Novel in situ manganese-promoted double-aldol addition

Autor: Cyril Cook, Ilia Korobkov, Muralee Murugesu, Fatemah Habib
Rok vydání: 2012
Předmět:
Zdroj: Inorganica Chimica Acta. 380:378-385
ISSN: 0020-1693
DOI: 10.1016/j.ica.2011.11.023
Popis: A novel in situ Mn n + -promoted double-aldol reaction is reported. Single crystal X-ray measurements confirm the addition of acetone to two o -vanillin molecules in an original in situ α , α double aldol reaction promoted by Mn ions in the presence of base. The newly formed ligands coordinate to four Mn III ions forming a defect-dicubane core structure ( 1 ) bridged exclusively by oxygen-based ligands. Other 3 d metals were employed under the same reaction conditions, however no aldol addition occurred and tetranuclear cubane-like structures formed using Co II ( 2 ) and Ni II ( 3 ) ions. Magnetic measurements were carried out on all complexes using SQUID magnetometry. Dominant ferromagnetic interactions were observed for complexes 1 and 3 with J = 1.8 cm −1 , J ′ = −2.5 cm −1 , g = 1.95 for 1 and J = 3.1 cm −1 , g = 2.17 for 3 while complex 2 exhibited antiferromagnetic exchange interactions. Notably, complex 1 was shown to exhibit spin frustration rarely seen in {Mn III } 4 systems resulting in an intermediate spin ground state of S T = 6.
Databáze: OpenAIRE