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The heterobimetallic peralkylated complexes [Ln(AlR4)2]n (Ln = Sm, Yb; R = Me, Et) were synthesized by a silylamide elimination route from Ln[N(SiMe3)2]2(THF)2 and an excess of AlR3. The solid-state structure of [Sm(AlEt4)2]n is isomorphous to that of the ytterbium derivative. Polymeric [Yb(AlMe4)2]n was examined by 1H and 13C MAS NMR spectroscopy revealing the presence of distinct bridging methyl groups. The reaction of [Yb(AlMe4)2]n and 1,10-phenanthroline (Phen) afforded the monomeric donor adduct Yb(AlMe4)2(Phen), while the protonolysis reaction with 2 equiv. C5Me5H (HCp*) yielded a separated ion pair of composition [Cp*Yb(THF)4][AlMe4]. Single-crystal X-ray diffraction data are provided for both ytterbium(ii) complexes. Solid-state magnetic measurements (SQUID) were performed on [Sm(AlMe4)2]n, [Sm(AlEt4)2]n, SmI2(THF)2 and Sm[N(SiMe3)2]2(THF)2 showing high effective magnetic moments 3.67µB < µeff < 4.43µB. [ABSTRACT FROM AUTHOR]

Abstract The effectiveness of a single treatment with either ivermectin or moxidectin was determined by administering a single subcutaneous injection of each endectocide at 200g per kg body weight to cattle infested with all parasitic developmental stages (adults, nymphs, and larvae) of Boophilus microplus (Canestrini). The percentage reduction in the number of females that reached repletion following treatment (outright kill) was 94.8 and 91.1% for ivermectin and moxidectin, respectively. In addition, the reproductive capacity of the females that did survive to repletion was reduced by >99%, regardless of the endectocide. Based on these two factors, the therapeutic level of control obtained against ticks on the cattle at the time of treatment was 99.0 and 99.1% for ivermectin and moxidectin, respectively. Engorged females recovered from either group of treated cattle weighed 3-times less than untreated females, and the egg masses produced by treated females weighed 58-times less than egg masses produced by untreated females. Partitioning of data into three separate 7-d post-treatment intervals allowed for an estimation of the efficacy of each endectocide against each individual parasitic development stage (adult, nymph, and larva). Results indicated that both endectocides were =99.7% effective against ticks that were in either the adult or nymphal stage at the time of treatment. However, the level of control against ticks in the larval stage of development at treatment was significantly lower at 97.9 and 98.4% for ivermectin and moxidectin, respectively. Analysis of the persistent (residual) activity of the two endectocides indicated that neither material provided total protection against larval re-infestation for even 1-wk following treatment. Against larvae infested 14wk following treatment, the level of control with moxidectin ranged from 92.4% (1wk) to 19.5% (4wk). These control levels were higher at each weekly interval than for ivermectin, which ranged from 82.4% (1wk) to 0.0% (4wk). The potential for the use of these injectable endectocide formulations in the US Boophilus Eradication Program is discussed. [ABSTRACT FROM AUTHOR]