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Science  10 Apr 2009:
Vol. 324, Issue 5924, pp. 149
DOI: 10.1126/science.324.5924.149b

The nitrogen column in the periodic table is perhaps the most diverse, ranging from the light, tightly bound N2 gas, through cluster-prone phosphorus and arsenic (As), on down to the semi-metals antimony (Sb) and bismuth (Bi). Molecular phosphoramides that combine the two lighter elements are well known, and recently a simple compound of phosphorus (P) and As emerged stably from solution (see Cossairt et al., Brevia, 30 January 2009, p. 602). Alloys of the heavier elements, in keeping with their semimetallic character, are also known. However, coordination complexes of As with its heavier congeners are comparatively rare. Conrad et al. present a straightforward synthetic route to this class of compounds, mixing trilkyl or triaryl arsines with chlorinated Sb and Bi substrates in dichloromethane solution. In addition to a neutral As-Sb adduct, the authors isolated cationic As-Sb and As2-Bi adducts after chloride abstraction by trimethylsilyltriflate, as well as a fourth cationic As-Sb adduct using aluminum trichloride as the abstracting agent. All three structures were crystallographically characterized and exhibited geometries consistent with electron donation from As to the heavier acceptor. — JSY

J. Am. Chem. Soc. 131, 10.1021/ja900968j (2009).

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