67292-48-2Relevant articles and documents
Synthesis, crystal structure and comparative electrochemistry of metallocenyldiphenylphosphines of ruthenocene, osmocene, ferrocene and cobaltocenium hexafluorophosphate
Fourie, Eleanor,Van Rensburg, J. Marthinus Janse,Swarts, Jannie C.
, p. 80 - 87 (2014/02/14)
The metallocenyldiphenylphosphines [M(C5H5)(C 5H4PPh2)] with M = Fe(II) (ferrocenyl = Fc), 1, Ru(II) (ruthenocenyl = Rc), 2, Os(II) (osmocenyl = Oc), 3, and Co(III) +PF6- (cobaltocenium hexafluorophosphate = [Cc][PF6]), 4, were synthesized and the crystal structure of RcPPh2, 2, (Z = 4, monoclinic, space group P21/c) was determined. The differences in reactivity of each metallocenyl derivative were such that 1 could be obtained from a Friedel Crafts reaction between ferrocene and PPh2Cl in the presence of AlCl3 as catalyst. Both the ruthenocene and osmocene derivatives 2 and 3 were obtained by reacting the monolithiated metallocene precursor with PPh2Cl. However, monolithiation of ruthenocene had to be achieved via a stoichiometric amount of tBuLi. For osmocene, monolithiation was achieved by a 20% excess of nBuLi. This was evidenced by the failure to isolate any bisphosphine, Oc(PPh2)2, during workup. Complex 4 could not be obtained via phosphination of free cobaltocenium hexafluorophosphate. Phosphine derivatisation of free cyclopentadiene prior to complexation with Co III was required to form [CcPPh2][PF6], 4. The electrochemistry of all phosphines was studied by voltammetric techniques in CH2Cl2/0.1 mol dm-3 [N(nBu) 4][B(C6F5)4]. A reversible one-electron transfer process for the ferrocenyl group of 1 was observed at 0.078 V vs. FcH/FcH+. The osmocenyl and ruthenocenyl derivatives exhibited irreversible metallocenyl oxidations at 0.355 and 0.476 V respectively. The cobaltocenium complex, 4, exhibited two reversible one-electron transfer reductions to liberate first a neutral CoII cobaltocene species at -1.062 V and then an anionic CoI cobaltocene species at -2.122 V. A single electrochemical irreversible, one-electron oxidation at the phosphorus centre which forms a quickly-decomposing phosphorus radical cation, Mc+Ph2P+, was also observed at Epa > 0.754 V. The newly-formed Mc+Ph2P + species or its chemical decomposition products can be oxidized at Epa > 1.090 V vs. FcH/FcH+.
Synthesis, molecular structure, and molybdenum complexes of 1,1′-bis(diphenylphosphino)cobaltocene
DuBois, Daniel L.,Eigenbrot Jr., Charles W.,Miedaner, Alex,Smart, James C.,Haltiwanger, R. Curtis
, p. 1405 - 1411 (2008/10/08)
The synthesis of 1,1′-bis(diphenylphosphino)cobaltocene (1), (C5H4PPh2)2Co, from TlC5H4PPh2 and CoCl2 is described. The ligand 1 coordinates to one Mo(CO)4 fragment as a chelating bidentate ligand to form [Co(C5H4PPh2)2] [Mo(CO)4] (2) and to two Mo(CO)5 fragments as a bridging bidentate ligand to form [Co(C5H4PPh2)2] [Mo(CO)5]2 (3). Molecular structure determinations have been carried out on compounds 1 and 3. Compound 1 crystallizes in the monoclinic space group P21/c with cell dimensions a = 8.5966 (16) ?, b = 18.765 (4) ?, c = 8.8137 (15) ?, β = 99.702 (14)°, Z = 2, and ρ = 1.32 g cm-3. The structure was solved from 1735 observed reflections (F > 6σ(F)) and refined to final residuals of R = 0.033 and Rw = 0.041. Compound 3 crystallizes in the monoclinic space group C2/c with a = 16.651 (5) ?, b = 12.669 (6) ?, c = 26.322 (9) ?, β = 99.42 (2)°, Z = 4, and ρ = 1.47 g cm-3. The structure was solved from 1474 reflections (F > 6σ(F)) and refined to final residuals of R = 0.048 and Rw = 0.060. The puckering of the substituted cyclopentadienyl ring of 1 is interpreted with the aid of molecular orbital calculations. Cyclic voltammetry of 1 and Fe(C5H4PPh2)2 (4) and their complexes indicate that substitution of the cyclopentadienyl ring and coordination of 1 and 4 to molybdenum carbonyl fragments affects both the redox potential and electrochemical reversibility of electron-transfer processes occurring at cobalt and iron.
