Cyclopentadienyl metal carbonyl derivative

The 18-electron rale is not obeyed as consistently by these types of oiganome-tank compounds a by the carbonyl and nitrosyl complexes and their derivatives. For example, in addition to ferrocene. M(i 5-CsHs)2 compounds are known for most of the other elements of the first transition series (M — V, Cr, Mn.Co, Ni) and these cannot obey ihe 18-electron rule. However, only ferrocene shows exceptional thermal stability (stable to 500 C) and is not oxidized by air. Furthermore, cobaltocene, a 19-electron species, is readily oxidized to the 18-electron cobaltocenium ion. (Co(ip-CsH )3)4 , which reflects much of the thermal stability of ferrocene. Mixed cyclopentadienyl carbonyl complexes are common K -CjHjMCO) ]. [(if-CjH )-Cr(CO), . [( -CjHOMnCCOjJ, [(>r-C,H,>Fe(CO ,, . [fo -CjiyCoCoy. and (ip-CsH,)Ni(CO) 2. Of interest is the fact that among these compounds, the odd-atomic-number elements (V. Mn, and Co) form monomers and the even-atomic-number elements (Cr. Fe. and Ni) Ibrm dimers, which is in direct contrast to the behavior shown by the simple carbonyl complexes. Cyclopentadienyl derivatives are now known for every main group and transition metal of the periodic table and for most of the -block metals.89... 

In most of the few metal carbonyl and cyclopentadienyl derivatives without an inert gas configuration for the central metal atom, such as V(CO)g, Cr(CO)5l 87), C5H5VC7H7 88), and CsHsCrCgHe 89), the metal atom has exactly one electron less than the inert gas configuration. The only exceptions to this are the biscyclopentadienyl derivatives of vanadium, chromium, cobalt, and nickel in which the central metal atom has neither the inert gas configuration nor one electron less than this configuration. 

A number of molecular mechanics studies of metal-cyclopentadienyl complexes have been reported recently. The systems studied include linear metallocenes (in particular ferrocene), ferrocene derivatives (such as complexes with substituted cy-clopentadienyl ligands, bis(fulvalene)diiron complexes, ferrocenophanes and mixed-ligand complexes with carbonyls and phosphines), and nonlinear cyclopentadienyl complexes 8,153,221 231]. 

The metal-n-cyclopenladienyl bond is somewhat stronger in n-cyclo-pentadienyl derivatives than the metal-carbon bond in metal carbonyl derivatives. However, stepwise loss of 7t-cyclopentadienyl ligands occurs in the mass spectra of 7t-cyclopentadienyl derivatives 24>. The following fragmentation of ferrocene is particularly important because of the occurrence of ferrocene as a pyrolysis product in numerous mass spectra ... 

As indicated above, the antiknock effect is shown by many compounds. Outstanding among these are the organometallic compounds of many metals. Effective derivatives of many metals include alkyl compounds, aryls, carbonyls, nitrosyls, phosphines, cyclopentadienyls, and many mixed compounds. The aromatic amines are also good antiknock agents, but far less effective than the organometallic compounds. The reason why commercialization efforts were concentrated on tetraethyllead early in the history of antiknock investigations is evident from Table 1, which is a composite of early data 6 8,216). 

The reaction of the transition-metal fragments with main group 15 elements directly has proven a very fruitful field for exploration. The methodology has been successful for a wide range of metal complexes. These fall generally into three basic types (1) reactions with cyclopentadienyl metal carbonyls, (2) reactions with homoleptic metal carbonyls and substituted derivatives, and (3) reactions with metal cations in the presence of a multi-dentate chelating ligand. 

The principle of reacting a silicon hydride HSiR3 with a polynuclear carbonyl (or carbonyl cyclopentadienyl derivative) was successfully applied to other transition metals such as Mo 37 Mn40,137 81,207 Re135> 137> 207),... 

Cyclopentadienyl metal carbonyls and some derivatives, synthesis 31... 

Kinetics of acid hydrolysis of a series of pyridioraethyl-carbonyl and -TT-cyclopentadienyl derivatives of molybdenum, tungsten, manganese, and iron have been reported. In the case of the 4-pyridiomethyl derivatives the mechanism is dissociative, and may be described either as 51 1 with respect to the metal or 5 eI with respect to the carbon of the pyridiomethyl ligand. For the 3-pyridiomethyl derivatives homolysis is important. ... 

Almost all stable olefin complexes of the chromium group metals are derivatives of carbonyl and cyclopentadienyl compounds (Table 6.13). Most of the metal alkene compounds may be classified as one of the following groups ... 

Some transition metal carbonyls may also form cyclopentadienyl derivatives with fulvenes. Most commonly, the solvent is the source of hydrogen. In the absence of the solvent, disproportionation reactions occur [equations (9.42) and (9.43)]. 

Numerous unusual organosulfiir transition metal compounds have been obtained by reactions of various metal carbonyls and cyclopentadienyl-metal carbonyls with certain mercaptans, sulfides, disulfides, and dithietenes (1,2). Other types of organosulfiir transition metal compounds have been obtained from metal sulfides and certain acetylene derivatives (3). This paper discusses a new and entirely different synthesis of new types of organosulfur derivatives of metal carbonyls with metal-sulfiir bonds. These new compounds have been obtained by thermal or photochemical decarbonylation of compounds of general formula CH S CH ) U(CO)yHC H )y (n = 1,2 or 3 M = Fe [x 2, y = 1], or Mn [x = 5, y = OJ) without metal-sulfur bonds. These sulfur-containing transition metal alkyl derivatives, none of which has been previously reported, may in turn be obtained from metal carbonyl anions and the chloroalkyl methyl sulfides CH S(CHpnCl. 

The chemistry of the metal carbonyls has been the subject of hundreds of research papers, most of them appearing in the last decade of renaissance of inorganic chemistry. Reviews have appeared on the metal carbonyls themselves (/, 2) and on such related topics as the anionic carbonyl-metallates (S), metal-olefin complexes (4,5), tricarbonyl(diene)iron species (6), perfluoroalkyl metal compounds (7), andTr-cyclopentadienyl andir-arene (S, 9) metal derivatives. ... 

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