62010-71-3Relevant articles and documents
A halogenophilic pathway in the reactions of transition metal carbonyl anions with [(η6-iodobenzene)Cr(CO)3]
Sazonov, Petr K.,Ivushkin, Vasiliy A.,Khrustalev, Victor N.,Kolotyrkina, Natal'Ya G.,Beletskaya, Irina P.
, p. 13392 - 13398 (2014/11/07)
The paper provides the first example of formal nucleophilic substitution by the halogenophilic pathway in Cr(CO)3 complexes of haloarenes with metal carbonyl anions. All metal carbonyl anions examined attack [(η6-iodobenzene)Cr(CO)3] at halogen, which is shown by aryl carbanion scavenging with t-BuOH. The reaction with K[CpFe(CO) 2] gives only the dehalogenated arene, but the reaction with K[Cp*Fe(CO)2] (Cp* = η5-C 5Me5) results in nucleophilic substitution to give [(η6-C6H5FeCp*(CO) 2)Cr(CO)3]. Reaction with Na[Re(CO)5] quantitatively gives the iodo(acyl)rhenate anion Na[(η6-C 6H5C(O)ReI(CO)4)Cr(CO)3] and in the case of K[Mn(CO)5] a mixture of σ-aryl complexes [(η6-C6H5Mn(CO)5)Cr(CO) 3] and K[(η6-C6H5Mn(CO) 4I)Cr(CO)3]. An analogous rhenium complex Na[(η6-C6H5Re(CO)4I)Cr(CO) 3] is formed from the initial iodo(acyl)rhenate upon prolonged standing at 20 °C, and its structure (in the form of [NEt4] + salt) is established by X-ray diffraction analysis. The reaction of [(η6-chlorobenzene)Cr(CO)3] with K[CpFe(CO) 2], in contrast, proceeds by the common SN2Ar mechanism.
Chromium tricarbonyl facilitated nucleophilic aromatic substitution by metal carbonyl anions: The synthesis and molecular structure of a new class of bimetallic π-arene complexes
Heppert, Joseph A.,Morgenstern, Mark A.,Scherubel, Devin M.,Takusagawa, Fusao,Shaker, Mohammad R.
, p. 1715 - 1723 (2008/10/08)
The highly nucleophilic metal carbonyl anions [CpFe(CO)2]- and [(C5Me5)Fe(CO)2]- (C5Me5 ≡ Cp*) react with (η-XRC6H4)Cr(CO)3 substrates in a previously unknown type of nucleophilic aromatic substitution to form (η6-{CpFe(CO)2}RC6H4)Cr(CO) 3 products. A variety of less reactive metal nucleophiles, including [CpMo(CO)3]-, [CpNi(CO)]-, [Mn(CO)5]-, and [Co(CO)4]-, fail to participate in the substitution reactions. The structure of (η-{CpFe(CO)2}ClC6H4)Cr(CO)3 has been determined by X-ray crystallography. The compound crystallizes in the space group P21/n with four molecules in the unit cell of dimensions a = 7.969 (2) A?, b = 18.982 (4) A?, c = 10.789 (2) A?, and β = 91.45 (3). Full-matrix least-squares refinement yielded R = 0.0353 for 2153 reflections. The structure shows that the conformation of the Cr(CO)3 fragment is determined by a cogging of the carbonyl ligands of the CpFe(CO)2 and Cr(CO)3 units to avoid steric interactions, although 1H and 13C NMR studies failed to show a perceptible barrier to Cr(CO)3 rotation about the Cr-Phcentroid vector. Certain haloarene substrates react predominantly through an apparent electron-transfer pathway to produce [CpFe(CO)2]2 and (η-RC6H5)Cr(CO)3. The fraction of reduced products formed is dependent on (1) the reducing power of the anion ([Cp*Fe(CO)2]- ? [CpFe(CO)2]-), (2) the electron-donating ability of the R group (electron donor ? electron acceptor), (3) the substitution pattern of the arene (in general ortho ? meta ? para), and (4) the identity of the halogen leaving group (I ? Cl > F).
