142260-89-7Relevant academic research and scientific papers
Synthesis, structure, and absolute configuration of chiral, pseudooctahedral perfluoroalkyl-substituted dimethylphosphonate complexes
Jablonski, Chet R.,Ma, Huaizhu,Hynes, Rosemary C.
, p. 2796 - 2802 (2008/10/08)
The substitution-labile complexes η5-CpCo(X)(PPh2N(R)C*H(Me)Ph)(I), 6(a,b)(α,β), react with trimethyl phosphite to afford η5-CpCo(X)(PPh2N(R)C*H(Me)Ph)(P(O)(OMe) 2), 7(a,b)α, and θ5;-CpCo(X)(P(OMe)3)(I), 8a,b (a, X = CF3; b, X = n-C3F7; α, R = H; β, R = Me). Arbuzov dealkylation to give 7 occurs only for R = H and requires intramolecular P=O?H-N hydrogen bonding, which develops early in the transition state to anchor the aminophosphine ligand. The chiral, Co-epimeric Arbuzov products were separated and characterized. The absolute configuration of (+)436-7bα was determined crystallographically. (+)436-7bα crystallizes in the monoclinic system P21 with a = 11.0941 (20) A?, b = 16.9200 (22) A?, c = 16.927 (3) A?, β = 91.241 (15)°, V = 3176.6 (9) A?3, Z= 4, and Rf = 8.4% (Rw = 5.1%) for 1638 reflections with I > 2.5σI and was found to contain two independent molecules in the asymmetric unit. Absolute configurations of (-)436-7bα, (-)436-7aα, and (+)436-7aα were assigned on the basis of chiroptical evidence. P=O?H-N hydrogen bonding establishes a pseudoboat conformation with pseudoaxial η5-Cp and pseudoequatorial n-C3F7 in the solid state. Nuclear Overhauser difference (NOED) spectra show that the solid-state conformation persists in solution.
