Question

what is the name of the ion Ti2(CrO4)3

Answer 1

The ions are titanium(III) and chromate. What you have, however, is not two ions; rather, a compound, titanium(III) chromate

Answer 2

Are you sure it is an ion? What is the ionic charge?

There are various forms of titanium chromate.

Answer 3

As Bob notes above it is necessary to indicate the oxidation state of the titanium as it can have +2, +3 and +4 oxidation state.
If the above is a neutral compound it would be titanium (III) chromate.

If, as you indcate, it is an ion then you are missing a charge on the ion. So possibilities might be:

[Ti2(CrO4)3]2-

which could be
bis(tetraoxochromato(VI))titanium (II)

[Ti2(CrO4)3]2+

bis(tetraoxochromato(VI))titanium (IV)

I am not sure of the stability of the various chromates, but I guess this is an academic naming exercise.