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X‐ray and Solution Structure of Inosine 5' ‐Monophosphate Coordinated to (Ethylenediamine)palladium(II). —the Importance of Intramolecular Hydrogen Bonding

1997; Wiley; Volume: 130; Issue: 10 Linguagem: Inglês

10.1002/cber.19971301032

0009-2940

Tobias Rau, Rudi van Eldik,

Metal complexes synthesis and properties

Abstract The compound [Pd(en)(5′‐IMP‐N7) 2 ].11 H 2 O, where 5′‐IMP = inosine 5′‐monophosphate, crystallizes in the tetragonal space group P4 3 22 with the unit cell parameters: a = b = 12.060(5) and c = 28.510(5) Å, V = 4147(3) Å3, Z = 4. A head‐to‐tail orientation with A configuration is observed for the nucleotides which are coordinated through the N(7) positions such that d[Pd‐N(7)] = 2.053(8) Å. The sugar moieties exhibit anti orientations toward the purine bases while their pukkers adopt C(3)′‐ endo conformation. The overall conformation about the phosphate backbone is gauche + . Intramolecular hydrogen bonding is observed between the phosphates and the NH groups of the en ligand with a donor‐acceptor distance of 2.88 Å. The coordination mode of the solid‐state structure is shown to be identical to that observed by 1 H‐NMR spectroscopy in solution under slightly acidic conditions, where the N (l) positions of the nucleotides are protonated. The results are discussed in reference to closely related systems reported in the literature with emphasis on the importance of hydrogen bonding in such complexes.