Structural and coordinating properties of platinum(II) chloride complexes with polypyridyl ligands. Single crystal X-ray structure of [Pt(ddpq)Cl2]·H2O (ddpq=6,7-dimethyl-2,3-di(2-pyridyl)quinoxaline)

Conformational landscape of platinum(II)-tetraamine complexes: DFT and NBO studies

“…It should be noted that the average value obtained here for the N3-Pt-N5 bond angle [29] to 92.5° [28], reported in the literature [24][25][26][27][28][29]. This discrepancy may be due to structural differences in the types of ligands, crystal packing or the environments in which these crystals were obtained.…”

“…A plausible explanation of these differences is that the primary amine groups were less constrained during optimizations, giving rise to a significant degree of movement away from the central Pt(II) ion. The experimental structures of some related Pt(II)-complexes with biological relevance have been elucidated via both theoretical methods using effective core potential (ECP) and a variety of basis sets [23], as well as with experimental X-ray methods [24][25][26][27][28][29]. The principal difference between the structures studied previously and the tetraamine investigated here is that the tetraamine is a single multidentate ligand that provides all the chelating moieties, while the previously reported structures comprised multiple ligands.…”

“…Among the experimental structures reported previously there were notable differences in the Pt(II)-N bond lengths, indicating that the environment of the central atom and possibly crystal packing may influence these geometrical values. For instance, the platinum-nitrogen distances in the experimental studies [24][25][26][27][28][29] ranged from 1.998 [27] to 2.121 Å [24]. Theoretical ab initio distances computed at the HF/LANL2DZ level of theory were 2.100 and 2.148 Å [23].…”

“…Despite the availability of ab initio [23] and X-ray crystallography data for other biologically active Pt(II)-amine complexes [24][25][26][27][28][29], to the best of our knowledge this is the first systematic characterization of the conformational landscape of metalpolyamine complexes of this type. Employing density functional theory methods we computed the potential energy surfaces of five diastereoisomers and determined their relative stabilities.…”

Experimental and DFT/Time‐Dependent DFT Studies on Neutral and One‐Electron‐Reduced Quinoxaline and Pyrazine Precursors and Their Mononuclear (PdII, PtII) Derivatives

“…In a wider look at the literature, it appears to be extensively proven that the dipyridinopyrazine fragment can indeed behave as a bidentate N donor by means of both “py–py”5 and “py–pyz”6 coordination (Scheme , B). Moreover, X‐ray structural data also indicate, in keeping with our findings with the above‐mentioned complexes [(CN) 2 Py 2 PyzMCl 2 ], that Pd II or Pt II metal ions are commonly bound by means of “py–py” coordination,7–10 and less frequently by means of the alternative “py–pyz” coordination, as established by NMR spectroscopic data 9,11…”