Metal ion interactions with 8-azapurines. Synthesis and structure of dichlorobis(8-azaadenine)mercury(II) and tetraaquabis(8-azahypoxanthinato)mercury(II)

<b>Synthesis, structure and photoluminescence of (HgCl₃)_<i>n</i> (C₆NO₂H₆)_<i>n</i>(C₆NO₂H₅)n•<i>n</i>H₂O</b>

“…The mercury atom is coordinated by four chlorine atoms to yield a HgCl 4 2-tetrahedron, with the bond lengths of Hg-Cl ranging from 2.350(1) to 2.8100(9) Å and the average value being 2.536(1) Å, which is similar to those reported [8,9]. Each HgCl 4 2-tetrahedron interconnects to two neighboring ones via corner-sharing to form a 1-D (HgCl 3 ) -anionic chain (Figure 1).…”

Characterisation of Metal Binding Sites for 8-Azaguanine and 8-Azahypoxanthine Derivatives Synthesis and X-Ray Structural Analysis of Methylmercury(II) and Zinc(II) Complexes

“…N 9 is the pri mary binding site followed by N 1. A consideration of the present findings, taken together with our study of C H 3H g+ complexes of 8-azaadenine [10] and the re ported structures of H g(H 20 ) 4(A H xH )2 [6] and C d(H 20 ) 4(A H xH )2 [7], leads to a reinforcem ent of our previous conclusion [10] that the ligand proper ties of the 8-azapurines are more similar to the natu ral purines than was previously supposed. Indeed metal coordination of an anomalous primary binding site at a biologically relevant pH value has only been confirm ed for Cd(H 20 ) 4(A H xH )2), in wich N 7 is coordinated, leaving N 9 both uncoordinated and unprotonated.…”

“…W hereas the reaction of 8-azaadenine with CuCl2 in 0.36 M HC1 leads to ring opening at C2 [4], Z n(II) interacts under similar acidic condi tions with the protonated base at N 3 in the complex Z n(A A dH 2)Cl3 [5]. Hg(II) also interacts with N3, albeit very weakly, in the complex H g(A A dH )2Cl2 [6]. Contrasting binding modes were observed for the metal cations in the tetraaquo-bis(8-azahypoxanthinato) complexes of Cd(II) and H g(II), namely N7 and N 9 coordination respectively [6,7], Crystal structure determ inations have established the pro tonation sites as N1 and N 9 for 8-azaguanine m onohydrate [8] and N1 and N 8 for 8-aza hypoxanthine [9].…”

“…Hg(II) also interacts with N3, albeit very weakly, in the complex H g(A A dH )2Cl2 [6]. Contrasting binding modes were observed for the metal cations in the tetraaquo-bis(8-azahypoxanthinato) complexes of Cd(II) and H g(II), namely N7 and N 9 coordination respectively [6,7], Crystal structure determ inations have established the pro tonation sites as N1 and N 9 for 8-azaguanine m onohydrate [8] and N1 and N 8 for 8-aza hypoxanthine [9]. No analogous information is available for 8-azaadenine.…”

Halide-bridged polymers of divalent metals with donor ligands – structures and properties

“…Straightforward distance criteria underline the efficiency of a vicinal diatomic bridge such as pyridazine. The closest intermetal Hg· · ·Hg distances along chloride-bridged polymer chains amount to 5.01 Å in the case of corner-sharing [110], to ca. 3.9 Å for edge-sharing, cf.…”