109786-30-3Relevant articles and documents
Dihydride complexes of the cobalt and iron group metals: An investigation of structure and dynamic behavior
Heinekey,Van Roon, Mirjam
, p. 12134 - 12140 (2007/10/03)
The previously reported cationic dihydride complexes (PP3)MH2+ (M = Co, Rh and Ir; PP3 = P(CH2-CH2PPh2)3) have been prepared using improved synthetic methods. Variable-temperature 1H and 31P NMR spectra of these complexes reveal complex dynamic behavior. The hydride region 1H NMR spectra have been accurately simulated at all temperatures using a simple site permutation model after taking into consideration the opposite signs of the cis and trans H-P coupling constants. Partial deuteration of the hydride ligands in the rhodium and cobalt complexes is achieved by exposure to D2. In the partially deuterated samples, no evidence is found for a bound dihydrogen ligand, but the involvement of a dihydrogen species in the dynamic process which interchanges the two hydride positions remains a mechanistic possibility, as indicated by a kinetic isotope effect k(H)/k(D) = 1.3(1). The partially deuterated samples exhibit large and temperature-dependent isotope effects on the 1H NMR chemical shifts observed for the hydride resonances, which are attributed to isotopic perturbation of resonance. This arises from non-statistical occupation of the two different hydride sites and also leads to perturbation of the averaged H-P coupling constants. Similar observations have been made for the neutral iron complex (PP3)FeH2.
Syntheses and characterization of trigonal-bipyramidal rhodium(I) complexes of tris(2-(diphenylphosphino)ethyl)phosphine and determination of a spectroscopic trans-influence series by 31P{1H} NMR spectroscopy
Gambaro, Jeffrey J.,Hohman, William H.,Meek, Devon W.
, p. 4154 - 4159 (2008/10/08)
A series of low-spin, five-coordinate rhodium(I) complexes of the tripod ligand tris(2-(diphenylphosphino)ethyl)phosphine, PP3, were synthesized and characterized by elemental analyses, infrared spectra, and 31P{1H} NMR spectra. The complexes have trigonal-bipyramidal geometries in which the PP3 ligand occupies four of the five sites of C3v symmetry and the variable fifth ligand is monodentate. The 31P NMR spectral patterns are consistent with AMX3 and AKMX3 spin systems. The NMR spectra permit a determination of the trans influence of the fifth ligand on the rhodium-phosphorus apical coupling constant and the chemical shifts of the apical and equatorial phosphorus atoms of PP3.
