Spin Crossover The stability of triple N1,N2-triazole bridges of neighboring FeII metal ions has allowed the isolation of whole families of 1D coordination polymers formed by propagation of these bridges. The resulting [Fe(Rtrz)3][A]x compounds, in which R could be any not-too-bulky substituent and A can be a mono- or divalent anion, systematically exhibit HS↔LS spin-crossover (SCO) properties, with associated magnetic and optical transitions that range from gradual to very abrupt, and often occur at or above room temperature, while providing one of the largest hysteresis known in SCO compounds. For more details, see the Minireview by O. Roubeau on page 15230 ff.
In their Communication on page 15277 ff., S. Mukherjee and M. S. Manna describe the development of a highly diastereo- and enantioselective protocol for the direct vinylogous Michael addition of deconjugated butenolides to maleimides using a tertiary-amine/thiourea-based bifunctional catalyst. This operationally simple protocol should be synthetically useful due to the mild reaction conditions, low catalyst loading, and excellent level of product stereoselectivity.
Bidentate phosphoramidite ligands based on a spiroketal backbone have been developed for rhodium-catalyzed hydroformylation reactions, as presented by C. Xia and K. Ding et al. on page 15288 ff. Both terminal and internal olefins were amenable to the protocol and both high catalytic activity and excellent regioselectivity for the linear aldehydes were observed. Remarkably, the catalysts showed excellent performance in the hydroformylation of industrially important olefin feedstocks such as propylene, 1-butylene, and 2-butylene.