The carbalkoxymethyl ligand on (.eta.-C5H5)(CO)[P(OCH3)3]FeCH2CO2CH3 as a carbon monoxide-derived C2 template for generating C2 organic ligands and molecules

Abstract

The carbalkoxymethyl ligand on Cp(CO) [P(OCH3)3] FeCH2C02R (7) (R = CH3, CH2CH3) serves as a C2 template for generating other C2-coordinated ligands and organic molecules. In this study 7 is procured by acid isomerization of the alkoxyacetyl complexes Cp(CO)[P(OCH3)3] FeCOCH2OR (5), which are obtained by P(OCH3)3-induced CO-insertion on Cp(CO)2FeCH2OR. (Overall, the carbalkoxymethyl ligand on 7 derives from two CO groups on Cp(CO)3Fe+.) A mechanism for this alkoxyacetyl-carbalkoxymethyl ligand isomerization is advanced whereby protonation of 5 generates a ligated ketene intermediate that regioselectively adds alcohol and gives 7. In excess acid either 5 or 7 quantitatively releases acetic acid ester, a selective generation of this C2 organic from CO. The carbalkoxymethyl ligand on 7 is activated as a hydride acceptor by converting it to the (dialkoxycarbenio)methyl salt Cp(CO)[P(OCH3)3]FeCH2C(OR)2+ ( 8). (Interestingly, 8 cannot be generated from the alkoxycarbene system Cp(CO)[P(OCH3)3]FeC(OR)CH2OR+ (6).) BH4~c onverts 8 into a mixture of ?/-ethylene and V-ethyl complexes of Cp(CO)[P(OCH3)3]Fe, whereas («c-Bu)3BH'Li+ generates the corresponding ?j1 2-ethyl vinyl ether and '-formylmethyl compounds. The conversion of these latter two into acetaldehyde is discussed.

A new mechanism of nucleophilic vinylic substitution and unexpected products in the reaction of chlorotrifluoroethylene with [Re(CO)5]Na and [CpFe(CO)2]K

“…Insertion of the carbene equivalent into Fe-C"O bond will produce the iron ketene complex C (Scheme 15). Nucleophilic addition of alkoxide to iron ketene complexes has been described [17]. It is directed at the central carbon atom of ketene ligand and gives alcoxycarbonyl iron complexes.…”

Carbon monoxide and carbon dioxide fixation: relevant C1 and C2 ligand reactions emphasizing (.eta.5-C5H5)Fe-containing complexes

“…?2-ethyl vinyl ether complex Cp-(P(OMe)3)(CO)Fe(CH2=CHOEt)+PF6-(115c) likewise results from treating its formylmethyl complex Cp-(P(OMe)3)(CO)Fe-CH2CHO (112c) with EtgO+PFg-. 85 Both Fp(? ?2-dialkoxyethylene)+ (116a)188,274 and the Fp(?…”

“…IR spectra of 69 thus indicate a reduced acyl C-0 bond order: the ester n(CO) of Fp-CH2C02Me is 1678 cm-1, vs 1738 cm-1 for methyl acetate (in CH2C12). 85 The results of X-ray structure determinations of Fp-CH2C02H,282® Cp(PPh3)(CO)Fe-CH2CO2(menthyl),90b and other transition-metal carboalkoxymethyl complexes,286 however, indicate the absence of significant contribution from a dipolar resonance form involving an ? ?2-ketene acetal structure.…”

“…The structures 122a,c, furthermore, resemble that of the Fp-jj1heptafulvene salt, which in agreement with spectral data and results of an X-ray structure determination favors delocalization of charge from the /3-position to the iron.288 The (dialkoxycarbenio) methyl complex 122c is an activated form of the otherwise unreactive carboalkoxymethyl system 69c. 85 For example, 69c is inert toward BH4". Sodium borohydride (1 equiv) in ethanol, however, converts 122c to a 1:1 mixture (total yield, 65%) of the ?/2-ethylene and V-ethyl complexes, whereas Ph3PMe+BH4" in CH2C12 quantitatively gives the ethyl complex.…”

Ethoxycarbonyl-, cyano- and methoxy-methyl complexes of nickel(II) and their carbonylation reactions

“…Pressurizing the reaction mixture with 2 instead of 4 atm of CO yielded, after ca. 15 [Ni(CH,CO,Et)(q-C,H,)(PMe,)]…”