Publications [#367753] of Stephen L Craig

Journal Articles

1. Yu, Y; Zheng, X; Duan, C; Craig, SL; Widenhoefer, RA, Force-Modulated Selectivity of the Rhodium-Catalyzed Hydroformylation of 1-Alkenes, ACS Catalysis, vol. 12 no. 22 (November, 2022), pp. 13941-13950 [doi]
   (last updated on 2026/01/15)

   Abstract:
   Here we quantify the regio- chemo-, and enantioselectivity of the hydroformylation of 1-alkenes catalyzed by Rh(I) complexes containing chiral macrocyclic biaryl bis(phosphine) ligands as a function of mechanical force applied to the biaryl backbone of these ligands. Extension forces increase the regioselectivity of the hydroformylation of 1-octene from l:b = 1.2 to 1.9 and decrease the chemoselectivity for C9aldehyde relative to 2-octene from 96% to 20% across a ∼230 pN change in applied force. Extension forces decrease the enantioselectivity of the hydroformylation of styrene from 28% to 18% ee across a similar force range. Variable temperature ¹H and ³¹P NMR analysis of five-coordinate rhodium complexes of the form (P-P)Rh(CO)2H established structures in which the bisphosphine ligand occupies one equatorial and one apical position in the trigonal bipyramid with rapid interconversion of the equatorial and apical phosphorus atoms (ΔG^‡223 K= 9.6-9.9 kcal/mol). Neither the isomeric composition nor fluxional behavior of these complexes was detectably perturbed across a ∼300 pN change in applied force.