1,721,004 research outputs found
Determinazione dei siti di metallazione di nucleobasi modello in complessi fosfinici di Pt(II)
No full textSono riportate le strategie di determinazione dei siti di metallazione di nucleobasi modello in complessi fosfinici di Pt(II) basate su esperimenti 1H,15N in inverse detection
Stabilization of the iminooxo tautomer of 1-methylcytosine in PtII complexes: Role of the ancillary ligands
No full textMono- and Polynuclear Complexes of the Model Nucleobase 1-Methylcytosine. Synthesis and Characterization of cis-[(PMe2Ph)2Pt{1-MeCy(-H)}]3(NO3)3 and cis-[(PPh3)2Pt{1-MeCy}]NO3
No full textA coordination polymer formed by cis-[(PMePh2)2Pt(NO3)2] and 2,5-bis(4-pyridyl)-1,3,4-thiadiazole
No full textCoordination modes of 9-methyladenine in cis-Platinum(II) complexes with dimethylphenylphosphanes as ancillary ligands
No full textThe reaction of 9-methyladenine with cis-[L2Pt(NO3)2] in a 2:1 molar ratio, generates a bis-adduct compound that was isolated and fully characterised by 1H, 13C, 31P, 195Pt and 15N NMR spectroscopy
Role of the phosphine ligands on the stabilization of monoadducts of the model nucleobases 1-methylcytosine and 9-methylguanine in platinum(II) complexes
Full text linkThe addition of 1-methylcytosine (1-MeCy) or 9-methylguanine (9-MeGu) to solutions of cis-(PPh3)2Pt(ONO2)2 (1a), in a molar ratio of 1:1, affords the monoadducts cis-[(PPh3)2Pt(1-MeCy)(ONO2)]NO3 (2a) and cis-[(PPh3)2Pt(9-MeGu)(ONO2)]NO3 (3a) and only trace amounts of the bisadducts cis-[(PPh3)2Pt(1-MeCy)2](NO3)2 (4a) and cis-[(PPh3)2Pt(9-MeGu)2](NO3)2 (5a), respectively. The X-ray structural determination of 2a and 3a indicates a strong π−π stacking interaction between one of the PPh3 phenyl groups and the pyrimydinic N3-platinated cytosine or the imidazole part of the N7-coordinated guanine base. The addition of a further equiv of nucleobase to the monoadducts forms quantitatively the bisadducts that have been isolated as pure compounds 4a and 5a. Under the same experimental conditions, the dinitrato analogue cis-[(PMePh2)2Pt(ONO2)2] (1b) forms the monoadducts 2b and 3b in equilibrium with a relatively high concentration (20–30%) of the bisadducts cis-[(PMePh2)2Pt(1-MeCy)2](NO3)2 (4b) and cis-[(PMePh2)2Pt(9-MeGu)2](NO3)2 (5b), which have been structurally characterized by single-crystal X-ray analysis. The characterization of the isolated complexes by multinuclear NMR spectroscopy is also described
Role of the ancillary ligands on the stabilization of the imino-oxo tautomer of 1-methyl-cytosine in PtII complexes
Full text linkThe mixed nucleobases complexes cis-[L2Pt{1-MeTy(-H)}(1-MeCy,N3)]NO3 (L = PPh3, 1a; PMePh2, 1b), containing the N(3)-deprotonated 1-methylthymine (1-MeTy(-H)) and the neutral 1-methylcytosine (1-MeCy) have been prepared and characterised. The compounds were obtained by reacting the hydroxo complexes cis-[L2Pt(μ-OH)]2(NO3)2 with 1-methylthymine (1-MeTy), followed by the addition of 1 equivalent of 1-MeCy. In solution of DMSO, DMF or chlorinated solvents, 1a converts quantitatively into the isomer cis-[L2Pt{1-MeTy(-H)}(1-MeCy,N4)]NO3 (2a) containing the tautomeric form of the cytosine stabilized through the coordination at the N(4) atom, as shown by single-crystal X-ray analysis. The structural determination of 2a shows the presence in the unit cell of two crystallographic independent complexes having similar conformation, with a different orientation of the two nucleobases (head–head and head–tail) according to the presence of both isomers in solution. Complex 1b, having the less hindered PMePh2 ligands, in DMSO solution, contains the tautomeric forms of the cytosine in equilibrium and the migration of the metal from the N(3) to N(4) site occurs only to a minor extent
Reactivity of coordinated nitriles - Formation of the acetamidine complex cis-[(PMe3)(2)Pt{1-MeTyH)}{CH3C(NH)NH2}](+) from the 1-methylthyminate compound cis-[(PMe3)(2)Pt{1-MeTyH)}(CH3CN)](+) - Synthesis, characterisation, and X-ray structures
No full text1-Methylthymine (1-MeTy) reacts reversibly with the hydroxo complexes cis-[(PMe3)(2)Pt(mu -OH)](2)X-2 (X- = NO3; ClO4) in various solvents (S = CH3CN, H2O, DMSO) to give the thyminate derivatives cis-[(PMe3)(2)Pt{1-MeTy(-H)}(S)]X that have been isolated as pure compounds when S is CH3CN. The single-crystal X-ray structure of cis-[(PMe3)(2)Pt{1-MeTy(-H)}(CH3CN)]ClO4 shows that the N(3)-platinated nucleobase acts as a monodentate ligand and a molecule of CH3CN completes the coordination sphere of the metal. Crystals of the acetamidine derivative cis-[(PMe3)(2)Pt{1-MeTy(-H)}{CH3C(NH)NH2}]X were isolated from an acetonitrile solution of this complex, in the presence of small amounts of water, after several months at room temperature, separated in 5-10% yield. The X-ray analysis of the perchlorate salt shows a configuration of the amidine ligand consistent with a formal trans addition of NH3 to the CN triple bond of the coordinated nitrile. The acetamidine complex was formed in high yield (70%), in a few weeks, when aqueous solution of NH3 was added to cis-[(PMe3)(2)Pt{1-MeTy(-H)}(CH3CN)](+) dissolved in CH3CN. Side products of this reaction are the ammonia complex cis-[(PMe3)(2)Pt{1-MeTy(-H)}(NH3)](+), which was also obtained as pure compound, acetamide, and other platinum containing species. All the isolated complexes were characterised by elemental analysis, IR, and multinuclear NMR spectroscopy
Carborane reductive-elimination reaction from a six-coordinate hydridocarboranyliridium(III) complex: Kinetic and mechanistic study
No full textA kinetic and mechanistic study of the reductive-elimination reaction of the carborane 1-H-T-C6H5-1,7-C2B10H10 (H-carb) from the six-coordinate iridium(III) complex Ir(H)(Cl)(σ-carb)(CO)(PPh3)2 has been carried out in 1,2-dichloroethane by IR spectroscopy between 20 and 50°C. The mechanism of the carborane-elimination reaction implies a preliminary PPh3 dissociation to give the five-coordinate Ir(H)(Cl)(σ-carb)(CO)(PPh3) complex. This intermediate then undergoes a reductive elimination of the carborane molecule through two pathways: (i) direct elimination to give the three-coordinate iridium(I) complex, IrCl(CO)(PPh3); (ii) a phosphine-induced elimination via trans → cis isomerization of the H and carb ligands. The kinetic and thermodynamic parameters are also reported and discussed. © 1984 American Chemical Society
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