Article,

Formation of Racemate and Mesocate Complexes from an Achiral Tripodal Ligand Containing Three Benzimidazole Groups

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Inorganic Chemistry, 42 (1): 163--168 (2003)
DOI: 10.1021/ic025934y

Abstract

Two complexes of the achiral tripodal ligand tris(1-benzimidazolylethyl)amine (nteb), viz., Mn(nteb)2(H2O)2(ClO4)2·MeOH, 1, and Ag2(nteb)2(CF3CO2)2·2H2O, 2, were synthesized and characterized by IR, 1H NMR, and EPR spectroscopy, electrospray mass spectrometry, TGA, and x-ray crystallog. Compd. 1 contains chiral complex cations due to the same handedness of two nteb ligands (dd or ll) but crystallizes as a racemate, while 2 contains a dinuclear mesocate because of the opposite handedness (dl) of two nteb ligands. Crystal data for 1: space group P1̅ with a 9.471(4), b 16.884(7), c 19.906(8) \AA, a 77.930(7), b 88.063(7), g 89.706(7)°, and Z = 2. Crystal data for 2: space group P1̅ with a 9.3390(12), b 10.2168(13), c 16.382(2) \AA, a 75.721(3), b 87.857(3), g 71.738(3)°, and Z = 1. In 1, H2O serves as an auxiliary ligand, connected to one imidazole N atom of each nteb ligand through a H-bridge; the cationic complexes are assocd. intermolecularly via p···p interactions. In contrast to 1, the coordination to the Ag+ ions in 2 occurs in a heterochiral manner and produces a dinuclear mesocate. on SciFinder(R)

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