155477-16-0Relevant 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.
