Symmetry and Group Theory- Point Group Tips and Practice 4

I wasn't planning to write anything today. But, I've just seen this on Inorganic Chemistry journal and
decided to do another practice.

The paper is here (DOI:  10.1021/ic401499j).

I will assume each NO3 group is a perfectly symmetric sphere for simplicity. Here we go:

Since this molecule has 3 different C2 axes perpendicular to each other, you can choose any of them. You will still find a perpendicular C2 and mirror plane (Sigma h).