Discrete Molecular Squares {[(en)M(CN)](4)}(4+) Derived from [(en)M(CN)(2)] (M = Pt-II, Pd-II)

作者：Galstyan Anzhela; Sanz Miguel Pablo J; Wolf Jacqueline; Freisinger Eva; Lippert Bernhard^*

来源：European Journal of Inorganic Chemistry, 2011, 2011(10): 1649-1656.

DOI：10.1002/ejic.201001216

• Cyanides
• Platinum
• Palladium
• Metallacycles
• Model nucleobases

C-2h-symmetrical tetranuclear metallacycles {[M(en)(CN)](4)}(NO3)(4) with M = Pd-II (4) and Pt-II (5) have been prepared upon reacting M(en)(CN)(2) [M = Pd-II (1), Pt-II (2)] with [M(en)(H2O)(2)](NO3)(2). Replacement of the nitrate anions of 5 by terephthalate anions yields the corresponding salt 5a. The X-ray crystal structures of 1, 4, 5, and 5a have been determined. In the metallacycles 4, 5, and 5a the four metals form almost ideal squares with average M center dot center dot center dot M distances of ca. 5.05 angstrom (5, 5a) and 5.08 angstrom (4) along the sides. As shown by H-1 NMR spectroscopy, the Pt square 5 is stable in aqueous solution, whereas the Pd square 4 undergoes rearrangement reactions upon aging or the presence of other Pd species such as (bpy)-Pd-II. Preliminary studies on the possibility of non-covalent interactions of 4 and 5 with model nucleobases in water reveal that only 5 is useful in this respect. According to the concentration-dependence H-1 NMR study, there is an interaction with the purine base 9-ethyladenine, molecular details of which are unclear at this stage, however. Compound 4 is substitutionally labile and is transformed into the coordination compound 8 with 1-methylcytosine. Two more side products, produced during the various reactions carried out, were characterized by X-ray crystallography: [Pt(en)(2)][Pt(CN)(4)] (3) and [Pd(bpy)(en)](SO4)center dot 3H(2)O (7).

• 出版日期2011-4