239123-51-4

Upstream product

• 37823-96-4 pentacarbonyl(methoxyphenylmethylene)tungsten⁽⁰⁾ 
• 62385-17-5 potassium propanethiolate 

Downstream Products

• 50507-81-8 W(CO)5(C(OH)C₆H₅) 

Relevant academic research and scientific papers

Physical organic chemistry of transition metal carbene complexes. 16.1 Reactions of (CO)5M=C(OR)Ph (M = Cr or W; R = Me or Et) with thiolate ions in aqueous acetonitrile. Complete kinetic dissection of the two-step mechanism

A kinetic study of the reactions of (CO)5M=C(OR′)Ph (1a, M = Cr, R′ = Me; 1b, M = W, R′ = Me; 1c, M = Cr, R′ = Et; 1d, M = W, R′ = Et) with n-PrS-, HOCH2CH2S-, MeO2CCH2CH2S-, and MeO2CCH2S- in 50% MeCN-50% water (v/v) at 25°C is reported. At low [RS-] and relatively low pH the reaction leads to the nucleophilic substitution products (CO)5M=C(SR)Ph without accumulation of any intermediate. At high [RS-] and high pH formation of a tetrahedral intermediate, (CO)5MC(OR′)(SR)Ph, is observed. Upon addition of acid the intermediate is converted into the substitution product. For the reactions of most thiolate ions a detailed kinetic analysis allowed the determination of the rate constants for nucleophilic attack on the carbene complexes (k1) and its reverse (k-1), the equilibrium constant for nucleophilic addition (K1 = k1/k-1), and the rate constants for alkoxide ion departure from the respective intermediates catalyzed by H+ (kh2) and N-methylmorpholinium ion (kBH2). The dependence of these rate and equilibrium constants on the metal, the leaving group, and the thiolate ion and comparisons with reactions of thiolate ions with other electrophiles provide insights into the transition state structure, the resonance effect of the (CO)5M moieties, the requirements for partial desolvation of the nucleophile prior to entering the transition state, and transition state imbalances.

Physical organic chemistry of transition metal carbene complexes. 17. Kinetics of the reactions of (arylthioalkoxycarbene)pentacarbonyl complexes of chromium(0) and tungsten(0) with thiolate ions in aqueous acetonitrile: pK(a) values of the metal-protonated tetrahedral adducts formed between carbene complexes and thiolate ion

Rate and equilibrium constants for the nucleophilic attachment of various thiolate ions to (CO)5M=C(SMe)Ph (M=Cr and W) and for the attachment of HOCH2CH2S- to (CO)5W=C(SCH2CH2OH)C6H4Z (Z=CF3, Cl, F, H, Me, MeO, and Me2N) have been determined in 50% MeCN-50% water (v/v) at 25 °C. For some of the adducts, those of the general structure (CO)5M?C(SR,SR')C6H4Z, a kinetic determination of the pK(a) of their metal-protonated conjugate acid, (CO)5M(H)C(SR,SR')C6H4Z, is also reported. On the basis of Bronsted coefficients, Hammett ρ values and comparisons with the reactions of the same thiolate ions with methoxy carbene complexes such as (CO)5M=C(OMe)Ph, insights into the role played by desolvation of the nucleophile prior to C-S bond formation, by the smaller π-donor and inductive but larger steric effects of the MeS compared to the MeO group, by transition state imbalances, etc. are discussed. The pK(a) values obtained for (CO)5M(H)C(SR,SR')C6H4Z were used to resolve a mechanistic ambiguity in the hydrolysis of Fischer carbenes that have acidic protons on the α-carbon, e.g., (CO)5Cr=C(OMe)Me.