Kinetics of nucleophilic attack on coordinated organic moieties. Part 10. Addition of N,N-dimethylaniline to tricarbonyl(cyclohexadienyl)-ruthenium cationa

Mechanism of addition of aryltrimethyl-silanes and -stannanes to tricarbonyl(cyclohexadienyl)ruthenium(II) cation

“…In addition, plots of log kx/k, for the reaction of complexes (1) and (5) with the Sn substrates at 45 "C uersus log kx/kH for the protiodemetallation of XC6H4Sn(CyC10-C6H 1)3 by HClO, in aqueous ethanol (at 50 "C) l4 are also linear indicating that these organometallic complexes behave in a similar manner to more classical electrophiles. As found earlier for the Fe reactions, one significant difference is the deactivating property of a 4-F substituent in the protiodemetallation process while it is slightly activating in reaction (1). Further support for a relatively early transition state for reaction (1) (M' = Sn) comes from a Yukawa-Tsuno plot l 5 of log kx/kH (M = Ru) uersus CT + r ( o + -CT) if an r value of 0.3 is chosen.…”

“…This Scheme is the same as that reported for the analogous iron complex [Fe(CO),{ 1-5-qdienyl)] (5) and suggests a common mechanism for addition of XC,H,M'Me, (M = Si or Sn) substrates to complexes (1) and (5). Hammett plots of log kx/kH uersus CT (the standard Hammett substituent constant) for the reaction of complexes (1) and (5) with the Sn substrates at 45 "C are linear with slopes, p, of -3.4 for Fe and -2.9 for Ru, suggesting a common mechanism for each of the reactions. However, the lower value found here for the Ru complex indicates an earlier transition state for reactions (1) than in the analogous Fe reactions.…”

“…This rate law has been rationalised in terms of a rate-determining electrophilic attack by complex (1) on the XC,H,M' Me, substrates to form Wheland type cr-complex intermediates of the type [Ru(C0),{14-q-C,H,(XC,H,M'Me,)}]…”

“…For the Sn reactions, a Hammett plot of log ( k x / k H ) versus cr (the standard Hammett substituent constant) is linear with a slope of -2.9 suggesting a common mechanism for each of the reactions. A plot of log (k,/kH) for the reactions of (1 ) with XC,H,Sn-Me, in MeNO, (at 45 "C) versus log ( k x / k H ) for the protiodemetallation of XC,H,Sn(cyclo-C,H,,), by HCIO, in aqueous ethanol (at 50 "C) is also linear indicating that organometallic complexes such as (1) behave in a similar manner t o more classical electrophiles.…”

“…The rate law (2) is the same as that found recently8 for the analogous reactions of these substrates with [Fe(CO),( 1-5-77dienyl)]BF, (5) in both nitromethane and acetonitrile solvents, and supports a common mechanism for all reactions. Rate law (2) may be rationalised in terms of a rate-determining electrophilic attack by complex (1) on the XC6H,M'Me3 substrates to form Wheland type o-complex intermediates of the type (2) (Scheme) followed by cleavage of the Me,M'-C(dieny1) bond to give the products (3). This Scheme is the same as that reported for the analogous iron complex [Fe(CO),{ 1-5-qdienyl)] (5) and suggests a common mechanism for addition of XC,H,M'Me, (M = Si or Sn) substrates to complexes (1) and (5).…”