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+ ). Copyright © 2008 John Wiley & Sons, Ltd.