Hydrogen bonding in organometallic crystals. 3.Transition-metal complexes containing amido groups

Abstract

Intermolecular hydrogen bond distribution and geometry in crystals of transition-metal complexes containing primary and secondary amido groups have been investigated by searching the Cambridge Structural Database (CSD). The hydrogen-bonding patterns have been compared with those observed in crystalline organic amides. Organometallic systems show a great structural variability as well as the participation in the hydrogen-bonding patterns of other donor/acceptor systems such as ligated or solvent water molecules. The effect of the coordination via the amide O-atoms to the metal centers on the hydrogen-bonding capacity has been examined as well as the participation of CO ligands. The hydrogen bonding parameter distribution has been analyzed also in the case of ionic species and compared to the neutral crystals. It has been shown that hydrogen bond interactions in organometallic amido complexes are generally longer than in pure organics, though this is compensated by the formation of a greater number of bonds per molecule because of the more frequent occurrence of bifurcation. Some selected crystal structures have been examined in detail, especially with respect to very short NH---O contacts.