Depending on the iron(ii) concentration, the mixed crystals of {[Zn1-xFex(bbtr)3](BF4)2}∞, bbtr = 1,4-di(1,2,3-triazol-1-yl)butane, 0.01 ≤ x ≤ 1, show macroscopic light-induced bistability between the high-spin and the low-spin state. In the highly diluted system with x = 0.01 and up to x = 0.31, the photoinduced low-spin state always relaxes back to the high-spin state independent of the initial light-induced low-spin fraction. In the highly concentrated mixed crystals with x = 0.67, 0.87 and 1, the strong cooperative effects coupled to a crystallographic phase transition result in light-induced bistability with decreasing critical light-induced low-spin fraction and increasing hysteresis width for increasing iron(ii) concentrations. The lower limit for the light-induced bistability was estimated to be x ≈ 0.5.
Reactions of α-diazo-β-ketoesters with cyclic ketones, lactones, and carbonates are reported. Thanks to the combined use of salt [CpRu(CH3CN)3][BArF] and 1,10-phenanthroline as catalyst for the diazo decomposition, effective and practical syntheses of spiro bicyclic ketals, orthoesters, and orthocarbonates are afforded.
(Cyclopentadienyl)tris(acetonitrile)ruthenium hexafluorophosphate [CpRu(CH 3 CN) 3 ][PF 6 ] in combination with pyridine-hydrazone ligands efficiently catalyzes the asymmetric decarboxylative allylic rearrangement of allyl aryl carbonates.F ormation of C À Ob onds with high regio-and enantioselectivity ratios (up to 95:5 and 98% ee)i so btained. Good stereocontrolo ft he pseudotetrahedral geometryo ft he CpRu moiety is achieved by the hydrazone liganda nd its "electron-poor" nature is evidencedt hrough the epimerization of the hexacoordinatedTRISPHAT-Na nion.
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