Metal binding to N(9), N(7), and N(3) of adenine. Crystal structure of μ-(adeninato-N3,N7,N9)tris(methylmercury(II)) perchlorate

Abstract

The title compound belongs to space group [Formula: see text] with the following cell parameters: a = 6.304, b = 11.925, c = 25.946 Å, α = 85.76, β = 89.78, γ = 83.57°, and Z = 4. The structure was solved by the heavy-atom method and refined on 2570 nonzero reflections to an R factor of 0.044. In the two crystallographically independent [Adeninato(CH3Hg)3]2+ ions, methylmercury groups are linearly bonded to N(3), N(7), and N(9) of a deprotonated adenine ring, forming Hg—N bonds of normal lengths (ave. 2.08 Å) for two-coordinated mercury. One half of the complex cations are associated in a dimeric unit by a pair of strong [Formula: see text] hydrogen bonds, while the others are packed as individual species in the crystal. The structure is stabilized by a number of contacts between mercury and perchlorate oxygens.