Physical Organic Chemistry of Transition Metal Carbene Complexes. 16.1 Reactions of (CO)5MC(OR)Ph (M = Cr or W; R = Me or Et) with Thiolate Ions in Aqueous Acetonitrile. Complete Kinetic Dissection of the Two-Step Mechanism

摘要: A kinetic study of the reactions (CO)5MC(OR‘)Ph (1a, M = Cr, R‘ Me; 1b, W, 1c, Et; 1d, Et) with n-PrS-, HOCH2CH2S-, MeO2CCH2CH2S-, and MeO2CCH2S- in 50% MeCN−50% water (v/v) at 25 °C is reported. At low [RS-] relatively pH reaction leads to nucleophilic substitution products (CO)5MC(SR)Ph without accumulation any intermediate. high formation a tetrahedral intermediate, (CO)5MC(OR‘)(SR)Ph, observed. Upon addition acid intermediate converted into product. For most thiolate ions detailed analysis allowed determination rate constants for attack on carbene complexes (k1) its reverse (k-1), equilibrium constant (K1 k1/k-1), alkoxide ion departure from respective intermediates catalyzed by H+ ( ) N-methylmorpholinium ). The dependence these con...