The reaction of Se8 with 6 equiv of Mn2(CO) 10 in concentrated KOH/MeOH solutions led to the formation of the odd-electron cluster [Se2Mn3(CO)9]2- (1), which was oxidized with [Cu(MeCN)4][BF4] to give the oxidation product [Se2Mn3(CO)9]- (2). Cluster 2 could be reconverted into cluster 1 by the addition of 4 M KOH/MeOH solutions in MeCN. While the trigonal-bipyramidal cluster 2 underwent cluster expansion to give rise to the large Se-inserted cluster [Se 6Mn6(CO)18]4- (3) upon the reaction with a 1/8 equiv of Se8 in KOH/MeOH solutions, the square-pyramidal cluster 1 was transformed into the even larger Se-rich cluster [Se 10Mn6(CO)18]4- (4) upon the addition of a 3/8 equiv of Se8 in MeOH. Cluster 3 underwent cluster expansion to form cluster 4 when treated with an additional 1/2 equiv of Se8 in MeCN. Conversely, cluster 4 was selectively reconverted into cluster 1 or 3 upon treatment with 4 or 2 equiv of Mn2(CO)10 in KOH/MeOH solutions, respectively. On the other hand, the Se6Mn6 cluster 3 was transformed into cluster 1 when treated with 2 equiv of Mn 2(CO)10 in KOH/MeOH solutions. Furthermore, when cluster 3 was treated with [Cu(MeCN)4][BF4] or Mn(CO) 5Br, cluster 2 and/or [Se5Mn4(CO) 12]2- (5) were obtained. X-ray analysis showed that cluster 5 consisted of four Mn(CO)3 fragments, which were further connected by one μ3-Se and two μ3- and μ4-Se2 moieties to give a nest-like cluster. Moreover, Se10Mn6 cluster 4 could also be transformed into cluster 5 upon reaction with [Cu(MeCN)4][BF4] or Mn(CO) 5Br. After a long reaction time, a new picnic-basket-like cluster, [Se4Mn3(CO)10]- (6), formed, which was also obtained from cluster 5 with [Cu(MeCN)4][BF4] or Mn(CO)5Br. Furthermore, the nature, cluster transformation and interconversion, and electrochemical properties of these Se-Mn-CO clusters were elucidated by molecular calculations at the B3PW91 level of the density functional theory.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry