Fluorine complexes double bridged

The double helix of DNA [25] and the more complex tertiary structures of RNA [26] are linked together by hydrogen bridges between pairs of nudeobases (approx. 0.5-1.8 kcal mol per Watson-Crick base pair) [27] and by hydrophobic "stacking forces . Fluorinated carbocyclic analogs of these nudeobases have been used to study and elucidate the factors underlying base pairing, replication, and the interaction of the bases with proteins such as DNA polymerases [28]. 

In the trinuclear complex [Ba /r-OCH(CF3)2 4Y2(thd)4] thd = Bu C(0)CHC(0)Bu the three metal atoms are in a non-Unear chain (YBaY, 129.3°) and the central Ba ion is joined to the Y ions by double fluoroalkoxo bridges and interacts with eight fluorine atoms from neighbouring CF3 groups. The yttrium ions are six-coordinated (trigonal prismatic)... 

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