Low-Valent Iron(I) Amido Olefin Complexes as Promotors for Dehydrogenation Reactions

FeI compounds including hydrogenases show remarkable properties and reactivities. Several iron(I) complexes have been established in stoichiometric reactions as model compounds for N2 or CO2 activation. The development of well‐defined iron(I) complexes for catalytic transformations remains a challenge. The few examples include cross‐coupling reactions, hydrogenations of terminal olefins, and azide functionalizations. Here the syntheses and properties of bimetallic complexes [MFeI(trop2dae)(solv)] (M=Na, solv=3 thf; M=Li, solv=2 Et2O; trop=5H ‐dibenzo[a,d]cyclo‐hepten‐5‐yl, dae=(N‐CH2‐CH2‐N) with a d7 Fe low‐spin valence‐electron configuration are reported. Both compounds promote the dehydrogenation of N ,N ‐dimethylaminoborane, and the former is a precatalyst for the dehydrogenative alcoholysis of silanes. No indications for heterogeneous catalyses were found. High activities and complete conversions were observed particularly with [NaFeI(trop2dae)(thf)3]

Cis interactions of immunoreceptors with MHC and non-MHC ligands

The conventional wisdom is that cell-surface receptors interact with ligands expressed on other cells to mediate cell-to-cell communication (trans interactions). Unexpectedly, it has recently been found that two classes of receptors specific for MHC class I molecules not only interact with MHC class I molecules expressed on opposing cells, but also with those on the same cell. These cis interactions are a feature of immunoreceptors that inhibit, rather than activate, cellular functions. Here, we review situations in which cis interactions have been observed, the characteristics of receptors that bind in trans and cis, and the biological roles of cis recognition

Perception of allophonic cues to English word boundaries by Japanese second language learners of English

Perception of stop aspiration and glottal stop allophonic cues for word juncture in English by Japanese second language (L2) learners of English was examined, extending a study of Spanish L2 learners [Altenberg, E. P. (2005). Second Lang. Res. 21, 325–358]. Thirty Japanese listeners ranging in length of residence (LOR) in the United States (2 weeks–12 years) were tested on 42 contrasting pairs (e.g., aspiration: keeps talking vs keep stalking, glottal stop: a nice man vs an ice man, and double cues: grape in vs grey pin). Phrases were presented in randomly ordered lists and subjects responded in a two-choice identification task followed by a phrase familiarity test. The Japanese listeners performed more poorly than an American English-speaking control group (N=10), especially on aspiration pairs. Aspiration pairs were differentiated significantly less well (73% correct) by Japanese listeners than were glottal stop pairs (91% correct) and double cue pairs (94% correct); response biases predicted from relative familiarity of phrases were evident only for aspiration pairs. Performance correlated with LOR and suggested that aspiration cues take more immersion experience to learn than glottal stop cues. The patterns of errors were similar, but not identical, to Altenberg’s Spanish data