Which of the following two sentences is more correct?

Solution 1:

Neither of those sentences sounds quite right.

If I've understood correctly, perhaps something like this might be appropriate:

We've decided to appoint you, Jim, as a contact person for Sam, given that you're his department manager.

EDIT: The questioner has clarified that the context is introducing one person to another. In that case, perhaps this would be appropriate:

This is Jim, Sam's department manager. He'll be the contact for X.