Unusual four-membered chelate rings of platinum(IV) with a cytosine nucleobase

Structural and anticancer properties of hydrogen bonded diphenyl phosphate adducts of Pt(IV) complexes: The importance of pKa matching

“…From the difference maps two hydrogen atoms were found to be bound to the ligand atom O(1), which has an effect on the Pt-O(1) bond length. This bond length is 2.039(4) Å, which is in good agreement with Pt(IV)-O (aqua) bond distances reported previously [27][28][29]. The Pt-O(2) bond distance is shorter at 1.978(4) Å, which is typical for axial Pt(IV)-hydroxido bond lengths.…”

“…Jeffrey has listed O ··· O distances in hydrogen bonds in some organic anions, obtained by neutron diffraction [24]. Typical values range from 2.393(3) Å for imidazolium hydrogenmaleate [25] [27][28][29] and these all have bond lengths of about 2.04 Å, which would indicate that this bond does not take on the full characteristics of a Pt(IV)-aqua bond. The short hydrogen bond may account for this anomaly and cause the oxygen to retain more of a hydroxido characteristic with the hydrogen atom shared equally.…”

Rationalizing the Structural Variability of the Exocyclic Amino Groups in Nucleobases and Their Metal Complexes: Cytosine and Adenine

“…At the same time this implies that intermolecular hydrogen bond formation of NH to an acceptor will cause N4 to become, in a kind of “push–pull” action, an acceptor itself. Metal migration from N3 to N4, as observed for 1‐MeC,13a, 19 or from N1 to N6, as seen with adenine nucleobases,20 might also be facilitated by this way.…”

Unusual Dimeric Zn(II)-cytosine complexes: New models of the interaction of Zn(II) with DNA and RNA

“…A particular situation is found in the dimer [ZnCl(9-Pr-en-GH-N7) 2 ] 2+ in which the functionalization of the N9 position of the nucleobase by a diamine group allows the Zn atom coordinate guanine via N7 and diamine sites [34]. It is also unusual the situation involv- [35][36][37][38][39][40][41][42][43][44], Pd(II) [45,46] probably due to an initial N3 ! N4 migration of the transition metal [38,47,48]; other cases are (1-MeC-N3)-Cu(II)-(1-MeC-N4) 2 [49], (1-MeC-N3)-Ag(I)-(1-MeC-O2) [13], (1-MeC-N4) 2 -Cu(II)-(1-MeC-O2) 2 [50], and (1-MeC À -N4)-Pd(II)-(1-MeC-O2) [51].…”