Stoicheiometric reduction of CO and CO₂to methanol: evidence for carbon monoxide insertion into zirconium–hydrogen bond

Abstract

The reaction of carbon monoxide with bis-(q5-cyclopentadienyl) hydridochlorozirconium( IV) , cp,Zr-(H)C1, at room temperature and atmospheric pressure, leads to a dinuclear zirconium (IV) derivative (cp,ZrCl),CH,O; replacing CO by CO, in this reaction results in the quantitative formation of cp,ZrCl(OMe) and (cp,ZrCI),O.A typical procedure is the carbonylation of 1.5 g of crude cp,Zr(H)Cl in 150 ml of T H F for 20 min.

Characterization of Reactive Intermediates by Diffusion-Ordered NMR Spectroscopy: A Snapshot of the Reaction of 13CO2 with [Cp2Zr(Cl)H]

“…For example, (S)-(À)-1-phenylethanesulfonic acid ((À)-PES) was found to be an efficient resolving agent for the optical resolution of dl-leucine. [5] The related ()-2-(2,3,4-trichlorophenyl)ethanesulfonic acid (()-TCPES) has been used as resolving agent for antifungal sulfoximines. [6] Considering their synthesis, enantiopure a-substituted sulfonic acids are commonly obtained from the corresponding racemates by resolution techniques with chiral amines.…”

“…succeeded in elucidating the long-standing postulated mechanism of this reaction by low-temperature NMR spectroscopy studies. [5,6] We were able to observe in situ both the formiato complex 2, which is formed by insertion of CO 2 into the ZrÀH bond of the hydride, and the binuclear diolato complex 3, which results from reaction with another equivalent of 1. Although complex 2 was synthesized in an earlier study, [7] the existence of the extremely unstable complex 3 was previously only postulated.…”

Characterization of chemisorbed species in CO/H2 and CO2/H2 reactions. Evolutive behaviour of the species

“…By hydrogenation of the formyl species we can obtain a chemisorbed form of formaldehyde 'C-0. Fachinetti et al (1978) in homogeneous systems prepared such a structure in (q5CSHS) ClZr-CH20-Zr(C1) (q5 CSH&. Such chemisorbed forms of formaldehyde could also be evidenced by Roper et al, (1979) on 0 s and Berke et a]., (1981) on Fe.…”

Hydrozirconation

“…to afford an η 2 -formaldehydo-type complex [(Cp 2 ZrCl)] 2 (µ-CH 2 O) [200][201][202]. Carbon dioxide [183,202] is reduced to formaldehyde with 1 (2 equiv.). Carbon dioxide [183,202] is reduced to formaldehyde with 1 (2 equiv.).…”