Premium
Multiple Isomers of a Small, Strained Phosphaphane
Author(s) -
Xiao Yonglong,
Mague Joel T.,
Pascal Robert A.
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201801106
Subject(s) - chemistry , phosphine , lone pair , tris , coupling constant , crystallography , stereochemistry , spin (aerodynamics) , cis–trans isomerism , molecule , organic chemistry , catalysis , biochemistry , physics , particle physics , engineering , aerospace engineering
Three cyclophanes with the formula (C 28 H 31 PS 3 ) n , where n = 1 or 2, were isolated from the base‐promoted macrocyclization of tris(2‐mercaptophenyl)phosphine ( 4 ) and tris(3‐bromopropyl)methane ( 5 ). Spectroscopic and X‐ray analysis showed them to be the in,in ‐isomer 1 , the in,out ‐isomer 2 , and a dimeric in,out,in,out ‐isomer 3 . Compounds 1 and 3 display approximately C 3 ‐symmetric and C i ‐symmetric structures, respectively, in the crystal, but compound 2 adopts two distinct low‐symmetry conformations in the solid state. In each case, the observed structures correspond to the lowest energy conformations of their respective isomers as calculated at the B3PW91/6‐31G(d) level of theory. The in,in ‐isomer 1 displays a close contact between the phosphine in ‐lone pair and the in ‐methine group, with through‐space spin–spin coupling constants of J PH = 9 Hz and J PC = 24 Hz, the latter of which appears to be the largest reported phosphorus‐carbon through‐space coupling constant.