113089-44-4Relevant academic research and scientific papers
Optically active transition-metal Compounds.1,2 Preparation, structure, absolute configuration, and conformational analysis of chiral pseudooctahedral cobalt(III) phosphonato and phosphinato complexes. Optical induction in the transition-metal Arbuzov reaction
Brunner, Henri,Jablonski, Chet R.,Jones, Peter G.
, p. 1283 - 1292 (2008/10/08)
(S)-η5CpCoI2(PPh2NHCH(Me)Ph) reacts with 1 equiv of trimethyl phosphite or dimethyl phenylphosphonite in benzene or methylene chloride solution to give diastereomeric Arbuzov products (R,SCo,SC)-η5-CpCoI(PPh 2NHCH(Me)Ph)(P(O)(OMe)2) (6a,b) and (R,SCo,R,SP,SC)-η 5-CpCoI-(PPh2NHCH(Me)Ph)(PhP(O)(OMe)) (7a-d), respectively. Compounds 6a and 7a were characterized by X-ray diffraction, including determination of absolute configuration. 6a crystallizes in the space group P212121 with a = 9.470 (2) A?, b = 15.136 (3) A?, c = 19.562 (4) A?, and Z = 4 and was refined to R = 0.041 for 4721 reflections. 7a also crystallizes in P212121 with a = 9.995 (2) A?, b = 13.934 (2) A?, c = 22.422 A?, and Z = 4 and was refined to R = 0.058 for 3749 reflections. The absolute configuration of all diastereomers was established by a combination of crystallographic, circular dichroism, and epimerization studies. Conformational analysis on the basis of crystallographic data in the solid state and proton nuclear Overhauser difference (NOED) spectra in solution show a quasi-chair conformation determined by the presence of a strong intramolecular NH?O=P hydrogen bond. Initial substitution of diastereotopic iodide occurs with essentially zero optical yield; however, considerable chiral induction occurs in the subsequent Arbuzov dealkylation step leading to the phosphinato complexes 7.
