55386-79-3Relevant articles and documents
Solvent dependent reactivities of di-, tetra- and hexanuclear manganese complexes: Syntheses, structures and magnetic properties
Yang, Hua,Cao, Fan,Li, Dacheng,Zeng, Suyuan,Song, You,Dou, Jianmin
, p. 6620 - 6629 (2015/04/14)
An unusual solvent effect on the synthesis of five manganese complexes [Mn2(L1)2(Py)4](1), [Mn2(L1)2(DMSO)4](2), [Mn4(L2)4(OH)4](3), [Mn4(L3)2(DMSO)7(H2O)](4), and [Mn6O2(L4)4(OAc)2(OMe)2(DMSO)4]·MeOH] (5), (H3L1 = 5-(2-oxyphenyl)-pyrazole-3-carboxylic acid; H2L2 = 5-(2-oxyphenyl)-pyrazole-3-carboxylic acid amide; H4L3 = di-[5-(2-oxyphenyl)-pyrazole]-3-hydroxamic ether; and H2L4 = 5-(2-oxyphenyl)-pyrazole-3-carboxylic acid methyl ester) has been reported. Five complexes have been characterized by X-ray single crystal diffraction, IR, element analysis, thermogravimetric analysis and UV-vis spectra. The analysis reveals that complexes 1 and 2 are isostructural with a bimetallic six-membered ring and L1 from the decomposition of the original H4ppha (H4ppha = 5-(2-hydroxyphenyl)-pyrazole-3-hydroxamic acid) ligand. Complexes 3 and 4 are two tetranuclear clusters, and 3 possesses an aza12-metallacrown-4 core with L2 from the amide functionalization of the decomposition L1; while 4 represents a novel linear [Mn4N8O2] core with L3 from the condensation of L1 and H4ppha. Complex 5 is the first Mn6 cluster linked by two stacked, off-set 8-azametallacrown-3 subunits with [M-N-N-M-N-N-M-O] connectivity, and L4 derived from the esterification of L1. The magnetic behaviour of complexes 1-5 show the dominant antiferromagnetic interactions between metal centers, whereas complex 5 further reveals the coexistence of antiferromagnetic and ferromagnetic interactions, and slow magnetic relaxation at T 6 K with S = 4 ground state, as well as field induced magnetization saturation. This journal is
Benzopyrones. Part 19. Synthesis and some Reactions of Ethyl 3-Bromo-4-oxochromen-2-carboxylate
Bevan, Peter S.,Ellis, Gwynn P.
, p. 1705 - 1709 (2007/10/02)
The product of the condensation of o-hydroxyacetophenone and diethyl oxalate, ethyl 2-hydroxy-4-oxochroman-2-carboxylate (13), slowly and partially isomerises in solution to the phenolic ketone (16), but in the presence of mineral acid, it is rapidly dehydrated directly to ethyl 4-oxochromen-2-carboxylate (2; R = Et).Bromination of the oxochroman (13) gave a 72:28 mixture of epimeric 3-bromo-esters.The major isomer (trans-OH,H) was readily dehydrated to give the title compound which contains a reactive bromine atom.
