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An unusual solVent effect on the crystallization of an anionic lanthanide sandwich complex has been discoVered, demonstrating how small changes can make big differences when crystallizing organometallic compounds. Crystallization of Li(DME)Tb(COT′′) 2 (1) from toluene leads to the formation of supramolecular [Li(DME)Tb(COT′′) 2 ] n (1a), while monomeric Li(DME)Tb(COT′′) 2 (1b) is formed upon crystallization from pentane, which is intercalated in the crystal structure of the latter.In organometallic chemistry, crystallization of new compounds from organic solvents is the method of choice for growing X-ray quality single crystals. However, given the vast range of organic solvents with different polarity, the right choice is not always easy. When typical donor solvents such as THF or 1,2-dimethoxyethane () DME) are employed, coordinative interaction with a metal center is frequently encountered. Thus, it is generally accepted that in such cases different crystal structures could arise as compared to crystallization from nonpolar solvents. In the case of nonpolar hydrocarbon solvents, especially hydrocarbons, there are of course significant differences between aromatic and aliphatic hydrocarbons. Quite frequently, one type of hydrocarbon solvent (e.g., toluene) yields suitable crystals while the other (e.g., n-pentane) does not or vice versa. However, one would not expect the formation of different crystalline forms when switching between these different nonpolar hydrocarbon solvents. We report here such an unusual solvent effect on the crystallization of an anionic lanthanide sandwich complex. The work reported here provides a fascinating example of how small changes can have big effects on crystal structure and coordination mode.The compound in question is Li(DME)Tb(COT′′) 2 (1), a formally anionic lanthanide sandwich complex containing bulky cyclooctatetraenyl ligands. The organometallic chemistry of the rare earth elements continues to be a highly attractive field of research, in particular due to the numerous applications of organolanthanides in catalysis 1 and organic synthesis. 2 An increasingly important area focuses on the development of noncyclopentadienyl organolanthanide complexes. 3 Here, cyclooctatetraenyl ligands () COT) play an important role because the large, flat COT dianions are ideally suited to form sandwich complexes of the rare earth metals. 4 Long known and well established are the anionic lanthanide(III) sandwich complexes M[Ln(COT) 2 ] (M ) alkaline metal). 4a,5 More recently, bulky organosilyl-substituted COT ligands such as the 1,4-bis(trimethylsilyl)cyclooctatetraenyl dianion () COT′′) have become increasingly popular. 6 Anionic sandwich complexes of the type [Li(THF) 4 ]-[Ln(COT′′) 2 ] (Ln ) Ce, Pr, Sm, Y) are formed upon treatment † Dedicated to Professor Rudolf Hoppe on the occasion on his 85th birthday.(1) (a) Yasuda, H.

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In this work, antimicrobial usage data from 2,546 commercial broiler chicken flocks originating from 37 farms are presented. Antimicrobial usage data at the flock level were based on mandatory documentation of antibiotic treatments in livestock in Germany, collected retrospectively for the time period of 2013–2018. The data encompasses all antimicrobial treatments during the fattening period of each flock, starting with the placement of day-old chicks at the barn. The aim of this analysis was to investigate antibiotic usage patterns in broiler chicken flocks in Germany, temporal trends in treatment frequency, the proportions of different antimicrobial classes and the weights of the broiler chickens at the time of treatment. The median treatment frequency over all flocks was six, and veterinary medicinal products belonging to nine different antimicrobial classes were used. Overall, the most frequently used classes were aminoglycosides (25.6%) and lincosamides (25.6%), followed by polypeptides (21.4%) and beta-lactams (16.2%). Over the 6 years evaluated, a considerable increase in the relative usage of lincosamides and aminoglycosides was observed. Compared to the first year of data collection, the percentage of treatments with fluoroquinolones, macrolides and polypeptides decreased in consecutive years. The median age of the broiler chickens at the time of treatment was 5 days, which corresponded to a median body weight at the time of treatment of 111 g, with substantial differences among various antimicrobial classes. We showed that in Germany, the median weight of broiler chickens at the time of treatment was substantially lower than the standard weight of broilers of 1,000 g proposed by the European Surveillance of Veterinary Antimicrobial Consumption. The median weight at treatment is very much influenced by the frequency of age-specific diseases. As different antimicrobial classes are used to combat these diseases, variations in the weight at treatment may have a considerable impact on the estimated treatment indicators. Additionally, a decrease in the relative usage of the highest-priority critically important antimicrobials, such as fluoroquinolones, macrolides and polypeptides, was shown, which might be the consequence of increasing awareness of the antibiotic resistance situation as well as of antibiotic monitoring and benchmarking systems currently running in Germany.