99Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

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• 作者：Sander Gaemers ; Joris van Slageren ; Christine M. O'Connor ; Johannes G. Vos ; Ronald Hage ; and Cornelis J. Elsevier
• 刊名：Organometallics
• 出版年：1999
• 出版时间：December 6, 1999
• 年：1999
• 卷：18
• 期：25
• 页码：5238 - 5244
• 全文大小：116K
• 年卷期：v.18,no.25(December 6, 1999)
• ISSN：1520-6041

文摘

The ruthenium(II) organometallic and coordination complexes of type Ru(X)(Y)(CO)₂(i-Pr-DAB) (i-Pr-DAB = 1,4-diisopropyl-1,4-diaza-1,3-butadiene; X, Y = Cl, Br, I, Me, Et,i-Pr, neo-Pe, Ph₃Sn, Me₃Sn, Ph₃Pb, Ph₃Ge, Mn(CO)₅, RuCp(CO)₂) have been analyzed bymeans of ⁹⁹Ru NMR spectroscopy. The ⁹⁹Ru NMR resonances for these compounds aregenerally sharp, allowing scalar couplings to group 14 nuclei to be observed. Correlationtimes _c have been determined from NOE factors and ¹³C T₁ values for selected compoundsand were found to parallel the molecular weight of the compounds studied. The M-Ru-M'and M-Ru-X complexes have ⁹⁹Ru NMR resonances in distinct chemical shift regions. Inthe series M-Ru-M' a correlation between the inverse of the crystal field splitting energyE and (⁹⁹Ru) exists. These complexes have a HOMO which is delocalized over the M-Ru-M' system and a LUMO which has predominantly *-DAB character; therefore, (E)^-1 isdominant in the paramagnetic shielding of the ruthenium nucleus. The difference in theobserved chemical shift regions of the M-Ru-M' and M-Ru-X compounds can be attributedto differences in d-orbital radius <r^-3>_d, which is in good agreement with previously performedDFT calculations. For the Ru(I)(R)(CO)₂(i-Pr-DAB) complexes, (⁹⁹Ru) follows the same trendas for a series of iron compounds, indicating an increase of the Ru-C bond length in theseries Me < Et < neo-Pe < i-Pr. This finding emphasizes the power of transition-metal NMRspectroscopy in the structural analysis of transition-metal complexes. Furthermore, ⁹⁹RuNMR provides a tool to identify and assign isomers in mixtures of Ru-polypyridyl complexes.The ⁹⁹Ru NMR resonances of coordination isomers of various triazole-containing rutheniumcomplexes are found at different frequencies, which can be used to unambiguously identifycoordination isomers in mixtures by means of ⁹⁹Ru NMR spectroscopy. The (⁹⁹Ru) value isfound to increase with increasing redox potential of the polypyridyl compounds.