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Reduction of [IndCpMo(L)Br]Br (L = 1a, CO; 2, NCMe) with under the same conditions. With the aim of continuing the comparative study of the

DFT calculations were performed on Os 3 (CO) 10 (α-diimine) clusters, for α-diimine = DAB (1,4-diaza-1,3-butadiene), PYCA (σ-N,σ-NЈ-pyridine-2-carbaldehyde-imine), and BIPY (2,2Ј-bipyridine). Geometry optimizations were performed for several models of the possible isomers under different conditions. Axial isomers were always found to be the most stable, in agreement with the available X-ray determined structures. A full optimization of the geometry was required in order to improve the quality of the results, but the dis-

Multipurpose zinc carbene catalystThe cover picture features a dinuclear zinc-N-heterocyclic carbene (NHC) catalyst. In their Full Paper on p. 1357 ff., S. Dagorne, T. AvilØs, M. J. Calhorda et al. report that such zinc-NHC alkoxide species polymerize lactide to produce well-defined polylactic acid and, remarkably, also mediate the controlled degradation (depolymerization) of polylactic acid under mild conditions to produce methyl lactate as the major reaction product. DFT studies of the polymerization reaction highlight the beneficial effect of two zinc centers in close proximity. The work shows that biocompatible zinc(II) complexes can mediate the polymerization of lactide and the controlled degradation of polylactic acid under mild conditions (room temperature).