Interactions of nucleosides with CrO(4) (2-) and Cr(3+) as studied by electrospray ionization mass spectrometry

The interactions of CrO(4) (2-) and Cr(3+) with nucleosides studied by electrospray ionization mass spectrometry (ESI-MS) are reported. In water, the nucleosides which do not contain the NH(2) group form the unstable M+HCrO(4)](-) anion. In the presence of a reducing agent, namely methanol, chromate anion forms stable complexes with nucleosides, M+CH(3)CrO(4)](-) anions. The fragmentation of M+CH(3)CrO(4)](-) anions involve elimination of the methanol molecule. Chromium cation-nucleoside complexes were not observed in water. In methanol solutions, adenosine and cytidine form (M-H)+CrOCH(3)](+) and (M-H)(2)+Cr](+) ions. Most probably, deprotonated imine tautomers form complexes in which a metal cation is simultaneously coordinated by two nitrogen atoms. Complexes containing chloride anions and a few methanol molecules were observed for other nucleosides. Guanosine and inosine form doubly charged ions of the type M(2)+CrOCH(3)](2+) that probably contain a bond between the oxygen atom and the chromium cation, (HN(1)--C(6)==O)(2) (....)Cr(3+)).