Experiments with Dihydrogen-Bonded Complexes in Solutions

EXPERIMENTS WITH DIHYDROGEN-BONDED COMPLEXES IN SOLUTIONS 

In contrast to solid or gas phases, the formation of dihydrogen complexes in solntions is always a reversible eqnilibrinm  

Among various physicochemical methods, IR spectroscopy and NMR are most appropriate tools for the study of dihydrogen bonds in solution. However, it is worth mentioning that these methods are basically different. First, they measure physical properties that change upon complexation bond vibrations and magnetic behavior. Second, equilibrium (4.1) is usually slow on the IR spectroscopy time scale and very fast on the NMR time scale. In other words, proton donors, proton acceptor, and their complexes are detected separately in IR spectra, whereas the NMR parameters of these moieties are usually averaged. 

IR Spectral Criteria for the Formation of Dihydrogen-Bonded Complexes in Solutions 

Since the stretching frequency of a chemical bond can be approximated by Hooke s law. 

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One of the key advantages of supercritical solvents over conventional liquids is their unique combination of gas-like and liquid-like properties. Thus, reactant gases such as H2 or N2 can, under the correct conditions of temperature and pressure, be totally miscible with SCF solutions. At Nottingham, this unique property has been exploited to synthesize a range of novel organometallic complexes with metals bonded directly to dinitrogen [17] and dihydrogen [7,18], as shown in eq (3.1.1). These experiments are outlined in more detail in chapter 4.2. 

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