Reactions of diiron mu-aminocarbyne complexes containing nitrile ligands

Abstract

O ligante acetonitrila nos complexos µ-aminocarbinos [Fe 2 {µ-CN(Me)R}(µ-CO)(CO)(NCMe) (Cp) 2 ][SO 3 CF 3 ] (R = Me, 2a, CH 2 Ph, 2b, Xyl, 2c) (Xyl = 2,6-Me 2 C 6 H 3 ) é facilmente deslocado por haletos e cianetos, resultando na formação das espécies neutras [Fe 2 {µ-CN(Me)R}(µ-CO)(CO)(X)(Cp) 2 ] (X = Br, I, CN). Os complexos 2 sofrem desprotonação e rearranjo da MeCN coordenada quando tratados com reagentes organolítio. A trimetilacetonitrila, a qual não contém hidrogênios α ácidos foi usada no lugar da MeCN para formar os complexos [Fe 2 {µ-CN(Me)R}(µ-CO)(CO)(NCCMe 3 ) (Cp)

Constructing Organometallic Architectures from Aminoalkylidyne Diiron Complexes

“…In addition, cis ‐ trans isomerism (referred to Cp) is sometimes observed in [Fe 2 Cp 2 (CO)(µ‐CO){µ‐CN(Me)(Xyl)}(L)] 0/+ , and complete trans to cis conversion is normally achieved by heating in refluxing tetrahydrofuran. [35b], …”

“…On the other hand, pivalonitrile ( t BuCN), lacking of acidic hydrogens, manifests its lability towards phenyllithium (compound 10 , Scheme b). [35b] Notwithstanding, this substitution reaction remains an exception, since the same pivalonitrile and also arylnitriles do not allow, in general, carbanionic nucleophiles to reach the iron coordination sphere. Instead, unclean reactions often take place, unless xylyl containing complexes are treated with lithium (4‐tolyl)acetylide: with such specific combination (e.g., phenylacetylide does not work), selective nucleophilic addition at the coordinated nitrile occurs to give the alkynyl‐ketimide intermediates 11 , followed by C–N coupling with the aminocarbyne (Scheme c, d).…”

“…From the aminoalkylidyne complexes 8 (R′ = CH 3 , Scheme ), acetonitrile is readily displaced by a variety of anionic/neutral compounds (L), i.e. hydride, cyanide, halides,, pseudo‐halides, diethyldithiocarbamate,[35b] phosphines,[35b] amines, imines, and also a mild carbanion such as dicyanomethanide,[35b] affording [Fe 2 Cp 2 (CO)(µ‐CO){µ‐CN(Me)(Xyl)}(L)] 0/+ complexes in good to high yields. These reactions take place without affecting the aminocarbyne moiety.…”

“…Assembly of nitrile/acetylide/aminocarbyne units in diiron complexes (Tol = 4‐C 6 H 4 Me). [35b], [38a], , …”

“…The iron‐trimethylsilylacetylide moiety is susceptible to hydrolysis promoted by alumina filtration, providing an alternative route to iron‐acyl species (compare Scheme d with Scheme d). [35b] Interestingly, methylation of the acetylide unit [Fe–C≡CR′] does not produce the expected iron vinylidene [Fe=C=CR′(Me)], but the vinyliminium complexes 44 via new insertion of MeC≡CR′ …”