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Bonding metal carbonyl cations

H. Willner, and F. Aubke, cr-Bonded Metal Carbonyl Cations and Their Derivatives Syntheses and Structural, Spectroscopic, and Bonding Principles, Organometallics 22, 3612-3633 (2003). [Pg.122]

Lupinetti, A.J., Jonas, V., Thiel, W., Strauss, S.H. and Frenking, G. (1999) Trends in Molecular Geometries and Bond Strengths of the Homoleptic d Metal Carbonyl Cations [M(CO)J ... [Pg.236]

B. von Ahsen, M. Berkei, G. Henkel, H. Willner, and F. Aubke, The Synthesis, Vibrational Spectra, and Molecular Structure of [Ir(CO)6][SbF6]3-4HF - The First Structurally Characterized Salt with a Tripositive, Homoleptic Metal Carbonyl Cation and the First Example of a Tetrahedral Hydrogen-Bonded (HF)4 Cluster, J. Am. Chem. Soc. 124, 8371-8379 (2002). [Pg.123]

In a recent comprehensive review Willner and Aubke [48] have set the range of syntheses of transition metal carbonyl cations in superacidic media within the general context of synthesis of these types of cations by all known methods. They have presented the available spectroscopic and crystallographic evidence for the structures of the cations and have discussed the nature of bonding in the carbonyl complexes. [Pg.354]

A commonly used nucleophile has been water. Although initial attack affords a hydroxy-carbene derivative, ready cleavage of the Ca—Cp bond resulting from formal keto-enol tautomerism occurs to give either the acyl or the metal carbonyl (usually cationic) and the corresponding organic fragment (Equation 1.13) ... [Pg.20]

Processes for two-electron reductions, two sequential one-electron reductions with a radical anion intermediate, and reactions of dianions with unreduced parents to give radical anions were observed. Structural reorganization is occasionally observed, particularly in the case of Fe(CO)2 and Fe(CO)3 complexes (26). There appears to be little correlation between structure and electrochemical behavior. In general, the presence of metal-metal bonds in the substrate appears to correlate well with the ability to yield a stable radical anion on reduction. The lack of a metal-metal bond correlates, although poorly, with the ability to form radical cations (25). At present, the predictability of results from reduction in metal-carbonyl complexes is very low. The area remains one in which a great deal more work is needed. [Pg.311]

Numerous synthetically useful carbon-carbon bond-forming reactions are based on the fact that unsaturated hydrocarbon ligands bound to electrophilic transition metal moieties are activated toward addition of nucleophiles. Normally the metal moiety in such complexes is a neutral or cationic metal carbonyl group. Prominent and well-studied examples include [Cr(arene)(CO)3] complexes (covered in Chapter 2.4, this volume),1 [Fe(dienyl)(CO)3]+ complexes (covered in Chapter 3.4, this volume),2 [FeCp(CO)2(alkene)]+ complexes3 and [M(CO) (diene)] complexes.4... [Pg.695]

Recently the unprecedented example of stereoselective C—Si bond activation in cu-silyl-substituted alkane nitriles by bare CQ+ cations has been reported by Hornung and coworkers72b. Very little is known of the gas-phase reactions of anionic metal complexes with silanes. In fact there seems to be only one such study which has been carried out by McDonald and coworkers73. In this work the reaction of the metal-carbonyl anions Fe(CO) (n = 2, 3) and Mn(CO) (n = 3, 4) with trimethylsilane and SiH have been examined. The reactions of Fe(CO)3 and Mn(CO)4 anions exclusively formed the corresponding adduct ions via an oxidative insertion into the Si—H bonds of the silanes. The 13- and 14-electron ions Fc(CO)2 and Mn(CO)3 were observed to form dehydrogenation products (CO) M(jj2 — CH2 = SiMe2) besides simple adduct formation with trimethylsilane. The reaction of these metal carbonyl anions with SiFLj afforded the dehydrogenation products (CO)2Fe(H)(SiII) and (CO)3Mn(II)(SiII). ... [Pg.1115]

The nature of bonding in the cationic metal carbonyls has been investigated by both vibrational and electronic spectroscopy, and molecular orbital calculations have been carried out these are consistent with a bonding scheme for carbon monoxide coordinated to a metal, consisting of a dative cr-bond from carbon to metal, augmented by a synergic metal-to-carbonyl dative 7r-bond (7, 57). [Pg.118]

The characteristic high carbonyl frequencies of cationic metal carbonyls are rationalized in terms of a reduced 77-back-donation from the metal (7, 56). Such a proposal implicitly assumes that the carbon-metal cr-bond is independent of charge on the metal, and has been supported by semi-empirical molecular orbital calculations. This assumption of invariance of carbon-metal and carbon-oxygen o--bonds with change in the metal s oxidation state has been invalidated by a Raman and infrared investigation of M(CO)6+, M(CO)6, and M(CO)6 species (3, 4). It appears that the carbon-metal cr-bond increases with rise of positive charge on the metal, with concomitant decrease of metal-carbon 7r-bonding. [Pg.118]

The relative reactivity of cationic metal carbonyls has been predicted in the case of Mn(CO)6+ relative to Cr(CO)6 and V(CO)6 (55). The substitution behavior of Re(CO)6+ relative to W(CO)6 indicates that the cation is not more readily substituted by neutral ligands (3, 6), which correlates with the spectroscopic investigations (3, 4) of the metal-carbonyl bond. [Pg.118]

The high carbon-oxygen bond order in cationic metal carbonyls due to the reduced 77-back-donation is further supported by the intensities of the infrared carbonyl stretching bands (25), estimates of the degree of back-donation from electronic spectra (4), and from calculations of 77-overlap populations (35). [Pg.118]

The addition of a proton to a metal carbonyl compound may occur in either of two modes the formation of metal-hydrogen bond, or protonation of a ligand attached to the central metal atom. If the ligand protonated is an organic radical, a carbonium ion is produced, which may be stabilized by suitable delocalization of charge over the complex, including the central metal atom. Consequently, such protonated species may be legitimately considered as examples of cationic metal carbonyl compounds. [Pg.121]

Because of the legion of unsaturated organic systems bonded to metal carbonyl residues, this method provides an abundance of cationic carbonyls. Our classification of the method employed is according to the nature of the protonation site. [Pg.121]

The alkylation of an unsaturated atom or moiety bonded to a metal carbonyl produces an onium salt. This complex may be considered to be a further example of a cationic metal carbonyl, provided that the formal charge on the alkylated center can interact with the atomic orbitals of the metal. This may be justified on the basis of electronegativity differences between the metal atom and the alkylated center. It seems reasonable to argue that the location of the formal positive charge is on the electropositive metal atom, although the metal is probably only fractionally charged. [Pg.125]

Hydride abstraction of a hydrogen directly bonded to a metal atom has been used to synthesize cationic metal carbonyls. This may be accomplished by protonation, as outlined in Section C,l,f, or with a Lewis acid, such as boron trifluoride, in the presence of carbon monoxide (98). [Pg.127]

The hexacarbonyl and substituted carbonyl cations react with a variety of anionic nucleophiles to produce neutral species. The metathetical reaction of metal carbonylate salts with those of the cationic carbonyls yield primarily a mixed metal carbonyl salt however, on warming, anionic attack may cause expulsion of carbon monoxide and the formation of a metal-metal bond (174-176). [Pg.142]


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See also in sourсe #XX -- [ Pg.118 ]




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Cationic metal carbonyls carbonylation

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Metal-carbonyl bond

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