70196-23-5Relevant academic research and scientific papers
Interconversion between zwitterionic and cationic rhodium(I) complexes of demonstrated value as catalysts in hydroformylation, silylformylation, and hydrogenation reactions. Dynamic 31P{1H} NMR studies of (η6-PhBPh3)-Rh+(DPPB) and [Rh(DPPB)2]+BPh4- in solution
Zhou, Zhongxin,Facey, Glenn,James, Brian R.,Alper, Howard
, p. 2496 - 2503 (2008/10/08)
Treatment of an orange solution of [Rh(COD)(DPPB)]+BF4- (2) in MeOH with 2 equiv of NaBPh4 at room temperature (RT) afforded an orange precipitate, [Rh(COD)(DPPB)]+BPh4- (3), in 94% yield. Reaction of the cationic rhodium complex 3 with H2 under ambient conditions in CH2Cl2 for 1 h gave the zwitterionic complex (η6-PhBPh3)-Rh+(DPPB) (4) in quantitative yield. Although 3 is stable in the solid state, it has the propensity in solution to convert to the zwitterionic complexes (η6-PhBPh3)-Rh+(COD) (1) and (η6-PhBPh3)-Rh+-(DPPB) (4) along with a small amount of [Rhx(DPPB)2x]x+[BPh4 -]x. Addition of 1, 2, and 4 equiv of DPPB to the CD2Cl2 solution of (η6-PhBPh3)-Rh+(NBD) (6) under N2 resulted in the formation of [Rh(NBD)(DPPB)]+BPh4- (7) and [Rh(DPPB)2]+BPh4- (5) in ratios of 90/ 10, 57/43, and 0/100, respectively, while addition of 2 equiv of DPPB to the CD2Cl2 solution of 6, under an atmosphere of H2 at RT, gave 4 and 5 in an ratio of 35/65. Slowed η6-PhBPh3- rotation about the (η6-PhBPh3)--Rh bond axis in (η6-PhBPh3)-Rh+(DPPB) (4) was established by a variable-temperature 31P{1H} NMR study. Variable-temperature 31P{1H} NMR spectra of [Rh(DPPB)2]+BPh4- (5) along with the low-temperature 31P{1H} COSY and EXSY NMR spectra demonstrated the presence of an equilibrium between [Rh(DPPB)2]+ (5α) and [Rh(DPPB)(μ-DPPB)]22+ (5β).
CATIONIC COMPLEXES OF RHODIUM(I) CATALYSTS IN THE HOMOGENEOUS O2-OXIDATION OF TERMINAL ALKENES TO METHYL KETONES
Bressan, Mario,Morandini, Franco,Morvillo, Antonio,Rigo, Pierluigi
, p. 139 - 146 (2007/10/02)
+, + and + complexes are effective as catalysts for the oxidation by dioxygen of terminal olefins to methyl ketones.The complexes act as monooxygenases, the second oxygen atom being transferred to the alcohol solvent
CARBONYL ADDUCTS OF BIS(1,4-BIS(DIPHENYLPHOSPHINO)BUTANE)RHODIUM(I) CATION. CRYSTAL AND MOLECULAR STRUCTURE OF (PF6)2
Pignolet, L. H.,Doughty, D. H.,Nowicki, S. C.,Anderson, M. P.,Casalnuovo, A. L.
, p. 211 - 224 (2007/10/02)
The reaction of CO with CH2Cl2 solutions of +X-, where X=BF4 or PF6 and dppb=Ph2P(CH2)4PPh2, yields the binuclear complex 2+ and uncoordinated dppb.This complex was isolated in the solid state as the PF6 salt and characterized by single crystal X-ray diffraction.The structure consists of two trigonal bipyramidal RhP3(CO)2 cores bridged by a dppb ligand via axial coordination sites.The CO ligands are cis and occupy equatorial sites and the chelating dppb ligands span equatorial and axial sites of their respective coordination cores.One binuclear molecule (Rh2(dppb)3)(CO)4>(PF6)2 is contained in the P1 unit cell such that an inversion center exists in the center of the backbone of the bridging dppb ligand.The unit cell dimensions are a=12.385(2), b=15.286(2), c=12.353(4) Angstroem, α=99.77(2), β=107.03(2), γ=103.66(1) deg, and V=2100 Angstroem3.A total of 5780 observed reflections were used to solve the structure and the final R value was 0.060.The formation of the binuclear complex in acetone solution was monitored by 31P NMR.The complex is fluxional at 25 deg C but exhibits a complicated pattern at -65 deg C in addition to a sharp singlet due to uncoordinated dppb ligand.
