科研之友
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摘要
A pair of enantiomers formulated as {Delta-cis-[Ni(en)(2)OAc][ClO4]} (n) (Delta-1) and {I >-cis-[Ni(en)(2)OAc][ClO4]} (n) (I >-1) (en = diaminoethane, OAc- = acetate anion) were obtained when nickel acetate was reacted with diaminoethane and sodium perchlorate in the absence of any chiral source, whereas the reactions of nickel acetate with 1,3-propanediamine and sodium perchlorate only gave a centrosymmetric complex [Ni(1,3-pn)(2)OAc][ClO4] (2) (1,3-pn = 1,3-propanediamine). Single-crystal X-ray diffraction analyses of all three complexes indicated that the central Ni(II) atoms all have a distorted octahedral coordination geometry, being coordinated by four nitrogen atoms of the diamine ligands, plus two oxygen atoms of OAc-. In complexes Delta-1 and I >-1, the monomers of {Delta-cis-[Ni(en)(2)OAc]}(+) and {I >-cis-[Ni(en)(2)OAc]}(+) are connected through intermolecular hydrogen bonds to generate one-dimensional right- and left-handed homochiral helical chains, respectively, while the monomers of [Ni(1,3-pn)(2)OAc](+) are linked by similar intermolecular hydrogen bonds to form one-dimensional zigzag chains instead of helical chains. The chiral natures of complexes Delta-1 and I >-1 have been confirmed by circular dichroism spectroscopy.
