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Irreversible Insertion of Benzonitrile into Platinum ( II ) - Nitrogen Bonds of Nucleobase Complexes. Synthesis and Structural Characterization of Stable Azametallacycle Compounds
Montagner, Diego; Venzo, Alfonso; Zangrando, Ennio; Longato, Bruno
Deprotonation of 1-methylcytosine (1-MeCy) and 9-methyladenine (9-MeAd) promoted by cis-[L2Pt(μ-OH)]2(NO3)2 (L = PPh3, PMePh2, 1/2dppe) in PhCN causes the irreversible insertion of a nitrile molecule into the Pt−N4 and Pt−N6 bonds of the cytosinate and adeninate ligands, respectively, to form the stable azametallacycle complexes cis-[L2PtNH═C(Ph){1-MeCy(−2H)}]NO3 (L = PPh3, 1; PMePh2, 2; 1/2dppe, 3) and cis-[L2PtNH═C(Ph){9-MeAd(−2H)}]NO3 (L = PPh3, 4; PMePh2, 5) containing the deprotonated form of the molecules (Z)-9-N-(1-methyl-2-oxo-2,3-dihydropyrimidin-4(1H)-ylidene)benzimidamide and (Z)-N-(9-methyl-1H-purin-6(9H)-ylidene)benzimidamide. Single-crystal X-ray analyses of 2 and 4 show the metal coordinated to the N3 cytosine site [Pt−N3 = 2.112(7) Å̊] and to the N1 site of adenine [Pt−N1 = 2.116(6) Å̊] and to the nitrogen atom of the inserted benzonitrile [Pt−N2 = 2.043(6) and 2.010(6) Å̊ in 2 and 4, respectively], with the exocyclic nucleobase amino nitrogen bound to the carbon atom of the CN group. Complex 2, in solution, undergoes a dynamic process related to a partially restricted rotation around Pt−P bonds, arising from a steric interaction of the oxygen atom of the cytosine with one ring of the phosphine ligands. The reaction of 4 with acetylacetone (Hacac) causes the quantitative protonation of the anionic ligand, affording the acetylacetonate complex cis-[(PPh3)2Pt(acac)]NO3 and the free benzimidamide NH═C(Ph){9-MeAd(−H)}. In the same experimental conditions, complex 3 reacts with Hacac only partially.
Keyword(s): Irreversible Insertion; Benzonitrile; Platinum(II)−Nitrogen Bonds; Nucleobase Complexes; Synthesis; Structural Characterization; Stable Azametallacycle Compounds
Publication Date:
2010
Type: Journal article
Peer-Reviewed: Yes
Institution: Maynooth University
Citation(s): Montagner, Diego and Venzo, Alfonso and Zangrando, Ennio and Longato, Bruno (2010) Irreversible Insertion of Benzonitrile into Platinum ( II ) - Nitrogen Bonds of Nucleobase Complexes. Synthesis and Structural Characterization of Stable Azametallacycle Compounds. Inorganic Chemistry, 49. pp. 2103-2110. ISSN 0020-1669
Publisher(s): American Chemical Society
File Format(s): other
Related Link(s): https://mural.maynoothuniversity.ie/7061/1/DM_irreversible2010.pdf
First Indexed: 2020-04-02 06:31:20 Last Updated: 2021-07-31 08:13:02