186432-35-9Relevant academic research and scientific papers
Preparation and electronic properties of rhenium(V) complexes with bis(diphenylphosphino)ethane
Baril-Robert, Francois,Beauchamp, Andre L.
, p. 1326 - 1340 (2007/10/03)
Complexes of bis(diphenylphosphino)ethane (dppe) of the types ReOX 3(dppe) and ReO(OR)X2(dppe) (with X= Cl or Br, and R = Me, Et, Pr, Ph, cyclohexyl (Cy), or -CH2CH2OH) were prepared to evaluate the influence of ligand changes on the low-energy d-d transitions in these Re(V) low-spin d2 systems. Arylimido compounds Re(NR)Cl 3(dppe) (with R = Ph and p-ClC6H4) were also obtained. X-ray diffraction studies on ReO(OPr)Cl2(dppe), ReO(OPh)Br2(dppe), and ReO(OCy)Cl2(dppe) confirmed the presence of the trans O=Re-OR unit and showed that the structural characteristics of the Re-O-R segment are not affected by the presence of a bulky cyclohexyl substituent or an aromatic phenyl group. The structure of the arylimido complex Re(p-ClC6H4N)Cl3(dppe) was also determined. The electronic absorption spectra of the ReOX3(dppe) compounds include two low-energy components at ～11 500 and ～16 000 cm-1, assigned to the two spin-allowed d-d transitions expected for these low-symmetry systems. Substitution of the oxo ligand by an arylimido group has little effect on the lower-energy component, but moves the two components closer together. Replacing the halogen trans to the Re=O bond by an alkoxo group shifts the whole system to higher energies. These variations were found to correlate well with the energies of the frontier orbitals determined from DFT calculations. While attempting to prepare ReOCl3(dppe) from ReOCl3(PPh3)2, the Re(III) compound fac-ReCl3(PPh3){Ph2PC2H 4PPh2(O)} was obtained, in which one end of dppe had become a phosphine oxide. Upon standing in DMSO, this compound gave the octahedral compound ReCl4{Ph2PC2H 4PPh2(O)}, in which the formation of a chelate ring involving a phosphine and a phosphine oxide was ascertained by X-ray diffraction.
The first rhenium(V)-imido compounds containing two chelating phosphine ligands of the type trans-[Re(NPh)X(L-L)2]2+ (L-L=bidentate phosphine ligand; X=halide or hydroxide). The structure of trans-[Re(NPh) (OH) (dppbe)2] (ClO4)2·2H2O
Bakir, Mohammed,McKenzie, Jacinth A.M.,Sullivan, B. Patrick
, p. 9 - 17 (2008/10/08)
The bidentate phosphine ligands 1,2-bis(diphenylphosphino)ethane (dppe), 1,2-bis(diphenylphosphino)ethene (dppee) or 1,2-bis(diphenylphosphino)benzene (dppbe) undergo reactions with the rhenium(V)-imido complex, trans-Re(NPh)Cl3(PPh3)2, in refluxing alcoholic solvent to give mixtures of fac-Re(NPh)Cl3(L-L) and trans-[Re(NPh)X(L-L)2]2+. Mild reaction conditions favor the monosubstituted complexes and harsh conditions favor the salts. The electrochemical properties of the salts reveal subtle differences associated with the backbone of the ligands. The structure of the hydroxy-imido salt trans-[Re(NPh) (OH) (dppbe)2] (ClO4)2?2H2O was determined and shows the rhenium atom displaced 0.536(2) A above the P4 equatorial plane, the largest displacement observed for rhenium(V) compounds containing π-donor ligands, and the Re-N(imido) distance of 1.757(10) A is the longest observed for rhenium(V)-imido compounds.
