Reactions of an osmium-hexahydride complex with cytosine, deoxycytidine, and cytidine: the importance of the minor tautomers.
Complex OsH(6)(P(i)Pr(3))(2) (1) deprotonates cytosine to give molecular hydrogen and the d(4)-trihydride derivative OsH(3)(cytosinate)(P(i)Pr(3))(2) (2), which in solution exists as a mixture of isomers containing κ(2)-N1,O (2a) and κ(2)-N3,O (2b) amino-oxo and κ(2)-N3,N4 (2c) imino-oxo tautomers. The major isomer 2b associates with the minor one 2c through N-H···N and N-H···O hydrogen bonds to form [2b·2c](2) dimers, which crystallize from saturated pentane solutions of 2. Complex 1 is also able to perform the double deprotonation of cytosine (cytosinate') to afford the dinuclear derivative (P(i)Pr(3))(2)H(3)Os(cytosinate')OsH(3)(P(i)Pr(3))(2) (3), where the anion is coordinated κ(2)-N1,O and κ(2)-N3,N4 to two different OsH(3)(P(i)Pr(3))(2) metal fragments. The deprotonation of deoxycytidine and cytidine leads to OsH(3)(deoxycytidinate)(P(i)Pr(3))(2) (4) and OsH(3)(cytidinate)(P(i)Pr(3))(2) (5), respectively, containing the anion κ(2)-N3,N4 coordinated. Dimer [2b·2c](2) and dinuclear complex 3 have been characterized by X-ray diffraction analysis.
Departamento de Química Inorgánica-Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain. maester@unizar.es
Miguel A
MA
Esteruelas
Jorge
J
García-Raboso
Montserrat
M
Oliván
D003596:Cytosine / Q000737:chemistry*; D003841:Deoxycytidine / Q000737:chemistry*; D007536:Isomerism; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D009992:Osmium / Q000737:chemistry*; D011522:Protons
D009942:Organometallic Compounds; D011522:Protons; D003841:Deoxycytidine; D009992:Osmium; D003596:Cytosine