Crystal and Molecular Structures of Asymmetric cis- and trans-Platinum(II/IV) Compounds and Their Reactions with DNA Fragments

Abstract

The asymmetrically substituted platinum(II) complexes cis-Pt(NH 3 )(c-C 6 H 11 NH 2 )Cl 2 and trans-Pt(NH 3 )(c-C 6 H 11 -NH 2 )Cl 2 have been synthesized and their crystal structures have been determined. Crystals of cis-Pt(NH 3 )(c-C 6 H 11 NH 2 )Cl 2 (1) are orthorhombic, space group Pbca (no. 61) with a ) 10. 1994(12), b ) 10.494(2), c ) 18.826(2) Å, Z ) 8. The structure refinement converged to R1 ) 0.0518 and wR2 ) 0.1143. Crystals of trans-Pt(NH 3 )(c-C 6 H 11 NH 2 )Cl 2 (2) are monoclinic, space group P2 1 /c (no. 14) with a ) 12.141(3), b ) 6.0965(9), c ) 19.864(3) Å, β ) 118.71(2)°, Z ) 4. The structure refinement converged to R1 ) 0.0711 and wR2 ) 0.1846. In addition, the Pt(IV) analogues with axial hydroxide ligands have been synthesized. Also the corresponding bis(carboxylato)platinum(IV) compound of formula trans,cis,cis-Pt(NH 3 )(c-C 6 H 11 NH 2 )Cl 2 (OOCCH 3 ) 2 has been obtained by conversion of the hydroxide with acetic anhydride. Reactions of these platinum complexes with 9-methylhypoxanthine and guanosine-5′-monophosphate (5′-GMP) have been studied in significant detail. The course of the reactions was followed by NMR spectroscopy, and 1 H and 195 Pt techniques were used to identify the formation of the products. It was found that the Pt(II) compounds easily react with the bases at the N7 position, whereas the Pt(IV) compounds react very slowly (for trans,cis,cis-Pt(NH 3 )(c-C 6 H 11 NH 2 )Cl 2 (OOCCH 3 ) 2 ) or not at all (for trans,trans,trans-Pt(NH 3 )(c-C 6 H 11 NH 2 )Cl 2 (OH) 2 ). Only in the presence of glutathione does a reaction of the latter with 5′-GMP takes place. In this case a major product was found to be the reduced trans-Pt(II) complex with one molecule of 5′-GMP and one molecule of S-bonded glutathione.

Synthesis and characterization of cis-[(PPh3)2Pt{9-MeAd(-H),N6N7}]X (X−= NO3, PF6): The first example of a platinum(II) complex containing the N6,N7-chelated 9-methyladenine anion

“…mass spectrometry. This binding mode of the adeninate ion has been previously described only for Mo(IV) [9], Rh(III) [10,11], Ir(III) [12] and Ru(II) [13,14] 15 N. Inverse detected spectra were obtained through heteronuclear multiple bond correlation (HMBC) experiments, using parameters similar to those previously reported [6]. ESI-MS spectra were performed with a MSD SL Trap mass spectrometer (Agilent Technologies, Palo Alto, CA, USA) operating in positive ion mode from m/z 100-2200.…”

“…The coordination mode of the NH 2 -deprotonated adenine has been studied through a multinuclear ( 1 H, 13 15 N NMR data are collected in Table 1.…”

Stereospecific and Kinetic Control over the Hydrolysis of a Sterically Hindered Platinum Picoline Anticancer Complex

“…Such intermolecular H bonds are common in chloro Pt II am(m)ine complexes. [14,15] A very weak, graphitic type of interaction between the picoline groups of neighbouring molecules of 1 may also be present. In complex 1, layers containing Cl´´´HÀN H-bonding interactions alternate with layers containing picoline groups.…”

“…Hydrolysis may be an important step in its intracellular activation and interaction with DNA. In this paper we employed [ 1 H, 15 N] 2 D NMR spectroscopy to determine the hydrolysis rates for each chloride ligand of this complex and its 3-picoline analogue 2. We also report the pK a values of the aqua and diaqua ligands as well as the X-ray crystal structures of 1 and 2.…”

Síntese e caracterização de complexos de platina(IV) com derivados N-benzilados da 1,3-propanodiamina

“…5 Acredita-se que os complexos de platina(IV) manifestem sua atividade citotóxica após serem reduzidos a análogos de platina(II) com a remoção dos ligantes axiais. [6][7][8][9][10][11][12] Se isso realmente é verdadeiro, há uma relação aparente entre os potenciais de redução dos complexos de platina(IV) e a citotoxicidade exibida por eles.…”