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Increasingly, the undergraduate chemistry curriculum includes nuclear magnetic resonance (NMR) spectroscopy. Advanced NMR techniques are often taught including two-dimensional gradient-based experiments. An investigation of intermolecular forces including viscosity, by a variety of methods, is often integrated in the undergraduate physical and organic laboratory curricula. An experiment is described that couples advanced NMR techniques with the investigation of viscosity, a physical property based on molecular structure. (Contains 1 table and 5 figures.)

An internal reference correlated diffusion-ordered NMR spectroscopy (DOSY) method is described for calculating the formula weight (FW) of unknown species in different solvents with different concentrations. The guidelines and other factors are discussed for successful application of this internal reference correlated DOSY method.

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The article presents a science experiment to help college students measure the solution viscosity via diffusion-ordered nuclear magnetic resonance (NMR) spectroscopy. In this experiment, students explore the intermolecular forces including viscosity through numerous methods. Emphasis is on the investigation of the viscosity, a physical property based on molecular structure, using advanced NMR techniques.

The tetrahydrofuran tetrasolvated dimeric lithium dienolate derived from 2,2,7,7-tetramethyloctan-3,6-dione is characterized in the solid state by X-ray diffraction analysis and in solution by diffusion NMR. This dienolate was reacted with tropanone to yield two new products that are also described. [ABSTRACT FROM AUTHOR]

The utility of recently introduced 6Li diffusion-ordered NMR spectroscopy (DOSY) is demonstrated. 6Li DOSY results can be correlated to 1H data through 2-D 6Li{1H} heteronuclear Overhauser effect NMR spectroscopy (HOESY) experiments. 6Li DOSY quickly confirms 1H DOSY results and allows unambiguous assignment of resonances to specific aggregates. Well known aggregates of lithium-6 n-butyllithium (n-Bu6Li) are examined in deuterated tetrahydrofuran (THF-d8) solution as an example, and to reaffirm the previous literature conclusions about these complexes. [ABSTRACT FROM AUTHOR]

The development of (6)Li diffusion-ordered NMR spectroscopy (DOSY) is reported. This technique is applied to (6)Li organometallic complexes. (6)Li DOSY provides a facile means of identification of peaks in the (6)Li spectrum, as well as evidence of mixed aggregates based on relative diffusion coefficients. (6)Li data is correlated to (1)H diffusion experiments through (6)Li{(1)H} HOESY and/or (1)H{(6)Li} HMBC experiments to obtain formula weight information of Li aggregates.

The development of (31)P DOSY NMR with diffusion coefficient-formula weight (D-FW) analysis is reported. Commercially available trialkyl phosphine internal references were used in a model system to establish the molecular weight of a phosphorous containing organolithium compound. The feasibility of (31)P DOSY D-FW studies is established. This extension of DOSY D-FW analysis expands its applicability to solution structure studies of a wide variety of compounds.