Organo—Iron Complexes. IV. Reactions of Substituted Dienes with Iron Pentacarbonyl

Synthesis of conjugated diene complexes of ruthenium(0) derived from Ru(η6-naphthalene)(η4-1,5-COD): Z to E isomerisation of coordinated 1,3-pentadiene

“…Although we do not have mechanistic information, a similar 1,5-hydrogen shift occurs in the (Z)-1,3-pentadiene complex, as described in the next section. It is also worth noting that a similar isomerisation to that described here occurs, under much more forcing conditions, when 2,5-dimethyl-2,4-hexadiene is heated with [Fe(CO) 5 ] to give the Fe(CO) 3 complex of cisoid-(E)-2,5-dimethyl-1,3-hexadiene [27].…”

“…by assuming that the 3-CH proton lies on a centre of symmetry of the dynamic operation, which is most likely a 1,5-hydrogen shift between the methyl and methylene groups [33]. A similar mechanism has been proposed for the corresponding process in [RuCp {(Z)-1,3-pentadiene}(CO)] þ by Green et al [27]. Moreover, an EXSY [34] measurement of Z-5a in acetonitrile-d 3 at À40 C clearly indicated proton exchange between the methyl and methylene fragments (Table 6), consistent with the occurrence of an intramolecular 1,5-hydrogen shift in Z-5a in acetonitrile.…”

The solid‐state decomposition and oxidation of dicobaltoctacarbonyl in a polymer matrix

“…The identification of metal carbonyl species in solution or in a solid polymer matrix as well as the quantitative determination of cobalt carbonyl concentrations in the polymer was carried out by infrared spectroscopy. IR was used because (1) most solvents and polymers do not have strong adsorption bands in the region between 1800 and 2200 cm-' where metal carbonyls absorb (if a solvent does absorb in this region it can be compensated with a reference), (2) the carbonyl bands of metal carbonyls, both terminal and bridging, are very sharp and well contoured in the 1800-2000 cm-' region and permit an accurate evaluation of concentration, and (3) the infrared spectra of a great number of metal carbonyls, including Co,(CO)a and Co,(CO),,, are well known.I6* l7 Moreover, the influence of various factors on the spectra (such as solvent effects, temperature, or substituting ligands) are also well kn~wn'~~'~ and therefore permit evaluation of changes in the spectra of the metal-polymer composite films.…”

Hydrogenation & Isomerization of Alkenes

“…Possibly one of the most simple reactions is the (Z) (E) conversion of penta-1,3-diene by [Fe(CO) 5 ]. 9 However, the usual course of events in the isomerization of cycloalkadienes is to achieve conjugation where coordination is impossible. Thus cyclohexa-1,4-diene is isomerized to cyclohexa-1,3-diene by [RuCl(PPh 3 ) 3 ].…”