52253-91-5Relevant articles and documents
Enthalpies of reaction of (benzylideneacetone)iron tricarbonyl, (BDA)Fe(CO)3, with phosphine ligands. Thermodynamic insights into iron chemistry
Luo, Lubin,Nolan, Steven P.
, p. 3483 - 3486 (1992)
The enthalpies of reaction of (BDA)Fe(CO)3 (BDA = benzylideneacetone) with a series of monodentate phosphine ligands (PR3) leading to the formation of trans-(PR3)2Fe(CO)3 complexes have been measured by solution calorimetry in THF at 50°C. These enthalpy data help establish the following relative order of stability: PEt3 > PnBu3 > PMe3 > PPhMe2 > PPh2Me > PPh3. The data span a range of 15 kcal/mol. This stability scale sheds light on the relative donating ability of phosphines. These data also allow comparison with other organometallic systems and give insight into factors influencing the Fe-PR3 bond disruption enthalpies in the (PR3)2Fe-(CO)3 system.
Reductive elimination of halogens assisted by phosphine ligands in Fe(CO)4X2 (X = I, Br) complexes
Bellachioma, Gianfranco,Cardaci, Giuseppe,Macchioni, Alceo,Venturi, Chiara,Zuccaccia, Cristiano
, p. 3881 - 3888 (2007/10/03)
Fe(CO)4X2 complexes [X = I (1), Br(1′)] react with phosphine ligands L (L = PMe3, PEt3, PMe2Ph, PMePh2, PPh3) via a two-step mechanism: in the first step fac-Fe(CO)3LX2 complexes are formed; in the second step two parallel pathways, a and b, are observed; in pathway a, reductive elimination with formation of equimolar amounts of Fe(CO)3L2 (5) and phosphonium salts [LX]+X- is observed; in pathway b, disubstituted dihalide complexes cis,trans,cis-Fe(CO)2L2X2 are formed. The relative weights of pathways a and b depend on the basicity, steric hindrance and concentration of ligand L, on the nature of the halogen and on temperature. A radical mechanism which accounts for most of the experimental results is proposed.
Ligand substitution processes on carbonylmetal derivatives. 1. Reaction of tetracarbonylhydridoferrates with phosphines
Brunet,Commenges,Kindela,Neibecker
, p. 1343 - 1350 (2008/10/08)
Ligand substitution processes on KHFe(CO)4 (1) have been demonstrated for the first time by reaction with various phosphines (2 equiv). The reaction times and the nature of the reaction products strongly depend on (i) the nature of the solvent, (ii) the cone angle of the phosphine, and (iii) the reaction conditions. In protic media (e.g. EtOH), phosphines with small cone angles (P(n-Bu)3, PMe2Ph) react with 1 below room temperature to give the newly characterized H2Fe(CO)2(PR3)2 in good yield, whereas phosphines with larger cone angles react only at higher temperature and afford the disubstituted Fe(CO)3(PR3)2 derivatives in quantitative yield. In aprotic medium (THF), phosphines (P(n-Bu)3, PPh3) react only slowly with 1 at room temperature but do so at reflux temperature to yield K2Fe(CO)4 (50%) and bis- or tris-(phosphine)carbonyliron derivatives. The reaction mechanism involves the formation of a monosubstituted K+[HFe(CO)3(PR3)]- derivative with a rate strongly dependent on the Tolman cone angle of the phosphine. In THF, this basic hydrido carbonyl anion reacts with 1 to yield K2Fe(CO)4 and H2Fe(CO)3(PR3). The latter further reacts to give bis- or tris(phosphine)carbonyliron derivatives. In ethanol, the monosubstituted K+[HFe(CO)3(PR3)]- derivative is protonated to give the neutral dihydride H2Fe(CO)3(PR3), which depending on the reaction conditions, is converted either to H2Fe(CO)2(PR3)2 by CO substitution (at low temperature) or to Fe(CO)3(PR3)2 by H2 elimination (at higher temperature). For phosphines exhibiting small cone angles, the disubstituted dihydride may react further with an excess of phosphine to yield the trisubstituted Fe(CO)2(PR3)3 derivative in good yield.
