STRUCTURE DETERMINATION WITH LAUE DIFFRACTION DATA - INCLUDING REFINEMENT WHEN ANOMALOUS SCATTERERS ARE PRESENT

Abstract

The structure of a small single crystal of the organometallic compound [AuOs3H(CO)8{Ph2PCH2P(Ph)-C6H4)(PPh3)]PF6.0.5C6H5Cl, whose chemical constitution was only partially known, has been determined and refined. Synchrotron radiation with wavelengths in the range 0.24-0.65 angstrom was used for recording the Laue diffraction patterns from which the reflection intensities were measured. Data processing and initial structure determination followed established procedures. Over this wavelength range, the scattering factors of Au and Os change significantly on account of the anomalous scattering contributions, f' and f''; the program SHELXL92 [Sheldrick (1992). Program for the Refinement of Crystal Structures. Univ. of Gottingen, Germany] can allow for this variation and with it the structure refinement was completed, giving R1 = 0.078, wR2 = 0. 192 for 10 625 (unmerged) reflection intensities in the space group C2/c. Metallation of one phenyl group of the dppm ligand has occurred and the chemical aspects am further discussed by Harding, Kariuki, Mathews, Smith & Braunstein [(1993), J. Chem. Soc. Dalton Trans. pp. 33-361. Synchrotron radiation Laue diffraction data for another organometallic compound, Ru(C12H10O4)(C8H11P)2(CO)2, have also been recorded and used for structure refinement. This crystal of already known structure is non-centrosymmetric, space group P2(1)2(1)2(1), and provided a further test of the use of wavelength-dependent structure factors in SHELXL92. Refinement converged to R1 = 0.075, wR2 = 0.201 for 7241 reflection intensities and the enantiomorph was unambiguously determined.