my professor asks for the M+ peak for a set of metal complexes, and on it he has Cu(bpy)2 + , isn't this already a M+ ion? Is this a trick question? bpy is a bipyridine ring
Technically I would think M+ ion is the Cu^2+ ion that comes from the bpy complex; i.e., if the ionization is
Cu(bpy)2^2+ ==> Cu^2+ + 2bpy
So you might expect three separate peaks but then you haven't told us that this is; i.e., infrared, mass spec, magnetic resonance, etc.
oh, this was for mass spec
The notation "M+" typically refers to the ion formed when a metal complex loses one electron. In the case of Cu(bpy)2+, the "+"" sign indicates that the complex has a positive charge, meaning it has lost an electron and is missing one negative charge.
Usually, when a professor asks for the "M+ peak," they are asking for the mass-to-charge ratio of the ion formed by removing one electron from the metal complex. In this case, since Cu(bpy)2+ already has a positive charge, it is indeed the "M+ peak" that your professor is referring to.
So, in this case, it is not a trick question. Your professor wants you to identify the "M+ peak" for Cu(bpy)2+, which corresponds to the mass-to-charge ratio of this ion. To determine the exact mass-to-charge ratio, you would typically use analytical techniques such as mass spectrometry.