Graphical Abstract: Eur. J. Inorg. Chem. 2/2009

Abstract

AbstractThe cover picture shows the X‐ray crystal structures of new benzo‐anellated N‐heterocyclic germylene complexes with nickel(0) and molybdenum(0). The low bathochromic shift of the valence vibration of CO in the trans position of the germylene ligands of fac‐(bnNHGe)3Mo(CO)3 indicates weak donor properties, the relatively short Mo–GeII bonds indicate stabilization by back‐bonding. The ligand properties contrast strongly with those of the homologous N‐heterocyclic carbene ligand (bnNHC) because of the different electronic structures, which can also be recognised from the photoelectron spectrum of the germylene ligand. The GeII electron lone pair is bound firmly, and according to quantum chemical calculations represents only the third band, whereas in bnNHC the lone electron pair is the HOMO. The extreme air and moisture sensitivity of the NHGe complexes is in sharp contrast with the background, depicting the Baltic Sea with the small island Greifswalder Oie at the seaside entrance to the site of one of the oldest universities in northern Europe. Details are discussed in the article by T. Veszprémi, J. Heinicke et al. on p. 221 ff. We thank Prof. Dr. Martin Köckerling (Rostock) and Dr. Lutz Wolf (Kahla) for support in designing this picture.