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{pi}-Stabilized, yet reactive, half-sandwich Cp*Ru(PR{sub 3})X compounds: Synthesis, structure, and bonding

Journal Article · · Inorganic Chemistry
; ; ; ; ;  [1]; ;  [2]
  1. Indiana Univ., Bloomington, IN (United States)
  2. Universite de Paris-Sud, Orsay (France)
The compounds Cp*RuLX (L = P{sup i}Pr{sub 2}h, PCy{sub 3}; X = Cl, Br, I, OCH{sub 2}CF{sub 3}, OSiPh{sub 3}, OSiMe{sub 2}Ph, NHPh), as well as their CO adducts, have been studied by NMR, IR, and X-ray diffraction in order to understand the nature of the Ru-X bond. Adducts were also formed with C{sub 2}H{sub 4}. CP*Ru(P{sub i}Pr{sub 2}Ph)(OCH{sub 2}CF{sub 3}) reacts with MeI (but not PhI) to give Cp*Ru(P{sub i}Pr{sub 2}Ph)I and MeOCH{sub 2}CF{sub 3}. The compounds Cp*RuLX have a mirror-symmetric structure with Ru, L, X, and the Cp* center coplanar. This is understood, using extended Hueckel calculations, to originate in the presence of a Ru-X partial {pi} bond which raises the LUMO. This increases the HOMO-LUMO gap and thus disfavors pyramidalization at the metal center. Calculations of the behavior of systems with X = pure {sigma} donor, {pi} donor, and {pi} acceptor support this analysis. The LUMO of Cp*RuLX still lies low enough to give visible color and to allow rapid addition of (small) Lewis bases. The {nu}(CO) values of the CO adducts show the X ligand donor power to vary in the order OSiMe{sub 2}Ph > NHPh > OSiPh{sub 3} > OCH{sub 2}CF{sub 3} {much_gt} Cl > Br > I. Comparison of the Ru-X bond lengthening upon addition of CO is also consistent with this ranking. The lack of facile {beta}-hydrogen migration when X = OCH{sub 2}CF{sub 3} is discussed.
Sponsoring Organization:
USDOE
OSTI ID:
75656
Journal Information:
Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 2 Vol. 34; ISSN 0020-1669; ISSN INOCAJ
Country of Publication:
United States
Language:
English