114594-82-0Relevant articles and documents
Synthesis and spectroscopic characterization of group 15/group 16 ligand derivatives of manganese(I) and rhenium(I) pentacarbonyl halides: Influence of the group 16 donor atom on thermodynamic and kinetic aspects of the oxidation of metal carbonyl complexes
Bond, Alan M.,Colton, Ray,Panagiotidou, Penny
, p. 1767 - 1773 (2008/10/08)
The interactions of the group 7 metal carbonyl halides M(CO)5X (M = Mn, X = Cl, Br; M = Re, X = Br) with mixed group 15/group 16 donor atom ligands (L-E) have been investigated. The ligands used were dpmE (Ph2PCH2P(E)Ph2, E = Se or S to give dpmSe or dpmS, respectively) and apeE (Ph2AsCH2CH2P(E)Ph2, E = Se or S to give apeSe or apeS, respectively). The products were characterized by microanalysis and infrared and NMR (31P,77Se) spectroscopies. dpmE act as bidentate ligands with both metals to give M(CO)3(dpmE)X, but the chemistry with apeE is more variable. With 1:1 stoichiometry, Mn(CO)5X gives [Mn(CO)3(apeE)X]2 with monodentate apeE coordinated through arsenic, although the compounds Mn(CO)3(apeE)X with chelated apeE are intermediates in the reaction. Re(CO)5Br gives stable Re(CO)3(apeE)Br with chelated apeE. Both metals react with 2 mol equiv of apeE to give M(CO)3(apeE)2X containing two monodentate apeE ligands. The electrochemical oxidation of the 18-electron M(CO)3(dpmE)X compounds to the 17-electron [M(CO)3(dpmE)X]+ cations has been compared to that of oxidation of M(CO)3(L-L)X compounds (L-L = Ph2PCH2PPh2, dpm; Ph2PCH2CH2PPh2, dpe). Replacement of phosphorus by sulfur or selenium leads to unexpectedly large thermodynamic, kinetic, and mechanistic effects. For example, the oxidation potential of Mn(CO)3(dpmSe)X derivatives is shifted by 280-300 mV in the negative direction relative to Mn(CO)3(L-L)X. All data imply enhanced redox stability of the 17-electron cations. However, greater kinetic lability leads to ready attack by coordinating solvents such as acetonitrile and loss of carbon monoxide so that [Mn(CO)3(dpmE)X]+ cannot be isolated by oxidative-controlled potential electrolysis or chemical oxidation. The difference in oxidation potentials between corresponding dpmE and L-L is remarkably constant over a wide range of carbonyl compounds including M(CO)3(dpmE)X/M(CO)3(L-L)X (M = Mn, Re) and M(CO)4(dpmE)/M(CO)4(L-L) (M = Cr, Mo, W).
