title: Formation of racemate and mesocate complexes from an achiral tripodal ligand containing three benzimidazole groups.
abstract: Two complexes of the achiral tripodal ligand tris(1-benzimidazolylethyl)amine (nteb), viz., [Mn(nteb)(2)(H(2)O)(2)](ClO(4))(2).CH(3)OH, 1, and [Ag(2)(nteb)(2)](CF(3)CO(2))(2).2H(2)O, 2, have been synthesized and characterized by IR, (1)H NMR, and EPR spectroscopy (1), electrospray mass spectrometry, thermogravimetric analysis, and X-ray crystallography. Compound 1 contains chiral complex cations due to the same handedness of two nteb ligands (deltadelta or lambdalambda) but crystallizes as a racemate, while 2 contains a dinuclear mesocate because of the opposite handedness (deltalambda) of two nteb ligands. Crystal data for 1: space group P(-)1 with a = 9.471(4) A, b = 16.884(7) A, c = 19.906(8) A, alpha = 77.930(7) degrees, beta = 88.063(7) degrees, gamma = 89.706(7) degrees, V = 3111(2) A(3), and Z = 2. Crystal data for 2: space group P(-)1 with a = 9.3390(12) A, b = 10.2168(13) A, c = 16.382(2) A, alpha = 75.721(3) degrees, beta = 87.857(3) degrees, gamma = 71.738(3) degrees, V = 1437.2(3) A(3), and Z = 1. In 1, water serves as an auxiliary ligand, connected to one imidazole N atom of each nteb ligand through a H-bridge; the cationic complexes are associated intermolecularly via pi.pi interactions. In contrast to 1, the coordination to the Ag(+) ions in 2 occurs in a heterochiral manner and produces a dinuclear mesocate.
authors.affiliation: School of Chemistry and Chemical Engineering, Zhongshan University, Guangzhou 510275, China.
authors.forename: Yue-Peng
authors.initials: YP
authors.lastname: Cai
authors.forename: Cheng-Yong
authors.initials: CY
authors.lastname: Su
authors.forename: Chun-Long
authors.initials: CL
authors.lastname: Chen
authors.forename: Yue-Ming
authors.initials: YM
authors.lastname: Li
authors.forename: Bei-Sheng
authors.initials: BS
authors.lastname: Kang
authors.forename: Albert S C
authors.initials: AS
authors.lastname: Chan
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kaim