90458-37-0Relevant academic research and scientific papers
Reactivity of Fe(CO)4(H)MPh3 (M = Si, Ge) and mechanism of substitution by two-electron-donor ligands: Implications for the mechanism of hydrosilylation of olefins catalyzed by Fe(CO)5
Bellachioma, Gianfranco,Cardaci, Giuseppe,Colomer, Ernest,Corriu, Robert J. P.,Vioux, André
, p. 519 - 525 (2008/10/08)
cis-Fe(CO)4(H)MPh3 (M = Si, Ge) complexes undergo carbonyl displacement with nucleophilic ligands (phosphines, phosphites) to give Fe(CO)3(H)(L)MPh3. With M = Si the geometry of these complexes depends on the nature of the solvent; in nucleophilic solvents the mer-OC-6-43 isomer is formed, while in nonnucleophilic solvents the mer-OC-6-23 isomer is obtained (the cis positions of H and Si are retained). These two isomers undergo concerted reductive elimination of silane with PPh3. The mer-OC-6-43 isomer reacts 183 ± 19 times faster than the mer-OC-6-23 isomer in toluene at 26.0°C, giving the same 16-electron intermediate; the calculated equilibrium constant for the interconversion of OC-6-43 and OC-6-23 is 823 ± 192 at 26.0°C in toluene. Owing to the strong acidity of Fe(CO)4(H)MPh3 (pKa estimated as 3CN) and of Fe(CO)3(H)(PPh3)MPh3 (pKa estimated as ≤8.94 in CH3CN), reaction with basic two-electron-donor ligands [P(alkyl)3, P(cycloalkyl)3, NR3] leads to the formation of the anionic trigonal-bipyramidal complexes [Fe(CO)4MPh3]- and [Fe(CO)3(L)MPh3]-. cis-Fe(CO)4(H)SiPh3 reacts with isoprene to give [Fe(CO)4SiPh3]2; this reaction is not observed with Fe(CO)3(H)(L)SiPh3. The versatile reactivity of these complexes sheds some light on the mechanism of hydrosilylation of olefins and conjugated dienes. Under thermal conditions previous coordination of the olefin to the metal in this reaction seems to be excluded.
Photochemistry of iron and ruthenium carbonyl complexes: Evidence for light-induced loss of carbon monoxide and reductive elimination of triethylsilane from cis-mer-HM(SiEt3)(CO)3(PPh3)
Liu, David K.,Brinkley, Cynthia G.,Wrighton, Mark S.
, p. 1449 - 1457 (2008/10/08)
The near-UV photochemistry of M(CO)4PPh3 and HM(SiEt3)(CO)3(PPh3) (M = Fe, Ru) has been investigated. The HM(SiEt3)(CO)3(PPh3) complexes have a meridional structure with the H cis to both PPh3 and the SiEt3 and are referred to as the cis-mer isomer. In low-temperature (～100 K) rigid organic glasses the M(CO)4PPh3 undergoes dissociative loss of CO to form the 16-electron M(CO)3PPh3, M-(CO)3(PPh3)(2-MeTHF), M(CO)3(PPh3)(1-C5H10), or cis-mer- and fac-HM(SiEt3)(CO)3(PPh3) complex when the organic glass is an alkane, 2-MeTHF, 1-C5H10, or Et3SiH, respectively. The fac-HM(SiEt3)(CO)3(PPh3) complexes undergo thermal isomerization to the cis-mer isomer upon warmup to 298 K. Near-UV excitation of cis-mer-HM(SiEt3)(CO)3(PPh3) at ～100 K in an organic glass gives evidence for both the loss of CO and reductive elimination of Et3SiH. Photochemistry of the complexes at 298 K in fluid solution accords well with photoreactions observed at ～100 K in rigid media. Irradiation of cis-mer-HM(SiEt3) (CO)3(PPh3) in a hydrocarbon solution of Ph3SiH at 298 K results in the formation of cis-mer-HM(SiPh3) (CO)3(PPh3) and Et3SiH with a 313-nm quantum yield of ～0.6. The process is photochemically reversed if the cis-mer-HM(SiPh3) (CO)3(PPh3) is irradiated in the presence of excess Et3SiH. Irradiation of cis-mer-HM-(SiEt3)(CO)3(PPh3) in a hydrocarbon solution at 298 K in the presence of 13CO yields both 13CO-enriched M(CO)4PPh3 and 13CO-enriched cis-mer-HM(SiEt3)(CO)3(PPh3). Irradiation of cis-mer-HM(SiR3)-(CO)3(PPh3) (R = OMe, OEt) or cis-mer-HRu(SiMeCl2)(CO)3(PPh3) at 298 K in the presence of Et3SiH yields cis-mer-HM(SiEt3)(CO)3(PPh3), establishing the light-induced reductive elimination of R3SiH to occur for a wide range of R groups for these complexes.
