WSOLIDS1: HR: Spin-1/2 Coupled to Quadrupolar Nucleus (Relaxation)

Description

Background

This model is actually intended for the calculation of the solution spectrum of a spin-1/2 nucleus coupled to a quadrupolar nucleus where the spin-lattice relaxation of the quadrupolar nucleus affects the spectrum of the spin-1/2 nucleus. This is illustrated here for the following spin system: ³¹P coupled to ⁵¹V (I = 7/2), with J(⁵¹V,³¹P) = 500 Hz and the ⁵¹V spin-lattice relaxation times T₁ indicated in the figure. At intermediate T₁'s, the apparent unequal intensities within the non-binomial octet are the result of the different life times of the associated ⁵¹V spin states, causing different line widths and hence different peak heights (but equal integrals).

Examples

The SVG images shown below were produced using the following tools: my own SpecPlot to plot the spectra, Platon or Ortep 3 for Windows to plot the molecular structures from X-ray data, and Inkscape to compose the picture.

H-1 NMR spectrum of iPr2HN-BH3 (solution): this example uses two isotopologues, with indirect spin-spin coupling to B-11 and B-10 and demonstrates how to use the tie feature to relate the B-10 parameters to those of B-11: J(X,B-10) = 0.334861 × J(X,B-11) T1Q(B-10) = 1.531164 × T1Q(B-11) Although the experimental spectrum does not reveal the presence of B-10 directly - the four-line pattern only points towards B-11 - inclusion of the second isotopologue with B-10 is required to "push up" the central two lines. The agreement between experimental and calculated spectrum is excellent then! The molecular structure is from calculations reported in this paper: E. M. Leitao, N. E. Stubbs, A. P. M. Robertson, H. Helten, R. J. Cox, G. C. Lloyd-Jones, I. Manners, J. Am. Chem. Soc. 2012, 134, 16805; DOI: 10.1021/ja307247g You can download a zip file of the WSolids1 document: (ZIP) or have a look at the report generated from the WSolids1 document: (XML)

C-13 NMR spectrum of 0.3 M K4[Ru(CN)6] (solution): this example uses three isotopologues, with indirect spin-spin coupling to Ru-99 and Ru-101. Again, only the presence of Ru-99 is obvious, but a close inspection of the base line reveals the presence of Ru-101, too. The T1 of Ru-101 is much shorter than the T1 of Ru-99. You can download a zip file of the WSolids1 document: (ZIP) or have a look at the report generated from the WSolids1 document: (XML)

H-1 NMR spectrum of B10H14 (solution): in this example both isotopologues containing B-11 or B-10 can be recognized. In this example, and the others above, only the region of interest has been exported from TopSpin to an ASCII file and read into WSolids1. This is convenient because every single point in the calculated spectrum requires extensive matrix manipulations (see help file for details)! You can download a zip file of the WSolids1 document: (ZIP) or have a look at the report generated from the WSolids1 document: (XML)