Hydrogen bonding to metals

Crabtree, R.H. (2004) Hydrogen Bonds to Metals and Metal Hydrides, in Encyclopedia of Supramolecular Chemistry (eds J.L. Atwood and J.W., Steed), Dekker, New York, pp. 666-672. 

Nearly all of the compounds were synthesized photochemically, which imposes a nuihber of quite strict limitations on larger-scale preparations of these compounds. The primary, or at least the initial, identification of these compounds has been via IR spectroscopy. (The sole exception has been Cp Re(CO)(C2H4)2 which was tentatively identified by NMR [18]). In most cases, characterization of the metal carbonyl moiety via v(C-O) IR bands is definitive, particularly if library spectra are available from liquid noble gas [23] or matrix isolation experiments [4]. This is because these bands are sharp and intense, and the C-O stretching vibrations are largely uncoupled from other vibrations of the molecule. Furthermore, the precise wavenumber of the bands are extremely sensitive to the oxidation state of the metal center as illustrated, for example, by Kazarian et al. in their study of hydrogen bonding to metal centers [25]. 

Hydrogen Bonds to Metals and Metal Hydrides, p 666 Second-Sphere Coordination, p. 1209 Secondary Bonding, p. 1215 X Ra Crystallography, p 1586... 

The crystal engineering community is also at the forefront of work into new kinds of intermolecular interactions. Recent single-crystal neutron diffraction studies revealed detailed information on OH-. -tc interactions " and on unconventional hydrogen bonds to metal center- as] well as MH-. HX-type interactions, where MH is a hydridic metal hydrogen moiety, and HX contains protic hydrogen. 

Figure 3.43. Examples of compounds with hydrogen bonds to metal hydrides.

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