Nuclear magnetic resonance spectra of the [AXn]3 spin system: calculations of X spectra when Jxx= 0

Abstract

Algebraic expressions are derived for the frequencies and intensities of some transitions in the X region of n.m.r. spectra of the [AX_n]₃ spin system, for the case J_XX= 0. It is shown that J_AX and J_AX′, with relative signs, can be measured directly from the spectrum, and that J_AA can also easily be found. The case of |J_AX–J_AX′||J_AA| is discussed in some detail, the spectrum being basically a doublet (splitting J_AX) of quintets (splitting ½J_AA), with fine structure giving J_AX′. Finally, a comparison is made of the work developed here and the method of subspectral analysis for the case of n= 1.