaticaJly centered reflections (MoKu radiation) on a Syntex P1 diffractometer equipped with a graphite monochromator. Collection and Reduction of Intensity DataThe intensity data were collected from a crystal of dimensions 0.106 x 0.120 x 0.434 mm. A total of 3461 independent reflections were measured in the region of 20 < 60" by the 2010 scan technique using MoKu radiation. The data collection was done at a variable speed (24" to 1 dealmin) depending on the intensity of the reflection (~G t e x 20/0iutocoilection program). 3475 (2) 1681 (1) 2807 (2) 0 1 1779 (7) 537 (4) 4649 (5) 0 2 2529 (7) 2327 (3) 3250(6) CI -1079 (10...

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Whole cells of an Escherichia coli strain that overexpresses Acinetobacter sp. NCIB 9871 cyclohexanone monooxygenase have been used for the Baeyer-Villiger oxidations of a variety of 4-mono- and 4,4-disubstituted cyclohexanones. In cases where comparisons were possible, this new biocatalytic reagent provided lactones with chemical yields and optical purities that were comparable to those obtained from the purified enzyme or a strain of bakers' yeast that expresses the same enzyme. The efficient production of cyclohexanone monooxygenase in the E. coli expression system (ca. 30% of total soluble protein) allowed these oxidations to reach completion in approximately half the time required for the engineered bakers' yeast strain. Surprisingly, 4,4-disubstituted cyclohexanones were also accepted by the enzyme, and the enantioselectivities of these oxidations could be rationalized by considering the conformational energies of bound substrates along with the enzyme's intrinsic enantioselectivity. The enzyme expressed in E. coli cells also oxidized several 4-substituted cyclohexanones bearing polar substituents, often with high enantioselectivities. In the case of 4-iodocyclohexanone, the lactone was obtained in > 98% ee and its absolute configuration was assigned by X-ray crystallography. The crystal belongs to the monoclinic P2(1) space group with a = 5.7400(10), b = 6.1650(10), c = 11.377(2) A, b = 99.98(2) degrees, and Z = 2. Taken together, these results demonstrate the utility of an engineered bacterial strain in delivering useful chiral building blocks in an experimentally simple manner.