155477-15-9Relevant academic research and scientific papers
Reactions of the 17-electron iron-centered radicals {η5-C5Ph5Fe(CO)2. and {η5-C5Ph4(p-tolyl)}Fe(CO)2 . with organic halides and Lewis bases
Kuksis, Inga,Kovács, Istvan,Baird, Michael C.,Preston, Keith F.
, p. 4991 - 5002 (2008/10/09)
The 18-electron dimers [Cp′Fe(CO)2]2 (Cp′ = η5-C5Ph5, η5-C5Ph4(p-tolyl)), which undergo only very slight thermal dissociation to the corresponding 17-electron monomers Cp′Fe(CO)2., nonetheless exhibit reactivity patterns which reflect the chemistry of the monomers. Thus, reactions with several organic halides RX give Cp′Fe(CO)2R and Cp′Fe(CO)2X, consistent with initial halogen atom abstraction by Cp′Fe(CO)2. followed by coupling of the resulting carbon-centered radical with a second molecule of Cp′Fe(CO)2.. Reactions of [(η5-C5Ph4(p-tolyl)}Fe(CO) 2]2 with small phosphines L result in displacement of η5-C5Ph4(p-tolyl) radicals rather than formation of isolable 17-electron compounds [{η5-C5Ph4(p-tolyl)}Fe(CO)L., while reaction with the isonitrile t-BuNC results in disproportionation to the salt [{η5-C5Ph4(p-tolyl)}Fe(t-BuNC) 3][{η5-C5Ph 4(p-tolyl)}Fe(CO)2], possibly via the substituted species (η5-C5Ph4(p-tolyl)Fe(CO)(t-BuNC) .. Reactions of [{η5-C5Ph4(p-tolyl)}Fe(CO) 2]2 with phosphites P(OR)3 do give the substituted radical species {η5-C5Ph4(p-tolyl)}Fe(CO){P(OR) 3}., but Arbuzov products such as {η5-C5Ph4(p-tolyl)}Fe(CO)2Me, {η5-C5Ph4(p-tolyl)}Fe(CO) 2{P(=O)-(OMe)2}, and {η5-C5Ph4(p-tolyl)}Fe(CO){P(OMe) 3}{P(=O)(OMe)2} are the major products formed when R = Me and, to a lesser extent, Et. The Arbuzov reaction is hindered when R is large, and the compound {η5-C5Ph4(p-tolyl)}Fe(CO){P(O-i-Pr) 3}. is a persistent radical which has been characterized by, inter alia, EPR spectroscopy. The EPR spectrum of a frozen solution in benzene can be analyzed in terms of a uniaxial g matrix (g∥ = 1.993, g⊥ = 2.103) with isotropic 31P hyperfine coupling of 37 G (3.7 mT), typical of d7 organometallic radicals in which the unpaired electron is essentially confined to a metal dz2 orbital.
New examples of Arbuzov rearrangements of coordinated phosphites initiated by metal-centred radicals
Kuksis, Inga,Baird, Michael C.
, p. 253 - 255 (2007/10/03)
Reaction of the persistent, iron-centred radical {η5-C5Ph4(p-tolyl)}Fe(CO)2 · with tertiary phosphites P(OR)3 (R = Me, Et) results in the formation of the Arbuzov rearrangement products {η5-C5Ph4(p-tolyl)}Fe(CO)2R, {η5-C5Ph4(p-tolyl)}Fe(CO)2{PO(OR)2} and {η5-C5Ph4(p-tolyl)}Fe(CO){P(OR)3}{PO(OR)2}. For both phosphites, the metal-centred radicals {η5-C5Ph4(p-tolyl)}Fe(CO){P(OR)3} · appear to be intermediates in a process which involves initial, direct abstraction by {η5-C5Ph4(p-tolyl)}Fe(CO)2 · of an alkyl group R from the coordinated P(OR)3 of {η5-C5Ph4(p-tolyl)}Fe(CO){P(OR)3} ·, followed by interception of the 16-electron intermediate, {η5-C5Ph4(p-tolyl)}Fe(CO){PO(OR)2}, by CO and P(OR)3.
Synthesis and chemical properties of the 17-electron compounds (η5-C5Ph4Ar)Fe(CO)2 (Ar = phenyl, p-tolyl)
Kuksis, Inga,Baird, Michael C.
, p. 1551 - 1553 (2008/10/08)
Treatment of (η5-C5Ph5)Fe(CO)2H and (η5-C5Ph4(p-tolyl))Fe(CO)2H with the trityl radical, Ph3C?, results in hydride hydrogen atom abstraction and formation of the corresponding 17-electron pentaarylcyclopentadienyl compounds (η5-C5Ph4Ar)Fe(CO)2 (Ar = Ph, p-tolyl). The dicarbonyl radicals exist in solution in facile equilibrium with the corresponding 18-electron dimers [(η5-C5Ph4Ar)Fe(CO)2] 2 and were characterized by their IR spectra, which resemble the spectra of the analogous compounds (η5-C5H5)Fe(CO)2 and (η5-C5-Me5)Fe(CO)2, and by their reactivities with organic halides and 13CO, which are characteristic of 17-electron, metal-centered radicals.
