A series of microcrystalline compounds between adenosine 5′-triphosphoric acid (ATP), 22′-bipyridyl and some 3d metal ions, such as Mn(II), Co(II), Cu(II) and Zn(II), have been obtained in 1:1 ratio . Crystal suitable for X-ray analysis were obtained for the zinc compound. Diffractometer data, collected on one of these crystals, gave the following results: a = 11.105(3), b = 25.223(7), c = 1.539(3) Å, β = 91.34(4)°, monoclinic, space group P21. 1617 reflections with intensity greater then twice their standard deviation were used for the structure determination and refinement (R = 0.098). The structure of the compound consists of dimeric molecules in which two zinc atoms are held together by two –OPO– bridges from the γ-phosphate groups of two ATP molecules (Fig. 1). Both zinc atoms show a distorted octahedral coordination, formed by two oxygen atoms from different γ-phosphate groups, one oxygen atom from the β-phosphate group and the two nitrogen atoms of the bipyridyl ligand. The sixth position is completed by an α-phosphate oxygen atom which is only weakly bound. ZnN and ZnO distances average respectively 2.15(4) and 2.0293) Å. The structure is held together by strong intermolecular bipyridyl–purine and bipyridyl–bipyridyl stacking interactions. Weaker bipyridyl–purine intramolecular stacking is also observed. The molecule provides a possible model for ATP transport and phosphate group transfer mechanism.
|Titolo:||Crystal and molecular structure of the ternary complex Zn(II)–ATP–2,2′-bipyridyl|
|Appare nelle tipologie:||1.5 Abstract in rivista|
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