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The gallium(I) derivative [Ga({N(dipp)CMe}(2)CH)] (1; dipp = 2,6-diisopropylphenyl) undergoes facile oxidative addition reactions with various element-hydrogen bonds including N-H, P-H, O-H, Sn-H, and H-H bonds. This was demonstrated by its reaction with triphenyltin hydride, ethanol, water, diethylamine, diphenylphosphane, and dihydrogen. All products were characterized by means of single-crystal X-ray structure determination, NMR spectroscopy, IR spectroscopy, and mass spectrometry.

The synthesis and Cu(II) coordination chemistry of the cyclic pseudo-octapeptide H(4)pat(1), a dimethyl-imidazole analogue of naturally occurring cyclic peptides (patellamide A-F, ascidiacyclamide) is reported. Substitution of the oxazoline and thiazole heterocycles by dimethyl-imidazoles leads to a slightly different structure of the macrocycle in the solid state. The Cu(II) coordination chemistry of H(4)pat(1), monitored with high-resolution electrospray mass spectrometry, spectrophotometric titrations, and EPR spectroscopy, revealed the presence of both mono- and dinuclear Cu(II) complexes. The dimethyl-imidazole analogue shows a high cooperativity in Cu(II) coordination, that is, the preferred formation of dinuclear complexes. The dinuclear unbridged Cu(II) complexes of H(4)pat(1) have unusual EPR features, reminiscent of those of patellamide D: the dipole-dipole interaction of the Cu(II) centers is negligible due to the "magic angle" orientation of the two Cu(II) ions. Density functional theory calculations (DFT) are used to model the structures of the Cu(II) complexes, and the structural assignments from the spectroscopic investigations are supported by the optimized and by X-ray structures of the metal-free macrocycle and dinuclear Cu(II) complexes of H(4)pat(1). The rigidity of the dimethyl-imidazole rings has a significant effect on the structures of the metal-free ligands and Cu(II) complexes and therefore changes the properties of these compounds. This may explain why Nature has chosen the thiazole-oxazoline combination for the patellamides and ascidiacyclamide.

The bis‐2‐methoxyphenyldiketopyrrolopyrrole 1 might serve as the basis for a new fluorescence solar collector. The dye crystallizes in two distinct fluorescing modifications, the lattice packings of which provide insight into fluorescence‐deactivating processes in the crystal.

The reactions of DL-1,4-disulfanylbutane-2,3-diol and 1,3-disulfanylpropan-2-ol with dodecacarbonyltriiron have been investigated. As main products, the iron complexes 1 and 2 were isolated and characterized by spectroscopic methods, as well as single crystal X-ray analysis. Additionally, the unusually large bond angles in the dithiolato bridge was investigated via density-functional theory (DFT) calculations. Moreover, the electrochemical features have been studied by cyclic voltammetry.

Keywords: Iron / Cluster compounds / S ligands / Hydrogenases / Density functional calculationsThe reactions of 1,2,4-trithiolane (1a), 3,3,5,5-tetramethyl-1,2,4-trithiolane (1b), 3,3,5,5-tetraethyl-1,2,4-trithiolane (1c), 3,3,5,5-bis(pentamethylene)-1,2,4-trithiolane (1d) and dispiro{tricyclo[3.3.1.1]decane-2,3ЈЈ-(1,2,4)-trithiolane-5Ј,2Ј-tricyclo[3.3.1.1]decane} (1e) with nonacarbonyldiiron (2) have been investigated. The sulfurdithiolatodiiron complexes 3a-e, which can be considered as novel model complexes of the active site of the [Fe-only] hydrogenase, were isolated as the main products of these reactions. X-ray structure analyses were performed on compounds 3b-e. The carbon dithiolato (SCR 2 S)-bridged diiron side-products 4a-e and the tetranu-

The novel neutral and anionic gallium clusters Ga 10 R′ 6 and [Ga 10 R* 6 ]as well as [Ga 13 R* 6 ]are obtained by reaction of "GaI", prepared sonochemically from gallium and iodine, with Li(THF) 3 R′ (R′ ) Si(SiMe 3 ) 3 ) hypersilyl) and Na(THF) 2 R* (R* ) SitBu 3 ) supersilyl), respectively. Both of the Ga 10 clusters may be considered as conjuncto clusters consisting of two edge-sharing octahedrons. In Ga 10 R′ 6 , these contain a Ga 4 R′ 4 and a Ga 2 R′ 2 unit, and in [Ga 10 R* 6 ] -, they contain two Ga 3 R* 3 units. In addition to the syntheses and X-ray structure analyses of these three clusters, some hypersilylgallium halides are described, namely the [Li(THF) 2 ] + and [Li(THF) 3 ] + salts of [R′GaI 3 ]as well as the [Li(THF) 2 ] + salts of [R′ 2 Ga 2 Br 4 ] 2and [R′ 2 Ga 2 I 4 ] 2-.