Klaus Eichele:
Publication Abstracts 2002
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Klaus Eichele:
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K. Eichele, R. E. Wasylishen, J. F. Corrigan, N. J. Taylor, A. J. Carty,
K. W. Feindel, G. M. Bernard: Phosphorus Chemical Shift Tensors of Phosphido Ligands in Ruthenium Carbonyl Compounds: 31P NMR Spectroscopy of Single-Crystal and Powder Samples and ab initio Calculations. J. Am. Chem. Soc. 2002, 124, 1541-1552. |
The phosphorus chemical shift (CS) tensors of several ruthenium carbonyl compounds containing a phosphido ligand, m-PR2, bridging a Ru-Ru bond were characterized by solid-state 31P NMR spectroscopy. As well, an analogous osmium compound was examined. The structures of most of the clusters investigated have approximate local C2v symmetry about the phosphorus atom. Compared to the "isolated" PH2- anion, the phosphorus nucleus of a bridging phosphido ligand exhibits considerable deshielding. The phosphorus CS tensors of most of the compounds have spans ranging from 230 to 350 ppm and skews of approximately zero. Single-crystal NMR was used to investigate the orientation of the phosphorus CS tensors for two of the compounds, Ru2(CO)6(m2-h2-C=C-Ph) (m2-PPh2) and Ru3(CO)9(m2-H) (m2-PPh2). The intermediate component of the phosphorus CS tensor, d22, lies along the local C2 axis in both compounds. The least shielded component, d11, lies perpendicular to the Ru-P-Ru plane while the most shielded component, d33, lies perpendicular to the C-P-C plane. The orientation of the phosphorus CS tensor for a third compound, Ru2(CO)6(m2-PPh2)2, was investigated by the dipolar-chemical shift NMR technique and was found to be analogous, suggesting it to be the same in all compounds. Ab initio calculations of phosphorus magnetic shielding tensors have been carried out and reproduce the orientations found experimentally. The orientation of the CS tensor has been rationalized using simple frontier MO theory. Splittings due to 99,101Ru-31P spin-spin coupling have been observed for several of the complexes. A rare example of 189Os-31P spin-spin splittings is observed in the 31P MAS NMR spectrum of the osmium cluster, where 1J(189Os, 31P) is 367 Hz. For this complex, the 189Os nuclear quadrupolar coupling constant is on the order of several hundred megahertz.
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C. Nachtigal, S. Al-Gharabli, K. Eichele, E. Lindner, H. A. Mayer: Structural Studies of an Array of Mixed Diamine Phosphine Ruthenium(II) Complexes Organometallics 2002, 21, 105-112. |
Treatment of RuCl2(h2-Ph2PCH2CH2OCH3)2 with various chelating diamines permitted the isolation of the corresponding RuCl2(h1-Ph2PCH2CH2OCH3)2(diamine) complexes in high yield (diamine = 1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopropane, 1,2-phenylenediamine, 1,8-diaminonaphthalene, 2,2'-bipyridine, 1,10-phenanthroline). In solution, all complexes prefer the trans-chloro cis-phosphine arrangement, as deduced by NMR spectroscopy. X-ray studies showed that in the solid state all three possible isomers of the octahedral RuCl2P2(diamine) complexes are present. The reaction of the RuCl2(h1-Ph2PCH2CH2OCH3)2(diamine) complexes with 1 equiv of AgSbF6, AgBF4, or TlPF6 leads to the abstraction of one chloride by simultaneously coordinating one ether oxygen to ruthenium and forming monocationic [RuCl(h1-Ph2PCH2CH2OCH3)(h2- Ph2PCH2CH2OCH3)(diamine)]+ compounds. If a large excess of silver or thallium salt is used, the dichloro complexes are converted to the [Ru(h2-Ph2PCH2CH2OCH3)2(diamine)]2+ dications. In the case of 1,2-phenylendiamine as coligand, the corresponding dication is only observed in traces. NMR spectroscopic investigations and X-ray structural analyses confirm the h1 and h2 coordination of the ether-phosphine ligands in the corresponding mono- and dicationic ruthenium(II) complexes.
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Last modified: 13.02.2002