Linear correlation of the phosphorus-hydrogen spin coupling constant with proton chemical shifts in a series of polycyclic phosphorus compounds

Article abstract of DOI:10.1021/ic50023a018

Stable phosphonium salts are reported of the type [R(I)]X and [R(II)]X where I and II are the polycyclic phosphites 4-methyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane and 2,8.9-trioxa-1-phosphaadamantane, respectively, wherein R is (C₆H₅)₃C or CH₃CH₂ and X is a perchlorate or tetrafluoroborate anion. Conductivity and n.m.r. spectral studies confirm their salt-like formulation and the caged structure of the phosphonium cation. A linear correlation is observed for the increase in the POCH coupling constant for the protons on the carbon β to the phosphorus atom with the downfield chemical shifts of protons on C_β, C_γ (axial), and C_δ in a series of derivatives of I and II including the salts. The results are discussed in terms of the decrease in s character of the phosphorus σ-bond to the fourth coordinate position on the phosphorus atom and the consequent increase in s character of the P-O links. Some new Arbuzov reactions of I and II are also reported.